Phage therapy

Definition

Phage therapy involves the use of viruses that attack bacteria to treat pathogenic bacterial infections. The advantage of such viruses, known as bacteriophages or phages, is that they selectively target and destroy certain bacteria without harming the host organism or other beneficial bacteria, such as gut flora, thereby minimising the possibility of complications. Most therapies use lytic phages, which take over the machinery of the bacterial cell and then destroy the cell.

The diagram shows how a phage infects a bacterial cell. Once a phage infects a bacterium, it takes over its cellular machinery to shut down its defence mechanism and synthesise new phage particles. The number of phage particles synthesised eventually reaches a point where they rupture the bacterial cell which allows them to be released into the environment to infect a new host.

Importance

Phage therapy is now seen as a major alternative treatment to the use of antibiotics. Spurred on by the rising incidence of antimicrobial resistance (AMR) in recent years, phage therapy is now considered an important means to treat various bacterial infections not amenable to antibiotics. With AMR predicted to cause up to 10 million deaths by 2050, far exceeding any other infections or even cancer (O’Neill), phage therapy is one of several approaches scientists are intensively exploring to treat bacterial infections. Indeed, as Table 1 shows phage therapy offers some advantages over the use of antibiotics.

Table 1. Comparison between antibiotics and phage therapy

Specificity

Antibiotics

Antibiotics target a broad spectrum of both pathogenic and harmless microorganisms. This can potentially disrupt the patient’s microflora and cause secondary infections.

Phages

Phages target very specific strains of bacteria without disrupting the microbial balance. This, though, requires the initial additional step of identification of the pathogens affecting a patient and finding a suitable phage for each infection.

Side-effect

Antibiotics

Disruption of normal microflora may allow opportunistic pathogens to cause secondary infections such as C. difficile infection.

Phages

No serious side effects have been reported. The body can typically eliminate phages within seven days of clearing an infection. This is because phages stop replicating once they have destroyed the bacteria.

Dosage

Antibiotics

Antibiotic therapy requires multiple doses because the drugs do not necessarily concentrate at the site of infection.

Phages

Phage therapy requires fewer doses because phages multiply quickly during the process of killing bacteria. This results in a high concentration of phages in the infected area that facilitates better clearance of the bacterial infection.

Resistance

Antibiotics

Antibiotic resistance is becoming more common due to the overuse of broad-spectrum antibiotics.

Phages

Phage resistance is uncommon and can be circumvented by using a cocktail of different phages.

Development

Antibiotics

Developing a new antibiotic may take several years.

Phages

Sourcing new phages can be done in a matter of days or weeks.

Treatment cost

Antibiotics

Antibiotic resistance adds $1,383 to the treatment cost on average, largely attributed to increased costs of inpatient care (Thorpe et al.).

Phages

The total cost per case range up to tens of thousands of US dollars but the cost varies depending on a country’s healthcare policy.

Approval for public use

Antibiotics

Antibiotics have their its own regulatory framework for approval and are largely available for public use.

Phages

Phage therapy is still undergoing clinical trials and is only used for compassionate treatment where all other conventional interventions have been exhausted.



Phage therapy has already been shown to be effective in animals for treating various multidrug resistant pathogens, such as Acinetobacter baumannii, Pseudomona aeruginosas, Escherichia coli and Klebsiella spp. All three pathogens are serious threats to patients in the hospital setting and to those with weakened immune systems. A. baumanii is associated with life-threatening diseases such as pneumonia (inflammation in the lungs) and meningitis (brain and spinal cord infection). P. aeruginosa is no less deadly, a frequent cause of chronic lung infections.

Just how much interest phage therapy is now generating can be seen by the amount of money currently being invested in such treatment. Armata Pharmaceuticals alone (a merger of AmpliPhi Biosciences and C3J Therapeutics) recently received over $130 million in funding towards the development of engineered phages and other antimicrobial approaches (Schmidt). In addition to corporate funding, between 2013 and 2017 the European Union invested 5 million euros in research to investigate the use of phages to prevent skin infections in burn victims (Phagoburn). Similarly, in 2018 the University of California San Diego School of Medicine awarded a three-year $1.2 million grant towards the advancement of phage therapy through the Center for Innovative Phage Applications and Therapeutics (Dall).

For more information on what phages are and how they work watch 'The Deadliest Being on Planet Earth - The Bacteriophage' by Kurzgesagt'

Discovery

The discovery of bacteriophages dates back to 1915, when Frederick William Twort, a British bacteriologist based at Brown Institution in London, experienced difficulties growing the vaccinia virus, a key component of the smallpox vaccine, on agar plates. The only thing that he could find on the plates were contaminating bacteria which soon after died. Twort noted that the death of the bacteria appeared to be linked to the presence of some sort of viral agent that, unlike bacteria, could pass through a porcelain filter. He published his findings in 1915 but was unable to take his work any further because of the First World War and financial constraints. By 1917 Félix d’Herelle, a French-Canadian microbiologist, had independently discovered what appeared to be a similar substance while working at the Pasteur Institute in Paris. He recovered it by filtering stools taken from recovering dysentery patients. Promisingly, it appeared to be capable of killing shigella bacteria. Concluding the substance to be a virus particle, d’Herelle called it a ‘bacteriophage'. Both d'Herelle and Twort are now credited with the discovery of bacteriophages.

The first medical application of phages in humans was undertaken by d’Herelle. In 1919 he administered phages to four patients at the Hospital des Enfants-Malades in Paris. They were suffering from dysentery, an intestinal infection often caused by Shigella bacteria, which can cause bloody diarrhoea, stomach cramps and a fever. D’Herelle had already demonstrated the safety of phages by administering them to himself, his coworkers and his family members. Each patient was given an oral dosage of the anti-shigella phages and quickly showed signs of recovery within a day. This was just the start of a number of experiments that d’Herelle undertook (d’Herelle).

While d’Herelle took time to publish his results, his work proved sufficiently inspiring to Richard Bruynoghe, a physician at Katholieke University Leuven, Belgium, and Joseph Maisin, his student, to try out the use of a phage to treat staphylococcal skin disease in patients. Reporting on their experiment in 1921, they found clear evidence of recovery within 48 hours after injecting an anti-staphylococcal phage into the patients’ infected areas (Wittebole, De Roock and Opal).

In 1925 d'Herelle’s treated four individuals in Egypt diagnosed with bubonic plague caused by Yersinia pestis bacteria. All four patients made a full recovery within a month after having been injected with d’Herelle’s anti-pestis phage mixture. The tale of this success caught the attention of Dr. A. Morrison, the British representative of the Quarantine Board in Egypt, who engaged d’Herelle to work with the Quarantine Board on phage therapy. By December 1926, d’Herelle had been requested to help with the Bacteriophage Inquiry set up by the Indian Office in collaboration with the Indian Research Fund Association (IRFA), several hospitals and research institutes. Begun in 1927 and completed in 1936, the Inquiry was designed to study the effect of phage therapy as a treatment for cholera, an intestinal infection that causes severe watery diarrhoea. Three studies were carried out in Kolkata and Kasauli within the first year. With all three showing promising results, phage therapy gained attention as an item of ‘particular importance’ at the 7th Congress of the Far Eastern Association of Tropical Medicine in Kolkata in 1927 (Summer, 1993).

