Microbiology of genital tract infections Flashcards
state the main group of normal vagina flora and what they produce?
-other organisms?
Lactobacillus, produce:
Lactic acid & hydrogen peroxide
these suppress growth of other bacteria
-Strep viridian’s
Group B beta haemolytic Strep
Candida Spp
what might normally be seen on a smear?
lactobacilli might be seen on epithelial cells
name the 3 non sexually transmitted genital tract infections
Candida infection
Bacterial vaginosis
Prostitis
candida infection
- predisposing factors? (4)
- indications for investigating candida?
- presentation?
- Dx?
- Treatment?
- appearance under microscope?
-recent antibiotic therapy
high oestrogen levels (preg) poorly controlled diabetes
immunocompromised patients
- ONLY if patient is SYMPTOMATIC
- intensely itchy white vaginal discharge
- Diagnosis is clinical, might take high vaginal swab for culture, likely C.albicans
-topical clotrimazole pessary/cream (available OTC)
Oral fluconazole
-see yeast with hyphae (budding)
Bacterial vaginosis
- causative organism?
- Predisposing factors?
- Symptoms?
- Dx?
- investigations?
- treatment?
- Gardnerella vaginalis/ Mobiluncus and other anaerobes
- dont really know :/ an increased Ph might mean an overgrowth of anaerobes
- thin, watery, fishy smelling vaginal discharge
- Clinical dx + raised vaginal Ph (Ph>4.5)
-high vaginal swab sent to laboratory and examined microscopically to look for the presence of CLUE CELLS, Hay-Ison scoring system estimates proportion of clue cells to to epithelial cells and lactobacilli
clue cells: stippled appearance full of gram neg anaerobes
-Metronidazole
give the 3 classifications of prostatitis
- Acute bacterial prostatitis
- chronic bacterial Prostatitis
- Chronic Prostatitis/Chronic Pelvic pain syndrome
Acute bacterial prostatitis
- presentation?
- cause?
- causative organisms?
- Dx?
- treatment?
- UTI symptoms + lower abdo/back/perineal/penile pain with tender prostate on examination
- rare complication of UTI in men
-same as UTI, e.coli & other coliforms, enterococcus
however check for STI if patient under 35
- Clinical dx + midstream urine sample for serology and cytology (chlamydia &gonorrhoea)
- ciprofloxacin for 28 days, trimethoprim if high C.diff risk
sexually transmitted genital tract infections (give organism and infection)
- bacterial? (3)
- viral? (3)
- Parasites? (3)
-chlamydia trachomatis
Neisseria gonorrhoeae
Treponema pallidum (syphilis)
-HPV (genital warts)
Herpes simplex (genital herpes)
Hepatitis & HIV
-Trichomonas vaginalis
Phthirus pubis (pubic lice or “crabs”)
Scabies
Chlamydia trachomatis
- sites of infection?
- type of organism?
- gram stain?
- serological groups? (3)
- treatment?
- urethra, rectum, throat, eyes, endocervix
- obligate intracellular bacteria with biphasic life cycle can’t reproduce outside host cell
- does NOT stain with gram stain as no peptidoglycan in the cell wall
- serovars A-C= trachoma (eye infection/NOT STI)
serovars D-K= genital infection
Serovars L1-L3= Lymphogranuloma venereum
-Azithromycin (1g oral) if uncomplicated
Lymphogranuloma venereum (LGV)
- presentation?
- treatment?
- complications?
-can mimic IBS in those who have contracted it via receptive anal intercourse
inflammation of the rectum gives constant feeling of fullness and PR bleeding, histologically the same as IBD
- doxycycline 100 mg twice-daily for 21 days
- fistulas etc.
describe the replication of chlamydia?
attachment and entry migration to the perinuclear area and EB (elementary body) > RB (reticulate body) transition
inclusion biogenesis and bacterial replication
RB > EB transition and cell lysis
Neisseria gonorrhoea
- site of infection?
- gram stain?
- type of organism?
- presentation?
-urethra, rectum, throat, eyes, endocervix
-gram neg diplococcus
looks like 2 kidney beans facing each other, often appears intracellularly on a gram film as easily easily phagocytosed
- fastidious organism, does not survive well outside the body
- Purulent discharge, i.e dripping tap with pus pouring from e.g. urethra
Diagnosis of chlamydia & gonorrhoea
- name test used
- how are the samples for this test obtained?
