ABSTRACT
Context: Tuberculosis (TB) is a major public health problem in India and a principal cause of death in adults, especially among the economically productive age group. India accounts for one‑fifth of the global burden of TB. It is estimated that about 40% of Indian population is infected with TB bacillus. The GenoType® MTBDRplus molecular method allows rapid diagnosis of the clinical samples and detection of the most common mutations in the genes associated with rifampicin (R) and isoniazid (H) resistance. Aims: To study the drug resistance and mutational patterns in multidrug‑resistant (MDR) suspects clinical strains using GenoType® MTBDRplus assay. Subjects and Methods: A total of 770 sputum samples of the MDR‑TB suspects were included in this study, which were received at Intermediate Reference Laboratory, Government TB Sanatorium, Dharampur, Solan, Himachal Pradesh from the Designated Microscopy Centres of Himachal Pradesh for the culture and susceptibility testing. All the 521 Mycobacterium tuberculosis complex (MTBC) strains were subjected to GenoType® MTBDRplus (HAIN Lifescience) assay to detect molecular resistance pattern to first line anti‑tubercular drugs (isoniazid and rifampicin). Results: Of 770 samples, 556 (72.20%) were from male and 214 (27.80%) were from female. Among the 521 MTBC strains, 19.76% were found to be MDR and mono‑resistance to isoniazid and rifampicin was detected in 8.63% and 6.14% strains respectively. About 74.81%, 76.35% and 5.40% strains harboured known mutation in rpoB, katG and inhA genes respectively. Conclusions: In rpoB gene, the most common mutation is associated with S531 L region. The GenoType® MTBDRplus assay is a rapid test for the detection of the most common mutations in MDR‑TB strains. In our study, unknown rpoB gene mutations were found in 25.18% strains that may further be detected by gene sequencing.
ABSTRACT
Aims: To evaluate GenoType® MTBDRplus line probe assay as a diagnostic tool for detection of Mycobacterium tuberculosis and drug susceptibility testing from cerebrospinal fluid of probable tuberculous meningitis patients. Study Design: A prospective, double blind study. Place and Duration of study: Dept. of Microbiology and Neurology, Institute of Human Behavior and Allied sciences, Delhi, India between February 2014 to October 2014. Methodology: Cerebrospinal fluid collected from 107 probable meningitis patients with diagnostic score >10 were subjected to smear microscopy, automated liquid culture (BACTEC MGIT 960) and Polymerase chain reaction (IS6110). All the samples were also subjected to GenoType® MTBDRplus line probe assay for detecting M. tuberculosis and drug susceptibility. Drug susceptibility testing of all the M. tuberculosis isolates was done by BACTEC MGIT 960 and GenoType® MTBDRplus line probe assay. Results: The sensitivity, specificity of the assay for M. tuberculosis detection was 49.5%, 100% against clinical diagnosis as reference standard and 68.9%, 100% against definitive diagnosis as reference standard. A diagnostic accuracy of 56.8% (kappa 0.22), 75% (kappa 0.46), were seen in patients with probable and confirmed diagnosis respectively. The drug susceptibility results for Isoniazid and Rifampicin could be delineated in only 39.2% of patients. Conclusion: This assay proved to have better sensitivity, diagnostic accuracy than smear microscopy and automated liquid culture for early detection of M. tuberculosis from probable tuberculous meningitis patients and has comparable sensitivity to culture (39.2%) for detection of drug susceptibility (though on different isolates). Rapid turnaround time and user friendliness makes it an acceptable assay for simultaneous early detection of M. tuberculosis and its drug susceptibility for better patient management.
