Microbiology of the GU Tract

Question 1

Normal vaginal flora

Answer 1

Lactobacillus spp

Question 2

What does Lactobacillus spp produce in the healthy vagina?

Answer 2

Lactic acid
+/- hydrogen peroxide
(These suppress growth of other bacteria)

Question 3

What is the result of adding 10% potassium hydroxide to vaginal discharge discharge to elicit an amine-like, fishy odor?

Answer 3

positive “whiff” test

Question 4

Obligate intracellular bacteria with biphasic life cycle – “energy parasite”

Answer 4

Chlamydia trachomatis

Question 5

Does NOT stain with Gram stain (no peptidoglycan in the cell wall)

Answer 5

Chlamydia trachomatis

Question 6

Treatment for Chlamydia trachomatis

Answer 6

Azithomycin (1g oral dose) for uncomplicated chlamidia

Doxycycline 100mg bd x 7 days

Question 7

Diagnosis of chlamydia & gonorrhoea

Answer 7

Combined nucleic acid amplification tests (NAATs) or polymerase chain reaction test (PCR)

Tests for both organisms in 1 test

Question 8

Taking sample from male patient

Answer 8

first pass urine sample

Question 9

Taking sample from female patient

Answer 9

HVS or vulvo-vaginal swab (VVS), which can be self-taken by patient or clinician-taken endocervical swab

Question 10

Advantages of NAAT test?

Answer 10

slight increase in sensitivity over culture

the ability to test urine specimens and self-obtained vaginal swabs

Question 11

Disadvantages of NAAT test?

Answer 11

Inability to perform antimicrobial susceptibility testing

poor or inadequately defined positive predictive value of some NAATs when they are used to test low-prevalence populations

Question 12

Recommended treatment for N. gonorrhoeae

Answer 12

intramuscular ceftriaxone + oral azithromycin

Question 13

4 stages of syphilis

Answer 13

Primary lesion (chancre) - organism multiplies at inoculation site and gets into bloodstream. Chancre will heal without treatment

Secondary stage – large nos. bacteria circulating in blood with multiple manifestations at different sites (“snail-track” mouth ulcers, generalised rash, flu-like symptoms etc.)

Latent stage – no symptoms, but low-level multiplication of spirochaete in intima of small blood vessels. Can be divided into early latent and late latent periods

Late stage syphilis – cardiovascular or neurovascular complications many years later

Question 14

Screening for syphilis

Answer 14

VDRL(Venereal Diseases Research Laboratory)
RPR (Rapid Plasma Reagin)

Useful for monitoring response to therapy and become negative after successful treatment

Question 15

Enveloped virus containing double-stranded DNA

Answer 15

Genital Herpes

Question 16

Caused by herpes simplex virus type 1 (cold sores) and type 2

Answer 16

Genital Herpes

Question 17

Pathogenesis of genital herpes

Answer 17

Primary infection may be asymptomatic (or very florid)
Virus replicates in dermis and epidermis

Gets into nerve endings of sensory and autonomic nerves
Inflammation at nerve endings → exquisitely painful multiple small vesicles, which are easily deroofed

Virus migrates to sacral root ganglion and “hides” from the immune system there (probably remains for life)

Virus can reactivate from there causing recurrent genital herpes attacks

Intermittent virus shedding can occur in the absence of symptoms

Question 18

Diagnosis of genital herpes

Answer 18

Swab in virus transport medium of deroofed blister for PCR test

Question 19

Treatment of genital herpes

Answer 19

Aciclovir may be helpful if taken early enough ( famciclovir/ valaciclovir )
Pain relief

Question 20

Single celled protozoal parasite that divides by binary fission

Answer 20

Trichomonas vaginalis

Question 21

Diagnosis of Trichomonas vaginalis

Answer 21

High vaginal swab for microscopy (PCR test also available, but not used in Tayside, so no good test for males)

Question 22

Treatment of Trichomonas vaginalis

Answer 22

Oral metronidazole

Question 23

Parasitic insect laying eggs in pubic hair

Answer 23

Pubic lice (Phthirus pubis)

Question 24

Treatment for pubic lice?

Answer 24

malathion lotion