Pyrazinamide Susceptibility and pncA Mutation Profiles of Mycobacterium tuberculosis among Multidrug-Resistant Tuberculosis Patients in Bangladesh

Breaking barriers: The potential of nanosystems in antituberculosis therapy

Tuberculosis (TB), caused by Mycobacterium tuberculosis, continues to pose a significant threat to global health. The resilience of TB is amplified by a myriad of physical, biological, and biopharmaceutical barriers that challenge conventional therapeutic approaches. This review navigates the intricate landscape of TB treatment, from the stealth of latent infections and the strength of granuloma formations to the daunting specters of drug resistance and altered gene expression. Amidst these challenges, traditional therapies often fail, contending with inconsistent bioavailability, prolonged treatment regimens, and socioeconomic burdens. Nanoscale Drug Delivery Systems (NDDSs) emerge as a promising beacon, ready to overcome these barriers, offering better drug targeting and improved patient adherence. Through a critical approach, we evaluate a spectrum of nanosystems and their efficacy against MTB both in vitro and in vivo. This review advocates for the intensification of research in NDDSs, heralding their potential to reshape the contours of global TB treatment strategies.

Global status of phenotypic pyrazinamide resistance in Mycobacterium tuberculosis clinical isolates: an updated systematic review and meta-analysis

Pyrazinamide (PZA) is an essential first-line tuberculosis drug for its unique mechanism of action active against multidrug-resistant-TB (MDR-TB). Thus, the aim of updated meta-analysis was to estimate the PZA weighted pooled resistance (WPR) rate in M. tuberculosis isolates based on publication date and WHO regions. We systematically searched the related reports in PubMed, Scopus, and Embase (from January 2015 to July 2022). Statistical analyses were performed using STATA software. The 115 final reports in the analysis investigated phenotypic PZA resistance data. The WPR of PZA was 57% (95% CI 48-65%) in MDR-TB cases. According to the WHO regions, the higher WPRs of PZA were reported in the Western Pacific (32%; 95% CI 18-46%), South East Asian region (37%; 95% CI 31-43%), and the Eastern Mediterranean (78%; 95% CI 54-95%) among any-TB patients, high risk of MDR-TB patients, and MDR-TB patients, respectively. A negligible increase in the rate of PZA resistance were showed in MDR-TB cases (55% to 58%). The rate of PZA resistance has been rising in recent years among MDR-TB cases, underlines the essential for both standard and novel drug regimens development.

Occurrence of tuberculosis among people exposed to cattle in Bangladesh

BACKGROUND

Tuberculosis (TB) has been an important public health concern in Bangladesh. The most common cause of human TB is Mycobacterium tuberculosis, while bovine TB is caused by Mycobacterium bovis.

OBJECTIVE

The objective of this study was to determine the frequency of TB in individuals with occupational exposure to cattle and to detect Mycobacterium bovis among cattle in slaughterhouses in Bangladesh.

METHODS

Between August and September 2015, an observational study was conducted in two government chest disease hospitals, one cattle market, and two slaughterhouses. Sputum samples were collected from individuals who met the criteria for suspected TB and had been exposed to cattle. Tissue samples were collected from cattle that had low body condition score(s). Both humans and cattle samples were screened for acid-fast bacilli (AFB) by Ziehl-Neelsen (Z-N) staining and cultured for Mycobacterium tuberculosis complex (MTC). Region of difference (RD) 9-based polymerase chain reaction (PCR) was also performed to identify Mycobacterium spp. We also conducted Spoligotyping to identify the specific strain of Mycobacterium spp.

RESULTS

Sputum was collected from a total of 412 humans. The median age of human participants was 35 (IQR: 25-50) years. Twenty-five (6%) human sputum specimens were positive for AFB, and 44 (11%) were positive for MTC by subsequent culture. All (N = 44) culture-positive isolates were confirmed as Mycobacterium tuberculosis by RD9 PCR. Besides, 10% of cattle workers were infected with Mycobacterium tuberculosis in the cattle market. Of all TB (caused by Mycobacterium tuberculosis) infected individuals, 6.8% of individuals were resistant to one or two anti-TB drugs. The majority of the sampled cattle (67%) were indigenous breeds. No Mycobacterium bovis was detected in cattle.

CONCLUSIONS

We did not detect any TB cases caused by Mycobacterium bovis in humans during the study. However, we detected TB cases caused by Mycobacterium tuberculosis in all humans, including cattle market workers.

