title: Clinical evaluation of mtp40 polymerase chain reaction for the diagnosis of extra pulmonary tuberculosis.
abstract: Rapid and sensitive detection of Mycobacterium tuberculosis from patient samples is vital for clinical diagnosis and treatment. The emergence of M. tuberculosis strains with either no copies or only a single copy of IS6110 in Asian countries makes the standard PCR based diagnosis of M. tuberculosis using IS6110 not reliable. We studied the diagnostic efficacy of the in-house PCR amplification of the candidate gene mtp40 as an alternative to IS6110 element based diagnosis. Clinical samples included pulmonary and extra-pulmonary specimens from TB suspected patients residing in Puducherry, South India and were analyzed using in-house PCR procedures targeting IS6110 element and mtp40 genes. Out of 317 clinical specimens analyzed, 132 (41.6 %) and 114 (36 %) were found positive for mtp40 PCR and IS6110 PCR, respectively. However, 18 specimens that were found to negative for IS6110 PCR were found positive for mtp40 PCR, which was further confirmed by DNA sequencing method. PCR amplification of mtp40 gene for the diagnosis of M. tuberculosis in clinical samples is fast, sensitive, and further identified clinical strains that lack IS6110 element in this region. It is clearly demonstrated that there is a significant difference between the two PCR procedures and the sensitivity and specificity levels of mtp40 PCR were found to be higher when compared with DNA sequencing method. Thus, mtp40 based PCR technique will be beneficial in diagnosis of TB where M. tuberculosis strains lack of IS6110 element is predominant.
authors.affiliation: Intermediate Reference Laboratory, Department of Microbiology, State TB Training and Demonstration Centre, Government Hospital for Chest Diseases, Gorimedu, Puducherry, 605006, India, katkin14@gmail.com.
authors.forename: Maruthai
authors.initials: M
authors.lastname: Kathirvel
authors.forename: Vallayyachari
authors.initials: V
authors.lastname: Kommoju
authors.forename: Usharani
authors.initials: U
authors.lastname: Brammacharry
authors.forename: Thirumurugan
authors.initials: T
authors.lastname: Ravibalan
authors.forename: Nandikolla
authors.initials: N
authors.lastname: Ravishankar
authors.forename: Balu
authors.initials: B
authors.lastname: Radhakrishnan
authors.forename: Muthuraj
authors.initials: M
authors.lastname: Muthaiah
mesh_terms: D001208:Asia; D001426:Bacterial Proteins / Q000235:genetics*; D004269:DNA, Bacterial / Q000032:analysis; D005069:Evaluation Studies as Topic; D006801:Humans; D009161:Mycobacterium / Q000145:classification* / Q000302:isolation & purification*; D057089:Pathology, Molecular; D016133:Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D013183:Sputum / Q000382:microbiology; D014376:Tuberculosis / Q000175:diagnosis* / Q000235:genetics / Q000382:microbiology; D010738:Type C Phospholipases / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D010738:Type C Phospholipases; C101028:MpcA protein, Mycobacterium tuberculosis