This study was performed as a contribution for a better understanding of Chlamydia pneumoniae frequency in children with respiratory infections. A total of 416 children were recruited from two clinical centers in Sao Luis, Brazil. Of these patients, 165 children had upper respiratory tract infections (URTI), 150 had community-acquired pneumonia (CAP), and 101 were asymptomatic volunteer children. Clinical and epidemiological data from the participants were recorded. Nasopharyngeal swab samples were collected to extract DNA. C. pneumoniae DNA positivity and copy numbers were obtained by an absolute quantitative real-time PCR method. RESULTS: Positivity for C. pneumoniae DNA was higher in samples from URTI children (38.2%) and from CAP children (18.0%) than in those from the control group (7.9%; p < 0.001). Moreover, C. pneumoniae DNA was denser in children with URTI than in asymptomatic children. Considering the cutoff, the highest value of C. pneumoniae DNA found in asymptomatic children of the 3.98 log10 copies/mL, 8.5% (14/165) of the children with URTI, and 3.3% (5/150) with CAP presented high copy numbers of C. pneumoniae DNA. CONCLUSION: Taken together, these results revealed a high frequency of C. pneumoniae in both children with URTI and CAP.

中文翻译：

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儿童急性呼吸道感染肺炎衣原体高发率及危险因素

进行这项研究是为了更好地了解呼吸道感染儿童的肺炎衣原体频率。总共从巴西圣路易斯的两个临床中心招募了 416 名儿童。在这些患者中，165 名儿童患有上呼吸道感染 (URTI)，150 名患有社区获得性肺炎 (CAP)，101 名是无症状的志愿儿童。记录了参与者的临床和流行病学数据。收集鼻咽拭子样本以提取 DNA。通过绝对定量实时 PCR 方法获得肺炎衣原体 DNA 阳性和拷贝数。结果：来自 URTI 儿童 (38.2%) 和来自 CAP 儿童 (18.0%) 的肺炎衣原体 DNA 阳性率高于对照组 (7.9%；p < 0.001)。此外，C. 与无症状儿童相比，患有 URTI 的儿童的肺炎链球菌 DNA 密度更高。考虑到临界值，在无症状儿童中发现的肺炎衣原体 DNA 最高值为 3.98 log10 拷贝/mL，8.5% (14/165) 的 URTI 儿童和 3.3% (5/150) 的 CAP 儿童呈现高拷贝肺炎衣原体DNA的数量。结论：综合起来，这些结果揭示了患有 URTI 和 CAP 的儿童中肺炎衣原体的高频率。