Detection of Mutations in pncA in Mycobacterium tuberculosis Clinical Isolates from Nepal in Association with Pyrazinamide Resistance

Without the proper information on pyrazinamide (PZA) susceptibility of Mycobacterium tuberculosis (MTB), PZA is inappropriately recommended for the treatment of both susceptible and multidrug-resistant tuberculosis (MDR-TB) in Nepal. This study aimed to collect information regarding PZA susceptibility in MTB isolates from Nepal by analyzing pncA and its upstream regulatory region (URR). A total of 211 MTB isolates were included in this study. Sequence analysis of pncA and its URR was performed to assess PZA resistance. First-line drug susceptibility testing, spoligotyping, and sequence analysis of rpoB, katG, the inhA regulatory region, gyrA, gyrB, and rrs were performed to assess their association with pncA mutation. Sequencing results reveal that 125 (59.2%) isolates harbored alterations in pncA and its URR. A total of 57 different mutation types (46 reported and 11 novel) were scattered throughout the whole length of the pncA gene. Eighty-seven isolates (41.2%) harbored mutations in pncA, causing PZA resistance in MTB. There was a more significant association of pncA alterations in MDR/pre-extensively drug-resistant (Pre-XDR) TB than in mono-resistant/pan-susceptible TB (p < 0.005). This first report on the increasing level of PZA resistance in DR-TB in Nepal highlights the importance of PZA susceptibility testing before DR-TB treatment.

Characterization of Fluoroquinolone-Resistant and Multidrug-Resistant Mycobacterium tuberculosis Isolates Using Whole-Genome Sequencing in Tianjin, China

Objective

Methods

Results

Conclusion

Next-generation sequencing to characterize pyrazinamide resistance in Mycobacterium tuberculosis isolates from two Balkan countries

OBJECTIVES

Next-generation sequencing (NGS) provide a comprehensive analysis of the genetic alterations that are most commonly linked with pyrazinamide (PZA) resistance. There are no studies reporting molecular background of PZA resistance in TB isolates from Balkan Peninsula. We aimed to examine the feasibility of full-length analysis of a gene linked with PZA resistance, pncA, using Ion Torrent technology in comparison to phenotypic BACTEC MGIT 960 DST in clinical TB isolates from two countries of the Balkan Peninsula.

METHODS

Between 1996 and 2017, we retrospectively selected 61 TB isolates. To identify gene variants related to drug resistance in genomic DNA extracted from TB isolates, AmpliSeq libraries were generated automatically using the AmpliSeq™ Kit for Chef DL8 and the Ion AmpliSeq TB Research Panel.

RESULTS

Of all 61 TB isolates included, 56 TB were phenotypically resistant to any antibiotic. Among them, 38/56 (67.9%) TB isolates were phenotypically resistant to pyrazinamide and pncA mutations were detected in 33/38 cases (86.8%). A mutation in the pncA promoter region was the most prevalent genetic alteration, detected in eight TB isolates. Comparison of NGS to conventional BACTEC MGIT 960 DST revealed very strong agreement (90.2%) between the two methods in identifying PZA resistance, with high sensitivity (89.5%) and specificity (95.7%) for NGS.

CONCLUSIONS

Detection of PZA resistance using NGS seems to be a valuable tool for surveillance of TB drug resistance also in the Balkan Peninsula, with great potential to provide useful information at least one weak earlier than is possible with phenotypic DST.

Comparative Performance of Genomic Methods for the Detection of Pyrazinamide Resistance and Heteroresistance in Mycobacterium tuberculosis

