Microbiology of the Genital tract Flashcards
What is the predominate bacteria in the normal vaginal flora and what does it do?
lactobacillus spp. - produces lactic acid and hydrogen peroxide to suppress the growth of other bacteria
What other organisms are present in the normal vaginal flora?
Strep viridans
Group B-haemolytic Strep
Candida spp.
Name 3 non-sexually transmitted genital tract infections
Candida (thrush)
Bacterial vaginosis (fishy smell)
prostatitis
What % of woman are colonised by Candida but show no symptoms of a thrush infection?
30%
What are predisposing factors for a candida infection?
recent antibiotic therapy
High oestrogen levels (pregnancy, some contraceptives)
Poorly controlled diabetes
Immunocompromised patients
What is the presentation of thrush?
Intensely itchy white vaginal discharge
How do you clinically diagnose thrush?
High vaginal swab for culture
What organism causes most cases of thrush?
Candida albicans
What is the treatment of Candida infections?
Topical clotrimazole pessary or cream
Oral fluconazole
What organisms can cause Bacterial vaginosis?
Gardnerella vaginalis
Mobiluncus sp.
Others include anaerobes
What are the predisposing factors of Bacterial vaginosis?
Uncertain
What are the symptoms of bacterial vaginosis?
Thin, watery, fishy smelling vaginal discharge
How do you diagnose bacterial vaginosis?
Raised vaginal pH >4.5
What is looked for in a laboratory sample of suspected bacterial vaginosis?
CLUE CELLS
What scoring system estimates the proportion of clue cells to epithelial cells and lactobacilli?
Hay-lyson scoring system
What is the treatment for bacterial vaginosis?
Metronidazole orally
What are the 3 classifications of Prostatitis?
- Acute bacterial prostatitis
- Chronic bacterial prostatitis
- Chronic prostatitis / chronic pelvic pain syndrome (CP/CPPS)
What are the organisms involved with acute bacterial prostatitis?
Same as a UTI, E.coli and other coliforms, enterococcus sp.
Always check for STI’s
What is acute bacterial prostatitis?
A rare complication of a UTI in men
What are the symptoms of acute bacterial prostatitis?
Symptoms of a UTI, may have lower abdo/back/perineal/penile pain
Tender prostate on examination
How is acute bacterial prostatitis diagnosed?
Clinical signs
MSSU for C&S
tests for STI’s
What is the treatment for acute bacterial prostatitis?
Ciprofloxacin for 28 days
Trimethoprim for 28 days if high C.diff risk
Name 3 bacterial STI’s
Chlamydia tachomatis
Neisseria gonorrhoeae
Treponema pallidum (Syphilis)
Name 3 viral STI’s
Human papilloma virus (genital warts)
Herpes simplex virus (Genital herpes)
Hepatitis and HIV
Name 3 parasitic STI’s
Trichomonas vaginalis
Phthirus pubis (Pubic lice/crabs)
Scabies
What parts of the body does Chlamydia effect?
urethra rectum throat eyes endocervix
Describe Chlamydia trachomatis
Obligate intracellular bacteria with biphasic life cycle - “energy parasite”
What colour does Chlamydia trachomatis stain with gram stain?
It doesn’t, no peptidoglycan in the cell wall
What are the 3 serological groupingsof Chlamydia trachomatis?
Serovars A-C = Trachoma (eye infection) (no an STI)
Serovars D-K = Genital infection
Serovars L1-L3 = Lymphogranuloma venereum
What is the treatment for Chlamydia trachomatis?
Azithromycin (1g oral dose) for uncomplicated chlamydia
What is the infectious cysle of Chlamydia?
0hrs - attachment and entry
2-12hrs - Migration to perinuclear area and EB–> RB transition
12-24hrs - inclusion biogenesis and bacterial replication
24-48hrs - RB–> EB transition and cell lysis
Where does Neisseria gonorrhoeae effect?
Urethra Rectum Throat Eyes Endocervix
Describe Neisseria gonorrhoeae
Gram -ve diplococcus
Like two kidney beans facing each other
Easily ohagocytosed by polymorphs, so often appear intracellularly on a gram film
What does the term ‘Fastidious organism’ mean?
does not survive well in less than ideal growth conditions
i.e. outside the body
How can you diagnose both chlamydia and gonorrhoea?
