Use of GenoType® MTBDRplus assay to assess drug resistance and mutation patterns of multidrug-resistant tuberculosis isolates in northern India

Patterns and profiles of drug resistance-conferring mutations in Mycobacterium tuberculosis genotypes isolated from tuberculosis-suspected attendees of spiritual holy water sites in Northwest Ethiopia

Purpose

This study examined the patterns and frequency of genetic changes responsible for resistance to first-line (rifampicin and isoniazid), fluoroquinolones, and second-line injectable drugs in drug-resistant Mycobacterium tuberculosis (MTB) isolated from culture-positive pulmonary tuberculosis (PTB) symptomatic attendees of spiritual holy water sites (HWSs) in the Amhara region.

Patients and methods

From June 2019 to March 2020, a cross-sectional study was carried out. A total of 122 culture-positive MTB isolates from PTB-suspected attendees of HWSs in the Amhara region were evaluated for their drug resistance profiles, and characterized gene mutations conferring resistance to rifampicin (RIF), isoniazid (INH), fluoroquinolones (FLQs), and second-line injectable drugs (SLIDs) using GenoType®MTBDRplus VER2.0 and GenoType®MTBDRsl VER2.0. Drug-resistant MTB isolates were Spoligotyped following the manufacturer's protocol.

Results

Genetic changes (mutations) responsible for resistance to RIF, INH, and FLQs were identified in 15/122 (12.3%), 20/122 (16.4%), and 5/20 (25%) of MTB isolates, respectively. In RIF-resistant, rpoB/Ser531Lue (n = 12, 80%) was most frequent followed by His526Tyr (6.7%). Amongst INH-resistant isolates, katG/Ser315Thr1 (n = 19, 95%) was the most frequent. Of 15 MDR-TB, the majority (n = 12, 80%) isolates had mutations at both rpoB/Ser531Leu and katG/Ser315Thr1. All 20 INH and/or RIF-resistant isolates were tested with the MTBDRsl VER 2.0, yielding 5 FLQs-resistant isolates with gene mutations at rpoB/Ser531Lue, katG/Ser315Thr1, and gyrA/Asp94Ala genes. Of 20 Spoligotyped drug-resistant MTB isolates, the majority (n = 11, 55%) and 6 (30%) were SIT149/T3-ETH and SIT21/CAS1-Kili sublineages, respectively; and they were any INH-resistant (mono-hetero/multi-). Of 15 RIF-resistant (RR/MDR-TB) isolates, 7 were SIT149/T3-ETH, while 6 were SIT21/CAS1-Kili sublineages. FLQ resistance was detected in four SIT21/CAS1-Kili lineages.

Conclusion

In the current study, the most common gene mutations responsible for resistance to INH, RIF, and FLQs were identified. SIT149/T3-ETH and SIT21/CAS1-Kili constitute the majority of drug-resistant TB (DR-TB) isolates. To further understand the complete spectrum of genetic changes/mutations and related genotypes, a sequencing technology is warranted.

Profile and Frequency of Mutations Conferring Drug-Resistant Tuberculosis in the Central, Southeastern and Eastern Ethiopia

Purpose

Advances in molecular tools that assess genes harboring drug resistance mutations have greatly improved the detection and treatment of drug-resistant tuberculosis (DR-TB). This study was conducted to determine the frequency and type of mutations that are responsible for resistance to rifampicin (RIF), isoniazid (INH), fluoroquinolones (FLQs) and second-line injectable drugs (SLIDs) in Mycobacterium tuberculosis (MTB) isolates obtained from culture-positive pulmonary tuberculosis (TB) patients in the central, southeastern and eastern Ethiopia.

Patients and Methods

In total, 224 stored culture-positive MTB isolates from pulmonary TB patients referred to Adama and Harar regional TB laboratories between August 2018 and January 2019 were assessed for mutations conferring RIF, INH, FLQs and SLIDs resistance using GenoType^®MTBDRplus (MTBDRplus) and GenoType^®MTBDRsl (MTBDRsl).

Results

RIF, INH, FLQs and SLIDs resistance-conferring mutations were identified in 88/224 (39.3%), 85/224 (38.0%), 7/77 (9.1%), and 3/77% (3.9%) of MTB isolates, respectively. Mutation codons rpoB S531L (59.1%) for RIF, katG S315T (96.5%) for INH, gyrA A90V (42.1%) for FLQs and WT1 rrs (100%) for SLIDs were observed in the majority of the isolates tested. Over a 10th of rpoB mutations detected in the current study were unknown.