ABSTRACT
Purpose: The emergence and spread of multidrug-resistant tuberculosis (MDR-TB) is a major public health problem. The diagnosis of MDR-TB is of paramount importance in establishing appropriate clinical management and infection control measures. The aim of this study was to evaluate drug resistance and mutational patterns in clinical isolates MDR-TB by GenoType® MTBDRplus assay. Material and Methods: A total of 350 non-repeated sputum specimens were collected from highly suspected drug-resistant pulmonary tuberculosis (PTB) cases; which were processed by microscopy, culture, differentiation and first line drug susceptibility testing (DST) using BacT/ALERT 3D system. Results: Among a total of 125 mycobacterium tuberculosis complex (MTBC) strains, readable results were obtained from 120 (96%) strains by GenoType® MTBDRplus assay. Only 45 MDR-TB isolates were analysed for the performance, frequency and mutational patterns by GenoType® MTBDRplus assay. The sensitivity of the GenoType® MDRTBplus assay for detecting individual resistance to rifampicin (RIF), isoniazid (INH) and multidrug resistance was found to be 95.8%, 96.3% and 97.7%, respectively. Mutation in codon S531L of the rpoB gene and codon S315T1 of katG genes were dominated in MDR-TB strains, respectively (P < 0.05). Conclusions: The GenoType® MTBDRplus assay is highly sensitive with short turnaround times and a rapid test for the detection of the most common mutations conferring resistance in MDR-TB strains that can readily be included in a routine laboratory workflow.
ABSTRACT
Background: The problem of multi-drug resistance tuberculosis (MDR-TB) is growing in several hotspots throughout the world. Rapid and accurate diagnosis of MDR-TB is crucial to facilitate early treatment and to reduce its spread in the community. The aim of the present study was to evaluate the new, novel GenoType® MTBDRplus assay for rapid detection of drug susceptibility testing (DST) of MDR-TB cases in Northern India. Materials and Methods: A total of 550 specimens were collected from highly suspected drug resistant from pulmonary and extra-pulmonary TB cases. All the specimens were processed by Ziehl- Neelsen staining, culture, differentiation by the GenoType® CM assay, fi rst line DST using BacT/ALERT 3D system and GenoType® MTBDRplus assay. The concordance of the GenoType® MTBDRplus assay was calculated in comparison with conventional DST results. Results: Overall the sensitivity for detection of rifampicin, isoniazid and MDR-TB resistance by GenoType® MTBDRplus assay was 98.0%, 98.4% and 98.2% respectively. Out of 55 MDR-TB strains, 45 (81.8%), 52 (94.5%) and 17 (30.9%) strains showed mutation in rpoB, katG and inhA genes respectively (P < 0.05). The most prominent mutations in rpoB, katG and inhA genes were; 37 (67.3%) in S531L, 52 (94.5%) in S315T1 and 11 (20%) in C15T regions respectively (P < 0.05). Conclusions: Our study demonstrated a high concordance between the GenoType® MTBDRplus assay resistance patterns and those were observed by conventional DST with good sensitivity, specifi city with short turnaround times and to control new cases of MDR-TB in countries with a high prevalence of MDR-TB.
ABSTRACT
Background and Objectives: Multidrug-resistant (MDR) Mycobacterium tuberculosis strains are serious threats to the control of tuberculosis and comprise an increasing public health problem. Rapid detection of such strains is quite critical in timely management of such issues. The study was performed with an objective to compare Genotype MTBDRplus reverse hybridization probe assay (Hain Lifescince, GmBH, Nehern, Germany) with culture based proportion method for rapidly identifying MDR-TB strains from suspected multi drug resistant cases, referred to GENETUP Kathmandu, Nepal. Methodology: A commercially available new Genotype MTBDRplus assay was evaluated for its ability to detect mutations in Mycobacterial isolates conferring resistance to rifampicin (RMP) and isoniazid (INH). A total of 64 MDR isolates (i.e., at least resistant to RMP and INH), 5 fully susceptible strains and 1 RMP sensitive strains by conventional proportion method were analyzed using Genotype MTBDRplus assay. MTBDRplus assay is designed to detect the mutations in the hot spot region of rpoB gene, katG and regulatory region of inhA gene. Results: The MTBDRplus assay detected 59 of 61 RMP resistant strains (96.72%) with mutations on 81-bp hot spot region of rpoB gene and 60 of 63 INH resistant strains (95.23%) with mutation in codon 315 katG and regulatory region of inhA. The sensitivity and specificity for the detection of RMP resistance were 96.72% and 100% respectively. While, value of the same two variables for INH resistance were 95.23% and 100%, respectively. Conclusions: The new Genotype MTBDRplus assay represents a rapid, reliable, upgraded tool with high sensitivity and specificity for the detection of INH and RMP resistance strains that can readily be included in a routine laboratory work for the early diagnosis and control of MDR-TB.