Pneumococcal meningitis in children: relationship of antibiotic resistance to clinical characteristics and outcomes.

BACKGROUND: The relationship of antibiotic susceptibility to clinical outcome in children with pneumococcal meningitis is uncertain. Previous studies have been limited by inclusion of relatively few patients infected with nonsusceptible pneumococci and inconsistent use of empiric vancomycin. METHODS: Medical records of 86 children with culture-confirmed pneumococcal meningitis at a single institution from October, 1991, to October, 1999, were retrospectively reviewed, and differences in presentation and outcome based on antibiotic susceptibility of pneumococcal isolates were assessed. RESULTS: Of 86 isolates 34 were nonsusceptible to penicillin (12 resistant). Of 60 isolates for which cefotaxime susceptibility data were available, 17 were nonsusceptible (12 resistant). Antibiotic susceptibility was not significantly associated with death, intensive care unit admission, mechanical ventilation, focal neurologic deficits, seizures, secondary fever, abnormal neuroimaging studies or hospital days. Children with penicillin-resistant isolates had significantly higher median blood leukocyte counts (24,100/microliter vs. 15,700/microliter, P = 0.03) and lower median CSF protein concentrations (85 mg/dl vs. 219 mg/dl, P = 0.04), were more likely to have a CSF glucose concentration of > or = 50 mg/dl (7 of 11 vs. 15 of 68, P = 0.009) and had lower rates of sensorineural hearing loss (1 of 8 vs. 25 of 40, P = 0.02) than children with isolates that were not resistant to penicillin. Children with cefotaxime-nonsusceptible isolates had an increased median duration of primary fever compared with those with nonsusceptible strains (6 days vs. 3.5 days, P = 0.02). CONCLUSIONS: In children with pneumococcal meningitis, penicillin resistance was associated with a reduced risk of hearing loss, while cefotaxime resistance was associated with a longer duration of fever. Other outcome measures were not significantly influenced by the antibiotic susceptibility of pneumococcal isolates.

Effects of antibiotic class on the macrophage inflammatory response to Streptococcus pneumoniae.

Antibiotic choice can alter host inflammation during invasive bacterial infections. Previous studies of gram-negative organisms concluded that antibiotic-mediated release of bacterial cell wall components amplifies inflammation. Less has been reported about antibiotic effect on gram-positive organisms. This study explored the hypothesis that Streptococcus pneumoniae would induce greater macrophage inflammatory mediator production when killed with cell wall active antibiotics rather than protein synthesis inhibitors. Stimulation of RAW 264.7 murine macrophages with pneumococci and oxacillin led to significantly higher inducible nitric oxide synthase (iNOS) and tumor necrosis factor (TNF) accumulation than did the same concentrations of pneumococci and clindamycin. Neither antibiotic alone or in combination with lipopolysaccharide acted directly on macrophages to modify the immune response. Endotoxin contamination did not confound the results, as preincubation with polymyxin B did not change iNOS or TNF protein levels. Thus, the antimicrobial mechanism of action affects macrophage inflammatory mediator production after stimulation with pneumococci.

Plastic bronchitis occurring late after the Fontan procedure: treatment with aerosolized urokinase.

OBJECTIVE: To describe the use of aerosolized urokinase in a patient with plastic bronchitis after a Fontan procedure. DESIGN: Case report. SETTING: Pediatric intensive care unit in a university-affiliated children's hospital. PATIENTS: Report of one patient with acute respiratory failure secondary to plastic bronchitis. INTERVENTIONS: Aerosolized urokinase, multiple bronchoscopies, corticosteroids, mucolytics, bronchodilators, and atrial pacing. MEASUREMENTS AND MAIN RESULTS: Airway obstruction secondary to recurring casts improved with the treatments. Histologic analysis of the casts demonstrated less fibrin after treatments with aerosolized urokinase. No adverse events were noted. CONCLUSIONS: The addition of aerosolized urokinase to this patient's treatment regimen helped to resolve life-threatening airway obstruction secondary to fibrin casts.

Pneumococci stimulate the production of the inducible nitric oxide synthase and nitric oxide by murine macrophages.

The role of nitric oxide (NO) in the pathophysiology of gram-positive sepsis is uncertain. In inflammatory conditions, high-output NO production is catalyzed by the enzyme inducible nitric oxide synthase (iNOS). The ability of 2 strains of pneumococci, pneumococcal cell wall preparations, and purified pneumococcal capsule (Pnu-Imune 23) to trigger the production of iNOS protein and NO in RAW 264.7 murine macrophages was tested. Live pneumococci, oxacillin-killed pneumococci, and pneumococcal cell wall preparations stimulated the production of iNOS and NO by RAW 264.7 cells in the presence, but not the absence, of low concentrations of recombinant murine interferon-gamma. In contrast, purified pneumococcal capsule induced little or no iNOS or NO production by these cells. Thus, pneumococci stimulate high-output NO production by murine macrophages. The potential role of NO in the pathogenesis of pneumococcal sepsis deserves further study.