Division of Medical Microbiology, University of Cape Town and National Health Laboratory Service, Cape Town, South Africa.
BMC Infect Dis. 2011 Nov 28;11:329. doi: 10.1186/1471-2334-11-329.
Pneumocystis pneumonia (PCP) is a major cause of hospitalization and mortality in HIV-infected African children. Microbiologic diagnosis relies predominantly on silver or immunofluorescent staining of a lower respiratory tract (LRT) specimens which are difficult to obtain in children. Diagnosis on upper respiratory tract (URT) specimens using PCR has been reported useful in adults, but data in children are limited. The main objectives of the study was (1) to compare the diagnostic yield of PCR with immunofluorescence (IF) and (2) to investigate the usefulness of upper compared to lower respiratory tract samples for diagnosing PCP in children.
Children hospitalised at an academic hospital with suspected PCP were prospectively enrolled. An upper respiratory sample (nasopharyngeal aspirate, NPA) and a lower respiratory sample (induced sputum, IS or bronchoalveolar lavage, BAL) were submitted for real-time PCR and direct IF for the detection of Pneumocystis jirovecii. A control group of children with viral lower respiratory tract infections were investigated with PCR for PCP.
202 children (median age 3.3 [inter-quartile range, IQR 2.2 - 4.6] months) were enrolled. The overall detection rate by PCR was higher than by IF [180/349 (52%) vs. 26/349 (7%) respectively; p < 0.0001]. PCR detected more infections compared to IF in lower respiratory tract samples [93/166 (56%) vs. 22/166 (13%); p < 0.0001] and in NPAs [87/183 (48%) vs. 4/183 (2%); p < 0.0001]. Detection rates by PCR on upper (87/183; 48%) compared with lower respiratory tract samples (93/166; 56%) were similar (OR, 0.71; 95% CI, 0.46 - 1.11). Only 2/30 (6.6%) controls were PCR positive.
Real-time PCR is more sensitive than IF for the detection of P. jirovecii in children with PCP. NPA samples may be used for diagnostic purposes when PCR is utilised. Wider implementation of PCR on NPA samples is warranted for diagnosing PCP in children.
肺囊虫肺炎（PCP）是感染艾滋病毒的非洲儿童住院和死亡的主要原因。微生物学诊断主要依赖于下呼吸道（LRT）标本的银染或免疫荧光染色，但在儿童中难以获得。PCR 用于上呼吸道（URT）标本的诊断已在成人中报告有用，但在儿童中的数据有限。该研究的主要目的是：（1）比较 PCR 与免疫荧光（IF）的诊断效果；（2）研究用于诊断儿童 PCP 时，上呼吸道样本与下呼吸道样本的有用性。
前瞻性纳入在学术医院因疑似 PCP 住院的儿童。采集上呼吸道样本（鼻咽抽吸物，NPA）和下呼吸道样本（诱导痰，IS 或支气管肺泡灌洗，BAL），用于实时 PCR 和直接 IF 检测肺孢子菌。对病毒性下呼吸道感染的儿童进行 PCR 检测以排除 PCP。
共纳入 202 名儿童（中位年龄 3.3[四分位间距，IQR 2.2-4.6]个月）。PCR 的总检出率高于 IF[180/349（52%）比 26/349（7%）；p<0.0001]。与 IF 相比，PCR 在 LRT 样本中检测到更多的感染[93/166（56%）比 22/166（13%）；p<0.0001]和 NPA 中[87/183（48%）比 4/183（2%）；p<0.0001]。与下呼吸道样本（93/166；56%）相比，上呼吸道样本（87/183；48%）的 PCR 检测率相似（比值比，0.71；95%置信区间，0.46-1.11）。仅 30 例对照中有 2 例（6.6%）PCR 阳性。
实时 PCR 比 IF 更敏感，可用于检测儿童 PCP 中的肺孢子菌。当使用 PCR 时，NPA 样本可用于诊断目的。有必要广泛实施 NPA 样本的 PCR 检测，以诊断儿童 PCP。
