Microbiology - Gender, Family & Culture Flashcards
Why are STIs difficult to control
Increasing density and mobility of human population
The difficulty of engineering changes in human sexual behaviour
The absence of vaccines for almost all STIs, expect for the HPV vaccine
Common STI causing organisms
Papillomaviruses (6, 11, 16 and 18) Chlamydia trachomatis Candida albicans Trichomonas vaginalis HSV-1, 2 Neisseria gonnorhrea HIV Trepenoma pallidum Hep B virus Haemophilus ducreyi Phthirus pubis
Disease cased by papillomaviruses
Genetic warts
Dysplasia
Disease caused by Phthirus pubis
Pubic lice
Treatment of pubic lice
Permethrin cream
How does the urogenital tract being a continuum affect the spread of microorganisms
Micro-organisms can spread easily from one part to another
The distinction between vaginitis and urethritis or urethritis and cystitis is not always easy or necesary
Microbrial strategies against urine flow (for urethral infection)
Infection of urethral epithelial or sub epithelial cells e.g. HSV or chlamidyia
Microbial strategy against cell-mediated immune response
Antigenic variation - allows re-infection
Why do most microbes require close contact or spread through vectors
Unstable on drying
Vaginal defences against microbes
Vaginal pH of 5.0 inhibits colonization by all except the lactobacilli and certain other streptococci and diphtheroids
How can intestinal bacteria cause cystitis
Common invaders of urinary tract and can adhere to GU tract e.g. E.coli
Whoa re STIs more common in
Uncircumcised males
Effect of female urogenital tract being shorter than male
More vulnerable to infection
Semen as source of infection
CMV shed from oropharynx, HIV and hep B found in semen
What organism causes syphilis
Trepenoma pallidum (spirochete)
How does T. palladium enter the body
Through minute abrasions or mucous membranes
Transmission of syphilis
Requires close personal contact; horizontal spread occurs through sexual contact and vertical spread via transplacental infection of the foetus
When is congenital syphilis acquired
After 3 months of pregnancy
How can congenital syphilis manifest
Serious infection resulting in intrauterine death
Congenital abnormalities, which may be obvious at birth
Silent infection, which may not be apparent until ~2 yrs (facial and tooth deformities)
Initial contact of syphilis
2-10 weeks
Primary chancre at site of infection
Primary syphilis
1-3 months
Enlarged inguinal nodes
Secondary syphilis
2-6 weeks
Flu-like illness, mucocutanoeus rash, spontaneous resolution
When do you experience latent syphilis
Last 3-30 years
Tertiary syphilis
Neurosyphilis
Cardiovascular syphilis
Serological dx of syphilis
Non-spp tests are VDRL and RPR
ELISA - IgM and IgG
Confirmation of a dx requires several serological tests
VDRL
Venereal Disease Research Lab
RPR
Rapid Plasma Reagin
Treatment of syphilis
Penicillin
Organism causing gonorrhoea
Gram-ve coccus Neisseria gonorrhoeae (the gonococcus)
Virulence factors of gonorrhoea
Pili
Opa Protein
Capsule
Pili as a virulence factor
Aids attachment to epithelium
Contains constant and hyper variable regions - contribute to antigenic diversity
Opa proteins
Assist binding to epthelial cells
Gonorrhoea capsule
Resists phagocytosis unless antibody present
What can persistent untreated gonorrhoea infection result in
Chronic infl and fibrosis
Is gonorrhoea infection localised or unlocalised
Usually localised, but in some cases bacteria isolates can invade the bloodstream and so spread to other parts of the body
How does gonorrhoea present in women
Initially asymptomatic but can cause infertility
When do gonorrhoea symptoms develop
Within 2-7 days
Gonorrhoea symptoms in males
Urethral discharge and dysuria
Gonorrhea symptoms in females (if not asymptomatic)
Vaginal discharge
Dx of gonorrhea
Made from microscopy and culture of appropriate specimens
Treatment of gonorrhoea
Dual therapy - ceftriaxone and azithromycin
Treats chlamydia
Resistance of penicillin and fluroquinones seen
Systemic spread of gonorrhoea
Skin lesions
Endocarditis
Arthritis
Opthalmia neonatorum
Which C trachomatis serotypes cause STIs
