Chapter 28: Infections

Bacterial · Viral · Fungal · Parasitic · Sepsis & Shock · Neonatal Infections · Fever without source · Antimicrobial Stewardship · Vaccination
🩺 Based on Forfar & Arneil's Textbook of Pediatrics 7e | Evidence-based clinical scenarios, symptom-based approach, stepwise management, congenital infections (TORCH), and emerging pediatric infectious diseases.

📖 Core concepts: Pediatric Infections

🦠 Common bacterial
Sepsis, meningitis (N. meningitidis, S. pneumoniae, GBS, Listeria), pneumonia (S. pneumoniae, Mycoplasma), osteomyelitis, UTI, GAS (pharyngitis, scarlet fever, rheumatic fever), TB.
🧬 Viral syndromes
RSV bronchiolitis, influenza, COVID-19, rotavirus gastroenteritis, enterovirus meningitis, EBV (mononucleosis), CMV, HSV, VZV, measles, mumps, rubella.
⚡ Fungal & parasitic
Candida (thrush, invasive), Aspergillus (immunocompromised), PCP (HIV), malaria, toxoplasmosis, giardiasis, ascariasis, schistosomiasis.
💊 Antimicrobial stewardship
Narrow-spectrum when possible, de-escalation, prevent resistance (MRSA, VRE, ESBL), PK/PD in children, vaccination schedule.
⚠️ Red flags for serious infection (NICE/SIGN): Ill/toxic appearance, lethargy, poor peripheral perfusion, petechial/purpuric rash, respiratory distress/grunting, bulging fontanelle, focal neurology, fever >5 days, rigors.

🩺 Symptom-based approach to pediatric infections

🔍
Fever without source – Age-based algorithm: 0–28d (full septic workup, empiric ampicillin+gent/cefotaxime); 1-3 mo (low-risk criteria: well appearing, no focus, lab: WBC 5-15, CRP<20, UA negative → can observe or treat); >3 mo (clinical + UTI screen, CXR if respiratory).
🌡️
Fever + rash – Maculopapular (viral exanthems, EBV, enterovirus); petechial/purpuric → meningococcemia (STAT ceftriaxone); vesicular (varicella, HSV, disseminated VZV in immunocompromised); urticarial (viral, serum sickness).
🫁
Cough + tachypnea – Fast breathing thresholds (age specific); lower chest indrawing → pneumonia (antibiotics). Stridor: croup (dexamethasone, epinephrine) vs epiglottitis (airway emergency).
🤧
Rhinitis / noisy breathing – Nasal congestion in infants can cause feeding difficulty; rhinorrhea with fever suggests viral URI; persistent unilateral purulent discharge → foreign body or sinusitis.
🧠
Suspected meningitis – Ill child + meningeal signs, bulging fontanel, altered sensorium. LP unless contraindicated. Empiric: ceftriaxone + vancomycin + dexamethasone (if >1 month); in <1 month: ampicillin + cefotaxime/gentamicin.

⚕️ Stepwise management of severe infections & septic shock

1
Recognition & resuscitation (ABC) – Airway, Breathing (oxygen), Circulation (IV/IO access). Septic shock: 20 mL/kg fluid bolus (isotonic), reassess, repeat up to 60 mL/kg; start vasoactive (dopamine, epinephrine, norepinephrine) if fluid refractory.
2
Early antibiotics (within 1 hour) – After blood culture. Empiric broad spectrum: ceftriaxone + vancomycin (if risk of MRSA, or severe sepsis/meningitis). Neonates: ampicillin + gentamicin/cefotaxime. Source control (abscess drainage, line removal).
3
Adjunctive therapies – Dexamethasone for bacterial meningitis (Hib, pneumococcus). Hydrocortisone if vasopressor refractory shock (absolute or relative adrenal insufficiency).
4
Monitoring & de-escalation – Daily review; narrow antibiotics based on culture/sensitivities. CRP, PCT trend. Antimicrobial stewardship: stop antibiotics if infection unlikely.
5
Infection control & prevention – Isolation precautions (contact/droplet/airborne). Notification of public health for reportable diseases (meningococcus, measles, TB). Vaccination catch-up.
📌 Sepsis Six in children: Give high-flow oxygen, obtain blood cultures, IV antibiotics, fluid resuscitation, check lactate, monitor urine output. Involve senior/ICU early.

🧠 Reflex prompts: high-yield pediatric infections

👶 2-week-old, fever, irritability, bulging fontanelle? LP shows GBS.
Neonatal meningitis. Empiric: ampicillin + cefotaxime/gentamicin. Dexamethasone not routinely in neonates.
🧪 3-year-old, fever, petechial rash, toxic appearance.
Meningococcemia until proven otherwise. IV ceftriaxone + notify public health. Chemoprophylaxis for close contacts (rifampin).
🌡️ 5-year-old, prolonged fever, red eyes, rash, cervical adenopathy, strawberry tongue.
Kawasaki disease (rule out bacterial causes). Echocardiogram, IVIG + aspirin.
🦷 8-year-old, sore throat, fever, sandpaper rash, circumoral pallor. Rapid strep (+).
Scarlet fever (GAS). Penicillin or amoxicillin for 10 days to prevent rheumatic fever.
🧬 4-month-old, winter, wheeze, tachypnea, RSV positive.
Bronchiolitis: supportive care (hydration, oxygen if sat <92%). No routine steroids/antibiotics.
🌍 Child returning from travel, fever, chills, sweats. Blood smear shows ring forms.
Plasmodium falciparum malaria. Artemether-lumefantrine (ACT) or IV artesunate for severe malaria.
🩸 Neonate with vesicular rash, seizures. Mother with genital herpes.
Neonatal HSV. IV acyclovir, PCR confirmation, ophthalmology review, neuroimaging.
🧫 Immunocompromised child, fever, dry cough, hypoxemia, bilateral CXR infiltrates.
Pneumocystis jirovecii pneumonia (PCP). TMP-SMX high dose, steroids if PaO2 <70 mmHg.
🍼 4-week-old, poor feeding, hypothermia, jaundice, direct hyperbilirubinemia.
Congenital CMV or sepsis. Check urine CMV PCR, treat with ganciclovir if symptomatic CMV disease.
💊 Child with sore throat, monospot positive. Avoid which antibiotic?
Amoxicillin (ampicillin) – causes maculopapular rash in EBV infectious mononucleosis.