Despite the Inquiry’s initial success, d'Herelle left it in 1927 to become a professor at Yale University. Igor Asheshov, a Yugoslavian bacteriologist, continued in his place. The Inquiry thereafter suffered a series of setbacks, hastened on by Asheshov’s shift in focus from clinical studies to basic research. To make matters worse, the IRFA cut its funds from 64,260 rupees to 8,500 rupees between 1932 and 1934. The Inquiry’s last study was completed in 1936. By this time Asheshov had managed to provide extensive classifications of different cholera phage strains and their various biological properties as well as to establish how they could be used for therapy. However, he had failed to fulfill the main object of the Inquiry which was to determine their usefulness for the treatment or prevention of cholera. His efforts in this area had been hampered by poor cooperation from both staff and patients and poor design of the trials, all of which served to undermine the end results. Increased political unrest in India in the mid-1930s further undermined the project (Summer, 1993).

The difficulties experienced during the Bacteriophage Inquiry took place against a wider controversy about the nature of phages and the immune system. Throughout the 1920s a number of hypotheses were put forward about the nature of phages. On the one side was d’Herelle who saw phages as a living parasite or virus, which after infecting bacteria went on to destroy them as part of their life-cycle. And on the other side there was Bordet, who viewed the phage as a self-perpetuating chemical enzyme produced by bacteria. Having been awarded a Nobel Prize in 1919 for his work on antibodies and immunity, Bordet’s phage theory carried far more weight in the scientific community than that of d'Herelle who then lacked any real institutional base.

Initially, scientists had very little understanding of how phages destroyed bacteria. Most observations in the early 1920s were confined to lytic phages, a strain that triggers the disintegration of the bacteria’s cell membrane, a process known as lysis. The lytic phage does this following its replication within the bacteria’s cells. This process is known as the lytic cycle. Another pattern, called the lysogenic cycle, was discovered in 1925 by Bordet and colleagues in another type of phages known as the temperate phage. In this situation the phage injects its DNA into a bacterial cell where it integrates into the host’s genome and becomes what is known as the prophage. This prophage will continue to replicate alongside the host genome without causing any harm unless the host conditions become unfavourable, in which case the prophage may initiate the lytic cycle.

Despite the advances in understanding how phages worked, arguments raged over their efficacy as treatment. This surfaced strongly in 1934 and 1940 when the American Medical Association (AMA), the largest association of physicians in the United States, issued two reports on phage therapy. What troubled the AMA in particular was the experimental design used by d’Herelle and others to test out the therapy because they had failed to include any reliable control groups in clinical trials.

While criticism of the efficacy of phage therapy continued to rumble on, it soon became clear that d’Herelle’s vision of phages as viruses held true. This was prompted by the availability of the first electron microscope image of a phage in 1940. Acceptance of phages as viruses, however, took time to materialise. In part this was because World War II prevented the widespread distribution of the new electron microscope image. Strikingly, the AMA only acknowledged d’Herelle’s concept of a phage as a virus in its third report, issued in 1945 (Morton, Engley). By the time the first electron microscope images of a phage had been produced, a number of steps had been taken to commercialise phage therapy. Amongst those leading this effort was d’Herelle, who in 1928 gained a position at Yale University. By the early 1930s d’Herelle had founded his own commercial laboratory, Laboratoire du Bacteriophage, in Paris, where he produced the first commercial phage preparations against various bacteria that cause diarrheal and upper respiratory infections. The preparations were marketed by Robert et Carriere, a French company later acquired by L’Oreal (Pirnay et al. 2012). Major companies such as Parke Davis, E.R. Squibb and Sons, Swan-Myers and Eli Lilly in the US and Western Europe soon followed suit by developing their own anti-staphylococcus phage therapies. Such products were directed toward treating various infections, including abscesses, festering wounds, upper respiratory tract infections and mastoid infections (Sherman).

Despite the initial commercial enthusiasm for phage therapy, the approach was largely abandoned in North America and Western Europe by the 1940s. In part this was due to the arrival of antibiotics. The spread of phage therapy was also hindered by a lack of convincing clinical data. Poor understanding of the biology of phages and phage-host specificity all contributed to poor results collected in many trials run up to this time. Added to this was the difficulty of securing standardised therapies. Characterisation of the preparations was also poor. Most were characterised as either strong or weak, depending on how completely they could clear an infection. Many were in fact subsequently found to be inactive. Varying instructions were also given as to how the treatment was to be given. All these factors made it difficult to accurately assess the efficacy of products in clinical trials (Summers 2001).

The one place where the idea of phage therapy was kept alive was in the Soviet Union, helped in part by d’Herelle who in 1933 took up a visiting post at Eliava Institute of Bacteriophages, Microbiology and Virology. D’Herelle moved to the Institute, in Georgia, following a dispute with Yale University over his funding and research plans. Founded in 1923 by George Eliava, one of d’Herelle’s protegees, the Institute had a strong partnership with the Kharkov Mechnikov Institute, a Ukranian institution founded in 1886 to combat infectious diseases among soldiers. The two institutes joined together in 1934 to advance the development of phage therapy, and in 1936 received support from the Communist Party to begin construction of a new research institute and accommodation for both d’Herelle and Eliava. The Georgian Institute, however, suffered a major blow during the Great Terror in Soviet Union between 1936 and 1938, which saw d’Herelle return to Paris and Eliava being executed on the drummed up charges of espionage for France, sabotaging vaccines and poisoning drinking wells with bacteriophages.

Despite the setback, the new research institute was built and merged with the Research Institute of Microbiology, Epidemiology and Bacteriophage in 1939, known as the Tbilisi Institute of Microbiology, Epidemiology, and Bacteriophage (IMEB). Several phage therapy research programmes were launched through the IMEB, financed by the Soviet state and led by Alexander Tsulukidze, who had worked closely with Eliava and d’Herelle, and Elena Makashvili, a long-standing assistant of Eliava. The scientists soon developed methods for the mass production of phage therapies, including for the treatment of cholera, dysentery and typhoid.

Astoundingly, in 1942, the Soviet microbiologist, Zinaida Ermol’eva, managed to set up her own production of cholera and dysentery phages in the midst of the prolonged siege of Leningrad which saw many people struck down with such enteric diseases. Despite some diversion of funding into antibiotics after the Second World War, Georgia remained an important centre for phage therapy into the 1950s (Myelnikov). Phages continued to be routinely used for the treatment of several bacterial pathogens in Soviet Union and other parts of Eastern Europe as a cheaper alternative to antibiotics throughout the latter half of the 20th century. Just how widespread it became can be seen by the fact to this day Russians and Georgians can buy over-the-counter phage remedies to treat upset stomachs, urinary tract infections and many other disorders. In some clinical trials phage therapy have proven effective in treating patients previously not responsive to antibiotics (Sulakvelidze, Alavidze; Sachs; Myelnikov).

