IM26.{8-11,14,17} | Bacterial Skin Visceral Urinary and Enteric Infections — Summary & Reflection

KEY TAKEAWAYS

This SDL covered six bacterial syndromes across four organ systems:

Skin and soft-tissue infections: impetigo/cellulitis/erysipelas (Gram-positive organisms, penicillin/cloxacillin) vs necrotising fasciitis (surgical emergency, polymicrobial, immediate debridement + meropenem/clindamycin) vs pyomyositis (S. aureus, MRI diagnosis, drainage + cloxacillin).

Liver abscess: pyogenic (elderly, biliary source, multiple abscesses, Gram-negative organisms, piperacillin-tazobactam + drainage) vs amoebic (young male, single right lobe abscess, chocolate pus, positive ELISA, metronidazole — drainage rarely needed).

Diarrhoea: secretory/watery (cholera — rice-water stool, ORS + doxycycline; ETEC — ORS alone) vs invasive/dysentery (Shigella — ciprofloxacin; E. histolytica — metronidazole) vs food poisoning (S. aureus 1–6h, B. cereus emetic 1–5h / diarrhoeal 8–16h, C. perfringens 8–16h — all self-limiting, ORS only). Anti-motility agents contraindicated in dysentery.

UTI spectrum: uncomplicated cystitis (nitrofurantoin/fosfomycin; avoid fluoroquinolones empirically in India) → pyelonephritis (blood + urine cultures, IV ceftriaxone or carbapenem for ESBL risk) → emphysematous pyelonephritis (CT diagnosis, diabetic, IV carbapenem + drainage).

Gram-negative enteric bacilli: ESBL-producing E. coli/Klebsiella require carbapenems for serious infections; hypervirulent Klebsiella causes primary liver abscess + endophthalmitis in diabetics.

Enteric fever: stepladder fever + relative bradycardia + rose spots + splenomegaly + leucopenia; blood culture in week 1 (gold standard); IV ceftriaxone or oral azithromycin (fluoroquinolones unreliable in India); dexamethasone for severe typhoid with encephalopathy.

REFLECT

Three patients opened this module — the diabetic man with necrotising fasciitis, the woman with pyelonephritis, and the food-poisoning cluster. Return to them now with the knowledge you have built. The diabetic man's 'wooden' skin texture and pain out of proportion to the skin findings should now immediately register as necrotising fasciitis requiring surgical consultation in minutes. The woman's flank pain and systemic fever should prompt you to order blood and urine cultures before choosing an antibiotic — and your awareness of ESBL prevalence in India should make you hesitate before prescribing an oral cephalosporin empirically. The food-poisoning cluster resolves with rehydration — and prescribing antibiotics for this group would be an error. Reflect on this: how does your antibiotic prescribing practice change when you know that 50% of community E. coli in your hospital's catchment area produce ESBL? What is your practical algorithm for the diabetic febrile patient with UTI symptoms admitted to the emergency department at 2 AM, when culture results will take 48 hours? These are the questions you will face in clinical practice — and the organ-system framework in this module gives you the tools to answer them.