Microbiology of the GU Tract Flashcards
(52 cards)
What are the most common bacterial, sexually transmitted infections?
Chlamydia (Chlamydia trachomatis)
Gonorrhoea (Neisseria gonorrhoeae)
Syphilis (Treponema pallidum)
Name 3 common viral STIs?
Human papilloma virus (genital warts)
Herpes simplex (genital herpes)
Hepatitis and HIV (not covered in this lecture)
What parasitic STIs are the most common?
Trichomonas vaginalis
Phthirus pubis (pubic lice or “crabs”)
Scabies
Why is pubic lice becoming less common?
shaving pubic hair is more common in today’s society
Describe how gonorrhoea and chlamydia can infect the same tissue but cause different symptoms
Gonococci in male urethra produce intense neutrophil response => pus discharge and dysuria
chlamydia in male urethra = produce a mild, watery discharge or no symptoms at all.
Immunity does not occur in the GU tract. TRUE/FALSE?
TRUE
- reinfection is very common
=> vaccine development is very difficult
What species predominates in normal vaginal flora?
Lactobacillus spp. predominate in the “healthy” vagina
What do the lactobacilli in the normal vaginal flora produce?
Lactic acid
+/- hydrogen peroxide
these suppress growth of pathogenic bacteria
What microbes can be found colonising the vagina in small traces?
Candida (just colonising - not causing symptoms)
Strep viridans
Group B Beta Haemolytic Strep
In what group of patients should you treat Group B Beta - haemolytic strep colonisation in the vagina?
Pregnant women (as this can cause complications when child is born)
Describe the discharge found in bacterial vaginosis
- may contain bubbles
- sometimes has a “fish-like” odour
How does a bacterial vaginosis appear on microscopy and what other test an be done?
- “clue cells”- coccobacilli osbcuring edge of vaginal epithelium
- large no.s of leukocytes may indicate coincident infection
- Positive “whiff” test - Add 10% potassium hydroxide to discharge to elicit a fishy odour
What does bacterial vaginosis put women at a higher risk of developing?
- increased rate of upper urinary tract infection (endometritis, salpingitis)
- premature rupture of the membranes and preterm delivery
- increased HIV risk
What STI is the most common in the UK?
Chlamydia
Where can chlamydia affect?
urethra, rectum, throat and eyes (♂ + ♀)
endocervix (♀)
Is chlamydia a gram positive or negative organism?
NEITHER
there is no peptidoglycan in its cell wall => it does not take up Gm stain well
What are the 3 serovar groups of chlamydia and what does each cause?
Serovars A-C = Trachoma - eye infection
Serovars D-K = Genital infection
Serovars L1-L3 = Lymphogranuloma venereum (LGV)
What investigation is used to diagnose gonorrhoea or chlamydia?
- Nucleic Acid Amplification Tests (NAATs) OR PCR
- Male patients – first pass urine sample
- Female patients – High/ vulvo-vaginal swab (can be self-taken by patient)
- Rectal/ throat/ eye swabs can also be self taken if req’d
What are the advantages of NAATs over culture?
- more sensitive (especially if organism has died on way to lab)
- can test urine specimens/self-obtained swabs
- faster (hours VS days)
What are the disadvantages of NAATs over culture?
- more expensive
- may be false positives for gonorrhoea
- doesn’t give antibiotic sensitivity for organism
What types of antibiotic are any strains of gonorrhoea now resistant to in the UK?
- penicillins
- tetracyclines
- quinolones (ciprofloxacin/ofloxacin)
- most oral cephalosporins
Guidance on how to treat gonorrhoea changes very frequently. How is it currently being treated in the UK (2019)?
IM Cetriaxone
What are the 4 stages of Syphilis infection?
- Primary lesion - (chancre)
- Secondary stage - (large nos. bacteria circulating in blood causing manifestations at different sites)
- Latent stage – (no symptoms, but low-level multiplication of spirochaete in small blood vessels)
- Late stage syphilis – cardiovascular or neurovascular complications
What non-specific serological tests can be used in diagnosing syphilis?
VDRL(Venereal Diseases Research Laboratory)
RPR (Rapid Plasma Reagin)
TPPA
