L6 Microbiology of the Genital and Urinary Tract Flashcards
_____________ normally dominate the vaginal flora, comprising >95% of the bacteria.
- gram ___________ bacilli
- metabolize glucose to _________ => normal vaginal pH of _______________
- produce _________________, which is bactericidal
Lactobacilli normally dominate the vaginal flora, comprising >95% of the bacteria
- gram positive bacilli
- metabolize glucose to lactic acid, => normal vaginal pH of 3.5 to 4.6
- produce hydrogen peroxide, which is bactericidal
Impact of Age on Vaginal Flora and pH?
Childhood
- Skin flora including Corynebacterium and Staphylococcus epidermidis
- Vaginal pH neutral or alkaline
Puberty
- Oestrogen levels rise
- Lactobacillus dominance ; pH 3.5 4.6
Menopause
- Reduction in oestrogen
- Reduction in Lactobacilli and rise in vaginal pH
- Often dominance of anaerobic and enteric bacteria e.g. E Coli
Effect of Contraception on Vaginal Flora?
Oral contraceptives: minimal effect on vaginal flora
Intrauterine contraceptive devices (coils)
- Increases anaerobic bacteria in cervix, including
Actinomyces - Increases risk for bacterial vaginosis
- Increases risk for pelvic inflammatory disease
Effect of Pregnancy and Childbirth on Vaginal Flora?
Progressive increase in colonization by lactobacilli during pregnancy
Post Partum:
- Marked increase in Anaerobes by day 3
- Do not require antibiotic therapy unless sign of infection is present. Return to normal after 6 weeks
Impact of Antibiotic use on Vaginal Flora?
Increase in ‘resistant’ flora
- Yeasts/thrush
- Antimicrobial resistant bacteria
Laboratory Diagnosis of Upper Genital Tract Infection?
High Vaginal swab (HVS)
White cells: Normal <5 WCC per high power field. Raised with certain infections e.g. Candida, chlamydia, Gonorrhoea (>10/HPF)
Bacterial vaginosis: Gram stain/Clue Cells
Diagnosis of Group A Streptococcus?
HVS
Diagnosis of Trichomonas vaginalis?
HVS or PCR
Diagnosis of Neisseria gonorrhoeae?
PCR or Culture
Diagnosis of Chlamydia trachomatis?
PCR
Diagnosis of Mycoplasma Genitalium?
PCR
Diagnosis of Herpes Simplex Virus?
PCR
Diagnosis of Treponema Pallidum?
Syphilis serology
Diagnosis of Human papilloma virus?
Usually clinical diagnosis
PCR for high risk subtypes
Causative organisms of UTI usually originate from ____________
Only _________ and _________ species can infect
the urinary tract
Causative organisms of UTI usually originate from the GIT
Only aerobic and facultative species can infect
the urinary tract
Common Causes of UTI?
Primary signs of Pyelonephritis?
Fever and flank pain
Suppurative necrosis or abscess formation
____________ is an uncommon cause of UTI, but a common cause of urine specimen contamination
Candida is an uncommon cause of UTI, but a common cause of urine specimen contamination
UTI Diagnosis:
- Bladder urine is normally _______________
- Urine dipstick for _________ and _________ (Useful screening test)
- UTI is usually caused by a single organism => Mixed organisms usually indicate ______________
UTI Diagnosis:
- Bladder urine is normally sterile
- Urine dipstick for leucocytes and nitrates (Useful screening test)
- UTI is usually caused by a single organism => Mixed organisms usually indicate contamination
of specimen
Laboratory Results indicative of UTI?
No epithelial cells (means no urethral contamination)
Urine white cell count >10 (usually > 100)
100,000 bacteria per ml (can be as few as 10,000 per ml)
Single organism (Pure Growth)
Laboratory results indicative of Normal or Contaminated Sample?
Many epithelial cells (indicates urethral contamination)
WCC <10
<10^4 bacteria per ml
Mixed growth
_____________________: persistent finding of white cells in the urine in the absence of bacteria
Causes?
Sterile Pyuria
Dangers in treating all potential pathogens?
