Antimicrobial resistance glossary

Definitions of antimicrobial resistance-related terms

Acinetobacter baumannii
Also known 'Iraquibacter', this is a type of bacteria that commonly causes ventilator-associated pneumonia and blood-stream infection in critically ill patients with compromised immune systems.
Actinomyces bovis
A species of Gram-positive rod-shaped bacteria that causes Lumpy jaw in cattle.
Agar diffusion test
A method used to test the effectiveness of antibiotics for specific bacteria. It involves the application of antibiotic solutions of different concentrations to cups, wells or paper discs, placed on the surface of agar plates seeded with a test bacterial strain.
Allele
One of two or more versions of a gene. Most organisms inherit two alleles for each gene, one from each parent. Where the two alleles inherited are the same, the term homozygous is used for that gene. If the alleles are different, the term heterozygous is used. Originally the term allele was used to describe variation among genes, but it can now also refer to variation among non-coding DNA sequences.
Amino acid
The building blocks that cells in the body use to build proteins. Each protein contains hundreds, even thousands of amino acids joined together in a specific sequence in chain-like formation. The order of the amino acids determines a protein's shape and function.
Antibiotic susceptibility test (AST)
A test that determines which antimicrobial drug can successfully inhibit the growth of specific bacteria.
Antibodies
Y-shaped proteins produced by specialised white blood cells (called B lymphocytes or B cells) to recognise and neutralise foreign objects like bacteria, viruses and pollen.
Antigen
Molecule found on the surface of a cell which is capable of triggering an immune response.
Antimicrobial resistance (AMR)
Umbrella term used to describe the diverse range of mechanisms that microbes, like bacteria, fungi, viruses and other parasites, use to survive the destructive effects of drugs like antibiotics, antivirals, antifungals and antimalarials.
Array card
A microfluidic card that that contains selected primers and probe sets that facilitates the running of hundreds of real-time PCR reactions simultaneously.
Attenuated bacteria or virus
Where the disease causing ability of a bacteria or virus has been sufficently weakened so that can still prompt an imune response but not the full-blown disease. Attentuated pathogens are commonly used for vaccines.
Avirulent bacteria
Benign bacteria that do not cause disease.
Bacteriophage (phage)
A bacteriophage, or phage, is a virus that infects and replicates within a bacterium. There are various types of bacteriophages, including R17, lambda, f1, phi X 174 and M13.
Base pairs (bases)
Pair of complementary nucleotides in DNA.
Cholera
Acute diarrhoeal illness caused by ingestion of food or water contaminated with the bacterium Vibrio cholerae. Poor sanitation and lack of clean drinking water contribute to the spread of cholera. If left untreated cholera can be fatal within hours. The disease can be prevented by vaccination.
Chromosome
Thread-like structure made up of a tightly coiled single strand of DNA located inside the nucleus of a cell. Usually found in pairs, chromosomes are involved in the transmission of hereditary information. They work in tandem with other nucleic acids to build proteins and are also involved in cell division.
Commensal bacteria
Bacteria that obtain food or other benefits from its host without causing harm.
Complementary DNA (cDNA)
A DNA copy of a messenger RNA (mRNA) molecule produced by reverse transcription. The term is used to reflect the fact that its sequence is a complement of the original mRNA sequence. Scientists often use cDNA deployed in gene cloning or as gene probes or in the creation of a cDNA library. Some viruses also use cDNA to convert their viral RNA into mRNA which allows viral proteins to take over the host cell.
Conjugation
Process where DNA is transferred directly from one bacterium to another via a plamid.
Corynebacterium diphtheriae
Bacteria that cause diphtheria.
Diphtheria
A serious and life-threatening disease caused by the bacterium Corynebacterium diphtheriae. Mainly spread from one person to another by direct contact or through the air, the bacteria produce a powerful toxin (poison) which kills cells in the mouth and the nose. If diphtheria is left untreated, patients find it increasingly difficult to breathe and are often strangled to death. Some people can carry and transmit the disease without knowing they have it. Diphtheria can now be prevented by a vaccine, first introduced in the 1940s.
DNA
This stands for DeoxyriboNucleic acid, which is a complex chemical found in the nucleus and mitochondria of a cell. It provides the genetic instructions needed for an organism to develop, survive and reproduce.
