Elek's test or the Elek plate test is an ''

in vitro ''In vitro'' (meaning ''in glass'', or ''in the glass'') Research, studies are performed with Cell (biology), cells or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in ...

'' test of

virulence Virulence is a pathogen's or microorganism's ability to cause damage to a host. In most cases, especially in animal systems, virulence refers to the degree of damage caused by a microbe to its host. The pathogenicity of an organism—its abili ...

performed on specimens of ''

Corynebacterium diphtheriae ''Corynebacterium diphtheriae'' is a Gram-positive pathogenic bacterium that causes diphtheria. It is also known as the Klebs–Löffler bacillus because it was discovered in 1884 by German bacteriologists Edwin Klebs (1834–1912) and Friedrich ...

'', the bacteria that causes

diphtheria Diphtheria is an infection caused by the bacteria, bacterium ''Corynebacterium diphtheriae''. Most infections are asymptomatic or have a mild Course (medicine), clinical course, but in some outbreaks, the mortality rate approaches 10%. Signs a ...

. It is used to test for toxigenicity of ''C. diphtheriae'' strains. The test uses immunodiffusion. A strip of

filter paper Filter paper is a semi-permeable paper barrier placed perpendicular to a liquid or air flow. It is used to separate fine solid particles from liquids or gases. The raw materials are typically different pulp (paper), paper pulps. The pulp may be ...

impregnated with

diphtheria antitoxin Diphtheria antitoxin (DAT) is a medication made up of antibodies used in the treatment of diphtheria. It is no longer recommended for prevention of diphtheria. It is administered through injection into a vein or muscle. Side effects are com ...

is buried just beneath the surface of a special

agar plate An agar plate is a Petri dish that contains a growth medium solidified with agar, used to Microbiological culture, culture microorganisms. Sometimes selective compounds are added to influence growth, such as antibiotics. Individual microorganism ...

before the

agar Agar ( or ), or agar-agar, is a jelly-like substance consisting of polysaccharides obtained from the cell walls of some species of red algae, primarily from " ogonori" and " tengusa". As found in nature, agar is a mixture of two components, t ...

hardens. Strains to be tested are streaked with known positive and known negative toxigenic strains on the agar's surface in a line across the plate, and at a right angle to the antitoxin paper strip. After incubation for 24 hours at 37 degrees Celsius, plates are examined with transmitted light for the presence of fine precipitin lines at a 45-degree angle to the streaks. The presence of precipitin lines indicates that the strain produced toxin that reacted with the antitoxin. The test was characterized in 1949 by Hungarian-born British

microbiologist A microbiologist (from Greek ) is a scientist who studies microscopic life forms and processes. This includes study of the growth, interactions and characteristics of microscopic organisms such as bacteria, algae, fungi, and some types of par ...

Stephen Dyonis Elek (1914–1992). It provided an easier way to test the toxigenicity of ''C. diphtheriae'' specimens compared with previous tests. It also allowed an ''in vitro'' test to replace a clinical test on laboratory animals, helping with the "reduce" component of the three R's. Diphtheria was a major public health scourge, killing entire families with acute airborne pulmonary disease, before

diphtheria vaccine Diphtheria vaccine is a toxoid vaccine against diphtheria, an illness caused by ''Corynebacterium diphtheriae''. Its use has resulted in a more than 90% decrease in number of cases globally between 1980 and 2000. The first dose is recommended ...

brought it under control. At the time Elek developed this test, control of the disease was not yet secured in all regions of the world. Today its control is threatened by

vaccine hesitancy Vaccine hesitancy is a delay in acceptance, or refusal of vaccines despite availability and supporting evidence. The term covers refusals to vaccinate, delaying vaccines, accepting vaccines but remaining uncertain about their use, or using ce ...

References

Medical tests Diphtheria {{microbiology-stub