Microbiology Flashcards
Produced by the commensal bacteria in the vagina to suppress the growth of other bacteria
Lactobacillus spp. produces lactic acid (+/- hydrogen peroxide)
Organism that is the cause of meningitis in neonates and can also be a commensal organism in the vagina
Group B beta-haemolytic streptococcus
Main organism that makes up the normal vaginal flora
Lactobacillus spp.
Name the predisposing factors for candida infection
Recent antibiotic therapy
High oestrogen levels (pregnancy, contraception)
Poorly controlled diabetes
Immunocompromised patients
Why does poorly controlled blood sugar within diabetes cause thrush?
High sugar levels encourage bacterial growth
Intensely itchy thick, white vaginal discharge - diagnosis?
Candid infection (vaginal thrush)
Treatment for candid infection (vaginal thrush)
Topical clotrimazole pessary or cream - put inside the vagina
Oral fluconazole
What is the typical appearance of candida infection on the male?
Spotty appearance
Thin, watery, fishy-smelling vaginal discharge (sometimes brown in colour) and a raised vaginal pH - diagnosis?
Bacterial vaginosis (BV)
Bacterial vaginosis is commonly caused by which organisms?
Anaerobes - Gardnerella vaginalis/Mobiluncus sp.
Treatment for Bacterial vaginosis?
Oral metronidazole (5 day course)
Laboratory testing that can be done for BV?
High vaginal swab (HVS) to look for the presence of clue cells
How may acute bacterial prostatitis present?
Symptoms of UTI; lower abdominal/back/perineal/penile pain; tender prostate on examination
Treatment for acute bacterial prostatitis?
Ciprofloxacin for 28 days (altered depending on culture result)
Trimethoprim if high C.diff risk (elderly)
Bacteria that causes Chlamydia?
Chlamydia tracahomatis
Sites where the chlamydia can infect
Urethra, rectum, throat and eyes
Endocervix (females)
Treatment for Chlamydia?
Azithomycin (1g oral dose)
How long after unprotected sex will chlamydia be detectable?
48hrs
Which is more common - chlamydia or gonorrhoea?
Chlamydia
Sites where gonorrhoea can infect
Urethra, rectum, throat and eyes
Endocervix (females)
Describe the morphology of Neisseria gonorrhoeae
Gram negative diplococcus: looks like two kidney beans facing each other
Which tests are used to diagnose chlamydia AND gonorrhoea?
Nucleic acid amplification tests (NAATs) or polymerase chain reaction test (PCR)
Which samples are taken for gonorrhoea and chlamydia testing?
Male patients - first pass urine sample
Female patients - HVS or VVS
Rectal and throat swabs
Eye swabs
What are the advantages of NAATs/PCR tests over culture?
Much less invasive
Much more sensitive
Will be positive even if organisms have died in transit
Takes hours not days
What are the disadvantages of PCR/NAATs tests?
Cannot test antibiotic sensitivities
Will detect dead organisms - not a test of cure
Recommended treatment for gonorrhoea in the UK?
IM ceftriaxone and oral azithromycin
Which STI should be tested for cure due to high numbers of resistant strains?
Gonorrhoea
Name the organism that causes syphilis
Treponema Pallidum
What testing cannot be done on syphilis?
Cannot be grown in culture medium - diagnosis relies on PCR test or serological tests
Describe the first stage of the syphilis illness
Organism multiplies at the inoculation site and get into bloodstream. Chancre will heal without treatment.
Describe the second stage of syphilis illness
Large numbers of bacteria circulate in the blood with multiple manifestations at different sites (snail-track mouth ulcers, generalised rash (palms of hands and soles of feet - copper colour), flu-like symptoms)
Describe the latent stage of syphilis
Patient will be asymptomatic. Low level of multiplication of the spirochaete in the small blood vessels
Describe late stage syphilis
Cardiovascular or neurovascular complications Aortic aneurysm (commonly in the ascending or the arch) Proprioception difficulty, difficulty focusing eyes, grandiose delusions)
What is the treatment for syphilis?
Injectable long-acting preparations of penicillin
Name the organism that causes genital warts
Human Papilloma Virus, types 6 &11
Which type of HPV is associated with an increased risk of cervical cancer?
Types 16 & 18
What is the treatment for genital warts?
Cryotherapy
Podophyllotoxin cream/lotion
What types of HPV does the vaccination immunise against?
6, 11, 16 and 18
Which type of herpes simplex virus causes both genital herpes and cold sores?
Type 1
How are genital herpes spread?
Via genital/genital or oropharyngeal/genital contact
How are genital warts spread?
Via genital-genital contact
Describe the appearance of genital warts
They are often whiter than the surrounding skin and the surrounding skin is rough
How is genital herpes diagnosed?
Deroof blisters and swab for PCR testing
What is the treatment for genital herpes?
Aciclovir if early enough, can also give pain relief
How is Trichomona Vaginalis diagnosed?
High vaginal swab
PCR can be done but not in Tayside - no good test for males.
Likely diagnosis in a women with multiple small painful ulcers on her genitalia and a flu-like illness. She is unable to urinate due to the discomfort.
Herpes Simplex
Likely diagnosis in a non-sexually active woman who presents with a frothy brownish vaginal discharge which has an offensive smell.
Bacterial vaginosis
Likely diagnosis in a women who presents with vulval irritation and a white discharge
Candida albicans
What is the most commonly reported STI in sexual health clinics?
Chlamydia
Which form of HSV has a higher rate of viral shedding?
HSV 2
How is a pregnant mother who is infected with a primary infection of HSV during the third trimester managed?
Mother will have no antibodies developed already and so no protection for foetus. Give IV acyclovir before delivery and then give dose to baby after birth.
What is the incubation period of HPV?
Ranges from 3 weeks to 9 months - average about 3 months
Which STI is known as the “great imitator” because its symptoms resemble those of other infections?
Syphilis