Conclusion

In this study, the most common mutations conferring drug resistance to RIF, INH, FLQs were identified. However, a significant proportion of RIF-resistant isolates manifested unknown rpoB mutations. Similarly, although few in number, all SLID-resistant isolates had unknown rrs mutations. To further elucidate the entire spectrum of mutations, tool such as whole-genome sequencing is imperative. Furthermore, the expansion of molecular drug susceptibility testing services is critical for tailoring patient treatment and preventing disease transmission.

Mutations in Mycobacterium tuberculosis Isolates with Discordant Results for Drug-Susceptibility Testing in Peru

Evaluation of resistance to antituberculosis drugs is routinely performed with genotypic or phenotypic methods; however, discordance can be seen between these different methodologies. Our objective was to identify mutations that could explain discordant results in the evaluation of susceptibility to rifampicin and isoniazid between molecular and phenotypic methods, using whole genome sequencing (WGS). Peruvian strains showing sensitive results in the GenoType MTBDRplus v2.0 test and resistant results in the proportions in the agar-plaque test for isoniazid or rifampin were selected. Discordance was confirmed by repeating both tests, and WGS was performed, using the Next Generation Sequencing methodology. Obtained sequences were aligned “through reference” (genomic mapping) using the program BWA with the algorithm “mem”, using as a reference the genome of the M. tuberculosis H37Rv strain. Discordance was confirmed in 14 strains for rifampicin and 21 for isoniazid, with 1 strain in common for both antibiotics, for a total of 34 unique strains. The most frequent mutation in the rpoB gene in the discordant strains for rifampicin was V170F. The most frequent mutations in the discordant strains for isoniazid were katG R463L, kasA G269S, and Rv1592c I322V. Several other mutations are reported. This is the first study in Latin America addressing mutations present in strains with discordant results between genotypic and phenotypic methods to rifampicin and isoniazid. These mutations could be considered as future potential targets for genotypic tests for evaluation of susceptibility to these drugs.

Analysis of drug resistance mutations in pulmonary Mycobacterium tuberculosis isolates in the Southern coastal region of Andhra Pradesh, India

Purpose and objectives

Detection of drug resistance plays a crucial role in tuberculosis (TB) treatment and prevention of Mycobacterium tuberculosis (MTB) transmission. The aim of this study was to determine the levels and patterns of resistance of MTB isolates to two key anti-TB drugs (rifampicin, RIF and isoniazid, INH) and the type of mutations in drug resistance genes (rpoB, katG and inhA) of the isolates at the southern coastal region of Andhra Pradesh, India, using commercially available GenoType MTBDRplus assay under the Revised National TB Control Program.

Methods

GenoType MTBDRplus assay was performed on 2859 sputum smear-positive samples and the mutations in the genes responsible for resistance (rpoB, katG and inhA) were analyzed.

Results

Among the line probe assay (LPA) valid isolates (2894), 1990 (68.76%) were drug susceptible, 437 (15.13%) were INH monoresistant, 104 (3.59%) were RIF monoresistant, and 363 (12.54%) were multidrug resistant. Codon 531 of rpoB gene and codon 315 of katG gene were found to have the highest mutation frequency for RIF resistance (270/467; 57.81%) and INH resistance (501/800; 62.62%), respectively. The RIF resistant rpoB mutations observed in the samples were S531 L (57.81%), H526Y (8.56%), D516 V (6.42%), and H526D (6.20%). Mutations in inhA promoter were found in 24.75% INH resistant isolates with C15 T being the most common (85.85%). The turnaround times of the LPA test were from 48 to72 h.

Conclusion

The frequency of mutations in MTB in the coastal region of Andhra Pradesh, India, is similar to that in retreatment cases from most settings, with close to 80% in rpoB codon 516, 526, and 531, and over 80% in codons katG 315 and/or inhA promoter. The increase in INH monoresistance underlines the need for greater enforcement of national TB control programs.

Prevalence and patterns of rifampicin and isoniazid resistance conferring mutations in Mycobacterium tuberculosis isolates from Uganda

BACKGROUND

Accurate diagnosis of tuberculosis, especially by using rapid molecular assays, can reduce transmission of drug resistant tuberculosis in communities. However, the frequency of resistance conferring mutations varies with geographic location of Mycobacterium tuberculosis, and this affects the efficiency of rapid molecular assays in detecting resistance. This has created need for characterizing drug resistant isolates from different settings to investigate frequencies of resistance conferring mutations. Here, we describe the prevalence and patterns of rifampicin- and isoniazid- resistance conferring mutations in isolates from Uganda, which could be useful in the management of MDR-TB patients in Uganda and other countries in sub-Saharan Africa.

