Antimicrobial Resistance of Streptococcus pneumoniae in the United States, 1979-1987

Abstract

The increasing number of Streptococcus pneumoniae isolates identified as relatively or fully resistant to penicillin or fully resistant to other antimicrobials in the United States supports the needto monitor for this resistance. Thus, 5459 S. pneumoniae isolates submitted to the Centers for Disease Control in 1979–1987 by 35 hospitals in a hospital-based pneumococcal surveillance system were evaluated. The MIC to penicillin or ampicillin was ⩾0.1 µg/ml for 274 (5%) isolates; 1 had an MIC of 4.0 µg/ml to penicillin. Seventeen (0.3%)were resistant to erythromycin (MIC, ⩾8 µg/ml), 157 (29%) were resistant to tetracycline (MIC, ⩾16 µg/ml), and 34 (0.6%) were resistant to sulfamethoxazole/trimethoprim (MIC, ⩾76 and 4 ¶g/ml). Isolates relatively resistant to penicillin represented 1.8% of isolates in 1979, 8%in 1982,and 3.6% in 1987. Sixty-five multiply resistant isolates were identified. Pneumococci fromthe southwestern United States (region 4) were morelikely to be relatively resistant to penicillin. Using logistic regression analysis, serotypes 14 and 19A, isolates from region 4, and isolates from middle ear fluidwere associated with penicillin resistance (P ⩽ .008, X:. These dataconfirm that antimicrobial resistance among pneumococcal isolates remained at low levels in the United States through 1987.