Microbiology of Genital Tract Infections Flashcards
What are the bacterial causes of STIs?
chlamydia trachomatis; neisseria gonorrhoeae and treponema pallidum
What is the difference between gonococci and chlamydia in terms of discharge?
gonococci- intense neurtrophil response with lots of pus whereas chlamydia produces a mild, watery discharge
What is the only method for transmission of STIs?
human-human, eg no fomites
How common is candida infection?
30% females are colonised with Candida and haven o symptoms
What ar ethe predisposing factors for candida infection?
recent antibiotic therapy; high oestrogen levels (pregnancy, contraceptives); poorly controlled DM; immunocompromise
How does candida present?
intensely itchy white vaginal discharge
What is the treatment for candida?
tropical clotrimazole pessary or cream; oral fluconazole
What is the most common form of candida?
candida albicans
What is the appearnace of C.albicans on gram film?
buds and hyphae
Who gets candida balanitis?
males
What is the presentation of candida balanitis?
red spotty rash over penis
What are the three types of prostatits?
acute bacterial; chronic bacterial prostatitis; chronic prostatitis/chronic pelvic pain syndrome
What are the symptoms of acute bacterial prostatits?
UTI symptoms; lower abdo/back/perineal/penile pain and tender prostate
What causes acute bacterial prostatitis?
complication of UTI
What causes acute bacterial prostatitis?
e.coli and other ocliforms; enterococcus sp.
What bugs should you check for in patients <35 with acute bacterial prostatitis?
gonorrhea and chlamydia
How is a test for chlamydia and gonorrhea done?
first pass urine
What is the treatment for acute bacterial prostattis?
trimethoprim for 28 days
What infection does the presence of genital ulcers increase the risk of getting?
HIV
What is the main bug in the normal vaginal flora?
lactobacillus spp.
What do lactobacilli produce?
lactic acid and hydrogen peroxide
What type of lactobacillus is found in yoghurt and why is it not effective as a remedy?
lactobacillus acidophilus which is rarely found in the normal vagina so yoghurt is not effective
What is the change in pH with bacterial vaginosis?
becomes more alkaline
What organism predominates in bacterial vaginosis?
gardnerella vaginalis and other anaerobic bacteria
What is the discharge in bacterial vaginosis like?
homogenous and may contain bubbles
What is a positive whiff test?
adding potassium hydroxide to the discharge on the slide elicits an amine-like, fishy odour
What is seen on a wet mount with bacterial vaginosis?
absence of bacilli and their replacement with clumps of coccobacilli which can obscure the cell edges (clue cells)
What does high numbers of leukocytes in the wet mount of a woman with BV suggest?
coincident infection eg trichomoniasis or bacterial cervicitis
What are the risks associated with bacterial vaginosis?
incrased rate of upper tract infection eg endometritis; salpingitis; preterm delivery if pregnant; increased HIV risk
What is the treatment of bacterial vaginsosi?
metronidazole for 7 days
What is the most common bacterial STI in the UK?
chlamydia trachomatis
What areas of the body does chlamydia infect?
urethra; rectum; throat and eyes; endocervix
Why does chlamydia not stain with gram stain?
no peptidoglycan in the cell wall
How does chlamydia live?
obligate intracellular bacteria
What does lymphogranuloma venereum cause?
proctitis
Who is at risk for lymphogranuloma venereum?
men who have sex with men
What is the treatment for chlamydia?
azithromycin 1 g oral dose or doxy bd 7 day
What serovars are genital infections usuall caused by?
D-K
What tests are used to diagnose chlamydia and gonorrhoea?
combined nucleic acid amplification or PCR
What samples are used for chlamydia and gonorrhea diagnosis?
male- first pass urine ; females- HVS or VVS; rectal and throat; eye
What areas of the body does neisseria gonorrhoeae infect?
urethra; rectum; throat and eyes; endocervic
How does gonorrhea appear on gram stain?
gram negative diplococcus - like two kidney beans facing each other
Why do gonorrohea often appear intracellularly on gramfilm?
easily phagocytosed by polymorphed
What is meant by gonorrhea being a fastidious organism?
doesnt survive well in less than ideal growth condition
Why is PCR/ NAAT better than culture?
less invasive specimens required; more sensitive; quicker
Why may culture be better than PCR/NAAT?
cannot track antibiotic resistance
How is gonnorhoeal infection of the pharynx aquired?
orogenital exposure- fellatio more than cunnilingus
How does pharyngeal gonorrhoea presnet?
mostly asymptomatic although can have exudative pharyngitis and cervical lymphadenopathy
What is the treatment for n.gonorrhoeae?
IM ceftriaxone and oral azithromycin
What should be done for all patients after treatment of gonorrhea?
test of cure
What is the function of azithromycin in the treatment of gonorrhoea?
cotreatment of chlamydia and treat against resistance
Why is routine screening for rectal gonorrhea done in MSM and not females?
> 50% of MSM with gonorrhea have only extragenital infections but this is rare in women
What bug causes syphilis?
treponema pallidum
How is syphilis diagnosed? wHy?
PCR or serological tests to detect antibodies as cannot be grown in artifical culture media
What is the priamry lesion in syphilis?
chancre- painless ulcer at site of infection, will heal without treatment
What is the secondary stage of syphilis?
snail track mouth ulcers, generalised rash, flu-like symptoms; larg numbers of bacteria in blood
What are the 4 stages of syphilis?
primary lesion; secondary stage; latenet stage; late stage syphilis
What are the non-specific serological tests that can be done for syhpilis?
VDRL ad RPR
What are the non-speciic serological tests measuring and what are they measuring?
useful for monitroing response to therapy, meausre tissue inflammation
What is the screnning specific serological test for syphilis?
IgM and IgG ELISA
What is the treatment for syphilis?
injectable lon-acting penicillin
what is the pathogenesis of genital herpes?
virus replicates in dermis and epidermis; gets into nerve endings of sensory and autonomic nerves- inflammation at nerve endings, virus migrates to root ganglion
How is genital herpes diagnosed?
swab in virus transport medium of deroofed lister for PCR
What is the treatment for genital herpes?
aciclovir and pain relief
How does trichomonas vaginalis divide?
binary fission
What is trichomonas vaginalis?
single celled protozoal parasite
What does trichomonas vaginalis presnet with?
vaginal discharge and irritation
How is trichomonas vaginalis diagnosed?
HVS for microscopy
What is the treatment for trichomonas vaginalis?
oral metronidazole
How is pubic lice acquired?
close genital skin contact
What causes itching with phthirus pubis?
lice bite skin and feed on blood
What is the treatment for phthirus pubis?
malathion lotion
