Chapter 28: Infections – Pertussis, Pneumococcus, Pseudomonas, Relapsing Fever

🫁 Bordetella pertussis · Streptococcus pneumoniae · Pseudomonas aeruginosa · Borrelia recurrentis (Relapsing fever) · Pediatric management · Vaccines · Antimicrobial therapy
Forfar & Arneil's Textbook of Pediatrics. Comprehensive coverage: whooping cough, pneumococcal disease, pseudomonas infections in CF and immunocompromised, tick/body louse-borne relapsing fever.

📖 Key bacterial pathogens: Pertussis, Pneumococcus, Pseudomonas, Relapsing fever

🐕 Pertussis (whooping cough)
Bordetella pertussis. Paroxysmal cough, inspiratory whoop, post-tussive vomiting. Infants: apnea, cyanosis, severe illness. Diagnosis: PCR/nasopharyngeal culture. Treatment: macrolide (azithromycin). Prevention: DTaP/Tdap vaccine. Post-exposure prophylaxis for high-risk contacts.
🦠 Streptococcus pneumoniae (pneumococcus)
Common cause of pneumonia, meningitis, bacteremia, otitis media. Invasive disease: fever, respiratory distress, altered mental status. Diagnosis: blood/CSF culture, urine antigen, PCR. Treatment: high-dose penicillin/ceftriaxone (if susceptible). PCV13 vaccine dramatically reduced invasive disease.
💧 Pseudomonas aeruginosa
Opportunistic pathogen in cystic fibrosis, immunocompromised, ventilator-associated pneumonia, hot tub folliculitis, malignant otitis externa (diabetes). Chronic infection in CF leads to bronchiectasis. Treatment: dual antipseudomonal therapy (ceftazidime/tobramycin, ciprofloxacin).
🪲 Relapsing fever (Borrelia)
Louse-borne (B. recurrentis) or tick-borne (B. hermsii, B. miyamotoi). Fever episodes separated by afebrile periods, with spirochetemia. Diagnosis: peripheral smear (spirochetes), serology. Treatment: doxycycline (≥8y), penicillin or erythromycin in younger children. Jarisch-Herxheimer reaction risk.
⚠️ Critical alerts: Infant with paroxysmal cough and apnea → pertussis until proven otherwise. High fever, altered mental status, stiff neck → pneumococcal meningitis (empiric vancomycin + ceftriaxone). CF patient with worsening respiratory symptoms → pseudomonas exacerbation. Recurrent fevers with hepatosplenomegaly → relapsing fever after travel to endemic areas.

🩺 Symptom-based approach: pertussis, pneumococcus, pseudomonas, relapsing fever

🫁
Paroxysmal cough with inspiratory whoop, post-tussive vomiting – Pertussis. Obtain PCR/nasal swab. Treat with azithromycin; erythromycin alternative. Isolate (droplet precautions). Notify public health.
🧠
High fever, headache, altered mental status, stiff neck – Possible pneumococcal meningitis. Stat blood culture, LP. Empiric ceftriaxone + vancomycin + dexamethasone. PCV13 history important.
🫁
CF patient with increased cough, sputum, decreased FEV1 – Acute pulmonary exacerbation. Sputum culture for pseudomonas. Treat with dual IV antibiotics (e.g., ceftazidime + tobramycin) and intensified airway clearance.
🪲
Relapsing fevers (3-5 episodes) with myalgia, hepatosplenomegaly, exposure to body lice or tick bites – Relapsing fever (Borrelia). Perform blood smear (spirochetes). Doxycycline (≥8y) or penicillin; monitor Jarisch-Herxheimer reaction.

⚕️ Stepwise management guidelines

1
Pertussis (hospitalized infant) – Respiratory isolation, supportive care (oxygen, hydration). Azithromycin (10 mg/kg/day x5 days). Post-exposure prophylaxis for household contacts (especially unvaccinated infants).
2
Invasive pneumococcal disease – IV ceftriaxone (50-100 mg/kg/day). Add vancomycin if meningitis or penicillin-resistant isolate. Dexamethasone for meningitis (before or with first antibiotic). Vaccination status review.
3
Pseudomonas in cystic fibrosis – Early eradication: inhaled tobramycin (or oral ciprofloxacin + inhaled). Chronic infection: combination IV (e.g., ceftazidime, tobramycin, or aztreonam) based on susceptibility, often 14 days. Chronic suppression with inhaled tobramycin or colistin.
4
Relapsing fever – Single dose doxycycline (if >8y) or tetracycline (adults); erythromycin/penicillin for young children. Observe for Jarisch-Herxheimer (can be life-threatening). Treat lice infestation.
📌 Prevention: DTaP/Tdap (pertussis), PCV13 (pneumococcus). Pseudomonas: infection control in CF centers. Avoid tick/body lice exposure (relapsing fever).

🧠 Reflex prompts – high-yield clinical pearls

🦠 4-month-old with paroxysmal cough, apnea, post-tussive vomiting. Likely organism?
Bordetella pertussis. PCR confirmation, azithromycin, respiratory isolation.
🧬 2-year-old with fever, seizure, neck stiffness. CSF: gram-positive diplococci. Next step?
Streptococcus pneumoniae. Ceftriaxone + vancomycin + dexamethasone. PCV13 status.
💧 Cystic fibrosis patient with chronic pseudomonas. What inhaled antibiotic is used for chronic suppression?
Inhaled tobramycin (TOBI) or colistin (colistimethate).
🪰 Child with relapsing fever (Borrelia) after sleeping in crowded, lice-infested conditions. First-line treatment if >8 years?
Doxycycline single dose or short course. Monitor Jarisch-Herxheimer.
⚠️ What is the most common cause of bacterial pneumonia in children worldwide?
Streptococcus pneumoniae (pneumococcus).
💊 Antibiotic of choice for pertussis in a neonate?
Azithromycin (macrolide). Erythromycin alternative but higher risk of pyloric stenosis.
🧫 What laboratory method is used to diagnose pneumococcal meningitis?
CSF Gram stain, culture, and latex agglutination or PCR.
🌡️ Jarisch-Herxheimer reaction is most commonly seen after treatment of which infection?
Relapsing fever (Borrelia), also syphilis and leptospirosis.
🛡️ Which vaccine reduced invasive pneumococcal disease by >90% in children?
PCV13 (pneumococcal conjugate vaccine).
🦠 Pseudomonas aeruginosa is often resistant to which class of antibiotics in CF?
Multiple classes; treat based on sensitivity, often using beta-lactams and aminoglycosides.