L6 Microbiology of the Genital and Urinary Tract

Question 1

_____________ normally dominate the vaginal flora, comprising >95% of the bacteria.

• gram ___________ bacilli
• metabolize glucose to _________ => normal vaginal pH of _______________
• produce _________________, which is bactericidal

Answer 1

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

Question 2

Impact of Age on Vaginal Flora and pH?

Answer 2

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

Question 3

Effect of Contraception on Vaginal Flora?

Answer 3

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

Question 4

Effect of Pregnancy and Childbirth on Vaginal Flora?

Answer 4

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

Question 5

Impact of Antibiotic use on Vaginal Flora?

Answer 5

Increase in ‘resistant’ flora

• Yeasts/thrush
• Antimicrobial resistant bacteria

Question 6

Laboratory Diagnosis of Upper Genital Tract Infection?

Answer 6

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

Question 7

Diagnosis of Group A Streptococcus?

Answer 7

HVS

Question 8

Diagnosis of Trichomonas vaginalis?

Answer 8

HVS or PCR

Question 9

Diagnosis of Neisseria gonorrhoeae?

Answer 9

PCR or Culture

Question 10

Diagnosis of Chlamydia trachomatis?

Answer 10

PCR

Question 11

Diagnosis of Mycoplasma Genitalium?

Answer 11

PCR

Question 12

Diagnosis of Herpes Simplex Virus?

Answer 12

PCR

Question 13

Diagnosis of Treponema Pallidum?

Answer 13

Syphilis serology

Question 14

Diagnosis of Human papilloma virus?

Answer 14

Usually clinical diagnosis

PCR for high risk subtypes

Question 15

Causative organisms of UTI usually originate from ____________

Only _________ and _________ species can infect
the urinary tract

Answer 15

Causative organisms of UTI usually originate from the GIT

Only aerobic and facultative species can infect
the urinary tract

Question 16

Common Causes of UTI?

Answer 16

Question 17

Primary signs of Pyelonephritis?

Answer 17

Fever and flank pain

Suppurative necrosis or abscess formation

Question 18

____________ is an uncommon cause of UTI, but a common cause of urine specimen contamination

Answer 18

Candida is an uncommon cause of UTI, but a common cause of urine specimen contamination

Question 19

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 ______________

Answer 19

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

Question 20

Laboratory Results indicative of UTI?

Answer 20

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)

Question 21

Laboratory results indicative of Normal or Contaminated Sample?

Answer 21

Many epithelial cells (indicates urethral contamination)

WCC <10

<10^4 bacteria per ml

Mixed growth

Question 22

_____________________: persistent finding of white cells in the urine in the absence of bacteria

Causes?

Answer 22

Sterile Pyuria

Question 23

Dangers in treating all potential pathogens?

Answer 23