D - K
3 species of chlamydia
C trachomatis
C. psittaci and C.pneumoniae infect the respiratory tract
Serotypes L1, L2, L3 of chlamydia
Usually associated with men who have sex with men
How does chlamydia enter host
Through minute abrasions in the mucosal surface
Binds to spp receptors on the host cells and enter the cells by ‘parasite-induced’ endocytosis
Clinical syndromes of chlamydia in men
Urethritis
Epididymitis
Proctitis
Conjuctivitis
Complication of chlamydia in men
Systemic spread
Reiter’s syndrome
Reiter’s syndrome
Urethritis
Conjunctivitis
Polyarthritis
Mucocutaneous lesion
Clinical syndromes of chlamydia in women
Urethritis Cervicitis Bartholinitis Salpinigitis Conjuctivitis
Complications of chlamydia in women
Ectopic pregnancy Infertility Systemic spread Perihepattitis Arthritis dermatitis
Clinical syndrome of chlamydia in neonates
Conjunctivitis
Complications of chlamydia in neonates
Interstitial pneumonia
Genital tract infections w/ serotypes D-K
Locally asymptomatic in most women but usually symptomatic in men
Dx of chlamydia
Nucleic-acid based tests
Treatment/ prevention of chlamydia
Doxycycline
Azithromycin
Chancroid (soft chancre)
Caused by Haemophilus ducreyi (Gram-ve)
Characterised by painful genital ulcers and local lymphadenitis
Other STIs
Mycoplasma hominis
M. genitalium
Ureaplasma urealyticum
Most common cause of genital herpes
HSV 2
What can HSV-2 infection result in
Twofold-increased risk for developing HIV; due to breaches in mucosal barrier because of the HSV ulcers
Presentation of genital herpes
Characterized by ulcerating vesicles that can take up to 2 weeks to heal
How is latent HSV infection established
The virus in the lesion travels up sensory nerve endings to establish latent infection in dorsal root ganglion neurones. From this site, it can reactivate, travel down nerves to the same area and cause recurrent lesions (‘genital cold sores’)
Rare complications of HSV
Aseptic meningitis
Encephalitis
What can spread of HSV from mother to infant at delivery cause
Neonatal disseminated herpes or encephalitis
Dx of HSV
Genital herpes is generally diagnosed by clinical appearance
HSV DNA can be detected and typed in vesicle fluid or ulcer swabs
Transmission of HIV
Involves mucosal surfaces e.g., cervicovaginal, penile and rectal
May be infected by IV or percutaneous routes
Treatment for HSV
Aciclovir
Window period for HIV detection
7-21 days as HIV multiplies in the mucosa and drain lymphoreticular tissues
1st targets of HIV infection
CD4 receptor-bearing cells incl Th cells, monocytes, Langerhans cells and other dendritic cell, macrophages, and microglia
What may primary HIV be accompanied by
A mild mononucleosis-type illness
HIV progression to AIDS
Viral invasion of the CNS, with self-limiting aseptic meningoencephalitis
Treatment for HIV
Anti-retroviral therapy
Candida albicans
(Thrush)
Can cause vaginitis and urethritis which are treated with topical or oral antifungals
Variation in Candida infections
Mild superficial, localised infection - healthy
Fatal - immunocompromised
Candida as a normal inhabitant if vagina
Whilst Candida can be transmitted sexually, the presence of vulvovaginal candidiasis does not necessarily imply sexual transmission
Trichomonas vaginalis
Protozoan parasite and causes vaginitis with copious discharge
What does T. vaginalis inhabit
The vagina in women and the urethra (and sometimes the prostate) in men
What is bacterial vaginosis associated with
Gardnerella vaginalis plus anaerobic infection and a fishy-smelling vaginal discharge
What is BV characterised by
At least 3 of: Excessive malodorous vaginal discharge Vaginal pH >4.5 Presence of clue cells (vaginal epithelial cells coated with bacteria) A fishy amine-like odour
Opportunist STIs
Salmonellae Shigellae Hepatitis A Giardia intestinalis Entamoeba histolytica infections
Structure of C. trachomatis
Oblingate intracellular bacteria
Virulence of C. trachomatis
Hemagglutinin facilitates attachment to cells
The cell-mediated immune response is responsible for tissue damage during inflammation
Endo-toxin like toxin is released
