Microbiology Flashcards
What is the normal pH of the vagina?
acidic - 4.5
What organism predominates in the vagina and is protective?
lactobacillis - gram +ve bacilli
What do lactobacillis produce?
lactic acid and hydrogen peroxide
What exist in small numbers in the vagina?
candida
group B haemolytic strep
strep viridens
What organism commonly causes candida infection?
Candida albicans
What predisposes to a candida infection?
recent antibiotic therapy
high oestrogen levels
poorly controlled diet
immunocomprimised patients
How does candida present?
“cottage cheese”
intensely itchy white vaginal discharge
What swab is done for candida?
high vaginal for culture
What is the treatment of candida?
AZOLE
topical clotrimazole pessentery or cream
oral fluconazole
What is candida balantis?
spotty rash on the tip of a males penis
Is candida balantis sexually transmitted?
NO
What organism causes gonorrhoea?
nisseria gonnorhea
What does nisseria gonnorhea look like on microscopy?
gram negative intracellular diplococcus
What is the action of nisseria gonnorhea?
attaches to host epithelial cells and is endocytosed into the cell to then replicate within the host cell and be released into the subepithelial space
How is gonnorhoea diagnosed?
1st line - NAATS
2nd line - swab of pus + culture
How does gonnorhea present?
purulent discharge
can infect the urethra, rectum, throat, and eyes
endocervix in females
Is gonnorhea always symptomatic?
NO - 50% of women with it have no symptoms
What happens to a baby if the pregnant mother has gonnorhea?
sticky eyes
What is the benefit of doing NAATs over culture?
the organism dies quickly so better to look for DNA remnants
How is gonnorhea treated?
IM Ceftriaxone 1G
What are possible gonorrhea complications for males?
tysonitis
rectal and periurethral abscesses
epididymis
prostatitis
What are possible gonorrhea complications for females?
bartholinitis rectal and periurethral abscesses PID endometritis ectopic pregnancy hydrosalphinix infertility
What is the most common bacterial STI?
chlamidya
What serovar corresponds to the genital infection?
D-K
What does serovars A-C correspond to?
trachoma - eye infection
NOT AN STI
What does serovars L1-L3 correspond to?
lymphogranuloma venerum (LGV)
What is LGV?
occurs in those who are from tropical places and MSM
histologically identical to crohns disease
How does LGV present?
rectal pain
discharge
bleeding
What organism causes chlamidya?
chlamidya trachomatis
How is chlamidya tachomatis seen on histology?
intracellular bacteria
surrounding inflammatory cells
no peptidoglycan so doesnt stain on gram staining - gram negative
What type of female swab is done for both chlamidya and gonorrhea?
vulvo-vaginal swab - can be self taken
What is done to diagnose chlamidya?
NAATS - 1st line done after 14 days
PCR
What male swab is done for chlamidya?
first pass urine
What is the treatment for chlamidya?
Doxycycline 100mg for 7 days
How does chlamidya present for women?
post coital or intermenstrual bleeding
pain during sex - dyspareunia
lower abdo pain
micropurulent cervicitis
How does chlamidya present for men?
urethral discharge
dysuria
urethritis
epididymio-orchitis
What disease do 9% of women with chlamidya develop?
pelvic inflammatory disease (PID)
What does PID increase?
risk of ectopic pregnancy x10
infertility 15-20%
Apart from PID, what are other chlamidya complications?
reactive arthritis
Fitz-hugh-curtis syndrome (perihepatitis - piano string adhesions)
What pathogen causes bacterial vaginosis?
trichomonas vaginalis - single celled protozoal parasite
What causes bacterial vaginosis?
acidic environment becomes more alkaline and anaerobes take over
How is bacterial vaginosis transmitted?
sexual contact
but can be just by using same towels etc
How does bacterial vaginosis present?
vaginal discharge and irritation in females
What are the complications of bacterial vaginosis?
increased rate of upper GU infections - endometritis and salpingitis
can cause premature rupture of membranes and preterm delivery
increased risk of HIV
How is bacterial vaginosis diagnosed?
high vaginal swab for microscopy
How is bacterial vaginosis treated?
oral metronidazole for 7 days
Should you offer treatment to the male sexual partners of those with bacterial vaginosis?
no - no benefit
What is the pathogen causing syphilis?
treponema pallidum
How is treponema pallidum seen on microscopy?
spirochaete
What is the primary lesion seen in syphilis?
chancre
Will the chancre heal without treatment?
YES
What is the incubation period for the chancre?
9-90 days
What is the pathogenesis of treponema pallidum?
organism multiples at innoculation site and gets into blood stream then it multiplies in the blood and there are manifestations at different sites
What is the secondary stage of syphilis?
large number of bacteria circulating in the blood stream
What is the incubation period for the second stage of syphilis?
6 weeks - 6 months
What is the latent stage of syphilis?
no symptoms
low level of multiplication of spirochete in intima of small blood vessels
What is the primary testing for syphilis?
dark ground microscopy
PCR
What is the secondary testing for syphilis?
serology - ELISA
VDRL and RPR
What serology is specific for syphilis?
ELISA
What serology is non specific for syphilis?
VDRL and RPR
What happens to serology after sucessful treatment?
becomes negative
decrease by 4 fold in 3-6 months
What is the treatment for syphilis?
penicillin - benzylpenicillin
What causes herpes?
HSV 1 and HSV 2
What most commonly causes herpes - HSV 1 or HSV 2?
HSV 2 - 4-5 attacks per year
How does HSV appear on microscopy?
enveloped virus containing double stranded DNA
How is herpes transmitted?
close contact with someone shedding the virus
genital/oropharyngeal
What is the pathogenesis of herpes?
virus replicates in the dermis and epidermis then gets into nerve endings of sensory and autonomic nerves
inflammation of the nerve endings cause exquisitively painful small vesicles when are easily reroofed
virus migrates to the sacral root ganglion and hides from the immune system there
the virus can reactivate
How is herpes diagnosed?
swab deroofed blister then PCR
How is herpes treated?
aciclovir if caught early enough
saline bathing or topical lidocaine if verysore
How does herpes present?
blistering and ulceration of external genitalia pain external dysuria discharge local lymphadenopathy
What pathogen causes pubic lice?
pthirus pubis
How is pubic lice treated?
malathion lotion
What is the most common viral STI?
HPV
What HPV types are covered by the vaccine?
6
11
16
18
What are the low risk HPV types? What do they cause?
6 + 11
anogenital warts
What are the high risk HPV types? What do they cause?
16 + 18
neoplasia
What do HPV 1 and 2 cause?
palmar and plantar warts
What is the incubation period of HPV?
3 weeks - 9 months
What is the lifetime risk of aquiring an HPV infection?
80%
How does HPV present?
cauliflower lesions around areas of friction
can also get them perianally
How is HPV treated?
Podophyllotoxin - warticon (cytotoxic so not for extragenital warts)
Imiquimod - 1st line for anogenital warts
Cryrotherapy
Electrocautery
When is the HPV vaccination given?
females aged 11-13
MSM
What is mycoplasma genitalium?
emerging sexually transmitted pathogen
associated with non gonococcal urethritis and PID
diagnosed by NAAT tests
40% levels of macrolide