Risk factors for penicillin-resistant systemic pneumococcal infections in children

The purpose of this study was to identify risk factors that may differentiate children who develop systemic infections with resistant strains of Streptococcus pneumoniae from those who develop penicillin-susceptible pneumococcal infections. A retrospective case-controlled study was performed of all patients with positive blood and/or cerebrospinal fluid isolates for S. pneumoniae over a 13 1/2-month period. Patients with penicillin-susceptible strains of S. pneumoniae were compared with those with penicillin-resistant infections in terms of age, race, gender, diagnosis, underlying conditions, antibiotic therapy within 1 month prior to systemic infection, treatment, and outcome. Sixty-nine patients with systemic pneumococcal infections were identified over the study period. Nine (13%) of these patients had infection with a penicillin-resistant isolate. Six of these patients were infected with a relatively resistant strain (MIC 0.1-1.0 microgram/mL) while three were infected with a fully resistant strain (MIC > or = 2.0 micrograms/mL). There was no difference between the two groups in terms of age, race, gender, underlying diagnosis, treatment, or outcome. Sixty-seven percent of the patients who developed a penicillin-resistant pneumococcal infection had received antibiotics in the month prior to systemic illness versus 4% of those infected with a penicillin-susceptible strain (P < 0.0000097). In conclusion, when compared with children who develop systemic infection with a penicillin-susceptible strain of S. pneumoniae, children who develop infection with a penicillin-resistant strain are significantly more likely to have received antibiotics within 1 month prior to their illness.