Penicillin-resistant systemic pneumococcal infections in children: A retrospective case-control study

Objective. To determine whether there are any risk factors that differentiate children with systemic infections due to Streptococcus pneumoniae relatively or fully resistant (minimum inhibitory concentration >0.1 μg/mL) to penicillin from those children with infections due to S pneumoniae susceptible to penicillin. Design. Retrospective case-control study. Setting. A large children's hospital. Participants. Forty-three children with systemic penicillin-resistant S pneumoniae infections identified at Texas Children's Hospital over the 51-month period from January 1989 through March 1993. Each case had one or two controls matched only for age and date of S. pneumoniae infection. Sixty-six controls were selected from a group of 341 children with susceptible isolates. Outcome measures. Variables compared included gender, race, diagnosis, underlying conditions, past hospitalization, geographic area of residence, antibiotic use in past month, amoxicillin-clavulanic acid use in past month, and outcome. Results. Thirty-seven patients (86%) had relatively resistant isolates (minimum inhibitory concentration range 0.125 to 1.0 μg/mL) and six patients (15%) had fully resistant isolates (minimum inhibitory concentration range 2.0 to 8.0 μg/mL). Thirty-three percent of the cases vs 36% of the controls had underlying conditions. Seventy-one percent of the cases vs 39% of the controls had received antibiotics in the previous month. Compared with their matched controls, the patients with penicillin-resistant systemic pneumococcal infections were more likely (P = .02) to have received a course of antibiotics within the month prior to their infection. Conclusion. The only identified associated risk factor in children who developed a systemic penicillin-resistant pneumococcal infection appears to have been the use of antibiotics within the month prior to their infection.