Microbiology of genital tract infections Flashcards
what bacteria predominates in the healthy vagina? what does this produce?
Lactobacillus spp. predominate in the healthy vagina and produce:
-lactic acid +/- hydrogen peroxide (suppressing growth of other bacteria
What predisposes to vaginal thrush?
- recent abiotic therapy
- high estrogen levels
- poorly controlled DM
- immunocompromised pt
What is the presentation of vaginal thrush?
- intensely itchy
- white cottage cheese like discharge
What is the diagnosis of vaginal thrush?
- clinical
- high vaginal swab for culture - majority caused by c. albacans
What is the treatment of vaginal thrush?
- oral fluconazole
- topical clotrimazole pessary/cream
How can thrush affect the penis?
-candida balanitis
=spotty appearance
What is the presentation of bacterial vaginosis?
-thin, watery, fishy-smelling vaginal discharge
What is the diagnosis of bacterial vaginosis?
- clinically
- raised pH >4.5
- HVS sent to lab and examined microscopically for CLUE CELLS (but is highly innaccurate, hay-ison scoring system estimates the proportion of clue cells to epithelial/lactobacilli cells)
What is the treatment of bacterial vaginosis?
metronidazole orally
What is the classification of prostatis?
1: Acute bacterial prostatitis
2: Chronic bacterial prostatitis
3: Chronic prostatitis/chronic prostatitis pelvic pain syndrome
Acute bacterial prostatitis:
- what are the symptoms
- what can precede this
- what organisms are causative
- what has to be checked in men<35
- what is the diagnosis?
- what is the treatment?
- Sx UTI +/- lower abdo/back/perineal/penile pain and tender prostate on examination
- rare complication of UTI in men
- same organisms as UTI (e.coli/coliforms/enterobacter sp)
- check STI in men
diagnosis:
-clinical signs and MSSU for C+S +/- 1st pass urine for STI check
Treatment:
-ciprofloxacin for 28days or trimethoprim for 28d if risk c diff
What bacterial STIs exist?
- chlamydia
- gonorrhea
- syphillis
Chlamydia trachomitis:
- common
- age incidence
- what type of bacteria is this
Commonest STI in UK
- 20-24yo
- gram -ve obligate intracellular cocci with biphasic life cycle (no reprod. outside cells)
What can chlamydia infect? how is it transmitted?
- urethra
- rectum
- throat
- eyes
- endocervix
Transmitted vaginally, orally, anally
How does chlamydia present in males and females?
70% females and 50% males are asymptomatic
Females:
- PCB/IMB
- lower abdo pain
- dysparaunia
- mucupurulent cervicitis
Males:
- urethral discharge
- dysuria
- urethritis
- epidymo orchitis
What different serology exists for chalmydia? what do they infect?
Serovars A-C: trachoma (eye infection)
Serovars D-K: genitals
Serovars L1-L3: lymphogranuloma venereum
What is the diagnosis for chlamydia?
test 14days post-exposure
NAAT (nucleic acid amplification test): females vulvovaginal swab, males first void urine
MSM: add rectal swab if receptive anal intercourse
What is the treatment of chlamydia?
Azithromycin 1g oral dose for uncomplicated
+ if MSM doxycycline 100mg BD for 1wk (gonorrhea)
What are the complications of chlamydia infection?
- 9% PID risk (episode of PID increases risk ectopic pre. by 10X and carries risk tubal factor infertility of 15-20%)
- tubal damage
- chronic pelvic pain
- transmission to neonate (17% conjunctivity/20% pneumonia)
- conjunctivitis
- SARA/reiters syndrome (commoner in men)
- fitz-hugh-curtis syndrome
What type of bacteria is neisseria gonorrhea? what can it infect?
- Gram -ve intracellular diplococcus (2 kidney beans facing eachother)
- fastidious organism: only survives inside body in ideal conditions
infects urethra, rectum, throat, eyes, endocervix
What is the incubation period of neisseria gonorrhea? is it more easily passed from male to female or female to male?
incubation period of urethral infection in men 2-5days
Male to female 50-90% risk, female to male 20% risk
What is the presentation of gonorrhea in males and females?
