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MI8.{1-2,4} | Urinary Tract & Sexually Transmitted Infections — SDL Guide (Part 2)

Viral STIs and Parasitic Genitourinary Infections

A four-panel medical diagram compares HSV genital infection pathogenesis, lesions, diagnosis and treatment with HPV low-risk warts and high-risk cervical cancer progression. — **Panel A:** HSV epithelial replication, retrograde axonal transport, sensory nerve axon, sacral dorsal root ganglion latency, reactivation to genital epithelium, stress, fever, immunosuppression, UV light.. **Panel B:** Grouped vesicles on erythematous base, painful ulcers, primary episode severe systemic symptoms, urinary retention, recurrence shorter and milder, HSV-2 predominant genital herpes, HSV-1 oral-genital transmission.. **Panel C:** Tzanck smear, multinucleated giant cells, vesicle base sample, PCR gold standard, Shell vial viral culture, type-specific IgG ELISA, acyclovir, valacyclovir, viral thymidine kinase, viral DNA polymerase inhibition.. **Panel D:** HPV double-stranded DNA virus, low-risk HPV 6 and 11, condylomata acuminata, cauliflower-like genital warts, high-risk HPV 16, 18, 31, 33, cervical intraepithelial neoplasia, cervical cancer, oropharyngeal cancer, anal cancer, penile cancer, vulvar cancer..

Herpes Genitalis (HSV-1/HSV-2)
- Pathogenesis: Primary infection → epithelial replication → retrograde axonal transport → latency in sacral dorsal root ganglia → reactivation triggers (stress, fever, immunosuppression, UV light)
- Clinical features: Multiple small grouped vesicles on an erythematous base → painful ulcers → heal in 10–14 days. Primary episode is more severe (systemic symptoms, urinary retention). Recurrences are shorter and milder.
- HSV-2 predominantly causes genital herpes; HSV-1 is increasingly common cause (oral–genital transmission)
- Neonatal herpes: Acquired during delivery through infected birth canal; devastating — can cause disseminated disease, encephalitis; mortality ~60% without treatment
- Diagnosis: Tzanck smear (vesicle base → multinucleated giant cells), viral culture (Shell vial), PCR (gold standard), type-specific IgG ELISA (seroprevalence studies)
- Management: Acyclovir (nucleoside analogue — phosphorylated by viral thymidine kinase → inhibits viral DNA polymerase); valacyclovir for recurrences

Human Papillomavirus (HPV)
- Double-stranded DNA virus; >200 types; sexually transmitted
- Low-risk types (6, 11): Genital warts (condylomata acuminata) — cauliflower-like, on glans, vulva, perianal region
- High-risk types (16, 18, 31, 33): Cervical intraepithelial neoplasia (CIN) → cervical cancer; also oropharyngeal, anal, penile, vulvar cancers. HPV 16 and 18 cause >70% of cervical cancers
- Pathogenesis: E6 oncoprotein binds and degrades p53 (tumour suppressor); E7 oncoprotein inactivates pRb → uncontrolled cell proliferation
- Diagnosis: Cervical cytology (Pap smear) — detects CIN (koilocytes = pathognomonic HPV-infected cells); colposcopy + biopsy for CIN grading; HPV DNA test (Cobas, Hybrid Capture 2)
- Prevention: Bivalent (HPV 16/18), quadrivalent (6/11/16/18), or 9-valent vaccines; India's UIP includes bivalent HPV vaccine for girls aged 9–14 years

Trichomonas vaginalis (Parasitic STI)
- Pathogen: Flagellated protozoan; anaerobic; pear-shaped; 5 flagella (4 anterior + 1 posterior forming undulating membrane)
- Clinical features: Females: frothy, yellow-green, malodorous vaginal discharge; pruritus; strawberry cervix (punctate haemorrhages on colposcopy). Males: usually asymptomatic; mild urethritis
- Pathogenesis: Binds to vaginal epithelial cells; alkaline pH (raised vaginal pH); cytotoxin production
- Diagnosis: Wet mount preparation of vaginal discharge (or urethral discharge) — motile trichomonads with characteristic tumbling motility; NAAT (most sensitive — PCR-based); culture on Diamond's medium; Gram stain less reliable
- Management: Metronidazole (single dose 2g) for patient and partner simultaneously