RESULTS

Ninety seven M. tuberculosis isolates were characterized, of which 38 were MDR, seven rifampicin-resistant, 12 isoniazid-mono-resistant, and 40 susceptible to rifampicin and isoniazid. Sequence analysis of the rpoB rifampicin-resistance determining region (rpoB/RRDR) revealed mutations in six codons: 588, 531, 526, 516, 513, and 511, of which Ser531Leu was the most frequent (40%, 18/45). Overall, the three mutations (Ser531Leu, His526Tyr, Asp516Tyr) frequently associated with rifampicin-resistance occurred in 76% of the rifampicin resistant isolates while 18% (8/45) of the rifampicin-resistant isolates lacked mutations in rpoB/RRDR. Furthermore, sequence analysis of katG and inhA gene promoter revealed mainly the Ser315Thr (76%, 38/50) and C(-15)T (8%, 4/50) mutations, respectively. These two mutations combined, which are frequently associated with isoniazid-resistance, occurred in 88% of the isoniazid resistant isolates. However, 20% (10/50) of the isoniazid-resistant isolates lacked mutations both in katG and inhA gene promoter. The sensitivity of sequence analysis of rpoB/RRDR for rifampicin-resistance via detection of high confidence mutations (Ser531Leu, His526Tyr, Asp516Tyr) was 81%, while it was 77% for analysis of katG and inhA gene promoter to detect isoniazid-resistance via detection of high confidence mutations (Ser315Thr, C(-15)T, T(-8)C). Furthermore, considering the circulating TB genotypes in Uganda, the isoniazid-resistance conferring mutations were more frequent in M. tuberculosis lineage 4/sub-lineage Uganda, perhaps explaining why this genotype is weakly associated with MDR-TB.

CONCLUSION

Sequence analysis of rpoB/RRDR, katG and inhA gene promoter is useful in detecting rifampicin/isoniazid resistant M. tuberculosis isolates in Uganda however, about ≤20% of the resistant isolates lack known resistance-conferring mutations hence rapid molecular assays may not detect them as resistant.

Evaluation of genotype MTBDRplus line probe assay in detection of rifampicin and isoniazid resistance in comparison to solid culture drug susceptibility testing in a tertiary care centre of western Uttar Pradesh

BACKGROUND

Isoniazid (INH) and rifampicin (Rif) are the key first-line antituberculosis drugs, and resistance to these drugs i.e., multi-drug-resistant tuberculosis (MDR-TB), is likely to result in treatment failure and poor clinical outcomes. India has the highest burden of TB and MDR-TB in the world, disproportionately high even for India's population. The GenoType® MTBDRplus molecular method allows rapid detection of Rif and INH resistance.

AIM

The present study was done to compare the performance of line probe assay test (GenoType® MTBDRplus) with solid culture method for an early diagnosis of MDR-TB.

METHODS

Totally 1503 sputum samples of MDR-TB suspects were subjected to fluorescent microscopy. Decontamination was done by N-acetyl-L-cysteine and sodium hydroxide method. Fluorescent microscopy-positive samples were subjected to GenoType® MTBDRplus (HAIN Lifescience) assay. Sixty-two random samples were compared with phenotypic drug susceptibility testing (DST) (1% proportion method) using solid culture method by Lowenstein-Jensen media.

RESULTS

The sensitivity, specificity, positive predictive value and negative predictive value for detection of resistance to Rif were 94.74%, 95.35%, 90% and 97.62% and to INH were 92.00%, 91.89%, 88.46% and 94.44%, respectively, in comparison with the phenotypic DST.

CONCLUSION

GenoType® MTBDRplus has good sensitivity and specificity in detecting MDR-TB cases with a significantly lesser turnaround time as compared to conventional DST method and simultaneous detection of Rif and INH resistance. This technique saves several weeks of time required for culture and DST.

Detection of katG and inhA mutations to guide isoniazid and ethionamide use for drug-resistant tuberculosis

BACKGROUND

Depending on the presence of mutations that determine isoniazid (INH) susceptibility (katG and inhA), Mycobacterium tuberculosis may be susceptible to high doses of INH or ethionamide (ETH).

OBJECTIVE

To describe the INH resistance profile and association of katG mutation with previous INH treatment and level of drug resistance based on rapid molecular drug susceptibility testing (DST) in southern Brazil and central Mozambique.

DESIGN

Descriptive study of 311 isolates from Ribeirão Preto, São Paulo, Brazil (2011-2014) and 155 isolates from Beira, Mozambique (2014-2015). Drug resistance patterns and specific gene mutations were determined using GenoType(®) MTBDRplus.

