北京上海广州深圳4家儿童医院肺炎住院患儿肺炎链球菌分离株的血清型分布

Surveillance of serotype distribution of Streptococcus pneumoniae isolated from children with pneumonia in children's hospitals located in Beijing,Shanghai,Guangzhou and Shenzhen

目的了解目前从中国住院治疗肺炎患儿分离到的肺炎链球菌的血清型分布,及几种蛋白多糖结合疫苗的覆盖率,评估应用蛋白多糖结合疫苗预防肺炎链球菌感染的价值。方法选择2006年2月16日至2007年2月16日在首都医科大学附属北京儿童医院、复旦大学附属儿科医院、广州市儿童医院和深圳市儿童医院呼吸科住院治疗的肺炎患儿为研究对象,采用一次性吸痰管收集全部病例的呼吸道分泌物标本分离肺炎链球菌,部分患儿进行脑脊液、血液和胸腔积液中肺炎链球菌的分离。采用荚膜肿胀实验进行血清型分析。对4家儿童医院肺炎链球菌分离率和血清型进行分析,率的比较采用χ2检验或Fisher精确概率法。结果研究期间共纳入2865例肺炎患儿,2865例呼吸道吸取物标本中分离到肺炎链球菌279株,其中有2株不同血清型菌株分离自同一病例,分离阳性率为9.7%(278/2865)。3/8例胸腔积液中分离到肺炎链球菌,其中2例同时从呼吸道分泌物分离到肺炎链球菌,取其一进行血清分型,另1株从胸腔积液中分离的肺炎链球菌复苏失败,未进行血清分型。脑脊液和血液标本中未分离到肺炎链球菌。共有279株肺炎链球菌进行了血清型分析,以19F型最常见(60.6%,169/279),其次为19A(9.7%,27/279)、23F(9.3%,26/279)和6B(5.4%,15/279),上述4种血清型占全部菌株的84.9%(237/279)。肺炎链球菌7价结合疫苗(PCV7)覆盖率为81.0%,但在北京仅为46.0%,明显低于上海(80.0%)、广州(98.4%)和深圳(94.4%)。9价、10价和11价疫苗的覆盖率与PCV7相比并没有明显增加。13价疫苗的覆盖率(92.8%)较PCV7明显升高。结论4家儿童医院肺炎住院患儿分离的肺炎链球菌以19F、19A、23F和6B型常见。PCV7覆盖率为87%。

Objective To investigate the situation of serotype distribution of Streptococcus pneumoniae （S. pneumoniae） isolated from Chinese children hospitalized for pneumonia and to evaluate coverage rate of pneumococcal conjugate vaccine in the isolates, especially of the 7-valent pneumococcal conjugate vaccine （PCV7, covering the serotype 4, 6B, 9V, 14, 18C, 19F, and 23 F）. Methods From February 16, 2006 to February 16, 2007, the following four centres, located in different parts of China's Mainland, took part in the study： Beijing Children＇s Hospital, Beijing （Beijing） ; Pediatric Hospital of Fudan University, Shanghai （Shanghai）, Guangzhou Childreu~ Hospital, Guangzhou （Guangzhou） and Shenzhen Children~ Hospital, Shenzhen （Shenzhen）. Children less than 5 years old with clinical pneumonia, who were admitted to the in-patient department of the four hospitals, were enrolled in the study after the informed consents were obtained from parents or legal guardian. Clinical pneumonia was defined as the subjects who had at least three of the followings ： fever （ temperature ≥ 38.0 % ）, tachypnea （ ≥ 50 breaths per minute for infants, or ≥40 breaths for children 12 -60 months old）, cough, auscultation findings indicative of lower respiratory disease （including rhonchi, crackles, or bronchial breath sounds）, and/or chest indrawing. Hypopharyngeal aspirates specimens were collected from the enrolled children and were sent to a local laboratory for bacterial culture. The pneumococcal isolates from aspirates were determined for the serotype using type-specific sera, while the other ones from blood, cerebrospinal fluid, pleural fluid in medical practice. All data were sent to the department for Clinical Data Management ＆ Statistical Analysis of APEX China Co. , Ltd. and were analysed with the software SAS version 8.2. The X2 test and Fisher＇s accurate probability method was performed for comparing the proportions. Results A total of 279 isolates of S. pneumoniae were recovered from respiratory aspirate and pleural fluid. The isolation rate of S. pneumoniae in deep respiratory aspirate was 9. 7% （278/2 865）. Serotype 19F was the most frequent type observed （ 60. 6% ）. Other frequently observed serotypes in decreasing order of frequency, were serotypes 19A （9. 7% ）, 23F （9. 3% ） and 6B （5.4%）. Any of the other identified types were found in less than 10 strains. The frequency of serotype distribution also showed difference among the four cities. The most remarkable one was serotype 19F covered only 28.6% （18/63） in Beijing in compared with 62. 2% -75.45% isolates in the other three cities （X2 = 38. 71, P 〈 0. 001 ）. The serotype 19A, which was not covered by the PCV7, was the second commonest type and was very frequent in Beijing （20. 6%, 13/63） and Shanghai （16. 9%, 11/65）. Of all these isolates, 81.0% （226/279） were covered in the PCV7. The coverage rates of PCV7 among cities ： only 46.0% （29/63） in Beijing, while 80.0% （ 52/65 ）, 98.4% （60/61） and 94.4% （ 85/90 ） in Shanghai, Guangzhou and Shenzhen, respectively （X2 = 72.62, P 〈 0. 001 ）. Compared to the PCV7, the 9-, 10-, and ll-valent vaccine coverage rates did not increase significantly because the additional serotypes 1, 3, 5, or 7F were isolated rarely while the 13-valent vaccine coverage rates had little increase in Guangzhou and Shenzhen, but 18.6% and 28.6% increase in Beijing （X2 = 10. 74, P 〈 0. 01） and Shanghai （X2 = 11.53, P 〈 0. 01 ） as the additional serotype 19A was common. Conclusions Sertotypes 19F, 19A, 23F and 6B were the common types among the pneumococcal strains isolated from Chinese children hospitalized for pneumonia. The case that the PCV7 could cover most of the isolates suggested the preventive effect of the vaccine on penumococcal infection was valid at present in China.