Department of Pediatric Immunology and Infectious Diseases, Wilhelmina's Children Hospital, University Medical Centre Utrecht, Utrecht, The Netherlands.
PLoS One. 2013;8(3):e60520. doi: 10.1371/journal.pone.0060520. Epub 2013 Mar 28.
The human nasopharynx is the main reservoir for Streptococcus pneumoniae. We applied conventional and molecular methods to determine the prevalence of S. pneumoniae nasopharyngeal colonization in adults. Paired trans-orally and trans-nasally obtained nasopharyngeal samples from 268 parents of 24-month-old children were assessed for pneumococcal presence. Parents were classified as colonized when live pneumococci were recovered from either sample cultured on medium selective for S. pneumoniae. Of the 52 (19%) colonized parents 49 (18%) were culture-positive in trans-nasal and 10 (4%) in trans-oral samples. Bacterial growth was harvested from these cultures, DNA isolated and tested by quantitative-PCR (qPCR) targeting lytA and piaA genes specific for S. pneumoniae. A sample was considered positive if signals for both genes were detected. Altogether 105 (39%) individuals were classified as positive for pneumococcus by qPCR including 50 (19%) in trans-nasal and 94 (35%) in trans-oral settings. Although significantly more trans-nasal compared to trans-oral samples were culture-positive for S. pneumoniae at the primary diagnostic step (p<0.001) the opposite was observed in qPCR results (p<0.001). To confirm the presence of live pneumococcus in samples positive by qPCR but negative at the initial diagnostic step, we serially-diluted cell harvests, re-cultured and carefully examined for S. pneumoniae presence. Live pneumococci were recovered from an additional 43 parents including 42 positive in trans-oral and 4 in trans-nasal samples increasing the number of individuals culture- and qPCR-positive to 93 (35%) and positive by either of two methods to 107 (40%). There were significantly more trans-oral than trans-nasal samples positive for pneumococcus by both culture and qPCR (n = 71; 27%; vs. n = 50; 19%; p<0.05). Our data suggest that pneumococcal colonization is more common in adults than previously estimated and point towards the superiority of a trans-oral over a trans-nasal approach when testing adults for colonization with S. pneumoniae.
人类鼻咽部是肺炎链球菌的主要储存库。我们应用常规和分子方法来确定成人鼻咽部肺炎链球菌定植的流行率。对 24 个月大儿童的 268 位父母的经口和经鼻配对鼻咽样本进行了评估，以确定肺炎链球菌的存在。当从选择性培养肺炎链球菌的培养基中回收活肺炎链球菌时，将父母归类为定植。在 52 位（19%）定植的父母中，49 位（18%）经鼻样本培养阳性，10 位（4%）经口样本培养阳性。从这些培养物中收获细菌生长物，提取 DNA 并通过针对肺炎链球菌特异性 lytA 和 piaA 基因的定量 PCR（qPCR）进行测试。如果检测到两个基因的信号，则认为样本为阳性。总共 105 位（39%）个体通过 qPCR 被归类为肺炎球菌阳性，包括 50 位（19%）经鼻样本和 94 位（35%）经口样本。尽管在初级诊断步骤中，经鼻样本比经口样本更显著地对肺炎链球菌呈培养阳性（p<0.001），但在 qPCR 结果中则相反（p<0.001）。为了确认在初始诊断步骤中 qPCR 呈阳性但培养阴性的样本中存在活肺炎球菌，我们对细胞收获物进行了连续稀释，重新培养并仔细检查肺炎链球菌的存在。从另外 43 位父母中回收了活肺炎球菌，其中包括 42 位经口样本阳性和 4 位经鼻样本阳性，使培养和 qPCR 阳性的个体数量增加到 93 位（35%），两种方法均阳性的个体数量增加到 107 位（40%）。经口样本比经鼻样本通过培养和 qPCR 检测到的肺炎球菌阳性的数量更多（n=71；27%；vs. n=50；19%；p<0.05）。我们的数据表明，肺炎链球菌定植在成人中比之前估计的更为常见，并指出在测试成人肺炎链球菌定植时，经口途径优于经鼻途径。
