Pneumococcal Infections

Key Features

Essentials of Diagnosis

Bacteremia

• High fever (> 39.4°C)

• Leukocytosis (> 15,000/μL)

Pneumonia

• Fever, leukocytosis, and tachypnea

• Localized chest pain

• Localized or diffuse rales

• Chest radiograph may show lobar infiltrate (with effusion)

Meningitis

• Fever, leukocytosis

• Bulging fontanelle, neck stiffness

• Irritability and lethargy

All types

• Diagnosis confirmed by cultures of blood, CSF, pleural fluid, or other body fluid.

General Considerations

• Sepsis, sinusitis, otitis media, pneumonitis, meningitis, osteomyelitis, cellulitis, arthritis, vaginitis, and peritonitis are part of the spectrum of pneumococcal infection

• Incidence rate of pneumococcal meningitis has decreased since incorporation of the pneumococcal conjugate vaccine into the infant vaccine schedule

• However, pneumococcal meningitis is still more common than Haemophilus influenzae type b meningitis

• Children with sickle cell disease, other hemoglobinopathies, congenital or acquired asplenia, and some immunoglobulin and complement deficiencies are unusually susceptible to pneumococcal sepsis and meningitis

• Children with cochlear implants are at higher risk for pneumococcal meningitis

Clinical Findings

Symptoms and Signs

• Clinical findings that correlate with occult bacteremia in ambulatory patients include age (6–24 months), degree of temperature elevation (> 39.4°C), and leukocytosis (> 15,000/μL)

• In pneumococcal sepsis

  • Fever usually appears abruptly, often accompanied by chills

  • Respiratory symptoms may be absent

• In infants and young children with pneumonia

  • Fever, and tachypnea without auscultatory changes are the usual presenting signs

  • Respiratory distress is manifested by nasal flaring, chest retractions, and tachypnea

  • Abdominal pain is common

• In older children, the adult form of pneumococcal pneumonia with signs of lobar consolidation may occur, but sputum is rarely bloody

• Meningitis

  • Characterized by fever, irritability, convulsions, and neck stiffness

  • Most important sign in very young infants is a tense, bulging anterior fontanelle

  • In older children, fever, chills, headache, and vomiting are common

  • Classic signs are nuchal rigidity associated with positive Brudzinski and Kernig signs

  • Opisthotonos, stupor, and coma may develop with progression of untreated disease

Differential Diagnosis

• viral infection, urinary tract infection, unrecognized focal infection elsewhere in the body, salmonellosis, or early acute shigellosis.

Diagnosis

Laboratory Findings

• Leukocytosis is often pronounced (20,000–45,000/μL), with 80–90% polymorphonuclear neutrophils

• Neutropenia may be seen early in very serious infections

• Large numbers of organisms are seen on Gram-stained smears of endotracheal aspirates from patients with pneumonia

• Isolation of S pneumoniae from a normally sterile site (eg, blood, CSF, joint fluid, middle ear fluid) or from a suppurative focus confirms the diagnosis

Diagnostic Procedure

• Pneumococcal meningitis is diagnosed by lumbar puncture

• CSF usually shows an elevated white blood cell (WBC) count of several thousand, chiefly polymorphonuclear neutrophils, with decreased glucose and elevated protein levels

Treatment

• For empiric therapy of serious or ...