RESULTS

katG gene mutations were detected in 12/22 (54.5%) Brazilian and 32/38 (84.2%) Mozambican isolates. inhA mutations were observed in 9/22 (40.9%) isolates in Brazil and in 4/38 (10.5%) in Mozambique. Both katG and inhA mutations were detected in respectively 1/22 (5%) and 2/38 (5.2%). The difference in the frequency of katG mutations in Brazil and Mozambique was statistically significant (P = 0.04). katG mutations were present in 68.8% (33/48) of patients previously treated with INH and 31.2% (15/48) of patients without previous INH. This difference was not statistically significant (P = 0.223).

CONCLUSION

INH mutations varied geographically; molecular DST can be used to guide and accelerate decision making in the use of ETH or high doses of INH.

Comparison of line probe assay to BACTEC MGIT 960 system for susceptibility testing of first and second-line anti-tuberculosis drugs in a referral laboratory in South Africa

Background

The incidence of multidrug-resistant tuberculosis (MDR-TB) is increasing and the emergence of extensively drug-resistant tuberculosis (XDR-TB) is a major challenge. Controlling resistance, reducing transmission and improving treatment outcomes in MDR/XDR-TB patients is reliant on susceptibility testing. Susceptibility testing using phenotypic methods is labour intensive and time-consuming. Alternative methods, such as molecular assays are easier to perform and have a rapid turn-around time. The World Health Organization (WHO) has endorsed the use of line probe assays (LPAs) for first and second line diagnostic screening of MDR/XDR-TB.

Methods

We compared the performance of LPAs to BACTEC MGIT 960 system for susceptibility testing of bacterial resistance to first-line drugs: rifampicin (RIF), isoniazid (INH), ethambutol (EMB), and second-line drugs ofloxacin (OFL) and kanamycin (KAN). One hundred (100) consecutive non-repeat Mycobacterium tuberculosis cultures, resistant to either INH or RIF or both, as identified by BACTEC MGIT 960 were tested. All isoniazid resistant cultures (n = 97) and RIF resistant cultures (n = 90) were processed with Genotype®MTBDRplus and Genotype®MTBDRsl line probe assays (LPAs). The agar proportion method was employed to further analyze discordant LPAs and the MGIT 960 isolates.

Results

The Genotype ®MTBDRplus (version 2) sensitivity, specificity, PPV and NPV from culture isolates were as follows: RIF, 100%, 87.9, 58.3% and 100%; INH, 100%, 94.4%, 93.5% and 100%. The sensitivity, specificity PPV and NPV for Genotype ® MTBDRsl (version 1 and 2) from culture isolates were as follows: EMB, 60.0%, 89.2%, 68.2% and 85.3%; OFL, 100%, 91.4%, 56.2% and 100%; KAN, 100%, 97.7%, 60.0% and 100%. Line probe assay showed an excellent agreement (k = 0.93) for INH susceptibility testing when compared to MGIT 960 system while there was good agreement (k = 0.6–0.7) between both methods for RIF, OFL, KAN testing and moderate agreement for EMB (k = 0.5). A high RIF mono-resistance (MGIT 960 33/97 and LPA 43/97) was observed.

Conclusion

LPAs are an efficient and reliable rapid molecular DST assay for rapid susceptibility screening of MDR and XDR-TB. Using LPAs in high MDR/XDR burden countries allows for appropriate and timely treatment, which will reduce transmission rates, morbidity and improve treatment outcomes in patients.

GenoType MTBDRplus assay for screening and characterization of isoniazid and rifampicin resistance-associated mutations in multidrug-resistant Mycobacterium tuberculosis from India

Multidrug resistant tuberculosis (MDR-TB) is rising and the World Health Organization has recommended the line probe assay (LPA) for screening. In this study we assess LPA at a tertiary care centre from North India in 1758 samples from suspected MDR-TB cases. All smear-positive and/or Mycobacterium tuberculosis culture confirmed cases (n = 1170) were subjected to the GenoType-MTBDR assay. Amongst these the majority were retreatment cases, smear-positive at diagnosis (n = 637). An MDR prevalence of 7·8% was observed with the highest cases reported amongst MDR contacts (33·3%). The most common rifampicin resistance encoding mutation seen overall and in individual patient groups was H531L (53·3%). A higher prevalence of H526D mutation was observed in retreatment cases, smear-positive at 4 months of anti-tubercular therapy vs other patient groups (P = 0·052). The most common mutation encoding isoniazid resistance was S315T1 in the katG (79·9%) and C-15T in the inhA gene (91·1%). Thirty rifampicin and nine isoniazid resistant isolates had wild type gene deletion but no detectable mutation by LPA. Although LPA is a practical and rapid screening method for most mutations expected to result in MDR-TB, we observed that it only detects the known major mutations in specific genes. Such studies can provide the knowledge required to formulate customized strips based on prevalent mutations in our region and in specific patient groups.

