Prakash S, Katiyar S K, Purwar S, Singh J P
Department of Tuberculosis and Respiratory Diseases, GSVM Medical College, Kanpur, India.
Indian J Med Microbiol. 2009 Apr-Jun;27(2):134-8. doi: 10.4103/0255-0857.49426.
Search for a cost-effective, rapid and accurate test has renewed interest in mycobacteriophage as a tool in the diagnosis of tuberculosis (TB). There has been no reported data on the performance of phage assay in a high burden, low-resource setting like Kanpur city, India.
To assess the sensitivity and specificity of the FASTPlaque TB kit ability to impact the bacillary load in the phage assay and its performance in the sputum smear sample negative cases.
The study involved a cross-sectional blinded assessment of phage assay using the FASTPlaque TB kit on 68 suspected cases of pulmonary TB against sputum smear microscopy by Ziehl-Neilsen staining and culture by the LJ method.
The sensitivity, specificity and positive and negative predictive values of the phage assay were 90.7, 96, 97.5 and 85.7%, respectively. The assay was negative in all the five specimens growing mycobacteria other than TB. The sensitivity of the phage assay tended to decrease with the bacillary load. Of the smear-negative cases, three were false negative, and all of which were detected by the phage assay. Smear microscopy (three smears per patient) had a sensitivity and specificity of 93 and 64%, respectively.
The phage assay has the potential clinical utility as a simple means of rapid and accurate detection of live Mycobacterium tuberculosis bacilli; however, its performance has been inconsistent across various studies, which highlights that the assay requires a high degree of quality control demanding infrastructure and its performance is vulnerable to common adversities observed in "out of research" practice settings like storage, transport and cross-contamination.
对具有成本效益、快速且准确的检测方法的探寻，重新引发了人们对分枝杆菌噬菌体作为结核病（TB）诊断工具的兴趣。在印度坎普尔市这样高负担、资源匮乏的地区，尚无关于噬菌体检测性能的报道数据。
评估FASTPlaque TB试剂盒在噬菌体检测中影响细菌载量的能力以及在痰涂片样本阴性病例中的性能的敏感性和特异性。
本研究采用FASTPlaque TB试剂盒对68例疑似肺结核病例进行噬菌体检测的横断面盲法评估，以齐-尼氏染色痰涂片显微镜检查和罗-琴氏法培养作为对照。
噬菌体检测的敏感性、特异性、阳性预测值和阴性预测值分别为90.7%、96%、97.5%和85.7%。在所有5例培养出非结核分枝杆菌的标本中，该检测均为阴性。噬菌体检测的敏感性倾向于随细菌载量降低。在涂片阴性的病例中，有3例假阴性，而这些均通过噬菌体检测检出。痰涂片显微镜检查（每位患者3张涂片）的敏感性和特异性分别为93%和64%。
噬菌体检测作为一种快速准确检测活结核分枝杆菌的简单方法具有潜在的临床应用价值；然而，其性能在不同研究中并不一致，这突出表明该检测需要高度的质量控制，对基础设施要求较高，并且其性能在“非研究”实际环境（如储存、运输和交叉污染）中常见的不利因素影响下较为脆弱。
