Clinical Microbiology, Health Sciences Centre, Diagnostic Services of Manitoba, Winnipeg, Manitoba, Canada.
Microb Drug Resist. 2012 Apr;18(2):176-82. doi: 10.1089/mdr.2011.0197. Epub 2011 Dec 28.
Changes in the epidemiology of Streptococcus pneumoniae were reported worldwide after the introduction of the 7-valent pneumococcal vaccine, particularly an increase in multi-drug resistant (MDR) 19A strains. Subsequently, a 13-valent pneumococcal vaccine (PCV-13) has been introduced. This study assessed the incidence of S. pneumoniae serotypes in all age groups prior to the introduction of PCV-13 in Canada (2007-2009). Eight hundred S. pneumoniae isolates from respiratory specimens and blood cultures were collected as part of a Canadian surveillance study (CANWARD) from patients in 15 tertiary-care centers. Serotyping was performed by the Quellung method and antimicrobial susceptibility testing was performed by broth microdilution in accordance with the Clinical and Laboratory Standards Institute guidelines. The most common serotypes were 19A (8.6%), 3 (7.3%), 22F (6.0%), 4 (4.6%), 5 (4.4%), and 11A (4.4%); and the first serotype 6D isolate in Canada was identified. Serotypes 5, 7F, and 19A were significantly (p<0.001) more frequently isolated from bloodstream infections. Considerable serotype variability was noted for different age groups: 15B (p<0.01) and 19A (p<0.001) were more frequently isolated from children ≤2 years old. Overall, 46.4% of currently circulating S. pneumoniae serotypes in Canada are included in PCV-13. Notably, 87.5% of MDR-S. pneumoniae were covered by PCV-13. Accordingly, PCV-13 will provide coverage against a significant proportion of circulating S. pneumoniae strains in Canada, including the critical antimicrobial-resistant strains.
在 7 价肺炎球菌疫苗推出后，全球范围内报道了肺炎链球菌的流行病学变化，特别是多药耐药（MDR）19A 菌株的增加。随后，推出了 13 价肺炎球菌疫苗（PCV-13）。本研究评估了加拿大在引入 PCV-13 之前（2007-2009 年）所有年龄段的肺炎链球菌血清型发生率。作为加拿大监测研究（CANWARD）的一部分，从 15 个三级护理中心的患者中收集了 800 株来自呼吸道标本和血液培养物的肺炎链球菌分离株。血清分型采用 Quellung 法，抗菌药物敏感性试验采用肉汤微量稀释法，按照临床和实验室标准协会指南进行。最常见的血清型为 19A（8.6%）、3（7.3%）、22F（6.0%）、4（4.6%）、5（4.4%）和 11A（4.4%）；并鉴定出了加拿大的首个 6D 血清型分离株。血清型 5、7F 和 19A 从血流感染中分离出来的频率显著更高（p<0.001）。不同年龄组的血清型变化较大：15B（p<0.01）和 19A（p<0.001）更频繁地从 2 岁以下儿童中分离出来。总的来说，加拿大目前流行的肺炎链球菌血清型中有 46.4%包含在 PCV-13 中。值得注意的是，87.5%的 MDR 肺炎链球菌被 PCV-13 覆盖。因此，PCV-13 将为加拿大流行的肺炎链球菌菌株提供重要的保护，包括关键的耐药菌株。