Attitudes towards phage therapy began to change in the West by the 1980s as a result of the rising threat of antibiotic resistance. One of the first to pursue phage therapy in the West was Herbert Williams Smith, a British veterinarian and experimental scientist at the Institute for Animal Disease Research in Houghton, Cambridgeshire. From the 1950s he began to investigate the rise of AMR in livestock which he concluded was caused by the overuse of antibiotics both as food additives to promote growth and as a preventative against infection. Familiar with d’Herelle’s work, Smith was convinced that the failure to demonstrate the therapy’s success was because the wrong methods had been used in the past (Datta). In 1981, together with Mike B. Huggins, Smith launched a series of experiments in different animals to explore the possibility of phage therapy. The animals were infected with diarrhoea-causing E.coli and successfully treated via intramuscular injection or oral administration of a phage mixture. Their work not only dispelled the stigma of the inconsistency of phage therapy, but also demonstrated phages to be potentially more effective than antibiotics. On publishing the results, Smith pointed out that one advantage that phages had over antibiotics was that once introduced they multiplied so continuous dosage was not necessary (Smith, Huggins 1982, 1983, 1987; Datta).

The success of Smith and his colleagues with phage therapy was soon repeated by other researchers in other animals. This work helped to rekindle interest in testing out phage therapy in the West to treat bacterial infections in humans. One of the key figures behind its promotion was Alexander Sulakvelidze, a Georgian molecular biologist trained at Tbilisi State Medical University, who took up a postdoctoral research fellowship with Glenn Morris, an American epidemiologist, at the University of Maryland Medical Center in 1993. Arriving just at the moment when Morris was struggling to contain an outbreak of vancomycin-resistant enterococcus which was causing the death of many patients, Sulakvelidze suggested, based on the routine use of phage therapy in Georgia, that a solution might lie in phage therapy. Within three years the two scientists had managed to isolate ideal phages for such purposes, sourced from the Baltimore Inner Harbour, and had formed an ongoing research partnership with the Eliava Institute. They also set up a new company, Intralytic, in 1998, which began developing phage-based products for use in livestock. The company won FDA approval for its first phage product, ListShield, in 2006, a food additive that targets listeria in meat and later in 2011, for its second product EcoShield, which targets E. coli O157:H7 (Sachs; Martin; Lang).

Application

For every strain of bacteria, there exists several of phages that can kill it. One of the biggest challenges is to find the right phage strain for treatment. Luckily, phages can be found wherever bacteria exist, including in the soil, rivers, plants and animals. When isolated from the environment, the phages are tested against common antibiotic-resistant pathogens. This typically involves infecting a bacteria culture with the isolated phages. Phages that are capable of lysing the bacteria culture are recovered and purified. Several strains of phages are often administered together in the form of a cocktail. This method provides a means to compensate for the high specificity of each strain. Most cocktails tested in clinical trials consist of at least three phages with overlapping host strains.

Efforts are also now underway to genetically engineer phages to enhance the bacterial killing capacity of antibiotics. In 2009 Lu and Collins demonstrated that it was possible to genetically modify phages to suppress the SOS DNA repair system bacteria use to ward off the effects of antibiotics. Such a method could pave the way to the use of phages in combination with antibiotics. The phage engineered by Lu and Collins, for example, helped increase the bactericidal effect of the antibiotic ofloxacin.

Numerous clinical trials are now being conducted to test out phage therapy in humans. In 2009 the FDA approved the first phase I clinical trial to assess a cocktail of eight phages to treat venous leg ulcers in humans. The phage mixtures were demonstrated to have no adverse effects in 42 patients (Potera; Rhoads et al.). In the same year, the UK also held its first phase II phage clinical trial to assess the efficacy of phages against chronic otitis, an ear infection caused by an antibiotic-resistant P. aeruginosa. The phage treated group of participants received a combination of up to six phages who had a significantly lower bacterial count after 42 days (Wright et al.).

Phage therapy is also being explored for the treatment of milder diseases such as acne. While seemingly harmless, up to 60 per cent of Propionibacterium acnes are antibiotic-resistant and can be a persistent cause of discomfort. In 2012 a team of dermatologists at the University of California identified a variety of phages effective against a broad range of antibiotic-resistant P. acnes. This study, however, discovered that the bacteria causing the acne soon developed resistance to the phage therapy. Such resistance was due to the presence of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR), an immune mechanism that bacteria use to cleave any foreign DNA. Coincidentally, the phages used in this study contained a DNA sequence recognised by the P. acnes’ CRISPR system, resulting in phage DNA being cleaved and inactivated upon entry into the cell. This resistance, however, was circumvented by genetically engineering phages to remove the recognised DNA sequence (Marinelli et al. 2012).

Although phage therapy has yet to receive regulatory approval to treat humans in the European Union and the United States, it can be used in these regions for compassionate treatment where all other conventional interventions have been exhausted. There have been 29 reports of compassionate use of phage therapy since 2000, half of which were published between 2017 and 2019. The therapy has been most frequently used to treat patients with S. aureus infections, followed by P. aeruginosa and E. coli. One of the best known cases is that of the 68-year-old diabetic, Tom Patterson, who in 2017 was suffering from necrotising pancreatitis, an extreme case of inflammation of the pancreas. His condition was caused by a multidrug resistant A. baumannii infection with no effective antibiotic treatment available. Patterson was successfully treated with a combination of phages contributed by various research institutes across the US and Patterson (Schooley et al.; McCallin et al.).

Beyond treating bacterial infections, the high specificity of phages allows for them to be harnessed as tools for cancer therapy. Although phages only normally target bacteria, Przystal et al. for example, have demonstrated that the M13 phage can be modified to specifically bind to human tumour cell receptors. They also incorporated an adeno-associated virus genome into the phage, a therapeutic gene which triggers cell death upon activation within tumour cells. A combination of modified M13 phages and the conventional chemotherapy drug temozolomide have shown significant improvement in suppressing growth of glioblastoma, the deadliest form of brain tumours with only 2 per cent 5-year survival rate.

In addition to their therapeutic applications, a phage’s ability to home in on specific bacteria is a useful characteristic for diagnosis. One example is that of fluorophages. These are phages that have been genetically engineered to carry a fluorescent protein that glows when they infect their target bacteria. In 2012 a team led by Jain used such phages to target Mycobacterium tuberculosis, the cause of tuberculosis (TB). The fluorophage allows for the detection of TB in less than a day, in contrast to the conventional cell culture tests that can take up to two months (Jain et al.).