-combined nucleic acid amplification tests (NAATs) or polymerase chain reaction (PCR) these test for both organisms in 1 and are highly sensitive and specific
-male: first pass urine sample
female: HVS/vulvo vaginal swab (VVS)/endocervical swab
HVS & VVS can be self taken by the patient or by clinician
+ rectal and throat swabs
eye swabs
tests for N.gonorrhoeae only?
Microscopy of urethral or endocervical swabs
culture on selective agar plates (selective agar suppresses growth of normal flora)
Not done on high vaginal swabs
done to check sensitivities in the SRH clinic
swabs from GP usually come back neg as organism would die in transit
PCR/NAATs
advantages (4) & disadvantages (2) ?
-how long will it take till you can do a test of cure?
adv
much less invasive specimens required esp if patient is asymptomatic (urine in men and VVS in women)
more sensitive than culture
will be + even if organisms have died in transit
test takes hours, not days
Disadv
cannot test antibiotic sensitivities without culture
will detect dead organisms
-have to wait 5 weeks
antibiotic resistance in N.gonorrhoeae means what treatment must now be used?
intramuscular ceftriaxone + oral azithromycin
Syphilis
- causative organism
- gram stain?
- diagnosis?
- caused by spirochaete organism treponema pallidum
- does not stain with gram stain
- cannot be grown in artificial culture media so Dx relies on PCR test or blood serology tests to detect antibodies
name and describe the 4 stages of Syphilis
1Y lesion (chancre) organism multiplies at inoculation site and gets into bloodstream, the chancre will heal without treatment
2Y stage
large no. bacteria circulate in the blood with multiple manifestations at different sites (snail-track mouth ulcers, generalised rash on plans and soles, flu like symptoms)
Latent stage
no symptoms, low level multiplication of spirochaete in intima of small blood vessels
can be divided into early latent &late latent periods
Late stage syphilis
cardiovascular or neurovascular complications many years later
Syphilis diagnosis
-done via what test?
-dark ground microscopy to look for spirochaetes in exudate form 1Y and 2Y lesions
swab of 1Y & 2Y lesions for PCR
serology tests for non-specific and specific antibodies to T.pallidum in blood
non-specific tests indicate how active the disease is and are useful to monitor the response to treatment
specific tests are to confirm the diagnosis but antibody levels decrease very slowly even after successful treatment, might remain + for life
name the non-specific serological tests used to test for Syphilis
VDRL(Venereal Diseases Research Laboratory)
RPR (Rapid Plasma Reagin)
non-specific tests that indicate tissue inflammation
may be falsely +
useful for monitoring response to therapy
usually become neg after successful treatment
name the specific serological tests used to test for syphilis
-what is the screening test for syphilis
TPPA (T. pallidum particle agglutination assay)
TPHA (T. pallidum haemagglutination assay)
specific but remain + for life so are not useful for monitoring response to therapy
-IgM & IgG ELISA
combined IgG & IgM ELISA used as the screening test for syphilis
syphilis treatment?
remains sensitive to penicillin so use injectable long-acting preparations of penicillin
genital warts
- causative organism?
- spread?
- Dx?
- treatment?
- vaccine?
- caused by HPV, a non-enveloped icosahedral virus containing double stranded DNA. types 6 & 11
- spread by close genital skin contact
- clinical dx, no routine microbiology
- cryotherapy, podophyllotoxin cream/lotion
- vaccin given to 11-13 year old girls, against 6,11,16 and 18
Genital herpes
- causative organism?
- spread?
- describe the pathogenesis?
- Dx?
- treatment?
- herpes simplex virus, type 1&2, it is an enveloped virus containing double stranded DNA
- spread by close genital/genital or oropharyngeal/genital contact
-primary infection may be asymptomatic
virus replicates in dermis & epidermis
gets into nerve endings on sensory and autonomic nerves
inflammation at nerve endings of sensory & autonomic nerves
inflammation at nerve endings causes exquisitely painful multiple small vesicles which are easily deroofed
Virus migrates to sacral root ganglion and hides from the immune system there
virus can reactivate from there causing recurrent attacks while intermittent virus shedding can occur in the absence o symptoms
- swab into virus transport medium of the deroofed blister for PCR
- Aciclovir might be helpful if taken early enough + pain relief