Females: up to 50% asymptomatic
- 40% increased/altered/purulent vaginal discharge/dysuria
- pelvic pain <5%
- pharyngeal/rectal usually asymp
Males: asymptomatic 10% or less, urethral discharge >80%
- dysuria
- pharyngeal/rectal infection asymptomatic
What is the diagnosis of gonorrhea?
Microscopy: urethral 90-95% sensitivity, endocervical 37-50% sensitivity
Culture: male urethra >95% sensitivity, female endocervix 80-92% sensitivity
NAATs: >96% sensitivity
what is the management of gonorrhea?
1st line ceftriaxone 50mg IM
2nd line cefixime 400mg oral - if IM contraindicated/refused
cotreatment azithromycin 1g oral
-test of cure in all patients
What are the complications of gonorrhea?
Lower genital tract:
- bartholinitis
- tysonitis
- peri-urethral abscess
- rectal abscess
- epidydimitis
- urethral stricture
Upper genital tract:
- endometriosis
- PID
- hydrosalpinx
- infertility
- ectopic pregnancy
- prostatis
What are the pros and cons of: -microscopy -culture -NAAT for gonorrhea?
Microscopy:
- pros = near pt. diagnosis and timely rx
- cons = invasive test, low sensitivity, requires confirmation
Culture:
- pros = abiotic sensitivity and monitoring
- cons = invasive test, requires specific media and incubation
NAAT:
- pros = non-invasive, less problems with transport or media or storage, takes hrs (quick)
- cons = risk of false +ves, + needs confirmation
What kind of organism is syphillis?
spirochete organism: treponema pallidum (gram -ve)
What is transmission of syphillis?
- sexual
- transplacental
- birth
- blood transfusion
- healthcare workers
-it can be congenital or acquired
Describe the stages of syphilis infection?
Primary lesion = organism multiplies at inoculation site and enters blood stream
- chancre/painless ulcer that heals with no treatment (90% genital sites)
- painless local lymphadenopathy
- incubation period 9-90 days
Secondary stage = large no. of bacteria in blood with multi-manifestations at diff. sites
- snail track mouth ulcers, generalised rash, flu-like symptoms
- macular/follicular/pustular rash on palms and soles
- mucous membrane lesions
- generalised lymphadenopathy
- patchy alopecia
- condylomata lata (highly infectious lesion exuding serum teeming with organism)
- incubation period is 6wks to 6mths
Latent stage = low-level multiplication of organism in intima of small blood vessels
-no symptoms
Late stage = cardiovascular/neurovascular complications
What is the diagnosis of syphilis?
- Dark ground microscopy to look for spirochetes in exudate (not done in tayside)
- Swab primary/secondary lesions or infected lymph nodes for PCR
- Serology: non-specific and specific abodies for t-pallidium in blood
What different serological tests exist for syphillis - which is done in tayside?
Non-specific: VDRL/RPR (not Tayside)
- indicate tissue inflammation = how active disease is
- monitoring response to therapy = usually becomes -ve after treatment
- may be falsely +ve in e.g. SLE, malaria, pregnancy
Specific: TPPA/TPHA (not Tayside)
-specific for syphillis but +ve for life
Screening test for syphillis: IgM/IgG Elisa on clotted blood sample (Tayside)
- if this is -ve = result goes out -ve
- if this is +ve further tests then performed on blood = IgM ELISA, VDRL test, TPPA test
What is the treatment for syphillis?
Early syphillis:
-2.4MU benzathine penicillin X 1
Late syphillis:
-2.4MU benzathine penicillin X 3
Follow up: until RPR is -ve or serofast
- titres should decrease 4 fold by 3-6mths in early
- serological relapse/reinfection if titres increase 4 fold
What causes genital warts?
HPV
- commonest viral STI
- lifetime risk is 80%
Describe the HPV virus, which types infect anogenital epithelium? which are assoc. with cervical cancer?
> 170 types
- 6 and 11 for anogenital warts
- 16 and 18 for cervical cancer
what is the transmission of HPV? what is the incubation period?