Pyrazinamide is an important component of both drug-susceptible and drug-resistant tuberculosis treatment regimens. Although approximately 50% of rifampin-resistant isolates are also resistant to pyrazinamide, pyrazinamide susceptibility testing is not routinely performed due to the challenging nature of the assay. We investigated the diagnostic accuracy of genotypic and phenotypic methods and explored the occurrence of pyrazinamide heteroresistance. We assessed pyrazinamide susceptibility among 358 individuals enrolled in the South African EXIT-RIF cohort using Sanger and targeted deep sequencing (TDS) of the pncA gene, whole-genome sequencing (WGS), and phenotypic drug susceptibility testing. We calculated the diagnostic accuracy of the different methods and investigated the prevalence and clinical impact of pncA heteroresistance. True pyrazinamide susceptibility status was assigned to each isolate using the Köser classification and expert rules. We observed 100% agreement across genotypic methods for detection of pncA fixed mutations; only TDS confidently identified three isolates (0.8%) with minor variants. For the 355 (99.2%) isolates that could be assigned true pyrazinamide status with confidence, phenotypic DST had a sensitivity of 96.5% (95% confidence interval [CI], 93.8 to 99.3%) and specificity of 100% (95% CI, 100 to 100%), both Sanger sequencing and WGS had a sensitivity of 97.1% (95% CI, 94.6 to 99.6%) and specificity of 97.8% (95% CI, 95.7 to 99.9%), and TDS had sensitivity of 98.8% (95% CI, 97.2 to 100%) and specificity of 97.8% (95% CI, 95.7 to 99.9%). We demonstrate high sensitivity and specificity for pyrazinamide susceptibility testing among all assessed genotypic methods. The prevalence of pyrazinamide heteroresistance in Mycobacterium tuberculosis isolates was lower than that identified for other first-line drugs.

Phenotypic and molecular characterization of pyrazinamide resistance among multidrug-resistant Mycobacterium tuberculosis isolates in Ningbo, China

Background

Detection of pyrazinamide (PZA) resistance in Mycobacterium tuberculosis (TB) patients is critical, especially in dealing with multidrug-resistant Mycobacterium tuberculosis (MDR-TB) case. Up to date, PZA drug susceptibility testing (DST) has not been regularly performed in China. The prevalence and molecular characteristics of PZA resistance in M.tuberculosis isolates, especially MDR-TB have not been studied in Ningbo, China. This study aimed to analyze the phenotypic and molecular characterization of PZA resistance among MDR-TB isolates in Ningbo.

Methods

A total of 110 MDR-TB isolates were collected from the TB patients who were recorded at local TB dispensaries in Ningbo. All clinical isolates were examined by drug susceptibility testing and genotyping. DNA sequencing was used to detect mutations in the pncA gene associated with PZA resistance.

Results

The prevalence of PZA resistance among MDR-TB strains in Ningbo was 59.1%. With regard to the history and the outcome of treatments among MDR-TB cases, the percentages of re-treated MDR-TB patients in the PZA-resistant group and of successful patients in PZA-susceptible group were significantly higher than the ones in the PZA-susceptible group and in the PZA-resistant group, respectively (P = 0.027, P = 0.020). The results showed that the resistance of streptomycin (67.7% vs 46.7%, P = 0.027), ethambutol (56.9% vs 33.3%, P = 0.015), ofloxacin (43.1% vs 11.1%, P = 0.000), levofloxacin (43.1% vs 11.1%, P = 0.000), pre-XDR (pre-Xtensively Drug Resistance) (38.5% vs 15.6%, P = 0.009), were more frequently adverted among PZA-resistant isolates compared with PZA-susceptible isolates. In addition, 110 MDR-TB was composed of 87 (PZA resistant, 78.5%) Beijing strains and 23 (PZA resistant, 21.5%) non-Beijing strains. Fifty-four out of 65 (83.1%) PZA-resistant MDR strains harbored a mutation located in the pncA gene and the majority (90.7%) were point mutations. Compared with the phenotypic characterization, DNA sequencing of pncA has sensitivity and specificity of 83.1 and 95.6%.

Conclusion

The mutations within pncA gene was the primary mechanism of PZA resistance among MDR-TB and DNA sequencing of pncA gene could provide a rapid detection evidence in PZA drug resistance of MDR-TB in Ningbo.

The 7H11 Agar Medium Supplemented with Calf Bovine Serum for Susceptibility Testing of Mycobacterium tuberculosis Isolates Against Pyrazinamide

Despite its importance, pyrazinamide (PZA) is a blind spot in drug susceptibility testing in tuberculosis laboratories. The aim of this study was to set up a reliable agar-based proportion method for detection of PZA-resistant phenotypes using Middlebrook 7H11 agar supplemented with calf bovine serum (CBS) compared with albumin/dextrose/catalase (ADC) enrichment and pncA/rpsA sequencing results. The 7H11 agar medium supplemented with 10% ADC or 10% CBS (pH 6.2) and 100 μg/mL PZA was used to detect PZA resistance among 64 Mycobacterium tuberculosis isolates. Sanger sequencing and whole-genome sequencing were performed to track mutations in the pncA, rpsA, and their upstream regions. A total of 43 rifampicin/multidrug-resistant, 20 drug-susceptible, and 1 isoniazid mono-resistant M. tuberculosis isolates were investigated. The 7H11+ADC and 7H11+CBS could detect 22 and 23 PZA-resistant strains, respectively. With the same specificity, the sensitivity and accuracy of 7H11+CBS was found to be a little greater than 7H11+ADC in PZA resistance detection compared with sequencing results. Twenty-four mutant strains were found to have different mutations in pncA-upstream, pncA and rpsA genes, in which Gly97Asp was the most dominant mutation. The results obtained from 7H11+CBS were comparable to the results of 7H11+ADC. Therefore, the 7H11 agar proportion method would be a less-expensive test using CBS and produces reliable results.

