Laboratory diagnosis of STI

Question 1

Gonococcal urethritis/cervicitis

Sample collection
• _______ swab, ________ swab

Macroscopy
• _________ , (clear or turbid?)

Microscopy
• Gram stain shows Gram ________ ______ and ______ cells

Culture
• Modified ________ medium, ___________ agar

Answer 1

Urethral swab, endocervical swab

Purulent, clear

Gram negative cocci and pus cells

Modified Thayer Martin medium, New York City agar

Question 2

Gonococcal urethritis/cervicitis

Incubation condition
5% _____, ___-____ oC, for ___-_____hrs

Identification
Oxidase __________, oxidises _____ but not _______ or _______ or _______ to produce acid

_______ directly on the sample to detect gonococcal _______

Answer 2

CO2 ; 35 – 37oC ; 24 – 48 hrs

positive; glucose

maltose ; lactose ; sucrose

PCR ; DNA

Question 3

Non gonococcal urethritis/cervicitis

Sample collection
________ swab, ——— urine, ________ swab

Identification
_______ to detect the DNA
•_________ ________
• ____________
•_____________ _______

Answer 3

Urethral swab ; first void urine

endocervical swab ; PCR

Chlamydia trachomatis

Mycoplasma

Ureaplasma urealyticum

Question 4

Syphilis

Non treponemal test – used as _________ test and can be used to follow up the efficacy of/response to treatment

•(slow or rapid?) plasma _____

_________ result are useful for making a diagnosis and evaluating the effect of treatment

Can revert to negative result _____________ after effective treatment

Answer 4

screening test and can be used to follow up the efficacy of/response to treatment

Rapid plasma reagin

Quantitative result

1 – 3 years

Question 5

Syphilis

Treponemal test
• Test for ___________ to syphilis
• Once positive after initial syphilis infection, test is _____________
• _________________________ (TP-PA)
• _______________________ (TPHA)
• _________________________________ (FTA-ABS)
• ELISA
• ________ ———- test

Answer 5

antibodies ; positive for life

T pallidum–particle agglutination

T pallidum hemagglutination

fluorescent treponemal antibody absorbed

Rapid syphilis test

Question 6

Interpretation of syphilis test

Non treponemal test : Treponemal test

Positive Positive
Positive Negative
Negative Positive
Negative Negative

Answer 6

Interpretation:

Syphilis

False positive

Effective treatment of syphilis in the past

No syphilis

Question 7

Vaginitis and vaginosis

Specimen – ____________ swab

Culture
_______________ agar for candida

Incubate in __________ air at ________ oC for _________

Answer 7

high vaginal swab

Sabouraud dextrose

atmospheric air

35 – 37oC ; 24hrs

Question 8

Vaginitis and vaginosis

Microscopy
____ mount for ______ of T. vaginalis

Wet mount for _______ to

Gram stain for bacterial vaginosis using the ________ score

Answer 8

Wet ; motility

yeast

Nugent

Question 9

Lymphogranuloma venerum

_____________________

Specimen
• swabs taken directly from __________ (when present)
• _________ swabs
• ______________ specimens in men,
• __________ in women,
• ___________ in MSM.

Polymerase chain reaction
Culture

Answer 9

Chlamydia trachomatis

primary lesions ; urethral swabs

first-catch urine ; endocervical swabs

rectal swabs in MSM.

Question 10

Chancroid –_________________

Specimen – swabs from the ______________

Culture
• _________ agar containing 1% IsoVitaleX and vancomycin, 3 μg/mL
• 5%CO2,32–34oCfor48hrs

Identification
• Requires _______ but not _______
• Oxidase ———-
• Detection of ——————

Answer 10

Haemophilus ducreyi

base of the ulcer

Chocolate agar

X factor ; V factor

Oxidase positive; alkaline phosphatase

Question 11

Granuloma inguinale
Specimen – swab from the ________

________ stained smear to detect ________

Polymerase chain reaction

Answer 11

ulcer

Giemsa

Donovan bodies