DNA microarray
Also known as a DNA chip, a DNA micoraary comprises a collection of microscopic DNA spots printed on to a solid surface that is used to measure the expression levels of large numbers of genes simultaneously.
DNA polymerase
An enzyme that facilitates the replication of DNA.
DNA probe
A fragment of single-strand DNA that contains a specific nucleotide sequence that is used to detect a complementary sequence in a sample genome. The probe is labeled with a radioactive or chemical tag which provides a signal when it binds to the complementary DNA.
DNA sequencing
A biochemical method used to determine the exact order of the four building blocks, nucleotide bases, that make up a piece of DNA.
Double-stranded
A molecule that consists of two bound strands, each of which complements the other. DNA is usually double-stranded.
Dysentery
A condition caused by either a bacteria or amoeba infection of the intestines. Symptoms include diarrhoea containing blood or mucus, fever and, abdominal pain.
Electrophoresis
An analytical method that uses an electric current to separate and sort out molecules based on their size. The method takes advantage of the charged particles in the molecules.
Enteric disease
Group of diseases that affect the stomach or intestine caused by microorganisms like bacteria, viruses and parasites frequently consumed through contaminated food or water. Symptoms are commonly nausea, vomiting, diarrhea, abdominal cramps, fever, chills, and a loss of appetite.
Enterobacteriaceae
Large family of Gram-negative bacteria which includes Escherichia coli, Klebsiella, Salmonella, Shigella and Yersinia pestis.
Enterococci
Type of bacteria that live in the gut and bowel. Most enterococci are harmless but they can cause urinary tract infections, Infective endocarditis, diverticulitis, meningitis, and spontaneous bacterial peritonitis.
Escherichia coli (E. coli)
A type of bacteria that commonly live in the intestines of people and animals. There are many types of Escherichia coli. Most pose no harm to human health, but one group produces a potent toxin which can cause food poisoning.
Faecal microbiota transplantation (FMT)
Therapy involving the transplant of stool from a healthy donor into a patient to restore microbial diversity in their gut whose bacterial infection has failed to respond to antibiotics.
Gene
A distinct stretch of DNA that codes for proteins that perform the cellular functions in an organism. It is the basic physical and functional unit of hereditary. Genes vary in size. Each person has two copies of each gene, one inherited from each parent.
Gene expression
The process by which genetic instructions in DNA are converted into a functional product, such as a protein.
Gene transcription
The process by which cells read out the genetic instructions in their genes to RNAs, such as messenger RNA, which is the first phase in the synthesis of proteins.
Genetic engineering
Also called genetic modification or genetic manipulation, genetic engineering involves the introduction, elimination or rearrangement of specific genes to change the genetic makeup of an organism.
Genetic mutation
A change that happens in the DNA sequence. Such a change can occur either when mistakes are made in the process of copying DNA or result from environmental factors, such ultraviolet radiation from the sun or cigarette smoke. Some mutations are only carried in an individual organism. A change can be carried over into the organism's offspring where the mutation occurs in a germline cell.
Genetics
A branch of science that studies how physical and behavioural characteristics, including medical conditions, are passed down from parents to offspring through genes.
Genome
Complete set of genetic material within the single cell of an organism.
Genomics
A branch of genetics established in the 1980s directed towards studying the structure, function, evolution and mapping genomes in organisms.
Genotype
The set of genes in DNA which is responsible for a particular trait.
Gonococci
A bacterium that causes gonorrhea. Aso called Neisseria gonorrhoeae.
Gonorrhoea
Sexually transmitted infection caused by Neisseria gonorrhoeae, bacteria that live in warm, moist parts of the body such as the throat, rectum, penis and vagina. If not treated early with antibiotics it can cause painful symptoms and serious health problems, including infertility.
Gram staining
Common technique used to differentiate two large groups of bacteria based on the chemical and physical properties of their cell walls. The method involves staining the cells with crystal violet dye and then adding iodine and potassium iodine. Gram-negative bacteria show up as purple while Gram-negative bacteria show up as pink..
