Changing trends in serotype distribution and antimicrobial susceptibility of Streptococcus pneumoniae causing invasive diseases in Central Thailand, 2009-2012.

To describe the trends in serotype distribution and antimicrobial susceptibility of S. pneumoniae causing invasive pneumococcal diseases (IPD) we tested 238 pneumococci isolates from normally sterile sites between 2009 and 2012 and compared these findings with previous data collected within our network. Serotyping was performed for 15 serotypes contained in the 7-,10-, 13-, and experimental 15-valent pneumococcal conjugate vaccines (PCV). The most common serotypes found were 6B (13.9%), 19A (12.6%), 14 (8.0%), 18C (5.9%), and 6A (3.8%); and 39.9% were non-PCV15 serotypes. One of 81 patients with available data had breakthrough infection with vaccine serotype (19F). There was a significant increase of serotype 19A among children ≤5 years (5.6% in 2000-2009 vs 18.3% in 2009-2012, P = 0.003). The all-age serotype coverage was 36.4%, 41.5%, 59.3%, and 59.7% for PCV7, PCV10, PCV13, and PCV 15, respectively. The corresponding coverage in children ≤5 years were 46.4%, 48.8%, 73.2%, and 73.2% respectively. High susceptibilities to penicillin (89.7%), cefotaxime (95.7%), cefditoren (90.2% by Spanish breakpoints), ofloxacin (97.9%), and levofloxacin (100%), but low to cefdinir (50.0%), cefditoren (45.1% by US-FDA breakpoints), macrolides (<50%), clindamycin (67.7%), tetracycline (41.4%), and trimethoprim-sulfamethoxazole (32.4%) were observed. Serotype 19A was less susceptible to penicillin (80.0 vs 91.2%, P = 0.046), cefditoren (66.7 vs 95.5% by Spanish breakpoints, P = 0.004), and tetracycline (9.1 vs 45.5%, P = 0.024) than non-19A isolates. These data emphasize the need for continued surveillance to monitor changes in serotypes as well as antimicrobial susceptibilities in order to guide strategies for prevention and treatment.

Serotype distribution and antimicrobial susceptibility of S. pneumoniae causing invasive disease in Thai children younger than 5 years old, 2000-2005.

In order to predict the potential benefit of pneumococcal conjugate vaccines (PCV), we evaluated the serotype coverage of the 7-, 9-, 11- and 13-valent PCV over the isolates causing invasive pneumococcal disease (IPD) in Thai children. One hundred and fifteen Streptococcus pneumoniae isolates from sterile sites in children younger than 5 years old between 2000 and 2005 were serotyped. The coverages of 7-, 9-, 11-, and 13-valent PCV were 69%, 73.8%, 73.8% and 85.7% in children younger than 2 years, and 73.9%, 77.4%, 77.4% and 87.8% in children younger than 5 years of age, respectively. 69.6% and 22.6% of the isolates were non-susceptible to penicillin and cefotaxime. 7-valent PCV covered 89% and 100% of penicillin and cefotaxime non-susceptible isolates.