Serotype distribution and antimicrobial resistance patterns of invasive isolates of Streptococcus pneumoniae:: Alaska, 1991-1998

From January 1991 through December 1998, a total of 1046 pneumococcal isolates were received from 23 laboratories participating in the statewide surveillance system. Of these, 1037 were recovered from normally sterile sites (blood and cerebrospinal and pleural fluid) and were available for serotyping and susceptibility testing. Ninety-two percent of these isolates were serotypes represented in the 23-valent pneumococcal polysaccharide vaccine. Serotypes in the 7-valent pneumococcal conjugate vaccine (4, 6B, 9V, 14, 18C, 19F, and 23F) were recovered from 72% of Alaska Natives and 84% of non-Native children <5 years old with invasive disease. Statewide, 7.3% and 3.2% of isolates had intermediate and high levels of resistance to penicillin, respectively; 9.2% were resistant to erythromycin (minimal inhibitory concentration, greater than or equal to 1 mu g/mL) and 19% to trimethoprim/sulfamethoxazole (minimal inhibitory concentration, greater than or equal to 4/76 mu g/mL). Twelve percent of invasive isolates were resistant to greater than or equal to 2 classes of antibiotics, of these, serotype 6B accounted for 33%, and 63% were recovered from children <5 years old.