Flashcards in Microbiology Deck (65):
What bacterial species predominates in healthy vaginal flora?
What does Lactobacillus spp. produce and what is the effect of these products?
Lactic acid +/- hydrogen peroxide
Suppresses growth of other bacteria
List some bacteria other than Lactobacillus spp. that can be part of the normal vaginal flora
Group B Strep
Candida spp. (small numbers)
What are the 3 main non-sexually-transmitted genital tract infections?
Which bacteria causes vaginal thrush?
Candida (usually albicans)
The presence of Candida on vaginal swab indicates vaginal thrush. True/False?
30% of females are colonised by small numbers of Candida as part of normal flora
List some predisposing factors to developing Candida infection
Recent antibiotic therapy
High oestrogen levels (pregnant, contraceptives)
Poorly controlled diabetes
Describe clinical presentation of vaginal thrush
White vaginal discharge "like cottage cheese"
How is the diagnosis of vaginal thrush made?
Vaginal swab to culture for C. albicans
How is vaginal thrush treated?
Oral fluconazole if no response
What is characteristic of Candida albicans on gram film?
Appearance of budding
Who typically gets other forms of Candida infection (other than albicans)?
Poorly controlled diabetics (C. balanitis)
Which organisms are the main causes of bacterial vaginosis?
Describe clinical presentation of bacterial vaginosis
Thin, watery, fish-smelling discharge that reeeeaally stinks
How is a diagnosis of bacterial vaginosis made?
Raised vaginal pH greater than 4.5
The presence of what cells on microscopy suggest bacterial vaginosis?
How is bacterial vaginosis treated?
Describe the clinical presentation of acute bacterial prostatitis
A mid-stream sample of urine is required to test for urethral infection in acute bacterial prostatitis. True/False?
Mid-stream for upper UTI, first-pass for lower UTI
How is acute bacterial prostatitis treated?
Ciprofloxacin for 28 days
Trimethoprim if high C. diff risk
List the 3 main sexually-transmitted bacterial infections
What is the commonest bacterial STI in the UK? What organism causes it?
Chlamydia, caused by Chlamydia trachomatis
What areas of the body can chlamydia infect?
Chlamydia reproduces both in and out -side the host cell. True/False?
Obligate bacteria that only reproduces inside the host
Does chlamydia stain with Gram stain?
No because no peptidoglycan in cell wall
What are the 3 serological groupings of chlamydia and their respective infections?
Serovars A-C = trachoma/eye infection
Serovars D-K = genital infection
Serovars L1-L3 = lymphogranuloma venereum
What condition does lymphogranuloma venereum mimic on presentation?
Inflammatory bowel disease - features of proptosis, PR bleed, irritation, fullness
How is chlamydia infection treated?
Azithromycin if uncomplicated
Doxycycline for 7 days
3 weeks if LGV
Which bacteria causes gonorrhoea?
Gonorrhoea is more common than chlamydia. True/False?
Describe the appearance of Neisseria gonorrhoeae on gram stain
Neisseria gonorrhoea is a fastidious organism. What does this mean?
Doesn't grow well in less than ideal conditions i.e. outside the body
What is the typical clinical appearance of gonorrhoea?
How are both chlamyida and gonorrhoea diagnosed?
Nucleic acid amplification test
Microscopy of swabs
Specific agar culture (gonorrhoea only)
What are the advantages of NAAT/PCR over culture?
What are the disadvantages of NAAT/PCR over culture?
Will detect dead organisms so have to wait 5 weeks before retest
Cannot detect antibiotic sensitivity
Many strains of gonorrhoea are now antibiotic resistant. True/False?
What is the recommended treatment for gonorrhoea?
Ceftriaxone + azithromycin
Which bacteria causes syphilis?
Treponema pallidum does not stain with gram stain. True/False?
Treponema pallidum cannot be grown in culture. True/False?
How does stage 1 syphilis present?
Chancre (painless ulcer)
How does stage 2 syphilis present?
Generalised rash, palms and soles affected
How does latent stage (stage 3) syphilis present?
How does late-stage (stage 4) syphilis present?
Cardiovascular (aortic aneurysm)
Neurovascular (high-stump gait)
Syphilis is not infectious in the latent period. True/False?
What method is used to diagnose syphilis?
How is serology testing for syphilis done?
Test for non-specific and specific antibodies to T. pallidum in blood
What is the main non-serological test done for syphilis? When is it useful?
Rapid plasma regain
Useful for monitoring response to therapy
List the main specific serological tests done for syphilis
IgM + IgG ELISA (screening test)
What is the gold-standard treatment for syphilis?
What are the 3 main sexually-transmitted viral infections?
Hepatitis and HIV
What is the commonest viral STI and its cause?
Genital warts, caused by human papilloma virus
What subtypes of HPV are the most common causes of genital warts?
6 + 11
What subtypes of HPV are associated with increased risk of cervical cancer?
16 + 18
How is genital warts diagnosed?
Clinical diagnosis as no lab test
How are genital warts treated?
Vaccination given to 11-13 year old girls
What virus causes genital herpes?
Herpes simplex virus types 1 &2
How is genital herpes diagnosed?
Swab for PCR
How is genital herpes treated?
What is the most common sexually-transmitted parasitic disease?
How is Trichomonas vaginalis diagnosed?
Vaginal swab for microscopy
How is Trichomonas vaginalis treated?
Which parasite causes pubic lice?