Issues

Although phage therapy has been around for nearly a century, phage therapy has yet to obtain regulatory approval in the US and Europe. Part of the problem stems from the fact that phage therapy does not mimic conventional industrially-made pharmaceutical products. The very fact that phages can self-replicate in the body makes the therapy very different from other drugs like antibiotics where its concentration in the body diminishes over time. Moreover, phages are highly specific and often administered in the form of a cocktail to cover a wide range of target strains. The use of several phages at once makes it difficult to monitor their replication in the body, which is the indication that the phages are working. Just how difficult it can be to get an approval was emphasised by James Soothill, a consultant microbiologist at Great Ormond Street Hospital who in May 2019 reported the successful use of phage therapy to treat a 15-year old cystic fibrosis patient who acquired a Mycobacterium infection after having a double-lung transplant (LeMieux). He suggests that individual patients should be initially treated with low doses to allow phages to be counted. This may provide useful and perhaps the only evidence of phage’s efficacy in individual monitored treatments, where scientists cannot make the comparison between the treated and placebo groups like in clinical trials. The establishment of phage therapy organisations in possession of well-characterised phages that could oversee the entire process would be valuable. This would facilitate monitored treatments where low doses of specific phages could be administered and evidence of multiplication sought (Interview with Soothill).

Preparation of a phage cocktail is no easy feat either. In some cases the phages need to be shipped, which poses biosafety questions. Regulation of their production is also challenging, as they are usually prepared outside of a pharmaceutical company setting (Fauconnier). Belgium is currently pioneering a pragmatic framework for phage therapy that allows phages to be used in magistral preparations as long as they are prepared by a certified Belgian Approved Laboratory. A magistral preparation is defined as ‘any medicinal product prepared in a pharmacy in accordance with a medical prescription for an individual patient.’ This provides a means for doctors to prescribe personalised treatment using unapproved ingredients. As of 2018 such magistral preparations could only be used to treat patients in Belgium, but other countries might adopt a similar scheme in the near future. A possible pitfall in Belgium’s strategy is that phage therapies are not currently eligible for reimbursement and therein lies another major challenge in developing phage therapy (Pirnay et al. 2018).

Development of phage therapy is expensive due to the cost of identifying suitable phages and purifying phage preparations. Purification is essential to its safety. The process removes any endotoxins released by bacteria upon lysis. Such endotoxins can trigger inflammatory responses in patients. Moreover, as is the case in the development of other drugs, phage therapies need to be produced in certified laboratories to ensure appropriate quality control and that they are safe for human use. All of this adds to the cost of phage therapy. Most treatments are also highly individualised for each patient who require a lot of monitoring during treatment. The total cost of such care can run up to tens of thousands of US dollars. In some places like the US, France and Australia, patients can get treatment free of charge based on compassionate grounds (McCallin et al.).

Difficulties in securing intellectual property (IP) protection further discourages entrepreneurs from investing in phage therapy. Patent law varies between different countries. For example, patenting a phage product in the UK mainly requires the invention to have a specific novel inventive step. This was achieved by Martha Clokie (2019), a researcher at University of Leicester who patented therapeutic bacteriophages to treat Clostridium difficile in August 2013 based on the fact it was counterintuitive to isolate a particular combination of phages in the environment that would target clinically relevant strains (JUSTIA Patent). In the US however, it is harder to patent natural products (Pirnay et al. 2012), however her patent has also been granted there.

As in the case of antibiotics, bacteria can develop resistance to phage therapy. Good stewardship in the development and handling of phage therapy is therefore important. Such resistance needs to be taken into account to design the best possible phage combinations to reduce the extent of this problem (Clokie). Yet bacterial resistance to phages is less of a problem than with antibiotics. Firstly, phages outnumber bacteria ten-fold and have enormous diversity. Secondly, the development of resistance to phages can reduce the virulence of the bacteria towards their host as well as lower their growth rate, shorten their life-span, and reduce their ability to attach to or invade the mammalian cell. Lastly, it is possible to genetically modify phages to make the evolution of such resistance harder. For example, phages can be engineered to carry plasmids, a small circular strand of DNA, designed to inhibit the action of a bacterial defense mechanism, such as the CRISPR system which aims to cleave phage DNA (Roach, Debarbieux).

While genetically engineered phages have gained traction in recent years, they have their own problems. Firstly, as with most genetically modified products, the release of engineered phages into the environment could have unforeseen negative consequences on the dynamics and ecosystem of the bacterial community (Nair, Khairnar). Some of the technical challenges were also highlighted by Antonia Sagona, a researcher at Warwick University involved in the engineering of K1F fluorescent phages. Among the difficulties she encountered was that most engineered phages are unstable and tend to ‘to mutate back to the wild type’. Such phages also have short shelf lives (Interview with Sagona). This will pose problems for manufacturers should phage products become commercially available in the future. Another concern was raised by Clokie regarding the regulation of such products. Regulating naturally-occurring phages is complex to begin with and this becomes more so for genetically modified products (Clokie). One approach to making mutants in a way that is more compatible with the current regulatory systems is through the use of techniques such as Bacteriophage Recombineering of Electroporated DNA (BRED) system (Marinelli et al. 2008). The BRED system makes it possible to delete a region of the phage DNA without introducing any marker genes. Interestingly, such mutants are not always classified as genetically modified. It was this method that Hatfull’s team used to develop a lytic derivative of a temperate phage to treat their patient with cystic fibrosis (Dedrick et al.).

This piece was written in November 2019 by Lara Marks and Jakrin Bamrungthai with generous input from Martha Clokie, Antonia Sagona and James Soothill.

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A. Sagona, Unpublished notes from an interview with Sagona by Jakrin Bamrungthai, October 2019.

C. Schmidt, 'Phage therapy’s latest makeover', Nature Biotechnology, 37 (2019), 581-586

R.T. Schooley, B. Biswas, J.J. Gill, et al, 'Development and use of personalized bacteriophage-based therapeutic cocktails to treat a patient with a disseminated resistant Acinetobacter Baumannii infection', Antimicrobial Agents and Chemotherapy, 61/10 (2017).

M. Sherman, 'Bacteriophage: Beyond antibiotics', US Pharm, 33/10 (2008), 46-51.

H.W. Smith, M.B. Huggins, ‘Successful treatment of experimental Escherichia coli infections in mice using phages: Its general superiority over antibiotics’, J. Gen. Microbiol., 128 (1982), 307–318.

H.W. Smith, M.B. Huggins, ‘Effectiveness of phages in treating experimental E. coli diarrhoea in calves, piglets and lambs’, J. Gen. Microbiol., 129 (1983), 2659–2675.

H.W. Smith, M.B. Huggins, ‘The control of experimental E. coli diarrhea in calves by means of bacteriophage’, J. Gen. Microbiol., 133 (1987), 1111–1126.

J. Soothill, Unpublished notes from an interview with Soothill by Jakrin Bamrungthai, October 2019.

A. Sulakvelidze, Z. Alavidze, ‘Minireview: Bacteriophage therapy’, Antimicrobial agents and chemotherapy, 45/3 (2001), 649-59.

W.C. Summers, ‘Cholera and plague in India: The Bacteriophage Inquiry of 1927–1936’, Journal of the History of Medicine and Allied Sciences, 48/3 (1993), 275–301.

W.C. Summers, ‘Bacteriophage therapy’, Annual Review of Microbiology, 55 (2001), 437-51.

K.E. Thorpe, P. Joski, K.J. Johnst, ‘Antibiotic-Resistant Infection Treatment Costs Have Doubled Since 2002, Now Exceeding $2 Billion Annually’, Health Affairs, 37(4) (2018).