Molecular characterization and drug resistance patterns of Mycobacterium tuberculosis complex in extrapulmonary tuberculosis patients in Addis Ababa, Ethiopia

Background

Molecular characterization of Mycobacterium tuberculosis (MTB) is important to understand the pathogenesis, diagnosis, treatment, and prevention of tuberculosis (TB). However, there is limited information on molecular characteristics and drug-resistant patterns of MTB in patients with extra-pulmonary tuberculosis (EPTB) in Ethiopia. Thus, this study aimed to determine the molecular characteristics and drug resistance patterns of MTB in patients with EPTB in Addis Ababa, Ethiopia.

Methods

This study was conducted on frozen stored isolates of EPTB survey conducted in Addis Ababa, Ethiopia. A drug susceptibility test was performed using BACTEC-MGIT 960. Species and strain identification were performed using the Geno-Type MTBC and spoligotyping technique, respectively. Data were entered into the MIRU-VNTRplus database to assess the spoligotype patterns of MTB. Analysis was performed using SPSS version 23, and participants’ characteristics were presented by numbers and proportions.

Results

Of 151 MTB isolates, 29 (19.2%) were resistant to at least one drug. The highest proportion of isolates was resistant to Isoniazid (14.6%) and Pyrazinamide (14.6%). Nine percent of isolates had multidrug-resistant TB (MDR-TB), and 21.4% of them had pre-extensively drug-resistant TB (pre-XDR-TB). Among the 151 MTB isolates characterized by spoligotyping, 142 (94.6%) had known patterns, while 9 (6.0%) isolates were not matched with the MIRU-VNTRplus spoligotype database. Of the isolates which had known patterns, 2% was M.bovis while 98% M. tuberculosis. Forty-one different spoligotype patterns were identified. The most frequently identified SpolDB4 (SIT) wereSIT149 (21.2%), SIT53 (14.6%) and SIT26 (9.6%). The predominant genotypes identified were T (53.6%), Central Asia Strain (19.2%) and Haarlem (9.9%).

Conclusion

The present study showed a high proportion of MDR-TB and pre-XDR-TB among EPTB patients. The strains were mostly grouped into SIT149, SIT53, and SIT26. The T family lineage was the most prevalent genotype. MDR-TB and pre-XDR-TB prevention is required to combat these strains in EPTB. A large scale study is required to describe the molecular characteristics and drug resistance patterns of MTB isolates in EPTB patients.

Pyrazinamide resistance and pncA mutations in drug resistant Mycobacterium tuberculosis clinical isolates from Myanmar

Pyrazinamide (PZA) is an important anti-tuberculosis drug, which is active against semi-dormant bacilli and used as a component of first-line drugs and drug-resistant tuberculosis regimens. Mutations in pncA and its promoter region are main cause of PZA resistance. There are limited PZA susceptibility data as there is no routine drug susceptibility testing (DST) for PZA. This study was aimed to determine the proportion of PZA resistance among rifampicin-resistant tuberculosis patients and to identify mutations which are responsible for PZA resistance in pncA and its promoter region. Liquid-based DST was performed to detect PZA susceptibility on 192 culture positive rifampicin-resistant isolates collected from National Tuberculosis Reference Laboratory. Sequencing on pncA including its promoter region was performed and analysis was done on 157 isolates. Phenotypic PZA resistance was detected in 58.9% of isolates. Sixty-five different mutations were distributed in pncA or promoter region of 82 isolates. Sensitivity and specificity of pncA sequencing in detection of PZA resistance showed 89.8% and 95.6% respectively. High proportion of PZA resistance among rifampicin-resistant cases highlighted the need for effective treatment regimen development for PZA-resistant MDR-TB. It is also suggested that routine PZA susceptibility test should be incorporated to treatment monitoring regimen and National Drug Resistance surveys.

