Microbiology of GU tract & STIs Flashcards
List microorganisms that cause STIs
Bacteria: Chlamydia trachomatis, neisseria gonorrhoea, mycoplasma genitalium, treponema pallidum
Viral: HSV, HPV, HIV
Parasites: trichonomas vaginalis, phthirus pubis, scabies
Can you become immune after having an STI
NO, reinfection becomes more common
STIs travel in groups, true or false
TRUE, test for one test for all
What is the predominant microorganism in normal vaginal flora
Lactobacillus - Gm +ve bacilli
What other microorganisms may or may not be present in normal vaginal flora
Group B strep
Candida
Strep viridans group
What is vaginal thrush/candidiasis caused by
Candida albicans fungus
Is vaginal thrush an STI
NO
What are predisposing factors to developing vaginal thrush
Recent antibiotic therapy
Poorly controlled diabetes mellitus
High oestrogen levels - some contraceptives
Immunocompromised patients
What are features of vaginal thrush
Intensely white itchy discharge
Diagnosed clinically or with a high vaginal swab
Treatment of vaginal thrush
Topical clotrimazole cream
PO fluconazole
Can you get candida albicans infection in males
Yes, as candida balanitis
It is far less common
What causes gonorrhoea
Neisseria Gonorrhoea = Gm -ve intracellular diplococcus
Which is less common, chlamydia or gonorrhoea
Gonorrhoea
Where can gonorrhoea infect
Urethra, endocervix, rectum, throat, eyes
What discharge occurs in gonorrhoea
PURULENT (pus) discharge
Neisseria gonorrhoea is a fastidious organism, what does this mean
Fastidious = dies easily if not in ideal conditions
what tests can look for gonorrhoea
Microscopy –> Gm- intracellular diplococci
Culture –> allows determination of antibiotic sensitivities
Nucleic Acid Amplification Test (NAAT) –> picks up genetic material
What is the treatment of gonorrhoea
IM ceftriaxone 1g
What samples are used for NAAT
Males - 1st void urine sample
Females - self taken vaginal swab
What causes Chlamydia
Chlamydia trachomatis = behaves like a gram negative
HAS NO GRAM STAIN
because of no peptidoglycan wall
Chlamydia is the most common STI in the UK, true or false
TRUE
Chlamydia is an obligate intracellular bacteria, what does this mean
It only grows inside the cell, cannot grow outside of the cell
Where can chlamydia infect
urethra, rectum, endocervix, throat, eyes
what are the serological groupings of chlamydia
Serovars A-C: trachoma eye infection
Seovars D-K: genital infection
Serovars L1-3: lymphogranuolma venereum (LGV)
What is LGV and what condition can it mimic
Lymphogranuloma venereum is a tropical disease common in MSM
It is clinically similar to Crohns disease
What is the treatment of Chlamydia
1st - PO doxycycline
2nd - PO azithromycin
3rd - PO erythromycin
How do you test for Chlamydia
NAAT - can test for at the same time as gonorrhoea
What are the disadvantages of NAAT
Cannot perform antimicrobial susceptibility testing
high risk of false positives in gonorrhoea
What is trichonomas vaginalis / trichomoniasis and what is its management
A trophozoite parasite
Presents with vaginal discharge and irritation / urethritis
Tx: PO metronidazole
What is bacterial vaginosis (BV)
Disturbance in the normal vaginal flora
Not caused by just 1 bug
Is BV an STI
No, but it can co-exist with STIs
What does BV present with
Fishy smelling thin homogenous vaginal discharge, may contain bubbles
Describe features of BV
+ve Whiff test from volatile amines
Absence of lactobacilli and presence of coccobacilli clumps as their replacement
Clue cells = vaginal epithelial cells coated with coccobacilli clumps
What are the 3 main features of BV
disturbed microbiome
loss of vaginal acidity
normal cellular protection has changed
Treatment of BV
PO metronidazole 7 days
NB - high relapse rate
No benefit in treating male sexual partner
What causes syphilis
Treponema pallidum
NO GRAM STAIN
Treponema pallidum can be cultured, true or false
FALSE, treponema pallidum cannot be cultured
How do you test for syphilis
Dark ground microscopy PCR serological testing IgM VDLR / RPR
What are the 4 stages of syphilis
Primary - chancre
Secondary - can manifest in anyway
Latent - no symptoms, but continues to grow
Tertiary - CVS or neurosyphilis
What are VDRL and RPR useful for
Useful for monitoring the disease response to therapy and can be used to see whether disease has been cured
Which antibiotic is syphilis very sensitive to
Penicillin
Tx: IM long lasting penicillin preparations
Anything else is inferior
Would even consider desensitising if patient is penicillin allergic
What causes genital herpes
Herpes simplex 1 + 2
virus containing double stranded DNA
Symptoms of genital herpes
painful multiple small vesicles that are easily deroofed
what is the test for genital herpes
viral swab of deroofed blister for PCR
Management of genital herpes
Aciclovir and pain killers
what is the incubation period of chlamydia
14 days
what is Fitz-Hugh-Curtis syndrome
perihepatitis associated with PID
what is the incubation period of gonorrhoea
2-5 days
how long do you wait to do the test of cure in gonorrhoea
2 weeks from site where they had a positive swab
in genital herpes, what is meant by primary infection
never been exposed to herpes before
in genital herpes, what is meant by non-primary first episode
been exposed before, but this is the first symptomatic presentation
what is the incubation period for primary infection of HSV
3-6 days
which has a better prognosis, HSV 1 or 2
HSV 1
what is the most common viral STI in the UK
HPV
what do HPV 1+2 cause
warts on hands and feet
What do HPV 6+11 cause
genital warts
what do HPV 16+18 cause
cervical cancer
what is the incubation of HPV
3 weeks to 9 months
what is the management of genital warts
podopyhyllotoxin
imiquimod
cryotherapy
what is the appearance of treponema pallidum
spirochete
what is the incubation period of primary syphilis
9-90 days
what is a chancre
painless ulceration at site of inoculation
what is the incubation period of secondary syphilis
6 weeks - 6 months