F.W. Twort, 'An investigation on the nature of ultra-microscopic viruses by Twort FW, L.R.C.P. Lond., M.R.C.S. (from the Laboratories of the Brown Institution, London)', Bacteriophage, 1/3 (2011), 127-129.

X. Wittebole, S. De Roock, S.M. Opal, 'A historical overview of bacteriophage therapy as an alternative to antibiotics for the treatment of bacterial pathogens', Virulence, 5/1 (2014), 226-235.

A. Wright, C.H. Hawkins, E.E. Anggard, D.R. Harper, 'A controlled clinical trial of a therapeutic bacteriophage preparation in chronic otitis due to antibiotic-resistant pseudomonas aeruginosa; a preliminary report of efficacy', Clinical Otolaryngology, 34/4 (2009), 349-57.

Phage therapy: timeline of key events

d'Herelle was a microbiologist who co-discovered bacteriophages (phages), viruses that infect bacteria that are now major tools in biotechnology. He isolated the first phage from chicken faeces in 1919. Following this he successfully treated chicken affected by a plague of typhus with the phage and in August 1919 cured a patient with dysentery using the same method. This laid the basis for the development of phage therapy. 1873-04-25T00:00:00+0000Twort was a bacteriologist who in 1915 discovered the first virus (bacteriophage) that infects bacteria. He found the virus after experiencing difficulties growing the varrina virus, a key component of the smallpox vaccine, on agar plates. Unable to take his work further because of the war, Twort's discovery was largely ignored at the time. Today bacteriophages are a vital tool in biotechnology and underpin the development of phage therapy, a treatment gaining popularity for the treatment of bacterial infections. 1877-10-22T00:00:00+0000Bacteriophages, also called phages, are a group of viruses that infect bacteria. It was first observed by the English bacteriologist Frederick Twort who published his finding in 'An Investigation on the Nature of Ultra-Microscopic Viruses', The Lancet. 186/4814 (1915), 1241–43, doi:10.1016/S0140-6736(01)20383-3. Twort's finding was initially ignored until after Félix d'Herelle independently also noted phages in 1917. Phages are now an important tool in molecular biology. 1915-12-04T00:00:00+0000Frederick W Twort, an English bacteriologist, noticed a filterable transparent material that could entirely break down bacteria when trying to grow the vaccina virus. F.W. Twort, 'An investigation on the nature of ultra-microscopic viruses', The Lancet, 2 (1915), 1241-3). Financial difficulties and war prevented Twort from pursuing the matter further.1915-12-04T00:00:00+0000The term was coined by Felix d'Herelle, a French-Canadian microbiologist, after he noticed anti-Shigella microbes in the filtrate of dysentery fluids taken from patients recovering from shigellosis F. d'Herelle, 'Sur un microbe invisible antagoniste des bacilles dysentériques', Comptes rendus de l'Académie des Sciences', 165 (1917), 373-5.1917-09-10T00:00:00+0000D’Herelle treated four patients (three of whom were brothers, aged 3, 7, 12) who suffered from severe dysentery in Paris under the clinical supervision of Victor-Henri Hutinel. This study was published later in 1931.1919-01-01T00:00:00+0000Winner of the Nobel Prize for his work on immunity, Bordet believed phages were a lytic enzyme.1919-01-01T00:00:00+0000George Eliava learnt about bacteriophage from d'Herelle and became fascinated with the idea while he was working at the Pasteur Institute in the late 1910s. He founded the Eliava Institute in Tbilisi to further study phage therapy.1923-01-01T00:00:00+0000Jules Bordet and Oskar Bail showed phages to have two reproductive patterns: the lysogenic and lytic cycles. In the case of lysogeny, the phage's nucleic acid is inserted into the bacterial host's genome. The inserted phage's DNA, called a prophage, then gets replicated alongside the host's normal reproduction cycle. By contrast in the lytic cycle the the virus replicates separately from the host bacterial DNA and eventually triggers a cell lysis to release its progeny. O. Bail, Med. Klin. (Munich) 21 (1925), 1271–73; J. Bordet, Ann. Inst. Pasteur, 39 (2005), 711–63.1925-01-01T00:00:00+0000D'Herelle treated four Egyptian patients in Alexandira suffering from Y.pestis infections. He developed the treatment based on a highly virulent anti-plague phage that been isolated from rat faeces in Indo-China in 1920. The patients made a full recovery after a month. 1925-01-01T00:00:00+0000D'Herelle supplied some plague phages to Haffking Institute in Bombay, India. The phages initially did not work because they could not be grown in the usual growth medium, made from a digest of macerated pigs, which offended both Muslim and Hindus. D'Herelle took unpaid leave to resolve the issue. He managed to cultivate the phages by using goat tissue, dissolved it in papaya juice. This provided a stock of active anti-plague phages for treating patients. 1926-01-01T00:00:00+0000The Inquiry was organised by the government of British India, the Indian Research Fund Association, several hospitals and research institutes.1927-01-01T00:00:00+0000Conducted by the Bacteriophage Inquiry, the study compared treatment with a control group which included patients who refused treatment. Overall the mortality rate of the untreated group was 62% compared to the phage treated group which was 8%. 1927-07-01T00:00:00+0000D'Herelle took up a position at Yale University.1927-08-01T00:00:00+0000The work was undertaken by d'Herelle, Reginald Malone and Dr. M.N. Lahiri under the umbrella of the Bacteriophage Inquiry. Results from the study was reported in the Indian Medical Gazette in November 1927. 1927-11-01T00:00:00+0000Carried out by J. Morison from King Edward VII Pasteur Institute, India, under the auspices of the Bacteriophage Inquiry, the study suffered from poor staff cooperation.1928-01-01T00:00:00+0000"Eugene Wollman put forward the theory that bacteriophages could transmit certain traits like lysis genetically to their descendents. E. Wollman, ‘Bacteriophage et processus similaire: Hérédité ou Infection?’ Bulletin Institute Pasteur, Paris, 26 (1928), 1-14. "1928-01-01T00:00:00+0000Carried out on behalf of the Bacteriophage Inquiry, two of the studies showed positive results, but a study in Puri Cholera Hospital proved disappointing. This was attributed to poor staff cooperation, compliance and inaccurate diagnoses.1928-08-01T00:00:00+0000Moisei Mel'nyk and his colleagues initiated a programme of testing phages to treat dysentery in Alchevsk, Rykovo, and Krasnyi Luch hospitals in Stalino (now known as Donetsk). The team made regular expeditions to the Donbass region where they found frequent outbreaks of scarlet fever, typhoid and dysentery. Anti-Shigella bacteriophages were isolated from local waters. The programme involved a total of 282 treated patients with 1059 untreated controls. Mortality was halved in phage patients and their recovery was much quicker.'1929-01-01T00:00:00+0000Asheshov's change in direction resulted in his grant funds being cut from 64,260 to 8,500 rupees.1929-01-01T00:00:00+0000D’Herelle used the Parisian courts to force the editor of the Annals of the Pasteur Institute to publish his challenge to Bordet to a scientific duel. Most textbooks at the time sided with Bordet.1931-01-01T00:00:00+0000D'Herelle summarised all of the experiments he had so far carried out with phage therapy. Most of them had shown positive results. His paper, however, mostly cited facts without elaborating on each experiment. The methods of administration varied from case to case. F. D’Herelle, ‘Bacteriophage as a treatment in acute medical and surgical infections’, Bulletin New York Academy of Medicine, 7 (1931), 329-48.1931-05-01T00:00:00+0000The Indian Research Fund Association concluded the Inquiry failed to provide conclusive evidence about the effectiveness of phage therapy for cholera due to the unreliable data obtained under field conditions. 