Evaluation of a commercial test based on ligase chain reaction for direct detection of Mycobacterium tuberculosis in respiratory specimens

Abstract

A ligase chain reaction DNA amplification method for direct detection of Mycobacterium tuberculosis (Abbott LCx MTB) in respiratory specimens was evaluated. Results from LCx MTB Assay were compared with those from acid fast bacilli smear, culture, and final clinical diagnosis for each patient. A total of 297 respiratory specimens (sputum and bronchial lavage) from 193 patients were tested. The sensitivity, specificity, positive predictive value and negative predictive value of LCx vs culture were 92.7%, 93%, 67.8% and 98.7%, respectively. When compared to the clinical final diagnosis, the sensitivity, specificity, PPV and NPV for LCx were 88.9%, 96.8%, 86.5% and 97.4%, respectively. The sensitivity of LCx MTB assay was 75% for smear-negative, culture positive samples. The results indicate that LCx MTB assay is a rapid, simple and valuable technique as a complementary tool for the diagnosis of tuberculosis.

Evolution of tuberculosis diagnostics: From molecular strategies to nanodiagnostics

“…This method display average sensitivity of 75%. It is an expensive test to detect drug resistance often giving false-positive results [ 83 ].…”

Nucleic acid amplification-based techniques for pathogen detection and identification

“…Uptake of this technology to the routine environment has been slow, possibly due to the market dominance of PCR. Commercial LCR kits (LCx, Abbott laboratories) for Mycobacterium tuberculosis seem to perform adequately (Leon Muinos et al, 2004;Ribeiro et al, 2004), but the Chlamydia trachomatis LCx kit had problems with reproducibility and had to be withdrawn from the market due to ''high negative control rates resulting in invalid runs and non-repeating positives'' (FDA product recall Z-0859-1/Z-0860-1, http://www.fda.gov/bbs/topics/ ENFORCE/2001/ENF00709.html). This technology holds great promise, particularly for SNP detection and use in microchips (Lou et al, 2004) or with universal microarrays (Busti et al, 2002).…”

A New Genotyping Method for Detecting Low Abundance Single Nucleotide Mutations Based on Gap Ligase Chain Reaction and Quantitative PCR Assay

“…Further Gap-LCR takes advantage of the primer extension ability of DNA polymerase. A complete match between primers and DNA template will result in specific extension of primers and gap filling by DNA polymerase equivalent to allele-specific PCR or a single-base extension reaction [7][8][9][10]. This reaction is highly sensitive: as few as 50 copies of mutant DNA can be detected in the presence of a 10,000-fold excess of wild-type DNA when Gap-LCR and automated enzyme-linked immunoassay are utilized [7].…”