Huang Susan S, Platt Richard, Rifas-Shiman Sheryl L, Pelton Stephen I, Goldmann Donald, Finkelstein Jonathan A
Channing Laboratory, Brigham and Women's Hospital, Boston, Massachusetts, USA.
Pediatrics. 2005 Sep;116(3):e408-13. doi: 10.1542/peds.2004-2338.
The introduction of heptavalent conjugate pneumococcal vaccine (PCV7) has raised concerns for replacement with nonvaccine serotypes in both invasive disease and asymptomatic carriage. Analysis of colonizing serotypes among healthy children in the community provides critical data on such changes.
Nasopharyngeal specimens were obtained from children who were younger than 7 years during well-child or sick visits in primary care practices in 16 Massachusetts communities during 2001 and 2004. Susceptibility testing and serotyping were performed on isolated Streptococcus pneumoniae strains. Vaccination history with PCV7 was abstracted from the medical record.
Among colonizing pneumococcal isolates, PCV7 serotypes decreased from 36% to 14%, and non-PCV7 serotypes increased from 34% to 55%. Overall carriage did not change (26% to 23%); neither did carriage of potentially cross-reactive serotypes (30% to 31%). The most common non-PCV7 serotypes were serotypes 11, 15, and 29. There was a substantial increase in penicillin nonsusceptibility from 8% to 25% in non-PCV7 serotypes; 35% were highly resistant to penicillin. Penicillin nonsusceptibility increased from 45% to 56% among PCV7 serotypes while remaining stable among PCV7 potentially cross-reactive strains (51% vs 54%).
Pneumococcal colonization has changed after the introduction of PCV7, both in serotype distribution and in patterns of antibiotic resistance. The frequency of nonvaccine strains has increased, and the proportion of nonvaccine isolates that are not susceptible to penicillin has tripled. This shift toward increased carriage of nonvaccine serotypes warrants vigilance for changes in the epidemiology of invasive pneumococcal disease.
七价结合肺炎球菌疫苗（PCV7）的引入引发了人们对侵袭性疾病和无症状携带中疫苗血清型被非疫苗血清型取代的担忧。对社区健康儿童中定植血清型的分析为此类变化提供了关键数据。
2001年至2004年期间，从马萨诸塞州16个社区初级保健机构进行健康儿童或患病儿童访视时年龄小于7岁的儿童中获取鼻咽标本。对分离出的肺炎链球菌菌株进行药敏试验和血清分型。从病历中提取PCV7疫苗接种史。
在定植的肺炎球菌分离株中，PCV7血清型从36%降至14%，非PCV7血清型从34%增至55%。总体携带率未变（26%至23%）；潜在交叉反应血清型的携带率也未变（30%至31%）。最常见的非PCV7血清型为11、15和29型。非PCV7血清型中青霉素不敏感率从8%大幅增至25%；35%对青霉素高度耐药。PCV7血清型中青霉素不敏感率从45%增至56%，而在PCV7潜在交叉反应菌株中保持稳定（51%对54%）。
引入PCV7后，肺炎球菌定植在血清型分布和抗生素耐药模式方面均发生了变化。非疫苗菌株的频率增加，对青霉素不敏感的非疫苗分离株比例增至三倍。这种向非疫苗血清型携带率增加的转变值得对侵袭性肺炎球菌疾病的流行病学变化保持警惕。