Pyrazinamide Resistance and Mutation Patterns Among Multidrug-Resistant Mycobacterium tuberculosis from Henan Province

Purpose

This study was designed to identify the phenotypic and genotypic characteristics of pyrazinamide (PZA) resistance among multidrug-resistant Mycobacterium tuberculosis (MDR-TB) from Henan and to evaluate the efficacy of pncA, rpsA, and panD mutations in predicting PZA resistance.

Materials and Methods

A total of 152 MDR strains were included in this study. The Bactec MGIT system was used to determine PZA susceptibility for all strains. The pncA, rpsA, and panD genes were sequenced to identify any mutations, and the sequences were then aligned with the sequence of standard strain H37Rv. Moreover, the correlations between PZA-resistant phenotypes and treatment outcomes were analysed.

Results

Of the152 strains, 105 had a PZA-resistant phenotype, and 102 harboured the pncA mutation. The PZA resistance rate was higher in the strains with resistance to all four first-line drugs and those that were pre-extensively drug-resistant (pre-XDR) and extensively drug-resistant (XDR). A total of 100 different pncA mutation patterns were identified, including 80 point mutations and 20 insertions/deletions, and 32 new pncA mutation patterns were detected. In this study, 13 strains had multiple mutations. Of the11 PZA-resistant strains without pncA mutations, two harboured the rpsA mutation, and one harboured the panD mutation. With PZA susceptibility results as the reference, single-gene pncA sequencing had sensitivity of 89.52% and specificity of 89.36%. With the combination of rpsA and panD, the sensitivity increased to 92.38%, and the specificity remained the same. No significant differences were observed in the sputum smear/culture conversion rate between PZA-resistant patients and PZA-sensitive patients. However, PZA resistance was related to the time to sputum smear/culture conversion (P = 0.018).

Conclusion

The combination of pncA, rpsA, and panD was beneficial for the timely diagnosis of PZA resistance and could provide a laboratory basis for customizing treatment regimens for MDR-TB patients.

Structural dynamics behind variants in pyrazinamidase and pyrazinamide resistance

Pyrazinamide (PZA) is an important component of first-line anti-tuberculosis (anti-TB) drugs. The anti-TB agent is activated into an active form, pyrazinoic acid (POA), by Mycobacterium tuberculosis (MTB) pncA gene encoding pyrazinamidase (PZase). The major cause of PZA-resistance has been associated with mutations in the pncA gene. We have detected several novel mutations including V131F, Q141P, R154T, A170P, and V180F (GeneBank Accession No. MH461111) in the pncA gene of PZA-resistant isolates during PZA drug susceptibility testing followed by pncA gene sequencing. Here, we investigated molecular mechanism of PZA-resistance by comparing the results of experimental and molecular dynamics. The mutants (MTs) and wild type (WT) PZase structures in apo and complex with PZA were subjected to molecular dynamic simulations (MD) at the 40 ns. Multiple factors, including root mean square deviations (RMSD), binding pocket, total energy, dynamic cross correlation, and root mean square fluctuations (RMSF) of MTs and WT were compared. The MTs attained a high deviation and fluctuation compared to WT. Binding pocket volumes of the MTs, were found, lower than the WT, and the docking scores were high than WT while shape complementarity scores were lower than that of the WT. Residual motion in MTs are seemed to be dominant in anti-correlated motion. Mutations at locations, V131F, Q141P, R154T, A170P, and V180F, might be involved in the structural changes, possibly affecting the catalytic property of PZase to convert PZA into POA. Our study provides useful information that will enhance the understanding for better management of TB. AbbreviationsDSTdrug susceptibility testingΔelecelectrostatic energyLJLowenstein-Jensen mediumMGITmycobacterium growth indicator tubesMTsmutantsMDmolecular dynamic simulationsMTBMycobacterium tuberculosisNALC-NaOHN-acetyl-l-cysteine-sodium hydroxideNIHNational Institutes of HealthNPTamount of substance (N), pressure (P) temperature (T)NVTmoles (N), volume (V) temperature (T)PZasepyrazinamidaseΔpspolar solvation energyPTRLProvincial Tuberculosis Reference LaboratoryRMSDroot mean square deviationsRMSFroot mean square fluctuationsΔSASAsolvent accessible surface area energyTBtuberculosisGTotaltotal binding free energyΔvdWVan der Waals energyWTwild typeCommunicated by Ramaswamy H. Sarma.

