50 - HIV and STIs Flashcards
in utero transmission
Trans placental
Peri-natal transmission
Passage through infected birth canal
Eye mucous membrane transmission
Conjunctivitis
Keratitis
Gonorrhoea - disease causing organism
Neisseria gonorrhoeae
Gram –ve coccus
Gonorrhoea - pathogensis
Pili on cell surface become virulent.
Ability to attach to mucosal epithelial cells
Primarily infect columnar/cuboidal epithelium
Gonorrhoea - where? incubation?
GU tract, rectum, oropharynx
2-5 days incubation
Gonorrhoea - presentation
60% women are asymptomatic
Urethral discharge
Gonorrhoea - local complications
Lots of -itis
Metastatic: disseminated gonococcal infection (DGI)
Bacteraemia, arthritis, dermatitis (meningitis)
Gonorrhoea - microscopy
Urethral swab (male) Endocervical (not high vaginal).
Culture created and tested for resistance.
PCR sometimes too
Gonorrhoea - treatment
B-lactams
Cephalosporins
Fluoroquinolones
Chlamydia - incubation, name type
Types D-K
1-2 weeks incubation period
Type of non-gonococcal urethritis
Chlamydia - diagnosis
NAAT for chlamydia
Chlamydia - target cells
Squamocolumnar epithelial cells of endocervix
Also, conjunctiva, urethra and rectum for M+F
Chlamydia - presentation
Often asymptomatic (f>M)
Urethritis - less purulent discharge then gonococcal
Cervicitis - mucopurulent
May have dysuria/frequency
Chlamydia - complications
PID (pelvic inflammatory disease (9.5% w/o Rx) Tubal infertility (10.6%), ectopic pregnancy, chronic pain
Epididymitis (2%)
Neonatal + infant get conjunctivitis + infant pneumonia
Conjunctivitis
Reiter’s syndrome: arthritis, conjunctivitis, urethritis, skin lesions
Chlamydia - diagnosis
Histology
Cell culture
NAAT (superseded EIA)
99.7%
Serology
Chlamydia - treatment
Azithromycin
Doxycycline
Paediatric: conjunctivitis, pneumonia, erythromycin (14 days)
HPV - why important
12 high risk types are causally associated with cancer
HPV 6,11
90% genital warts
HPV 16, 18
Cervical carcinomas
Gardasil
Vaccine for HPV 6, 11, 16, 18
Genital herpes -
Double stranded DNA viruses
HSV-2 more common in women than man
Genital herpes - presentation
Pain, itching, dysuria, vaginal/urethral discharge
Bilateral vesicles / ulcers with viral shedding
Genital herpes - pathogenesis
Latency - sensory neuron cells (sacral nerve ganglia)
Reactivated by: local trauma, menstruation, stress
Genital herpes - diagnosis
Clinical
PCR (HSV 1 or 2)
Histology
Genital herpes - treatment
Acyclovir (primary or recurrence)
If frequent consider suppression
Genital herpes - complications
Dissemination Meningitis Encephalitis Sacral nerve parasthesiae Urinary retention
Syphilis - caused by
Spirochaete, Treponema pallidum
Syphilis - pathogenesis
Penetrates intact mucous membranes, disseminated within days via lymphatics/bloodstream
Syphilis - histology
Obliterative endarteritis (microvascular compromised)
Syphilis - incubation time
21 days
Syphilis - primary chancre
Site of inoculation, painless indurated lesion
Heals spontaneously within 3-6 weeks
Syphilis - secondary chancre
2-8 weeks post onset
Syphilis - clinical presentation
Skin - rash, condylomata lata, mucous patches
Constitutional symptoms - fever, malaise, weight loss
Generalised lymphadenopathy
CNS involvement (40%), headache, meningismus
Syphilis - prognosis and treatment
Spontaneous resolution 3-12 weeks
Latent: no clinical manifetation, positive serology
W/o treatment: 30% will develop late w/ tertiary syphilis
Syphilis - tertiary
Neurosyphilis - meningovascular (hemiplegia, seizures)
Parenchymatous - paresis of cortex - personality, argyll robertson pupils
Tabes dorsalis - spinal cord - demyelinisation of cord, lightening pain in legs, loss of position/vibratory sense
CVS - aortic regurg, saccular aneurysm
Late benign syphilis - non-specific granulomatous rxn
Argyll robertson pupils
Accommodate to near vision
Don’t react to light
