Microbiology Technique – Immunofluorescence Bacterial Detection


Malgorzata Rekas and Marilena Ioannou


College, University, Specialist Biomedical

OER FEATURES: (bundle of 5 resources)

Biomedical science resources: Video


Transcript of Immunofluorescence Video (DOC)

Transcript of Immunofluorescence Video (PDF)

Multiple Choice Questions on Immunofluorescence (DOC)

Multiple Choice Questions on Immunofluorescence (PDF)



In the biomedical science laboratory, routine screening and detection of common diseases can place a burden on the laboratory as there can be vast numbers of patient samples to process. Sexually transmitted diseases are widely prevalent in society and infections such as that caused by Neisseria gonorrhoeae (N. gonorrhoeae) can affect the reproductive organs, rectum and throat. The infection can also be asymptomatic – meaning it does not present any symptoms – so an individual may be unaware they have the infection. But problems can manifest in later life for example causing infertility, ectopic pregnancy and other complications (1).

So, accurate and rapid screening of patient samples is necessary, and a simple immunofluorescence procedure is widely used to detect N. gonorrhoeae. In previous years, N. gonorrhoeae would have been identified using a Gram stain, but immunofluorescence has been demonstrated to be much more specific and sensitive, thus is a well used technique today. However, other high-throughput automated detection methods are being developed.

A bacterial colony is grown on an agar plate, and a small sample placed on a mono-spot slide. A small volume of immunofluorescence reagent is placed on the sample. Essentially the reagent is a fluorescent dye (e.g. FITC fluorescein isothiocyanate) bound to an antibody. The antibody binds to bacterial antigen on the N. gonorrhoeae, so the presence of fluorescence (a green colour) under the microscope indicates the presence of bacteria.

The simple technique takes around 20 minutes and the slide is viewed with a fluorescent microscope to complete the test. This is a typical microbiology technique performed in biomedical science laboratories to determine the presence of N. gonorrhoeae in patient samples.

(1). Centres for Disease Control and Prevention, US (2002). Screening Tests to Detect Chlamydia trachomatis and Neisseria gonorrhoeae Infections. Morbidity and Mortality Weekly Report , October 18, 2002 / Vol. 51 / No. RR-15. Available: http://www.cdc.gov/mmwr/pdf/rr/rr5115.pdf

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