Pyrazinamide resistance and mutations in pncA among isolates of Mycobacterium tuberculosis from Khyber Pakhtunkhwa, Pakistan

Background

Pyrazinamide (PZA) is an important component of first-line drugs because of its distinctive capability to kill subpopulations of persistent Mycobacterium tuberculosis (MTB). The prodrug (PZA) is converted to its active form, pyrazinoic acid (POA) by MTB pncA-encoded pyrazinamidase (PZase). Mutation in pncA is the most common and primary cause of PZA resistance. The aim of the present study was to explore the molecular characterization of PZA resistance in a Pashtun-dominated region of Khyber Pakhtunkhwa, Pakistan.

Methods

We performed drug susceptibility testing (DST) on 753 culture-positive isolates collected from the Provincial Tuberculosis Control Program Khyber Pakhtunkhwa using the BACTEC MGIT 960 PZA method. In addition, the pncA gene was sequenced in PZA-resistant isolates, and PZA susceptibility testing results were used to determine the sensitivity and specificity of pncA gene mutations.

Results

A total of 69 isolates were PZA resistant (14.8%). Mutations were investigated in 69 resistant, 26 susceptible and one H37Rv isolates by sequencing. Thirty-six different mutations were identified in PZA-resistant isolates, with fifteen mutations, including 194_203delCCTCGTCGTG and 317_318delTC, that have not been reported in TBDRM and GMTV Databases and previous studies. Mutations Lys96Thr and Ser179Gly were found in the maximum number of isolates (n = 4 each). We did not detect mutations in sensitive isolates, except for the synonymous mutation 195C > T (Ser65Ser). The sensitivity and specificity of the pncA sequencing method were 79.31% (95% CI, 69.29 to 87.25%) and 86.67% (95% CI, 69.28 to 96.24%).

Conclusion

Mutations in the pncA gene in circulating isolates of geographically distinct regions, especially in high-burden countries, should be investigated for better control and management of drug-resistant TB. Molecular methods for the investigation of PZA resistance are better than DST.

Determining Genotypic Drug Resistance by Ion Semiconductor Sequencing With the Ion AmpliSeq™ TB Panel in Multidrug-Resistant Mycobacterium tuberculosis Isolates

BACKGROUND

We examined the feasibility of a full-length gene analysis for the drug resistance-related genes inhA, katG, rpoB, pncA, rpsL, embB, eis, and gyrA using ion semiconductor next-generation sequencing (NGS) and compared the results with those obtained from conventional phenotypic drug susceptibility testing (DST) in multidrug-resistant Mycobacterium tuberculosis (MDR-TB) isolates.

METHODS

We extracted genomic DNA from 30 pure MDR-TB isolates with antibiotic susceptibility profiles confirmed by phenotypic DST for isoniazid (INH), rifampin (RIF), ethambutol (EMB), pyrazinamide (PZA), amikacin (AMK), kanamycin (KM), streptomycin (SM), and fluoroquinolones (FQs) including ofloxacin, moxifloxacin, and levofloxacin. Enriched ion spheres were loaded onto Ion PI Chip v3, with 30 samples on a chip per sequencing run, and Ion Torrent sequencing was conducted using the Ion AmpliSeq TB panel (Life Technologies, USA).

RESULTS

The genotypic DST results revealed good agreement with the phenotypic DST results for EMB (Kappa 0.8), PZA (0.734), SM (0.769), and FQ (0.783). Agreements for INH, RIF, and AMK+KM were not estimated because all isolates were phenotypically resistant to INH and RIF, and all isolates were phenotypically and genotypically susceptible to AMK+KM. Moreover, 17 novel variants were identified: six (p.Gly169Ser, p.Ala256Thr, p.Ser383Pro, p.Gln439Arg, p.Tyr597Cys, p.Thr625Ala) in katG, one (p.Tyr113Phe) in inhA, five (p.Val170Phe, p.Thr400Ala, p.Met434Val, p.Glu812Gly, p.Phe971Leu) in rpoB, two (p.Tyr319Asp and p.His1002Arg) in embB, and three (p.Cys14Gly, p.Asp63Ala, p.Gly162Ser) in pncA.

CONCLUSIONS

Ion semiconductor NGS could detect reported and novel amino acid changes in full coding regions of eight drug resistance-related genes. However, genotypic DST should be complemented and validated by phenotypic DSTs.