Thayer–Martin agar (or Thayer–Martin medium, or VPN agar) is a Mueller–Hinton agar with 5% chocolate sheep blood and

antibiotics An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention o ...

. It is used for culturing and primarily isolating pathogenic ''

Neisseria ''Neisseria'' is a large genus of bacteria that colonize the mucosal surfaces of many animals. Of the 11 species that colonize humans, only two are pathogens, '' N. meningitidis'' and ''N. gonorrhoeae''. ''Neisseria'' species are Gram-negativ ...

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...

, including '' Neisseria gonorrhoeae'' and ''

Neisseria meningitidis ''Neisseria meningitidis'', often referred to as meningococcus, is a Gram-negative bacterium that can cause meningitis and other forms of meningococcal disease such as meningococcemia, a life-threatening sepsis. The bacterium is referred to as a ...

'', as the medium inhibits the growth of most other microorganisms. When growing ''Neisseria meningitidis'', one usually starts with a normally sterile body fluid (blood or CSF), so a plain

chocolate agar Chocolate agar (CHOC) or chocolate blood agar (CBA), is a nonselective, enriched growth medium used for isolation of pathogenic bacteria. It is a variant of the blood agar plate, containing red blood cells that have been lysed by slowly heating ...

is used. Thayer–Martin agar was initially developed in 1964, with an improved formulation published in 1966.

Components

It usually contains the following combination of antibiotics, which make up the VPN acronym: *

Vancomycin Vancomycin is a glycopeptide antibiotic medication used to treat a number of bacterial infections. It is recommended intravenously as a treatment for complicated skin infections, bloodstream infections, endocarditis, bone and joint infections, ...

, which is able to kill most

Gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bact ...

organisms, although some Gram-positive organisms such as ''

Lactobacillus ''Lactobacillus'' is a genus of Gram-positive, aerotolerant anaerobes or microaerophilic, rod-shaped, non-spore-forming bacteria. Until 2020, the genus ''Lactobacillus'' comprised over 260 phylogenetically, ecologically, and metabolically div ...

'' and ''

Pediococcus ''Pediococcus'' is a genus of gram-positive lactic acid bacteria, placed within the family of Lactobacillaceae. They usually occur in pairs or tetrads, and divide along two planes of symmetry, as do the other lactic acid cocci genera '' Aerococc ...

'' are intrinsically resistant *

Polymyxin Polymyxins are antibiotics. Polymyxins B and E (also known as colistin) are used in the treatment of Gram-negative bacterial infections. They work mostly by breaking up the bacterial cell membrane. They are part of a broader class of molecules ...

, also known as colistin, which is added to kill most

Gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wa ...

organisms except ''Neisseria'', although some other Gram-negative organisms such as ''

Legionella ''Legionella'' is a genus of pathogenic gram-negative bacteria that includes the species '' L. pneumophila'', causing legionellosis (all illnesses caused by ''Legionella'') including a pneumonia-type illness called Legionnaires' disease and a mil ...

'' are also resistant *

Nystatin Nystatin, sold under the brandname Mycostatin among others, is an antifungal medication. It is used to treat '' Candida'' infections of the skin including diaper rash, thrush, esophageal candidiasis, and vaginal yeast infections. It may also be ...

, which can kill most

fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...

Trimethoprim Trimethoprim (TMP) is an antibiotic used mainly in the treatment of bladder infections. Other uses include for middle ear infections and travelers' diarrhea. With sulfamethoxazole or dapsone it may be used for ''Pneumocystis'' pneumonia in peo ...

inhibits swarming of ''Proteus'' spp

Clinical implications

A negative culture on Thayer–Martin in a patient exhibiting symptoms of pelvic inflammatory disease most likely indicates an infection with ''

Chlamydia trachomatis ''Chlamydia trachomatis'' (), commonly known as chlamydia, is a bacterium that causes chlamydia, which can manifest in various ways, including: trachoma, lymphogranuloma venereum, nongonococcal urethritis, cervicitis, salpingitis, pelvic infla ...

''.

References

Microbiological media {{Microbiology-stub