Question

Case study

A male, 24 years of age presents to the STI clinic. He complains of a burning and sore sensation upon urination, along with discharge from his penis that has a mucopurulent consistency and is green-yellow in colour. In the preceding two weeks, he has had unprotected sex with numerous partners.

Laboratory tests

A penile/urethral swab is taken from the male and is inoculated onto NYC agar and chocolate agar. The plates are incubated at 37˚C in CO2 at the clinic and later that evening are transported to the microbiology laboratory. A Gram stain is carried out on a smear of the penile discharge. The patient is also screened for other STI’s and is interviewed in relation to contact tracing his sexual partners.

Results

The following are the results obtained for the organisms growing on the chocolate agar and the organism growing on the NYC agar. Both agars were incubated in CO2 at 37˚C. Two organisms, A and B, were growing on the chocolate agar. Organism B was growing on both agars. This organism was identified as Neisseria gonorrhoeae. The preliminary identification of organism A was not obtained. Neisseria gonorrhoeae is the causative pathogen of gonorrhoeae, a sexually transmitted infection that is characterised by a pus filled infection of the surfaces of the mucous membranes of the throat, eye, vagina and urethra in males and females. This pathogen can be spread through direct sexual contact or through vertical transmission from mother to baby during birth. Symptoms of this bacteria in males include painful urination and urethral discharge, while females present with increased vaginal discharge. Usually females infected with this pathogen present as asymptomatic and are the biggest reservoir of this STI (Edwards and Apicella, 2004).

Using your texts for this class:

Compare and contrast the assessment findings for the following 3 STD’s: for men and women:

Chlamydia

Genital herpes

Human Papilloma virus HPV

Answer 1

Chlamydia:

Chlamydia trachomatis (serovars D - K) are characterised by Genital infections. The infections are:

• Non-gonococal urethritis
• Post-gonococcal urethritis
• Epididymitis and proctitis
• Reactive arthritis

Lab diagnosis:

Specimen: Depends on the type of lesion

Microscopy: For detection of chlamydial inclusion bodies

Antigen detection: By enzyme immuno assay (EIA)

Culture: Inoculation or cell line culture

Nucleic Acid Amplification Test (NAAT): example: PCR

• This is the most sensitive and specific method.

Serology(Antibody detection): CFT , Micro-IF test

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Genital herpes :

Herpes simples virus-2 (HSV -2)is more common to cause genital lesions than HSV-1.

• The genital lesions are usually bilateral, painful, multiple, tiny vesicular ulcers.
• This may be associated with other symptoms like fever and lymph node enlargement.

Lab diagnosis:

Cytopathology(Tzank preparation) : detects Lipschultz bodies(inclusion bodies) and Tzank cell (multinucleated giant cells)

Virus isolation: by cell line culture

Viral antigen detection: by diect IF.

HSV DNA detection by real time PCR.

Antibody detection: by ELISA.

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Human Papilloma Virus (HPV)

Produces a list of infections ranging from benign warts like Anogenital warts(condyloma acuminatum) to maliganant cervical neoplasia like Cervical Intraepithelial Neoplasia(CIN) and Carcinoma Cervix.

Lab diagnosis:

Molecular methods: PCR to detect HPV DNA.

Papanicolou smeras to detect cervical carcinomas.

Antibody detection is not very helpful.

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