1933-01-01T00:00:00+0000Using serological methods, Frank Macfarlane Burnet showed the existence of different species of phages and that they could be distinguished with regard to the range of bacteria species that they lysed. F.M. Burnet, ’The classification of coli-dysentery bacteriophages. III. A correlation of the serological classification with certain biochemical tests’, Journal of Pathology & Bacteriology, 37/2 (1933), 179–84. 1933-01-01T00:00:00+0000After conflicts over his research directions and money, d’Herelle left his position at Yale University and went to work at the Eliava Institute of Bacteriophages, Microbiology and Virology in Georgia.1933-01-01T00:00:00+0000The report was highly critical of phage therapy because of the poor experimental designs d'Herelle had used to test it out. M.D. Eaton, S Bayne-Jones, ‘Bacteriophage therapy: review of the principles and results of the use of bacteriophage in the treatment of infections’, JAMA, 10323 (1934), 1769–76.1934-01-01T00:00:00+00001934-01-01T00:00:00+00001935-01-01T00:00:00+00001936-01-01T00:00:00+0000Increasing political unrest in India and various difficulties in administering field studies and a sanitary reform, which promised to reduce cholera, contributed to the closing of the Inquiry.1936-01-01T00:00:00+0000Eliava was executed on the pretext of anti-Soviet activities during the Great Terror including spying for France, sabotaging vaccines and poisoning wells with bacteriophages. Much speculation exists about the motivation behind his arrest, including a feud with Lavrenti Beria, chief of the secret police, for competing for a woman. Eliava's name was erased from most records, including his own research institute. His name only resurfaced in the late 1960s.1937-07-10T00:00:00+0000The therapy was administered to the local population and phages were also put into wells and ponds. 1938-01-01T00:00:00+0000The new combined institute,, aka Tbilisi Institute, opened in 1939.1938-01-01T00:00:00+0000A team of 11 people, including surgeons, bacteriologists and laboratory assistants, deployed a phage therapy developed at the Tbilsi Institute to treat the soldiers. They found that the treatment worked best when given within the first few hours of the wound getting infected. Elimination of the infection with phages enabled surgeons to suture the wound a week later. 1939-01-01T00:00:00+00001939-01-01T00:00:00+0000Ernst Ruska produced the first electron micrograph of a phage in pre-war Germany. It was first published in H. Ruska, 'Uber die Sichtbarmachung der bakteriophagen Lyse im Ubermikroskop', Naturwissenschaften, 28 (1940), 45-6. World War II delayed the distribution of Ruska's phage image. 1940-01-01T00:00:00+0000More than 200,000 litres of phage therapies were produced to treat purulent infections and gangrene.1941-01-01T00:00:00+0000The second AMA report supported Bordet’s concept of phage as an auto-catalytically activated lytic principle. It stated phage 'is a protein of high molecular weight and appears to be formed from a precursor originating within the bacterium'. AP Krueger, EJ Scribner, 'The Bacteriophage', JAMA, 116 (1941), 2160-7, 2269-77.1941-05-10T00:00:00+00001941-06-22T00:00:00+0000Zanida Ermolieve from the Institute of Experimental Medicine established a secret underground laboratory in besieged Leningrad to produce cholera phage therapy. The treatment was given to nearly 50,000 people every day. 1942-01-01T00:00:00+0000The AMA fully accepted d’Herelle’s concept of phage as a virus based on electron micron image. H.E. Morton, FB Engley, 'Dysentery Bacteriophage', JAMA , 127 (1945), 584-91.1945-01-01T00:00:00+0000Twort was an English bacteriologist who in 1915 discovered the first virus (bacteriophage) that infects bacteria. He found the virus after experiencing difficulties growing the varrina virus, a key component of the smallpox vaccine, on agar plates. Unable to take his work further because of the war, Twort's discovery was largely ignored at the time. Today bacteriophages are a vital tool in biotechnology and underpin the development of phage therapy, a treatment gaining popularity for the treatment of bacterial infections.1950-03-20T00:00:00+0000Founded by Professor Ludwik Hirszfeld, the institute focuses on the isolation, characterization and human application of phages. Between 1981 and 1999, they cured approximately 2000 people with phages, mostly after the failure of antibiotics. The institute has developed phages for the treatment of Shigella, septicemia, furunculosis and pulmonary and urinary tract infections.1952-01-01T00:00:00+0000The study involved 30,769 children (six months – seven years old), with 17,044 of them being treated once a week with oral anti-shigella phages, and the remainder being given a placebo. Those who received the therapy experienced a decrease in dysentery over those given the placebo (From 6.7 to 1.8 incidence per 1000). EG Babalova, KT Katsitadze, LA Sakvaredidze, et al. 'Preventive value of dried dysentery bacteriophage', Zh Mikrobiol Epidemiol Immunobiol, 2(1968), 143–45 (in Russian).1963-01-01T00:00:00+0000The treatment was given to mice, calves, piglets and lambs infected with diarrhoea-causing E.coli. The phage mixture was given either by an intramuscular injection or oral administration. HW Smith, M.B Huggins, Journal General Microbiology, 128 (1982), 307-18; HW Smith, M.B Huggins, Journal General Microbiology, 129 (1983), 2659-75; H.W. Smith, M.B Huggins, Journal General Microbiology, 133 (1987), 1111-26; HW Smith, M.B Huggins, KM Shaw, Journal General Microbiology, 133 (1987), 1127-35.1982-01-01T00:00:00+0000J.S. Soothill, J.C. Lawrence, G.A.J. Ayliffe, 'The efficacy of phages in the prevention of the destruction of pig skin in vitro by Pseudomonas aeruginosa', Medical Science Research, 16 (1988), 1287–88; JS Soothill, 'Treatment of experimental infections of mice by bacteriophage. Journal Medical Microbiology, 37 (1992), 258–61; JS Soothill, 'Bacteriophage prevents destruction of skin grafts by P. aeruginosa', Burns, 20 (1994), 209–11. 1988-01-01T00:00:00+0000Alexander Sulakvelidze and J. Glenn Morris formed a company, Intralytix, in order to license phage treatment for Vancomycin-resistant Enterococcus. However, they could not get an approval due to the strict criteria of clinical trials and the huge uncertainty over phage therapy.1998-01-01T00:00:00+0000Different life cycles of phages; lytic, lysogenic, chronic infection (lysogenic that mutated and lost lytic property, becoming permanent prophage) and pseudo lysogenic (stalled development with no lysis or multiplication similar to lysogenic cycles) published in MG Weinbauer, 'Ecology of prokaryotic viruses', FEMS Microbiology Review, 28 (2004), 127-81.2004-01-01T00:00:00+0000Organised by the American Society for Microbiology, the summit was the first major international gathering devoted to phage biology with over 350 conferees from 24 countries.2004-08-01T00:00:00+0000Intralytix won FDA approval for its first phage product ListShield (formerly known as LMP-102), a food additive that targets Listeria monocytogenes in meat. The preparation is made from 6 different phages to be used in poultry products as an antimicrobial agent against Listeria. Listeriosis can cause life-threatening diseases such as sepsis and meningitis. L.H. Lang, 'FDA approves use of bacteriophages to be added to meat and poultry products', Gastroenterology, 131/5 (2006), 1370.2006-01-01T00:00:00+0000The clinical trial evaluated the safety of phage therapy to treat chronic venous leg ulcers infected with S.aureus and P. aeruginosa. The phages were administered topically and recorded to have no difference in frequency of adverse effects. D.D. Rhoads et al, 'Bacteriophage therapy of venous leg ulcers in humans: Results of a phase I safety trial', Journal Wound Care, 18 (2009), 237-8, 240-3.2009-01-01T00:00:00+0000The first controlled clinical trial of a therapeutic phage preparation showed efficacy and safety in the treatment of a chronic otitis, caused by an antibiotic-resistant P.aeruginosa. 