Syphilis - neonates
Early signs: snuffles, rash, hepatosplenomegaly
Late: frontal bosses, saddle nose, sabre shins. Hutchinson’s incisors
Syphilis - diagnosis
Lack of culture
Direct detection by darkfield microscopy
PCR more sensitive than microscopy
Syphilis - indirect tests
Serology - specific: anti-treponemal antibodies
Non-specific: reaginic antibodies vs lipoidal antigens
Syphilis - treatment
Penicillin
Length/route IM IV
Jarish-Herxheimer rxn: commonest in 2* syphilis, fever, chills, myalgia, hypersensitivity rxn, self-limiting
Alternatives: amoxicillin, ceftriaxone, doxycycline
Trichomoniasis - causative organism
Trichomonas vaginalis
Protozoa - lacks mitochondria
Trichomoniasis - clinical presentation
Profuse greenish frothy vaginal discharge
Mucosal inflammation
Males may have urethritis but usually asymptomatic
Trichomoniasis - diagnosis
Microscopy/culture (high vaginal swab)
Trichomoniasis - treatment
Metronidazole
Bacterial (anaerobic) vaginosis (BV) -
Reduced vaginal lactobacilli
Increased gardnerella vaginalis & anaerobes
Bacterial (anaerobic) vaginosis (BV) - clinical presentation
Watery discharge
+ve KOH test (fishy odour)
Vaginal pH >4.5
Clue cells on microscopy
Bacterial (anaerobic) vaginosis (BV) - treatment
Amoxycillin
Topical clindamycin
Candidiasis - two types
Thrush
Balanitis
Candidiasis - risk factors
Oral contraceptives, poorly controlled diabetes
Antibiotics - inhibition of normal flora
Candidiasis - clinical presentation
Vulval, vaginal and penile erythema w/ itching and irritation
Classically: thick/adherent discharge and white plaques
Maculopapular & fissuring lesions
Candidiasis - investigations
Microscopy (10% KOH)
Culture
Candidiasis - causative agent
Candida albians 85% cases - more susceptible but low risk of recurrence
Candidiasis - uncomplicated
C albicans
Topical - clo-trimazole (Canesten)
Fluconazole: single 150mg oral dose
Candidiasis - complicated
Treatment for 10-14 days
Consider partner treatment
Long term suppressive if freq.
HIV - causative organism
Retrovirus - possesses reverse transcriptase script
converts viral RNA into linear DNA which is incorporated into host genome
error prone so high mutability rate
HIV - why causative organism so hard to fight
RNA-based means survival advantage with great genetic diversity
DNA intermediary - latent and can incorporate into host genome
CD4/macrophage tropic - reduction of host immune response
HIV - transmission routes
Sexual- genital or colonic mucosa
Infected fluid - blood
Mother to infant
HIV - how does it gain entry?
Viral glycoprotein gp120
Interacts w/ CD4 and chemokine receptor for virion to gain entry
HIV - WHO classification
Stage 1 - CD4 >500 cells/uL
Stage 2 - 349-499
Stage 3 - 200-349 (adv. HIV)
Stage 4
HIV - primary infection clinical presentation
Acute retroviral syndrome - fever, pharyngitis, lymphadenopathy, rash
Asymptomatic
Early: pulm TB, persistent oral candidiasis, chronic diarrhoea, persistent fever, severe bacterial infections
HIV - AIDS clinical presentation
HIV wasting syndrome (HIV encephalopathy)
Oesophageal candidiasis Pneumocystis jirovecii pneumonia CMV CNS toxoplasmosis Progressive multifocal leukoencephalopathy (PML) Extra-pulm TB Disseminated non-TB mycobacterial disease Chronic cryptosporidiosis Kaposi's sarcoma, lymphoma
HIV - diagnosis
25% undiagnosed
Universal testing - GUM clinics w/ TB or lymphoma. Also antenatal
HIV - investigations
Antibody testing
PCR - detects viral nucleic acid + copy #, genotypic mutations conferring drug resistance
HIV - treatment (drug types used)
Nucleoside reverse transcriptase inhibitors
Non-nucleoside reverse transcriptase inhibitors
Protease inhibitors (ritonavir)
Viral entry inhibitors
Integrase strand transfer inhibitors
HIV - treatment (methods)
Combinations
Highly active antiretroviral therapy (HAART)
Guidelines
Prophylaxis vs opportunistic infections
