MI8.{1-2,4} | Urinary Tract & Sexually Transmitted Infections — Summary & Reflection

REFLECT

Consolidate your understanding with these integrative clinical scenarios:

1. A 19-year-old unmarried woman presents with lower abdominal pain, fever, and mucopurulent cervical discharge. She has multiple sexual partners and does not use condoms. Develop a differential diagnosis of organisms responsible, the specific laboratory tests you would request for each, and the public health steps you would initiate.

1. A midwifery nurse asks you why a neonate born to a mother with untreated gonorrhoea must receive antibiotic eye drops even if the eye looks normal at birth. Explain using pathogenesis and clinical course of gonococcal ophthalmia neonatorum.

1. A 55-year-old diabetic woman presents with 3 months of haematuria, mild flank pain, and weight loss. Urine culture on CLED agar is repeatedly reported as 'no growth.' A dipstick shows 3+ leucocyte esterase but no nitrite. What organism do you suspect, and what specific diagnostic tests would you order?

KEY TAKEAWAYS

Key take-home points from this module:

• UTIs ascend via the urethra (females, short urethra → higher risk); E. coli (P fimbriae, haemolysin) causes >80% of community UTIs; Proteus (urease → alkaline urine → struvite stones) and Pseudomonas dominate catheter-associated and complicated UTIs.
• Specimen collection determines diagnosis: MSU (≥10⁵ CFU/mL), catheter port specimen (≥10³ CFU/mL), suprapubic aspiration (any growth); CLED agar is the standard culture medium. Sterile pyuria → always investigate for renal TB (AFB × 3 early morning urine).
• Gonorrhoea: Gram-negative diplococci; Gram stain of urethral discharge showing intracellular organisms is diagnostic; culture on Thayer-Martin medium; NAAT is gold standard; N. gonorrhoeae is increasingly fluoroquinolone-resistant in India.
• Chlamydia: Obligate intracellular; elementary body (infectious) vs reticulate body (replicating); NAAT on urine/swab is gold standard; often asymptomatic — major driver of PID and infertility.
• Syphilis: Painless chancre (primary) → palmoplantar rash (secondary) → gumma/neurosyphilis (tertiary). Dark-field microscopy for primary; VDRL (non-treponemal, titre follows disease activity) confirmed by TPHA (treponemal, remains positive for life).
• Herpes genitalis: HSV-2 (mainly); latent in sacral ganglia; recurrent vesicular/ulcerative lesions; PCR is gold standard; acyclovir treats and reduces recurrences.
• HPV: Low-risk types (6/11) → genital warts; high-risk types (16/18) → cervical cancer via E6/E7 oncoprotein disruption of p53/pRb; prevent with vaccine and screen with Pap smear/HPV DNA test.
• Trichomonas: Protozoan; wet mount showing motile organisms is diagnostic; treat with metronidazole (patient + partner).
• India's syndromic management (NACO) and antenatal syphilis screening are the key public health tools for STI control.