Combined nucleic acid amplification tests (NAATs) or polymerase chain reaction test (PCR)
tests for both organisms in 1 test
What other tests are available for Neisseria gonorrhoeae?
Microscopy of urethral / endocervical swabs
Culture on selected agar plate
What are some advantages for PCR/NAATs over culture?
Less invasive specimens required
More sensitive than cultures
+ve even if organism has died in transit to the lab
Takes hours, not days
What are disadvantages of PCR/NAATs over culture?
Cannot test antibiotic sensitivities without culture, so difficult to track resistance
Will detect dead organism (have to wait 5 weeks to do “test of cure” tests
What is the recommended treatment for Neisseria gonorrhoeae?
Intramuscular ceftriaxone + oral azithromycin
What organism causes Syphilis?
the spirochaete organism that is Treponema pallidum
What colour does Treponema pallidum gram stain?
It doesn’t
How do you test for Treponema pallidum?
PCR or serology tests for antibodies. No culture as it can’t be grown in artificial culture media
Describe the 1st stage of syphilis
1 y lesion (chancre) - organism multiplies at inoculation site and gets into bloodstream. Chancre will heal without treatment
Describe the second stage of syphilis
2y stage - large nos. bacteria circulating in blood with multiple manifestations at different sites (snail-track mouth ulcers, generalised rash, flu-like symptoms)
Describe the 3rd stage of syphilis
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
Describe the 4th stage of syphilis?
Late stage - cardiovascular or neurovascular complications many years later
How do you diagnose syphilis?
Dark ground microscopy to look for lesions for spirochaetes in exudate from 1y to 2y lesions
Swab of 1y and 2y lesions for PCR
Serology for specific and non-specific antibodies to Treponema pallidum
What are the non-specific tests for Treponema pallidum for?
Tests indicate how active the disease is and are useful to monitor the response to treatment
What are the specific tests for Treponema pallidum for?
Confirm the diagnosis, but antibody levels decrease very slowly even after successful treatment, ad often remain for life
When may non-specific tests for Treponema pallidum give a false positive?
SLE
Malaria
Pregnancy
What are specific serological tests for Treponema pallidum?
TPPA - Treponema pallidum particle agglutination assay
TPHA - Treponema pallidum haemagglutination assay
What two antibodies are looked for in the ELISA screening test for syphilis?
IgG and IgM
What is Treponema pallidum very sensitive to?
Penicillin
What are genital warts?
Non-enveloped icosohedral virus containing double stranded DNA
What strands of HPV cause genital warts?
6 and 11
What strands of HPV cause cervical cancer?
16 and 18
What is the diagnosis of genital warts?
Mainly clinical
What is the treatment for genital warts?
Cryotherapy
Podophyllotoxin
Cream/lotion
What age group is the quadrivalent vaccine given to?
11-13 year olds girls
What does the quadrivalent vaccine protect against?
HPV type 6,11,16 and 18
Describe genital herpes?
Enveloped virus containing double stranded DNA
What causes genital herpes?
HSV-1
HSV-2
How may the primary infection present?
Asymptomatic or very florid
Where does the virus in genital herpes replicate?
In the dermis and epidermis
Where do genital herpes viruses get into?
Into the nerve endings of sensory and autonomic nerves
Causes inflammation, exquisitely painful, multiple small vesicles which are easily deroofed
Where does the virus in genital herpes migrate to?
The sacral root ganglion and “hides” from the immune system
How is genital herpes diagnosed?
Swab for virus transport medium of deroofed blister for PCR testing
What is the treatment for genital herpes?
Aciclovir helpful if taken early
Pain relief
Are the vaccines for genital herpes?
Yes, but they have been dissapointing
What is Trichomonas vaginalis?
Single celled protozoal parasite.
divides by binary fission (no cyst form is known) and it’s only host is human
What does Trichomonas vaginalis?
Vaginal discharge and irritation in females (and urethritis in males
How do you diagnose Trichomonas vaginalis?
High vaginal swab for microscopy PCR
What is the treatment for Trichomonas vaginalis?
Oral metronidazole
What is Phthirus pubis?
Pubic lice
Lice bite skin and feed on blod, which causes itching in pubic area
How do pubic lice replicate?
Female louse lays eggs on hair next to skin
How long do pubic lice live for?
Males for 22 days, females for 17 days
What is the treatment for pubic lice?
malathion lotion
