Serotype distribution and antimicrobial resistance of Streptococcus pneumoniae in Austria

OBJECTIVES: To determine the prevalence of antibiotic resistance and the distribution of serotypes among Streptococcus pneumoniae isolated in Austria. MATERIALS AND METHODS: A total of 2367 strains of S. pneumoniae were collected in an Austrian-wide surveillance system between 1996 and 2002. Isolates were tested for their susceptibility to penicillin and clarithromycin and were serotyped by the capsular swelling method. RESULTS: An overall rise in penicillin resistance was observed from 4.9% in 1996 to 10.0% in 2002 (including both intermediate-resistant and resistant strains). A rise in clarithromycin resistance was also recorded in this period. The overall distribution of serogroups/types remained relatively stable, with 23, 19, 6 and 14 being the most frequent ones. Whereas in 1996 penicillin resistance was predominantly associated with serotype 23F, in 1998 and 2002, resistance was most frequently found in isolates of serogroup 9 and serotype 14, respectively. Coverage rates for currently available vaccines ranged from 57.4% (7-valent) to 72.4% (23-valent) of all serotyped strains. CONCLUSIONS: This rise in pneumococcal resistance to penicillin and clarithromycin, and the change in distribution of serotypes in these resistant strains, indicates that ongoing surveillance programmes are warranted, in order to be able to formulate both effective vaccination strategies and optimal antibiotic therapies.