12 out of 24 patients were randomly selected for treatment with a combination of one or more of the six phages present in Biophage-PA. The phage treated group had a significantly lower bacterial count after 42 days. A. Wright, C.H. Hawkins, E.E. Anggard, D.R. Harper, 'A controlled clinical trial of a therapeutic bacteriophage preparation in chronic otitis due to antibiotic-resistant pseudomonas aeruginosa; a preliminary report of efficacy', Clinical Otolaryngology, 34/4 (2009), 349-57.2009-01-01T00:00:00+0000Intralytix developed the 'ShigaShield' phage cocktail after failing to secure a license for a phage cocktail for human therapy. The cocktail is active against S. flexneri, S. sonnei and S. dysenteriae, bacteria linked to food poisoning. 2016-01-01T00:00:00+0000AmpliPhi Biosciences, now incorporated into a joint company, Armata, announced the dosing of the first patient in phase 1 clinical trial of AB-SA01.2016-01-01T00:00:00+0000The patient, Tom Patterson, was successfully given intravenous bacteriophage therapy to treat his necrotizing pancreatitis which had the complication of a multidrug resistant A. baumannii infection for which there was no effective antibiotic treatment. R.T. Schooley, B. Biswas, J.J. Gill, et al, 'Development and use of personalized bacteriophage-based therapeutic cocktails to treat a patient with a disseminated resistant A. Baumannii infection'. Antimicrobial Agents and Chemotherapy 61/10 (2017).2017-10-01T00:00:00+0000
Date Event People Places
25 Apr 1873Felix d'Herelle was born in Montreal, Canadad'HerellePasteur Institute
22 Oct 1877Frederick W Twort was born in Camberley, Surrey, United KingdomTwortBrown Animal Sanatory Institution
4 Dec 1915First bacteriophage discoveredTwort 
4 Dec 1915First published observation of filterable agent with anti-bacterial actionTwortBrown Institution
10 Sep 1917Term 'bacteriophage' coined for first timed'HerellePasteur Institute
1919First application of phage therapy to treat dysenteryd'HerelleHospital des Enfants-Malades
1919Jules Bordet, unable to replicate d'Herelle's results with phage therapy, challenged d'Herelle's conception of a phage as a virusBordet, d'Herelle 
1923Establishment of Eliava Institute of Bacteriophages, Microbiology and Virology in Tbilisi, Georgiad'Herelle, EliavaGeorge Eliava Institute
1 Jan 1925Bacteriophages shown to have two different reproductive cyclesBordet, BailPasteur Institute
1925Phages successfully used to treat bubonic plagued'Herelle 
1926Modification of methods to grow phages for therapyd'HerelleHaffking Institute, India
1927Bacteriophage Inquiry launched to study the effectiveness of phage therapy 
July 1927Phage therapy tested in Kasauli, India, indicated phage therapy a promising treatment for choleraMaloneCentral Research Institute, India
August 1927Yugoslavian bacteriologist, Igor Asheshov replaced d'Herelle at the Bacteriophage Inquiryd'Herelle, Asheshov 
November 1927Phage therapy proved promising in patients with cholera in Campbell Hospital, Calcutta, Indiad'Herelle, Malone, LahiriCampbell Hospital, Kolkata, India
1928 - 1929Study of phage therapy conducted in Assam, India, failed to collect sufficient evidence to prove efficacy of phage treatment for choleraMorisonKing Edward VII Pasteur Institute, India
1928Theory put forward about the contagious and hereditary nature of bacteriophagesWollmanPasteur Institute
August 1928Mixed results reported from three studies carried out with phage therapy for cholera treatmentAsheshovPuri Cholera Hospital
1929 - 1935First phage therapy programme launched in RussiaMel'nyk 
1929Igor Asheshov shifted the focus of the Bacteriophage Inquiry away from clinical application to mainly research issuesAsheshov 
1931d’Herelle issued a public challenge to Bordet's theory about bacteriophagesBordet, d'HerellePasteur Institute
1931D’Herelle published his first paper on intravenous phage therapyd'HerelleYale University School of Medicine
1933Asheshov published three long articles on the classification and various properties of cholera plagues but failed to assess the effectiveness of phage therapyAsheshov 
1933Serological test established to classify phagesBurnetNational Institute for Medical Research
1933D'Herelle relocated to Georgiad'Herelle 
1934First American Medical Association (AMA) review of phage therapyEaton, BayneYale University School of Medicine
1934Eliava Institute and the Kharkov Mechnikov Institute formed a collaboration to study phages and their medical applicationsKharkov, EliavaKharkov Mechnikov Institute Eliava Institute
1935Asheshov left the Bacteriophage InquiryAsheshov 
1936Results from Bacteriophage Inquiry's last study undertaken at Campbell Hospital concluded that phage therapy 'appeared to reduce mortality by about 2.5 fold'.PasrichaCampbell Hospital, Kolkata, India
1936The Bacteriophage Inquiry ended 
July 1937George Eliava executed and d'Herelle left GeorgiaEliava, d'Herelle 
1938Soviet phage therapy used to curb outbreak of cholera in several areas of Afghanistan near the Soviet Border 
1938 - 1939The Bacteriological Institute merged with the Institute of Microbiology & Epidemiology (founded in 1936) to become the Research Institute of Microbiology, Epidemiology and BacteriophageTbilisi Institute
1939 - 1940Staphylococcal and streptococcal phages used to save Soviet soldiers wounded in the war with Finland 
1939D’Herelle imprisoned by the Germans in Paris for refusing to share his expertise on phage therapyd'Herelle 
1940First visualisation of a phage using electron microscopyRuskaSiemens, Halske laboratory
1941 - 1945Mass production of phage therapy launched by Soviet bacteriological institutions to treat Soviet troops wounded in World War II 
May 1941Second AMA review of phage therapyKrueger, Scribner 
22 Jun 1941Germans invaded Russia, not only to capture the oil wells but also to obtain the phages preparations at the Tbilisi Institute in GeorgiaTbilisi Institute
1942 - 1943Phage therapy proved key to the Soviet Army winning the Battle of Stalingrad 
1945Third AMA review of phage therapyMorton, Engley 
20 Mar 1950Frederick W Twort diedTwortBrown Animal Sanatory Institution
1952Ludwik Hirszfeld Institute of Immunology and Experimental Therapy establishedHirszfeldHirszfeld Institute
1963 - 1964Large-scale investigation of phage therapy for dysentery caused by Shigella undertaken by researchers at Tbilisi InstituteTbilisi Institute
1982 - 1987Phages successfully used to treat different animals infected with diarrhoea-causing E.coliHerbert Smith, HugginsHoughton Poultry Research Station
1988 - 1994Phage therapy shown to be effective in animals to control A. baumannii, P. aeruginosa, and S. aureus infections and to prevent destruction of skin grafts by P. aeruginosa Soothill, Lawrence, AyliffeUniversity of Birmingham Medical School
1998Intralytix foundedSulakvelidze, MorrisIntralytix
2004Publication of a review on the different life cycles of bacteriophagesWeinbauerNetherlands Institute for Sea Research
August 2004First major intentional phage summit 
2006FDA approved the first bacteriophage preparation to be used as an antimicrobial agentIntralytix
2009First phase I clinical trial with phage therapy in USRhoadsSouthwest Regional Wound Care Center, Texas
2009First phase II clinical trial with phage therapy in UKWrightRoyal National Throat, Nose and Ear Hospital, London
2016FDA granted granted safe status to 'ShigaShield' phage cocktails for use in food productionIntralytix
2016Phase I clinical trial launched for phage therapy to treat S. aureus infections in patients with chronic rhinosinusitisArmata
October 2017Successful treatment of antibiotic-resistant A. baumannii infection using personalised bacteriophagesSchooley 