Renal tuberculosis and other genitourinary infections
- Renal TB: M. tuberculosis reaches kidney haematogenously; granulomata form in renal cortex → caseous necrosis → cavitation → spread to ureters (structure/stricture) and bladder. Sterile pyuria is the classic microbiological clue.
- Schistosomiasis (S. haematobium): Endemic in Africa; rare in India; eggs deposited in bladder wall → haematuria, chronic cystitis, squamous cell carcinoma of bladder
- Filariasis (Wuchereria bancrofti): Lymphatic obstruction → lymphoedema; scrotal lymphoedema → hydrocele; chyluria (lymph in urine — milky white urine)

CLINICAL PEARL

Syndromic management of STIs in India: NACO's syndromic management approach treats STI syndromes (urethral discharge, genital ulcer, vaginal discharge) empirically without microbiological diagnosis, targeting the commonest causative organisms. For urethral discharge: treat both gonorrhoea (ceftriaxone 500 mg IM single dose) and chlamydia (azithromycin 1g stat or doxycycline 100 mg BD × 7 days) simultaneously — this two-drug approach covers the syndromic cause without culture. Partner treatment and condom promotion are integral to the NACO STI management protocol used at all PHC-level clinics across India.

Prevention of STIs and UTIs

⚑ AI image — pending faculty review (auto-QA score 7/10; best of 3 attempts)

A three-panel medical infographic summarizes prevention of STIs through vaccination, screening, PrEP, partner notification and neonatal prophylaxis, and prevention of UTIs through behavior, pregnancy screening, catheter care, cranberry products and antibiotic prophylaxis. — **Panel A:** STI prevention flowchart showing primary prevention, condom use, abstinence, reduced partners, HPV vaccination, antenatal syphilis screening with VDRL/RPR, partner notification, HIV PrEP with tenofovir-emtricitabine, hepatitis B vaccination schedule, and neonatal eye prophylaxis.. **Panel B:** Female urinary tract showing kidneys, ureters, bladder, urethra, adequate fluid intake, post-coital voiding, avoiding urine retention, and screening/treating asymptomatic bacteriuria in pregnancy.. **Panel C:** Catheter-associated UTI prevention with aseptic insertion, closed drainage, reduced catheter duration, avoidance of unnecessary irrigation, plus recurrent UTI prevention showing cranberry proanthocyanidins blocking E. coli pili adhesion and antibiotic prophylaxis options..

Prevention of STIs:
- Primary prevention: Condom use (male and female), sexual abstinence, reducing number of partners, HPV vaccination (before sexual debut, most effective)
- Screening: Antenatal syphilis screening (VDRL/RPR) in all pregnant women is mandatory in India — early treatment prevents congenital syphilis
- Partner notification: Index patient's sexual contacts must be traced and offered testing/treatment
- Pre-exposure prophylaxis (PrEP): Tenofovir–emtricitabine for HIV-negative high-risk individuals (now available under NACO)
- Hepatitis B vaccination: UIP schedule (birth + 6 weeks + 10 weeks + 14 weeks) prevents HBV STI
- Neonatal prophylaxis: Eye drops at birth (prophylaxis for gonococcal/chlamydial ophthalmia neonatorum)

Prevention of UTIs:
- Behavioural: Post-coital voiding, adequate fluid intake (≥2 L/day), avoid holding urine
- Catheter care (CAUTI prevention): Minimise catheter use and duration; maintain closed drainage system; aseptic insertion technique; avoid unnecessary bag irrigation
- Cranberry products: Proanthocyanidins inhibit E. coli type 1 pili adhesion to uroepithelium — evidence for prevention in women with recurrent UTIs is moderate
- Antibiotic prophylaxis: Low-dose prophylactic antibiotics for women with >3 UTIs/year (nitrofurantoin, trimethoprim); post-coital prophylaxis is an alternative
- Asymptomatic bacteriuria in pregnancy: Must be screened and treated (risk of progression to pyelonephritis is 20–40%)

Interactive practice: Multiple Choice

Interactive practice: True / False

Interactive practice: Multiple Choice

Interactive practice: Match the Images

Interactive practice: Multiple Choice