Penicillin- and Cephalosporin-Resistant Streptococcus pneumoniae: An Emerging Microbial Threat

Recent reports from South Africa,1 Spain,2 Hungary,3 Texas,4-6 and Memphis7,8 document an increasing incidence of penicillin-resistant Streptococcus pneumoniae infections in children. The emergence of penicillin-resistant pneumococci that also demonstrate decreased susceptibility to extended-spectrum cephalosporins presents an even greater clinical challenge.6-9 This commentary reviews recent developments in the epidemiology, identification, and management of penicillin- and cephalosporin-resistant pneumococcal disease in children. Pneumococcal susceptibility to penicillin is defined as a minimal inhibitory concentration (MIC) <0.1 µg/mL. Intermediate (relative) penicillin resistance is defined as an MIC from 0.1 to 1.0 µg/mL and high-level resistance as an MIC >1.0 µ/mL. Pneumococcal penicillin resistance is mediated by alterations in penicillin-binding proteins involved in cell wall synthesis.10