Outcome of invasive infections outside the central nervous system caused by Streptococcus pneumoniae isolates nonsusceptible to ceftriaxone in children treated with beta-lactam antibiotics

Objective. To determine the outcome of children treated primarily with beta-lactam antibiotics for a systemic infection outside the central nervous system (CNS) caused by isolates of Streptococcus pneumoniae nonsusceptible to ceftriaxone (MIC ≥ 1.0 μg/ml). Design. Retrospective review of the medical records of children identified prospectively with invasive infections outside of the CNS caused by isolates of S. pneumoniae that were not susceptible to ceftriaxone between September, 1993, and August, 1999. A subset of this group treated primarily with beta-lactam antibiotics was analyzed for outcome. Patients. Infants and children with pneumococcal infections cared for at eight children's hospitals. Results. Among 2100 patients with invasive infections outside the CNS caused by S. pneumoniae, 166 had isolates not susceptible to ceftriaxone. One hundred patients treated primarily with beta-lactam antibiotics were identified. From this group 71 and 14 children had bacteremia alone or with pneumonia, respectively, caused by strains with an MIC of 1.0 μg/ml. Bacteremia or pneumonia caused by isolates with a ceftriaxone MIC ≥ 2.0 μg/ml occurred in 6 and 5 children, respectively. Three children with septic arthritis and 1 with cellulitis had infections caused by strains with an MIC to ceftriaxone of 1.0 μg/ml. Most were treated with parenteral ceftriaxone, cefotaxime or cefuroxime for one or more doses followed by an oral antibiotic. All but one child were successfully treated. The failure occurred in a child with severe combined immune deficiency and bacteremia (MIC = 1.0 μg/m1) who remained febrile after a single dose of ceftriaxone followed by 12 days of cefprozil. Conclusion. Ceftriaxone, cefotaxime or cefuroxime are adequate to treat invasive infections outside the CNS caused by pneumococcal isolates with MICs up to 2.0 μg/ml, a concentration currently considered resistant for these antibiotics by National Committee for Clinical Laboratory Standards breakpoints.