Nizami S Q, Bhutta Z A, Siddiqui A A, Lubbad L
Department of Pediatrics, The Aga Khan University and Hospital, Karachi, Pakistan.
Scand J Clin Lab Invest. 2006;66(5):429-36. doi: 10.1080/00365510600791724.
Yield of blood culture in clinically suspected cases of typhoid fever is low, whereas indirect serological diagnostic tests are unreliable. Hence, polymerase chain reaction (PCR)-based detection of Salmonella enterica Serovar typhi was used as an aid for diagnosis of typhoid fever in addition to other diagnostic tests. Two periurban communities in Karachi were selected for an epidemiological study of typhoid fever. The aim of the study was to assess whether PCR increased the detection rate of typhoid fever in children in the community.
Children aged 2 to 14 years presenting with fever lasting for three or more days were selected. PCR using Hashimoto's protocol based on ViaB gene sequence was used in addition to blood culture and other serological tests.
Of the 214 children included in the study, blood culture was found positive for S. enterica S. typhi in 26 (12.4%) cases, whereas 24 children (11.7%) were diagnosed as suffering from typhoid fever when the PCR-based method was used. Both tests were positive in only 10 (4.9%) children. The number of children found positive for either test was 40. PCR increased the rate of detection of typhoid fever by 51%.
The sensitivity, specificity, +ve and -ve predictive values of PCR in this study were 40%, 93%, 45% and 92%, respectively.
在临床疑似伤寒热病例中，血培养的阳性率较低，而间接血清学诊断测试不可靠。因此，除其他诊断测试外，基于聚合酶链反应（PCR）的伤寒沙门氏菌检测被用作伤寒热诊断的辅助手段。选择卡拉奇的两个城郊社区进行伤寒热的流行病学研究。该研究的目的是评估PCR是否提高了社区儿童伤寒热的检出率。
选取2至14岁持续发热三天或更长时间的儿童。除血培养和其他血清学检测外，还使用基于ViaB基因序列的桥本氏方案进行PCR检测。
在纳入研究的214名儿童中，26例（12.4%）血培养发现伤寒沙门氏菌呈阳性，而使用基于PCR的方法时，有24名儿童（11.7%）被诊断为患有伤寒热。两种检测均呈阳性的儿童仅10例（4.9%）。两种检测中任何一种呈阳性的儿童数量为40例。PCR将伤寒热的检出率提高了51%。
本研究中PCR的敏感性、特异性、阳性和阴性预测值分别为40%、93%、45%和92%。
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