SIGNIFICANCE AND IMPACT OF THE STUDY

To the best of our knowledge this is the largest study evaluating the GenoType-MTBDR line probe assay from India. We have studied the prevalence of mutations encoding rifampicin and isoniazid resistance in different patient groups based on criteria for multidrug resistance (MDR) suspicion. The translational impact of this study is in the design of customized country- or region-wise line probe assay strips. The identification of a few mutations in particular patient groups and the detection of wild type deletion mutants with no observable mutations both point toward the need for such customization enabling us to combat the rising trend of MDR tuberculosis.

Detecting mutation pattern of drug-resistant Mycobacterium tuberculosis isolates in Himachal Pradesh using GenoType(®) MTBDRplus assay

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.

Frequency and Distribution of Tuberculosis Resistance-Associated Mutations between Mumbai, Moldova, and Eastern Cape

Molecular diagnostic assays, with their ability to rapidly detect resistance-associated mutations in bacterial genes, are promising technologies to control the spread of drug-resistant tuberculosis (DR-TB). Sequencing assays provide detailed information for specific gene regions and can help diagnostic assay developers prioritize mutations for inclusion in their assays. We performed pyrosequencing of seven Mycobacterium tuberculosis gene regions (katG, inhA, ahpC, rpoB, gyrA, rrs, and eis) for 1,128 clinical specimens from India, Moldova, and South Africa. We determined the frequencies of each mutation among drug-resistant and -susceptible specimens based on phenotypic drug susceptibility testing results and examined mutation distributions by country. The most common mutation among isoniazid-resistant (INH(r)) specimens was the katG 315ACC mutation (87%). However, in the Eastern Cape, INH(r) specimens had a lower frequency of katG mutations (44%) and higher frequencies of inhA (47%) and ahpC (10%) promoter mutations. The most common mutation among rifampin-resistant (RIF(r)) specimens was the rpoB 531TTG mutation (80%). The mutation was common in RIF(r) specimens in Mumbai (83%) and Moldova (84%) but not the Eastern Cape (17%), where the 516GTC mutation appeared more frequently (57%). The most common mutation among fluoroquinolone-resistant specimens was the gyrA 94GGC mutation (44%). The rrs 1401G mutation was found in 84%, 84%, and 50% of amikacin-resistant, capreomycin-resistant, and kanamycin (KAN)-resistant (KAN(r)) specimens, respectively. The eis promoter mutation -12T was found in 26% of KAN(r) and 4% of KAN-susceptible (KAN(s)) specimens. Inclusion of the ahpC and eis promoter gene regions was critical for optimal test sensitivity for the detection of INH resistance in the Eastern Cape and KAN resistance in Moldova. (This study has been registered at ClinicalTrials.gov under registration number NCT02170441.).

Occurrence of diverse mutations in isoniazid- and rifampicin-resistant Mycobacterium tuberculosis isolates from autochthonous and immigrant populations of Saudi Arabia

For the first time in Saudi Arabia, the impact of a patient's ethnic background on mutations conferring resistance to rifampicin (RIF) and isoniazid (INH) in Mycobacterium tuberculosis isolates was analyzed on a nationwide sample collection. Four hundred fifteen isolates were subjected to drug susceptibility testing, mutation analysis, spoligotyping, and 24 loci-based Mycobacterial Interspersed Repetitive Units-Variable Number Tandem Repeat typing, respectively. Phenotypically, 41 (9.9%) isolates were resistant to RIF, 239 (57.6%) to INH, and 135 (32.5%) to both RIF and INH, respectively. Forty (9.6%), 236 (56.8%), and 133 (32%) isolates were determined as resistant to RIF, INH, and to both by molecular assay. Codon 531 (S531L) mutations (69.4%) in the rpoB gene and codon 315 (S315T) mutations (67.2%) in the katG gene were the most prominent among RIF- and INH-resistant isolates, respectively. The autochthonous population showed a predominance of rpoB codon 516 and 526 mutations, while the inhA promoter position -15 and -8 mutations were prominent among immigrants. A strain cluster ratio of 32% (30 clusters) was observed and 24 clusters displayed identical mutations. Overall, Euro-American lineages were predominant. However, Beijing (56.7%) and EAI (42.7%) were noticed with the highest cluster rate. In Saudi Arabia, the occurrence of mutations responsible for INH and RIF resistance was significantly associated with the ethnic origin of the patient.