In this article, we are going to discuss the laboratory procedures required to diagnose Neisseria Gonorrhoea ,the causative organism of Gonorrhea which is one of the known sexually-transmitted diseases (STDs) allover the world .
A. Specimens
The specimens can be obtained from urethral discharge in male , and from urethral and cervical discharge in addition to Rectal swabs in female .
B. Direct detection
1. Gram-stained smears : show intra-cellular, Gram-negative diplococci inside some PMNs .
- Smears of urethral discharge from men with symptomatic gonococcal urethritis are highly sensitive and sufficient for diagnosis of male Acute Gonorrhoea .
- Smears of females or chronic males are less sensitive since the small number of gonococci maybe overlooked by the predominant microbial flora.Cultivation is necessary to reach a diagnosis .
2. Direct detection of gonococcal antigen in specimens by ELISA .
3. A nucleic acid probe test can detect gonococcal nucleic acid in specimens .
4. Nucleic acid amplification tests : Ligase chain reaction (LCR) or PCR .
- One of those methods allows a level of diagnosis adequate to initiate Antimicrobial therapy and sufficient for people at high risk of gonorrhea .
- When there are sociologic or medicolegal implications , a definitive diagnosis is essential .This diagnosis can only be made by culture and identification of the viable organism as follows :
C. Cultivation
- The specimens are plated onto chocolate agar and modified Thayer-Martin medium (MTM)
- Cultures should be incubated in a humid atmosphere with 5-10 % CO2 at 37'C .
D. Identification
- After incubation for 1-3 days , colonies should be examined for morphology and Gram stain and Oxidase test .
- Colonies showing Gram-negative diplococci and oxidase positive are considered Neisseria .
- Neisseria Gonorrhoeae produces acid from Glucose ,, its antigens can be identified by agglutination of fluorescent antibody test .
- It can also be identified by one of the molecular methods e.g Nucleic acid probe, LCR or PCR .
E. Serology
Detection of gonococcal antibodies in patients' sera is not useful .
Read Also :
Gonorrhoea causes , symptoms , prevention and treatment with video
A. Specimens
The specimens can be obtained from urethral discharge in male , and from urethral and cervical discharge in addition to Rectal swabs in female .
B. Direct detection
1. Gram-stained smears : show intra-cellular, Gram-negative diplococci inside some PMNs .
- Smears of urethral discharge from men with symptomatic gonococcal urethritis are highly sensitive and sufficient for diagnosis of male Acute Gonorrhoea .
- Smears of females or chronic males are less sensitive since the small number of gonococci maybe overlooked by the predominant microbial flora.Cultivation is necessary to reach a diagnosis .
2. Direct detection of gonococcal antigen in specimens by ELISA .
3. A nucleic acid probe test can detect gonococcal nucleic acid in specimens .
4. Nucleic acid amplification tests : Ligase chain reaction (LCR) or PCR .
- One of those methods allows a level of diagnosis adequate to initiate Antimicrobial therapy and sufficient for people at high risk of gonorrhea .
- When there are sociologic or medicolegal implications , a definitive diagnosis is essential .This diagnosis can only be made by culture and identification of the viable organism as follows :
C. Cultivation
- The specimens are plated onto chocolate agar and modified Thayer-Martin medium (MTM)
- Cultures should be incubated in a humid atmosphere with 5-10 % CO2 at 37'C .
D. Identification
- After incubation for 1-3 days , colonies should be examined for morphology and Gram stain and Oxidase test .
- Colonies showing Gram-negative diplococci and oxidase positive are considered Neisseria .
- Neisseria Gonorrhoeae produces acid from Glucose ,, its antigens can be identified by agglutination of fluorescent antibody test .
- It can also be identified by one of the molecular methods e.g Nucleic acid probe, LCR or PCR .
E. Serology
Detection of gonococcal antibodies in patients' sera is not useful .
Read Also :
Gonorrhoea causes , symptoms , prevention and treatment with video