25 Apr 1873

Felix d'Herelle was born in Montreal, Canada

22 Oct 1877

Frederick W Twort was born in Camberley, Surrey, United Kingdom

4 Dec 1915

First bacteriophage discovered

4 Dec 1915

First published observation of filterable agent with anti-bacterial action

10 Sep 1917

Term 'bacteriophage' coined for first time

1919

First application of phage therapy to treat dysentery

1919

Jules Bordet, unable to replicate d'Herelle's results with phage therapy, challenged d'Herelle's conception of a phage as a virus

1923

Establishment of Eliava Institute of Bacteriophages, Microbiology and Virology in Tbilisi, Georgia

1 Jan 1925

Bacteriophages shown to have two different reproductive cycles

1925

Phages successfully used to treat bubonic plague

1926

Modification of methods to grow phages for therapy

1927

Bacteriophage Inquiry launched to study the effectiveness of phage therapy

Jul 1927

Phage therapy tested in Kasauli, India, indicated phage therapy a promising treatment for cholera

Aug 1927

Yugoslavian bacteriologist, Igor Asheshov replaced d'Herelle at the Bacteriophage Inquiry

Nov 1927

Phage therapy proved promising in patients with cholera in Campbell Hospital, Calcutta, India

1928 - 1929

Study of phage therapy conducted in Assam, India, failed to collect sufficient evidence to prove efficacy of phage treatment for cholera

1928

Theory put forward about the contagious and hereditary nature of bacteriophages

Aug 1928

Mixed results reported from three studies carried out with phage therapy for cholera treatment

1929 - 1935

First phage therapy programme launched in Russia

1929

Igor Asheshov shifted the focus of the Bacteriophage Inquiry away from clinical application to mainly research issues

1931

d’Herelle issued a public challenge to Bordet's theory about bacteriophages

1931

D’Herelle published his first paper on intravenous phage therapy

1933

Asheshov published three long articles on the classification and various properties of cholera plagues but failed to assess the effectiveness of phage therapy

1933

Serological test established to classify phages

1933

D'Herelle relocated to Georgia

1934

First American Medical Association (AMA) review of phage therapy

1934

Eliava Institute and the Kharkov Mechnikov Institute formed a collaboration to study phages and their medical applications

1935

Asheshov left the Bacteriophage Inquiry

1936

Results from Bacteriophage Inquiry's last study undertaken at Campbell Hospital concluded that phage therapy 'appeared to reduce mortality by about 2.5 fold'.

1936

The Bacteriophage Inquiry ended

Jul 1937

George Eliava executed and d'Herelle left Georgia

1938

Soviet phage therapy used to curb outbreak of cholera in several areas of Afghanistan near the Soviet Border

1938 - 1939

The Bacteriological Institute merged with the Institute of Microbiology & Epidemiology (founded in 1936) to become the Research Institute of Microbiology, Epidemiology and Bacteriophage

1939 - 1940

Staphylococcal and streptococcal phages used to save Soviet soldiers wounded in the war with Finland

1939

D’Herelle imprisoned by the Germans in Paris for refusing to share his expertise on phage therapy

1940

First visualisation of a phage using electron microscopy

1941 - 1945

Mass production of phage therapy launched by Soviet bacteriological institutions to treat Soviet troops wounded in World War II

May 1941

Second AMA review of phage therapy

22 Jun 1941

Germans invaded Russia, not only to capture the oil wells but also to obtain the phages preparations at the Tbilisi Institute in Georgia

1942 - 1943

Phage therapy proved key to the Soviet Army winning the Battle of Stalingrad

1945

Third AMA review of phage therapy

20 Mar 1950

Frederick W Twort died

1952

Ludwik Hirszfeld Institute of Immunology and Experimental Therapy established

1963 - 1964

Large-scale investigation of phage therapy for dysentery caused by Shigella undertaken by researchers at Tbilisi Institute

1982 - 1987

Phages successfully used to treat different animals infected with diarrhoea-causing E.coli

1988 - 1994

Phage therapy shown to be effective in animals to control A. baumannii, P. aeruginosa, and S. aureus infections and to prevent destruction of skin grafts by P. aeruginosa

1998

Intralytix founded

2004

Publication of a review on the different life cycles of bacteriophages

Aug 2004

First major intentional phage summit

2006

FDA approved the first bacteriophage preparation to be used as an antimicrobial agent

2009

First phase I clinical trial with phage therapy in US

2009

First phase II clinical trial with phage therapy in UK

2016

FDA granted granted safe status to 'ShigaShield' phage cocktails for use in food production

2016

Phase I clinical trial launched for phage therapy to treat S. aureus infections in patients with chronic rhinosinusitis

Oct 2017

Successful treatment of antibiotic-resistant A. baumannii infection using personalised bacteriophages

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