SCHOOL OF MEDICINE

Department of Medicine

IU Infectious Diseases Laboratory

Detection of Neisseia gonorrhoeae by Culture Isolation

The detection of Neisseria gonorrhoeae (GC) by culture isolation remains relevant as a means to evaluate the efficacy of new antimicrobials and to monitor drug resistance over time. GC is isolated by swabbing the specimen on a selective media such as modified Thayer Martin agar (MTM).  This medium selects for the growth of GC and Neisseria meningitidis while inhibiting the growth of other commensal Neisseria species. The MTM plate is incubated at 370 C for up to 48 hours in a 5 % CO2 atmosphere.  Colonies that exhibit morphology consistent with GC are tested for oxidase reactivity (oxidase positive), Gram stain reaction (Gram negative diplococci), and are subject to speciation using a commercially available carbohydrate degradation assay.  Routine culture of this organism requires 48 hours from the time of receipt in the laboratory.