Gramicidin
Gramicidin was one of the first antibiotics to be clinically tested and manufactured commercially. It was first isolated from the soil bacterium Bacillus brevis by the French-born American microbiologist René Dubos in 1939 with the help of Rollin Hotchkiss. The antibiotic inhibits the growth of Gram-positive bacteria.
Klebsiella
A harmless type of Gram-negative bacteria that lives in the gut but can cause different types of infections, including pneumonia, bloodstream infections, wound or surgical site infections, and meningitis.
Lactis aerogenes (Aerobacter aerogenes)
Harmless organism sometimes involved in the souring of milk.
Lipopolysaccharide
Also known as endotoxin, a lipopolysaccharide is a large molecule found on the outer membrane of the bacterial cell wall which can activate the immune system and cause harm.
Loop mediated isothermal amplification (LAMP)
A single-tube technique that enables the amplification of DNA which unlike conventional PCR does not require a thermocycler.
Methicillin-resistant Staphylococcus aureus (MRSA)
A staphylococci species that is resistant to many widely used antibiotics.
Monoclonal antibody
Laboratory produced antibody designed to recognise and bind to specific receptors found on the surface of cells. Derived from natural antibodies, monoclonal antibodies are produced by creating a hybrid cell line, known as a hybridoma, by fusing a short-lived antibody-producing B cell, a type of white blood cell, collected from the spleen of an immunised animal with an immortal cancer cell line. Maintained in a medium, the hybridoma will secrete endless quantities of antibodies. Each of these antibodies are identical and clones of a unique parent cell - hence the term 'monoclonal'.
Multilocus enzyme electrophoresis (MLEE)
Technique that enables the differentiation of organisms based on an how far their intracellular enzymes migrate during electrophoresis.
Multilocus sequence typing (MLST)
Method that makes it possible to classify bacterial isolates based on the sequencing of six or seven well-conserved, housekeeping genes within the bacterial genome.
Mycobacterium tuberculosis
Type of microorganism that causes tuberculosis.
Neisseria meningitidis (N. meningitidis)
Also known as meningococcus, N. meningitidis, is a Gram-negative bacterium that is responsible for meningitis and severe sepsis. Meningitis symptoms typically includes fatigue, fever, and headache that can rapidly progress to neck stiffness, coma and death. The bacteria are most commonly spread by coughing, sneezing, and respiratory droplets.
Nosocomial infections
Hospital-acquired infections.
Nucleic acid
Long molecule made up of smaller molecules called nucleotides which are chemically linked together in a chain. Nucleotides are instrumental in transferring genetic information from one generation to another. There are two types of nucleic acids: are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
Nucleic acid hybridisation
The process in which two complementary strands of nucleic acids - RNA, DNA or oligonucleotides - are joined.
Nucleotides
Nucleotides are molecules present in all cells of the body. They serve many purposes, including acting as cellular messengers between the outside and the inside of a cell's nucleus, storing energy and as physiological mediators. Nucleotides are also necessary to the construction of the nucleic acids DNA and RNA. DNA is made up of four base nucleotides: adenine (A), cytosine (C), guanine (G) and thymine (T). RNA is made up of A, G, and C, plus uracil.
Pathogen
An organism that is capable of causing disease. Other terms used to describe such organisms are 'germ' or 'infectious agent'.
Pathogenic
Term used to describe a bacterium, virus or other microorganism that has the ability to cause disease.
Penicillin
Group of antibiotics produced from common Penicillium moulds.
Penicillium
Common mould species that grows in diverse range of habitats
Phage therapy
Treatment to combat bacterial infection using phages, viruses that destroy bacteria.
Phage typing
Means of classifying bacteria based on whether they get destroyed by specific phages.
Phenotype
The physical characteristics of an organism that result from the interactions between genes, environment, disease, molecular mechanisms, and chance.
Plasmids
Small self-replicating piece of DNA found in the cytoplasm of a bacterium or protozoan
Pneumococci
Bacteria that are the most common cause of bloodstream infections, pneumonia, meningitis, and middle ear infections in young children.
Pneumonia
Respiratory infection that affects the air sacs in one or both lungs which is caused by a variety of microorganisms including bacteria, viruses and fungi. Pneumonia symptoms include coughing with phlegm or pus, fever, chills, and difficulty breathing. The condition can range from mild to life-threatening. Pneumonia is most serious for young children and people over the age of 65 as well as for those with weakened immune systems.
