High incidence of penicillin resistance among α-hemolytic streptococci isolated from the blood of children with cancer

Objectives: To survey the susceptibility profiles to several beta-lactam antibiotics and to identify factors related to resistance among blood isolates of alpha-hemolytic streptococci (AHS) obtained from children with cancer. Study Design: All pediatric oncology patients with AHS bacteremia occurring from January 1996 through June 1999 at one cancer center were identified. Isolates were categorized based on the minimum inhibitory concentration as susceptible, intermediate, or resistant to several beta-lactam antibiotics. Demographics and potential factors related to antibiotic resistance were obtained from the medical record. Results: Thirty-eight AHS isolates were obtained from 33 patients. Penicillin susceptibility testing revealed that only 8 (21%) isolates were susceptible, 16 (42%) were intermediate, and 14 (37%) were resistant. All 14 of the penicillin-resistant isolates were also resistant to the 3 cephalosporins tested. Ceftriaxone and ceftazidime were the most active cephalosporins. Antibiotic resistance correlated with the recent use of systemic antibiotics, number of prior infectious episodes, and species type. Conclusions: Blood culture isolates of AHS obtained from children with cancer are frequently resistant to beta-lactam antibiotics. These results indicate that clinically relevant AHS isolates should be tested for antibiotic susceptibility and that beta-lactam antibiotics may not be optimal empiric therapy for fever and neutropenia in children with cancer who have a high risk of AHS infections.