Microbiology Flashcards
what organisms make up normal vaginal flora
Lactobacillus spp. [predominate]
Strep Viridans
Group B beta-haemolytic Strep
Candida spp
why is Lactobacillus spp. important for the vagina flora
produced lactic acid +/- hydrogen peroxide
which suppress growth of other bacteria
what does it mean by beta-haemolytic
complete clear zone around it
what are the non-sexually transmitted genital tract infections
Candida infection (“vaginal thrush”) Bacterial vaginosis
Prostatitis
what are predisposing factors for a candida infection
Recent antibiotic therapy
High oestrogen levels (pregnancy, certain types of contraceptives)
Poorly controlled diabetes
Immunocompromised patients (severely immunocompromised)
what is the Sx of candida infection
intensely itch white vaginal discharge
- “cottage cheese”
spotty rash - just in C. balanitis
diagnosis of candida infection
Clinical diagnosis
High Vaginal Swab [HVS] for culture
Tx for candida infection
1st line - Topical Clotrimazole 500mg 2-3 times daily
2nd line - Oral Fluconazole 150mg as a single dose + Topical Clotrimazole
what is the appearance of c. albicans
yeasts structure with budding
what is the Sx of bacterial vaginosis
thin, watery, fishy-smelling vaginal discharge
Ix of bacterial vaginosis
clinical diagnosis
raised vaginal pH (pH > 4.5)
HVS = looking for presence of clue cells
Tx of bacterial vaginosis
Metronidazole 500mg twice daily
what is the classification of prostatitis
- Acute bacterial prostatitis
- Chronic bacterial prostatitis
- Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS)
Sx of acute bacterial prostatitis
Sx of UTI [dysuria, frequency, nocturia, haematuria]
lower abdomen pain, back/perineal/penile pain,
tender prostate O/E
what organism is responsible for acute bacterial prostatitis
E.Coli
- same as UTI
if a patient has acute bacterial prostatitis, what else should they be tested for
STI in patients < 35y/o: Gonorrhoea, chlamydia
Ix for acute bacterial prostatitis
Clinical signs + MSSU for C&S
First pass urine for STI tests
Tx for acute bacterial prostatitis
1st line = Ciprofloxacin for 28 days
2nd line = Trimethoprim for 28 days if high C. Diff risk
what is the commonest bacterial STI in the UK
Chlamydia trachomatis
what can chlamydia affect
urethra, rectum, throat and eyes
how does chlamydia strain with gram stain
NO stain
- no peptidoglycan in the cell wall
what are the 3 serological groupings of chlamydia
Serovars A-C = Trachoma (eye infection) (NOT an STI)
Serovars D-K = Genital infection
Serovars L1-L3 = Lymphogranuloma venereum
Tx of chlamydia
Azithomycin (1g oral dose) for uncomplicated chlamidia
Doxycycline 100mg bd x 7 days
what is Lymphogranuloma venereum
inflammation of the rectum
- can mimic crohns disease as people think they need to go to the toilet
what does neisseria gonorrhoea affect
urethra, rectum, throat, eyes, endocervix
how does neisseria gonorrhoea appear on gram staining
Gram negative diplococcus
- Look like “2 kidney beans facing each other”
Ix of chylamydia and gonorrhoea
NAAT or PCR - tests for both
For males, need first pass urine sample
For females, HVS or vulvo-vaginal swab (VVS)
what is the advantages of PCR/NAAT over culture
less invasive
more sensitive
takes hours for result [not days]
what is the disadvantages of PCR/NAAT over culture
Cannot test antibiotic sensitivities without culture, so difficult to track antibiotic resistance
Will detect dead organisms
how long do you have to wait to do a test of cure
5 weeks
Tx of gonorrhoea
IM ceftriaxone + oral azithromycin
what causes syphilis
Treponema pallidum
how does Treponema pallidum stain
does not stain with gram stain
what are the 4 stages of syphilis
1y lesion (chancre)
2y stage
Latent stage
Late stage
what is 1y lesion stage
organism multiplies at inoculation site and gets into bloodstream.
Chancre will heal without treatment
what is 2y lesion stage
large nos. bacteria circulating in blood with multiple manifestations at different sites
(“snail-track” mouth ulcers, generalised rash, flu-like symptoms etc.)
what is the latent stage
no symptoms, but low-level multiplication of spirochaete in intima of small blood vessels.
Can be divided into early latent and late latent periods.
Not infectious in the latent stage.
what is late stage syphilis
cardiovascular or neurovascular complications many years later
Ix of syphilis
1 - Swab of 1y or 2y lesions for PCR
2 - Serology – tests for non-specific and specific antibodies to T. pallidum in blood
what are the two type of tests done in serology of syphilis
non specific
- indicates how active the disease is
- useful to monitor the response to treatment
specific
- confirm diagnosis
1st line test for syphilis
IgM & IgG ELISA
2nd line test for syphilis if 1st line positive
IgM ELISA
VDRL test
TPPA test
Tx for syphilis
2.4 IM Benzathine penicillin x1
if penicillin allergic
- Doxycyline 100mg oral + Prednisolone 40-60mg
what is the commonest viral STI
genital warts
what causes genital warts
HPV
what types of HPV are associated with pathology
6 & 11 = genital warts
16 & 18 = risk of cervical cancer
how is genital warts spread
by close genital skin contact
diagnosis of genital warts
clinical
Tx for genital warts
cryotherapy; podophyllotoxin cream/lotion
what vaccine is given for HPV
quadrivalent vaccine give to 11-13 year old girls
immunises against types 6,11,16 & 18
how do genital warts appear
whiter than the surrounding skin with a rough surface
what causes genital herpes
HSV type 1 and type 2
HSV-1 and HSV-2
what is HSV-1 also associated with
cold sores
how are genital herpes spread
genital/genital or oropharyngeal/genital contact
what is the pathogenesis of genital herpes
Primary infection may be asymptomatic (or very florid)
Virus replicates in dermis and epidermis
Gets into nerve endings of sensory and autonomic nerves
Inflammation at nerve endings
Virus migrates to sacral root ganglion and “hides” from the immune system there
Virus can reactivate from there causing recurrent genital herpes attacks
presentation of genital herpes
exquisitely painful multiple small vesicles, which are easily deroofed
Ix for genital herpes
Swab deroofed blister for PCR test
Tx for genital herpes
pain relief
aciclovir may help if taken early enough
what is Trichomonas vaginalis
single celled protozoal parasite
Sx of Trichomonas vaginalis
vaginal discharge
irritation
urethritis in males
Ix and Tx of Trichomonas vaginalis
HVS for microscopy
Oral metronidazole
what is Tx for lice
malathion lotion
