Chapter 28: Infections

Bacterial · Viral · Fungal · Parasitic · Sepsis · Antimicrobial stewardship · Vaccination · Fever in the immunocompromised · Emerging infections
🦠 Key concepts: Fever without source, sepsis recognition (qSOFA, PELOD-2), antibiotic stewardship, MRSA, VRE, vaccine-preventable diseases, congenital infections (TORCH), tropical diseases, infection control.

📖 Pediatric infections: epidemiology, diagnosis & management

🦠 Bacterial infections
Sepsis, meningitis (N. meningitidis, S. pneumoniae, GBS), pneumonia (S. pneumoniae, Mycoplasma), osteomyelitis, UTI, TB, GAS (pharyngitis, scarlet fever, rheumatic fever).
🧬 Viral infections
RSV bronchiolitis, influenza, COVID-19, rotavirus, enterovirus, EBV (infectious mononucleosis), CMV, HSV, VZV, measles, mumps, rubella.
⚡ Fungal & parasitic
Candida (thrush, invasive), Aspergillus (immunocompromised), PCP (HIV), malaria, toxoplasmosis, giardiasis, ascariasis, schistosomiasis.
💊 Antimicrobial stewardship
Judicious use of antibiotics, narrow spectrum when possible, de-escalation, prevention of resistance (MRSA, VRE, ESBL).
⚠️ Red flags for serious infection in children: Ill appearance, toxic, lethargy, poor perfusion, petechial rash, respiratory distress, persistent vomiting, focal neurology, fever >5 days.

🩺 Clinical approach to fever and suspected sepsis

1
Assessment of ill child – ABCs, rapid assessment of perfusion, respiratory effort, mental status. Look for signs of septic shock (cold shock vs warm shock).
2
Fever without source – Age-based approach: <28 days (full sepsis workup, admit, empiric antibiotics), 1-3 months (low-risk criteria may allow observation), >3 months (clinical judgment, urine test).
3
Laboratory evaluation – CBC, CRP, PCT (procalcitonin), blood cultures, urine analysis/culture, lumbar puncture (if meningeal signs or <1 month). CXR if respiratory symptoms.
4
Risk stratification – Neonatal sepsis risk factors (GBS, prematurity, chorioamnionitis). Immunocompromised patients require broader coverage.
📌 Clinical pearl: A child with fever and petechial rash should be assumed to have meningococcemia until proven otherwise. Immediate IV antibiotics (ceftriaxone) after blood culture.

📋 Antimicrobial therapy & infection management

1
Sepsis & septic shock – IV antibiotics within 1 hour (broad-spectrum: ceftriaxone + vancomycin if MRSA risk). Fluid resuscitation (20 ml/kg boluses). Vasopressors if refractory.
2
Meningitis (bacterial) – IV ceftriaxone (or cefotaxime) + vancomycin + dexamethasone (for Hib/pneumococcus). Age-specific coverage (ampicillin for Listeria in <3 months).
3
Antibiotic stewardship – De-escalate based on culture results. Narrow spectrum (penicillin for GAS, amoxicillin for pneumococcus if susceptible). Avoid unnecessary antibiotics for viral URI.
4
Infection control – Hand hygiene, isolation precautions (contact, droplet, airborne), PPE. Vaccination (routine and catch-up).
🚨 Common empiric antibiotic regimens: Neonate: ampicillin + gentamicin/cefotaxime. Infant/child: ceftriaxone + vancomycin (meningitis/sepsis). Community-acquired pneumonia: amoxicillin or macrolide (atypical).

🧠 Reflex prompts: pediatric infections

🦠 2-month-old with fever, irritability, bulging fontanelle. LP shows gram-positive cocci in pairs. Likely organism?
Streptococcus pneumoniae (or Group B Strep if <1 month). Empiric ceftriaxone + vancomycin + dexamethasone.
🧬 4-year-old with fever, exudative pharyngitis, palatal petechiae, cervical lymphadenopathy. Rapid strep negative. Likely?
Adenovirus or EBV (infectious mononucleosis). Avoid ampicillin (rash).
🩺 Child with fever, petechial rash, hypotension. Most likely diagnosis?
Meningococcemia (Neisseria meningitidis). IV ceftriaxone, notify public health, chemoprophylaxis for contacts.
🦠 6-year-old with fever, cough, conjunctivitis, Koplik spots. Diagnosis?
Measles. Supportive care, vitamin A, isolation, vaccination of contacts.
🧫 Immunocompromised child with fever, cough, hypoxemia. CXR shows bilateral interstitial infiltrates. Most likely?
Pneumocystis jirovecii pneumonia (PCP). TMP-SMX, steroids if hypoxic.
🩸 Child with prolonged fever, chills, headache, myalgia after travel to malaria-endemic area. Test?
Thick and thin blood smear for Plasmodium. Rapid diagnostic test.
🦷 8-year-old with fever, sore throat, ‘strawberry tongue’, desquamation. Diagnosis?
Scarlet fever (Group A Strep). Penicillin or amoxicillin.
🩺 Neonate with fever, lethargy, poor feeding. Maternal GBS positive. Empiric antibiotics?
Ampicillin + gentamicin or cefotaxime.
🧬 Child with fever, parotid swelling, tender cheeks. Diagnosis?
Mumps. Supportive care, isolation.
💊 Antibiotic of choice for uncomplicated urinary tract infection in a child?
Trimethoprim-sulfamethoxazole or nitrofurantoin (if susceptible). Cephalexin or amoxicillin-clavulanate.