Evaluation of Methods for Rapid Detection of Resistance to Isoniazid and Rifampin in Mycobacterium tuberculosis Isolates Collected in the Caribbean

Abstract

The rapid identification of drug-resistant strains of Mycobacterium tuberculosis is crucial for the timely initiation of appropriate antituberculosis therapy. The performance of the Genotype MTBDRplus assay was compared with that of the Bactec 460 TB system, a "gold standard" culture-based method. The Genotype MTBDRplus assay was quicker and more cost-effective for the detection of rifampin resistance, but it was not as good for the detection of isoniazid-resistant strains in our setting.The major serious challenges associated with the management of tuberculosis in Caribbean countries are diagnosis of the infection, drug resistance, and the paucity of reports on the prevalence of drug resistance. Although laboratories in many of these countries have the ability to perform smear microscopy, there is still a shortage of a laboratory capability for the performance of accurate, rapid culture and drug susceptibility tests (DSTs). As a result, many cases with low bacillary loads are misdiagnosed, underdiagnosed, or poorly treated.The rapid detection of drug-resistant Mycobacterium tuberculosis strains facilitates early access to the appropriate therapy, reduces rates of transmission, and improves treatment outcomes (12). M. tuberculosis resistance to isoniazid (INH) and rifampin (RIF), which are two of the most important antituberculosis drugs, often results in treatment failure and death (6); hence, the detection of resistance to these agents is crucial.The phenotypic DST method is routinely performed only after a pure, viable culture is obtained, and this usually takes 4 to 6 weeks, resulting in long diagnostic delays (7). The administration of inappropriate therapy during the period of delay may lead to the acquisition of further drug resistance as well as the dissemination of drug-resistant strains through person-toperson transmission. To improve treatment and prevent the transmission of drug-resistant M. tuberculosis strains, effective alternative diagnostic tests that will enable the rapid detection of drug resistance after the collection of specimens from infected patients are required. This study was carried out to determine the turnaround time, cost, and reliability of the Genotype MTBDRplus assay, a relatively new molecular test, in comparison with those of the Bactec 460 TB system, a "gold standard" conventional method, for the identification and the detection of susceptibility to INH and RIF of M. tuberculosis isolates from the Caribbean. MATERIALS AND METHODSEighty-one samples (26 sputum specimens and 55 culture material specimens on Lowenstein-Jensen medium) received at the Caribbean Epidemiology Centre of Trinidad and Tobago from several Caribbean islands for further confirmatory tests were used for this study. These were processed by standard microbiological methods (9, 11) to identify and confirm the presence of M. tuberculosis as well as to carry out the DSTs (3, 14). Informed consent was not required since no detailed patient information was known and the results were not linked to a patient identif...

Performance Assessment of the GenoType MTBDR plus Test and DNA Sequencing in Detection of Multidrug-Resistant Mycobacterium tuberculosis

“…The frequency of the major mutation S531L (63.2%) is consistent with those found in other studies (50% and 86%) (1,4,6,10,15,21). Our results were consistent despite reports that the D516V mutation was commonly found (38%) in Hungarian strains (5), while it was not common in our MDR isolates (2%) (data not shown).…”

“…This test is useful due to its accuracy and specificity, as well as its short turnaround time and ease of use. Previous studies have demonstrated that the GenoType MTBDRplus test had outstanding performance: 91.7% to 100% accuracy in detecting RIF resistance, 34.6% to 94.6% accuracy in detecting INH resistance, and 92% to 100% accuracy in detecting MDR (1,4,6,10,15,21). In comparison, the GenoType MTBDRplus test identified 95.4% of RIF-resistant isolates, 81.8% of INH-resistant isolates, and 78.5% of MDR isolates in our study.…”

“…The World Health Organization and partners have endorsed the use of the molecular test GenoType MTBDRplus (Hain Lifescience GmbH, Nehren, Germany) for rapid detection of high-risk MDR-TB cases, even directly from certain clinical specimens (1,4,6,10,15,21). The GenoType MTBDRplus test is a PCR-based amplification and reverse blotting assay that employs specific probes hybridized to nitrocellulose strips to detect RIF and INH resistance.…”

Rapid Diagnosis of Mycobacterium tuberculosis Infection and Drug Susceptibility Testing

“…[32][33][34][35][36][37][38][39][40][41][42] Conceptually similar to the INNO-Lipa Rif.tb assay, the MTBDRplus assay has been reported to have a diagnostic sensitivity of approximately 94% for detecting M tuberculosis DNA in smear-positive respiratory specimens. 33 It is of interest that most clinical evaluations of this device have focused on its use for susceptibility testing, not detection of M tuberculosis, so the performance characteristics for the latter use are less well defined.…”

Evaluation of the Performance of GenoType® MTBDRplusAssay for Rapid Detection of Multi-drug ResistantMycobacterium tuberculosisin Sputum Specimens

“…정도로 보고된 것과 유사하다 [11, 16-19, 22, 23, 25]. 하지만 캐리비 안 지역에서 실시한 연구에서는 34.6%로 훨씬 낮아서 지역에 따라 상당한 차이를 보인다 [14]. …”