EMERGENCE OF DRUG-RESISTANT PNEUMOCOCCAL INFECTIONS IN THE UNITED-STATES

Objective.-To estimate drug susceptibility patterns of Streptococcus p neumoniae in selected hospitals in the United States and to characteri ze the epidemiology of invasive drug-resistant pneumococcal infections . Design.-Minimum inhibitory concentrations (MICs) for a variety of co mmonly used antimicrobial drugs were determined for pneumococcal isola tes submitted to the Centers for Disease Control and Prevention (CDC). Risk factors for drug-resistant pneumococcal infection were evaluated . Setting.-Hospital laboratories in the United States submitting pneum ococcal isolates to the CDC between October 1, 1991, and September 30, 1992. Participants.-A total of 544 persons with pneumococci isolated from normally sterile sites. Results.-A total of 13 hospitals in 12 st ates actively participated in an ongoing pneumococcal surveillance stu dy. Resistance to penicillin was detected in 6.6% of isolates, includi ng 1.3% of isolates with MICs of 2.0 mu g/mL or more (compared with <0 .02% of isolates with MIC greater than or equal to 2.0 mu g/mL identif ied by CDC surveillance from 1979 to 1987). A total of 16.4% were resi stant to at least one of the following drugs or drug classes: penicill in, cephalosporins, macrolides, combination trimethoprim and sulfameth oxazole, and chloramphenicol. Six serotypes (6B, 23F, 14, 9V, 19A, and 19F) accounted for nearly 85% of strains resistant to at least one dr ug class. Children were more likely than adults to be infected with st rains resistant to trimethoprim-sulfamethoxazole, erythromycin, or chl oramphenicol. Conclusions.-Emergence of drug-resistant pneumococcal in fections will present critical challenges to clinicians for treating p atients with pneumococcal disease. Widened and intensified surveillanc e is needed. These data suggest that current recommendations for use o f 23-valent pneumococcal capsular polysaccharide vaccines should be ag gressively promoted and that development and evaluation of new conjuga te pneumococcal vaccines may be a crucial part of strategies for preve ntion.