- close skin to skin, likely from asymp. partner
- incubation = 3wks - 9mths
- subclinical disease in common on all anogenital sites
- transmission of more than 1 HPV type is common
What is the diagnosis and treatment of HPV?
Diagnosis: clinical (no test)
Treatment:
- podophyllotoxin (warticon) - unlicensed use
- imiquimod (aldera) - immune modifier for all anogenital warts
if dont work:
- cryotherapy
- electrocautery
What is the prognosis of genital warts?
Warts often recur after treatment - immune system fights the infection
- spontaneous clearance warts 20-34%
- clearance with treatment 60%
- persistance despite treatment 20% (smokers/immunosupressants)
What strains does the vaccine for HPV contain? who gets it?
11-13yo girls, MSM up to age 45, HIV pts.
-6,11,16,18
What causes genital herpes? what is this?
Herpes simplex virus type 1(HSV-1, cold sores) and type 2 (HSV-2, genital sores)
-enveloped virus containing double stranded DNA
How is genital herpes transmitted?
Close contact with someone shedding virus - genital-genital or genital -oral
Describe the pathogenesis of herpes simplex virus
Primary infection: asymptomatic or v. florid
-virus replicates in dermis/epidermis
-gets into nerve endings sensory/autonomic nerves
=inflamm. at nerve endings
=exquisitely painful multiple small vesicles, easily de-roofed
Then virus migrates to sacral root ganglion and ‘hides’ from immune system
-virus can reactivate from there = recurrent genital herpes attacks
Intermittant viral shedding can occur in absence of symptoms
Primary herpes infection:
- incubation time
- duration
- symptoms
Incubation time: 3-6 days
Duration: 4-21 days
Symptoms:
- blistering and ulceration of genitalia
- pain
- dysuria externally
- local lymphadenopathy
- vaginal/urethral discharge
- fever/myalgia prodrome
Recurrent herpes infection:
- what is this often misdiagnosed as?
- what are the symptoms?
- duration?
- is this more common with HSV-1 or HSV-2?
Often misdiagnosed as thrush:
- mild/localised anogenital tingling/burning/soreness
- unilateral small blisters and ulcers
- minimal systemic symptoms
Duration: 5-7days
More common with HSV-2
What is the diagnosis of herpes infection?
Swab in virus transport medium of de-roofed blister for PCR, at base of blister (highly sensitive/highly specific)
What is the treatment of herpes infection?
Acyclovir if early stage
Saline bathing
pain relief - topical lidocaine ointment
if a lady is pregnant in the third trimester or 6wks from her EDD and she has a primary herpes simplex infection what is offered?
-planned C-section (if recurrence this isnt routinely offered)
What is trichomonas vaginalis? how does this divide?
single cell protozoal parasite
-divides by binary fission and human hosts only
How is trichomonas vaginalis transmitted? what is the presentation?
Transmission - sexual
Presentation:
- vaginal discharge and irritation in females
- urethritis in males
What is the diagnosis and treatment for trichomonas vaginalis?
Diagnosis: high vaginal swab for microscopy
Treatment: oral metronidazol
Pubic lice:
- what causes this?
- what is the presentation?
- what is the treatment?
Caused by phthirus pubis from close genital skin contact
Presentation:
- lice bite skin and feed on blood = itchy pubic area
- female louse lays eggs on hair next to skin
- males live for 22days, females for 17days
Treatment:
-malathion lotion
What test is done for chlamydia and gonorrhea in the sexual health clinic/GP in practice? What other tests are available?
Combined NAAT or PCR test which tests both organisms in 1 test
- highly specific and sensitive
- 1st pass urine in males
- HVS or vulvo-vaginal swab or endocervical swab during smear for females
- rectal and throat swabs
- eye swabs on babies
Microscopy of urethral/endocervical swabs in sexual health clinics:
-90+% specificity in males, less for females
Culture on selective agar plates: endocervical , rectal, throat swabs in sexual health clinics to check abiotic sensitivity and epidemiology
- selective agar suppresses normal flora growth
- if from GP organisms die on way to lab NAAT/PCR can be done even if they’re dead (that’s why have to wait 5 weeks for test of cure)