Polymerase chain reaction (PCR)
A technique that is used to copy a specific DNA sequence. The technique provides the means to make one billion exact copies of an original target DNA within a couple of hours.
Primer
Template strand of DNA used to generate a new double-strand of DNA.
Protein
Proteins are large complex molecules that do most of the work in the cells in a living organism. They play a crucial role in almost all biological processes, being involved in building, maintaining and replacing tissues in the body, as well helping to pro
Pseudomonas aeruginosa (P. aeruginosa)
Also known as Pseudomonas spp, P aeruginosa is aa common rod-shaped Gram negative bacterium that can cause infections in the blood, lungs (pneumonia), or other parts of the body after surgery.
R plasmid (R factor)
Small self-replicating extrachromosomal DNA.
Recombinant DNA (rDNA)
Also known as gene cloning or splicing, recombinant DNA is a technique that produces identical copies (clones) of a gene. The procedure involves joining together DNA segments in a cell-free system (e.g. in a test tube outside living cells or organisms). The recombinant DNA molecule is then introduced into a cell where it will replicate itself, either as an independent entity (autonomously) or as an integral part of a cellular chromosome.
Salmonella
Type of rod-shaped Gram-negative bacteria that affects the intestinal tract. First discovered by Daniel E. Salmon in 1885, Salmonella commonly causes salmonellosis, a disease which has the symptoms of diarrhoea, fever, and stomach cramps. Occasionally Salmonella can cause infection in urine, blood, bones, joints, or the nervous system. Salmonella infections can be caused by consumption of contaminated food or water and touching infected animals.
Salvarsan
Also known as arsphenamine or compound 606, Salvarsan is credited with being the first the first man-made chemotherapy agent. It provided the first effective treatment for syphilis,
Septicaemia
A condition that arises when a bacteria or their toxins enters the bloodstream and causes blood poisoning setting off sepsis which can rapidly become life-threatening.
Serotyping
A method used to classify microorganisms based on whether structures (antigens) found on their cell surface clump together when with antibodies in serum taken from a previously immunised human or animal.
Shigella
A group of Gram-negative bacteria that causes an infection called shigellosis, also known as dysentery. Common symptoms include severe bloody diarrhoea, stomach cramps and fever. The illness is most common in young children. Shigella can be caught by touching infected surfaces, eating contaminated food or swallowing contaminated water. It can also be spread by sexual contact.
Staphylococci
A group of Gram-positive, round-shaped bacteria responsible for a broad spectrum of diseases with varying degrees of severity. They are responsible for for a large proportion of hospital acquired infections.
Staphylococcus aureus (S. aureus)
Most common staphylococcal bacterial. They are responsible for any different health problems in humans, including carbuncles, food-poisoning, and infections around medical devices and wounds.
Streptococci
A type of Gram-positive spherical bacteria that cause many disorders, including pharyngitis, pneumonia, wound and skin infections, sepsis, and endocarditis.
Sulphonamides
Also called sulpha drugs, sulphonamides are a group of synthetic antibacterial drugs that stop bacteria from reproducing and interfere with bacteria's ability to synthesize folic acid.
Transduction
Process by which bacteria pick up genetic material from bacteriophages and gets passed on to other bacteria
Transformation
Process by which bacteria acquire new genetic material from the environment
Trypanosoma brucei
Parasite that causes sleeping sickness
Tuberculosis (TB)
A highly infectious disease caused by the bacterium Mycobacterium tuberculosis. The bacterium most commonly attacks the lungs but it can also attack other parts of the body, including the abdomen, glands, bone and nervous system. Tiny droplets from coughs and sneezes of infected patients spread the disease. Most common symptoms are a persistent cough which can be bloody, night sweats, fever, neck swelling, fatigue and loss of appetite. the disease can be cured with the right antibiotics.
Viron
Virus particle.
Virulent bacteria
Bacteria that have the ability to cause disease.
Whole genome sequencing (WGS)
Laboratory process to determine the complete DNA sequence of an organism's genome.

Respond to or comment on this page on our feeds on Facebook, Instagram or Twitter.