Chapter 28: Infections – Enteric & Systemic Bacteria

🦠 Salmonellosis · Shigella (bacillary dysentery) · Staphylococcus · Streptococcus & Enterococcus · Tetanus · Tularemia · Yersiniosis & Plague
Forfar & Arneil's Textbook of Pediatrics – Comprehensive coverage: diarrhea pathogens, gram-positive cocci, toxin-mediated diseases, zoonotic infections, and emergency management.

📖 Key pathogens & clinical syndromes

🍗 Salmonellosis
Nontyphoidal Salmonella: gastroenteritis (diarrhea, fever, cramps). High-risk (young infants, immunocompromised) → bacteremia. Treatment: supportive; antibiotics for invasive disease. Typhoidal (S. Typhi/Paratyphi): enteric fever, prolonged fever, rose spots. Ceftriaxone or azithromycin.
🦠 Shigella (bacillary dysentery)
Bloody diarrhea, tenesmus, fever, abdominal cramps. Complications: HUS (S. dysenteriae type 1). Treatment: azithromycin or cefixime/ceftriaxone (susceptibility dependent). Antimotility drugs contraindicated.
💉 Staphylococcus aureus
Skin/soft tissue infections, osteomyelitis, septic arthritis, pneumonia, toxic shock syndrome, MRSA (community/hospital). Treatment: clindamycin, TMP-SMX, vancomycin (MRSA), drainage of abscesses.
🩺 Streptococcus & Enterococcus
Group A Strep (GAS): pharyngitis, scarlet fever, cellulitis, necrotizing fasciitis, rheumatic fever. Group B Strep (GBS): neonatal sepsis/meningitis. Pneumococcus (see previous). Enterococcus: UTIs, bacteremia (VRE concerns).
⚡ Tetanus
Clostridium tetani toxin → generalized rigidity, trismus (lockjaw), opisthotonos. Prevention: wound care, tetanus toxoid, immunoglobulin (TIG). Treatment: muscle relaxants, metronidazole, ICU support.
🐇 Tularemia (Francisella tularensis)
Ulceroglandular, glandular, oculoglandular, pneumonic, typhoidal. Tick/deer fly, rabbit contact. Treatment: streptomycin/gentamicin or doxycycline/ciprofloxacin.
🐀 Yersiniosis & Plague
Y. enterocolitica: enterocolitis, pseudoappendicitis. Y. pestis (plague): bubonic (lymphadenitis), septicemic, pneumonic (highly contagious, high mortality). Streptomycin/gentamicin or fluoroquinolones.
⚠️ Red flags: Bloody diarrhea – Shigella or STEC. Trismus after wound – tetanus (immediate IM TIG). Buboes with fever – suspect plague (notify public health). Osteomyelitis in a healthy child – S. aureus (MRSA risk).

🩺 Symptom-based approach

🩸
Bloody diarrhea + fever + tenesmus → Shigella (or STEC, Campylobacter). Stool culture. Avoid loperamide. Antibiotics if severe or high risk.
🤕
Lockjaw, rigidity, back arching (opisthotonos) → Tetanus (wound history). Airway protection, tetanus immunoglobulin, metronidazole.
🐾
Ulcer + regional lymphadenopathy after rabbit/tick contact → Tularemia (Francisella). Serology, PCR. Gentamicin or ciprofloxacin.
🪢
Fever + painful inguinal bubo (lymph node) → Bubonic plague (Y. pestis) – emergency, droplet precautions, notify public health. Streptomycin or gentamicin.
🍳
Fever + right lower quadrant pain + diarrhea → Yersinia enterocolitica (pseudoappendicitis). Stool culture, supportive care; severe cases TMP-SMX or cefotaxime.

⚕️ Stepwise management guidelines

1
Shigellosis (severe dysentery) – Hydration, stool culture. Azithromycin (or ceftriaxone if parenteral). Avoid antidiarrheals. Notify public health if outbreak.
2
Staphylococcal septic shock / toxic shock syndrome – IV vancomycin + clindamycin (toxin suppression), fluid resuscitation, vasopressors, IVIG if severe.
3
Tetanus (generalized) – ICU: airway management, benzodiazepines (diazepam), baclofen, magnesium. Human tetanus immunoglobulin (TIG) 5000 IU IM. Metronidazole (10 days). Wound debridement. Vaccination catch-up.
4
Enteric fever (typhoid) – Ceftriaxone (7-14 days) or azithromycin (5-7 days). Fluoroquinolones if susceptible. Monitor for intestinal perforation.
5
Plague (suspected) – Immediate isolation (droplet/airborne for pneumonic). Streptomycin IM (or gentamicin). Alternative: doxycycline or ciprofloxacin. Notify health department.
📌 Prevention: Tdap vaccine (tetanus). Safe food/water (Salmonella, Shigella). Tick/animal avoidance (tularemia, plague). MRSA decolonization in recurrent infections.

🧠 Reflex prompts – high-yield pearls

🍗 5-year-old with bloody diarrhea, fever, tenesmus. Stool culture grows Shigella sonnei. Treatment?
Azithromycin (or cefixime). Avoid loperamide.
🦠 8-year-old with fever, severe abdominal pain, R iliac fossa tenderness, diarrhea. Appendix normal at surgery. Likely?
Yersinia enterocolitica pseudoappendicitis. Stool culture, supportive care.
🧴 Child with deep puncture wound, trismus, risus sardonicus. Most likely diagnosis?
Tetanus. TIG, metronidazole, ICU, muscle relaxants.
🐇 Child with fever, skin ulcer, painful axillary lymph node after handling a dead rabbit. Likely?
Tularemia (Francisella tularensis). Gentamicin or ciprofloxacin.
🪤 Child with fever, painful inguinal bubo, and recent rodent exposure. Suspected plague. Next step?
Isolate, obtain cultures, notify public health, start streptomycin/gentamicin.
💊 First-line antibiotic for MRSA skin abscess requiring coverage?
Clindamycin, TMP-SMX, or doxycycline (≥8y). Drainage essential.
🧪 Group A Strep pharyngitis treatment and prevention of rheumatic fever?
Penicillin V or amoxicillin for 10 days.
🩸 Enteric fever (typhoid) classic physical finding?
Rose spots (faint pink macules on trunk).
⚕️ Neonatal sepsis with GBS. Empiric regimen?
Ampicillin + gentamicin (or cefotaxime).
🐀 Pneumonic plague: transmission & precautions?
Droplet/airborne; high mortality; treat with aminoglycosides/fluoroquinolones.