Antimicrobial resistance patterns and serotype distribution of invasive Streptococcus pneumoniae isolates from children in Taiwan from 1999 to 2004

Streptococcus pneumoniae causes substantial morbidity and mortality worldwide. Because only limited data are available for the antibiotic resistance patterns and seroepidemiology of invasive S. pneumoniae isolates in Taiwanese children, this national surveillance of invasive pneumococcal infections in children was conducted during a 5-year period. Invasive isolates of S. pneumoniae were obtained from sterile sites (yielding blood and cerebrospinal, pleural, and intra-articular fluids) in children (aged ≤14 years) at a total of 40 regional hospitals and medical centers distributed throughout Taiwan. The collection period was between July 1999 and June 2004, with a total of 286 isolates (including 30 cerebrospinal fluids) collected. All the samples were sent to the Center for Disease Control in Taipei for serotyping and susceptibility testing. Of the 286 S. pneumoniae isolates studied, the 5 most common serotypes were 14 (28.3%), 23F (21.0%), 6B (17.1%), 19F (13.6%), and 3 (4.9%). Intermediate- and high-level penicillin resistance was determined for 50.7% and 25.5% of the isolates, respectively. Isolate resistance was demonstrated to erythromycin (93%), tetracycline (82.2%), trimethoprim/sulfamethoxazole (79.4%), cefotaxime (11.2%), and levofloxacin (0.3%). Multiple drug resistance was found for each serotype, but mostly in types 14, 23F, 6B, and 19F. Overall, 85.0% of the serotypes, 90.8% of the penicillin-nonsusceptible S. pneumoniae (PNSSP), and 90.1% of the multiple drug-resistant (MDR) isolates were covered by the heptavalent pneumococcal conjugated vaccine (PCV7). In this study, we found a diverse pulse-field gel electrophoresis pattern among MDR isolates: a high prevalence of drug resistance and a continued increasing trend in penicillin resistance among nationwide pneumococcal isolates from children in Taiwan. The highest prevalence of invasive pneumococcal disease was in children aged 2 to 5 years, and the highest PNSSP prevalence and highest PCV7 coverage were in children aged <2 years. In terms of reducing the risk of invasive pneumococcal illness in Taiwan, the use of PCV7 is likely to have a beneficial effect similar to that obtained in countries that have used it.