Molecular detection of rifampin, isoniazid, and ofloxacin resistance in Iranian isolates of Mycobacterium tuberculosis by high-resolution melting analysis

Modeling the limits of detection for antimicrobial resistance genes in agri-food samples: a comparative analysis of bioinformatics tools

BACKGROUND

Although the spread of antimicrobial resistance (AMR) through food and its production poses a significant concern, there is limited research on the prevalence of AMR bacteria in various agri-food products. Sequencing technologies are increasingly being used to track the spread of AMR genes (ARGs) in bacteria, and metagenomics has the potential to bypass some of the limitations of single isolate characterization by allowing simultaneous analysis of the agri-food product microbiome and associated resistome. However, metagenomics may still be hindered by methodological biases, presence of eukaryotic DNA, and difficulties in detecting low abundance targets within an attainable sequence coverage. The goal of this study was to assess whether limits of detection of ARGs in agri-food metagenomes were influenced by sample type and bioinformatic approaches.

RESULTS

We simulated metagenomes containing different proportions of AMR pathogens and analysed them for taxonomic composition and ARGs using several common bioinformatic tools. Kraken2/Bracken estimates of species abundance were closest to expected values. However, analysis by both Kraken2/Bracken indicated presence of organisms not included in the synthetic metagenomes. Metaphlan3/Metaphlan4 analysis of community composition was more specific but with lower sensitivity than the Kraken2/Bracken analysis. Accurate detection of ARGs dropped drastically below 5X isolate genome coverage. However, it was sometimes possible to detect ARGs and closely related alleles at lower coverage levels if using a lower ARG-target coverage cutoff (< 80%). While KMA and CARD-RGI only predicted presence of expected ARG-targets or closely related gene-alleles, SRST2 (which allows read to map to multiple targets) falsely reported presence of distantly related ARGs at all isolate genome coverage levels. The presence of background microbiota in metagenomes influenced the accuracy of ARG detection by KMA, resulting in mcr-1 detection at 0.1X isolate coverage in the lettuce but not in the beef metagenome.

CONCLUSIONS

This study demonstrates accurate detection of ARGs in synthetic metagenomes using various bioinformatic methods, provided that reads from the ARG-encoding organism exceed approximately 5X isolate coverage (i.e. 0.4% of a 40 million read metagenome). While lowering thresholds for target gene detection improved sensitivity, this led to the identification of alternative ARG-alleles, potentially confounding the identification of critical ARGs in the resistome. Further advancements in sequencing technologies providing increased coverage depth or extended read lengths may improve ARG detection in agri-food metagenomic samples, enabling use of this approach for tracking clinically important ARGs in agri-food samples.

Direct Detection of Fluoroquinolone Resistance in Sputum Samples from Tuberculosis Patients by High Resolution Melt Curve Analysis

Multidrug-resistant tuberculosis (MDR-TB) requires treatment with fluoroquinolone (FLQ) drugs, however, the excessive use of FLQ has led to the rise of extensively drug-resistant TB. In 2019, ~ 20% of total MDR-TB cases were estimated to be resistant to FLQ drugs. In the present study, we developed and evaluated the utility of high-resolution melt curve analysis (HRM) for the rapid detection of FLQ-resistant Mycobacterium tuberculosis for the first time directly from sputum samples. A reference plasmid library was generated for the most frequently observed mutations of gyrA gene and was used to discriminate between mutant and wild-type samples in the FLQ-HRM assay. The developed assay was evaluated on n = 25 MDR M. tuberculosis clinical isolates followed by validation on archived sputum DNA (n = 88) using DNA sequencing as a gold standard. The FLQ-HRM assay showed a 100% sensitivity [95% Confidence Interval (CI): 71.5 to 100] and specificity (95% CI: 39.7 to 100) in smear-positive category, and a sensitivity of 88.9% (95% CI: 77.3 to 95.8) with 84.2% (95% CI: 60.4 to 96.6) specificity in smear-negative category. The assay showed a high level of concordance of ~ 90% (κ = 0.74) with DNA sequencing, however, we were limited by the absence of phenotypic drug susceptibility testing data. In conclusion, HRM is a rapid, cost-effective (INR 150/USD 1.83) and closed-tube method for direct detection of FLQ resistance in sputum samples including direct smear-negative samples.

Genetic diversity of drug-resistant Mycobacterium tuberculosis clinical isolates from Khuzestan province, Iran

The emergence of drug-resistant strains of the Mycobacterium tuberculosis (MTB) has challenged tuberculosis control programs. So far, few studies using the 24-locus mycobacterial interspersed repetitive unit variable number tandem repeats (MIRU-VNTR) have investigated the genetic diversity of MTB in Iran. This study aimed to determine the genetic diversity of MTB isolates resistant to first-line anti-tuberculosis drugs using 24-locus MIRU-VNTR in southwestern Iran. Out of 6620 MTB clinical isolates, 29 resistant isolates to one or more isoniazid, rifampin, and ethambutol were detected using drug susceptibility testing by the proportional method. The manual 24-locus MIRU-VNTR was used to determine the MTB resistant isolates’ phylogenetic relationship. MIRU-VNTRplus web application tools were applied to analyze the associated data. Using 24-locus MIRU-VNTR, 13.8% of isolates (n = 4) were distributed in two clusters, and the remaining 86.2% (n = 25) showed a unique pattern. Four clonal complexes were observed in the minimum spanning tree based on the double-locus variant. Most isolates belonged to Delhi/CAS (34.5%, 10/29) and NEW-1 (24.1%, 7/29) sub-lineages, followed by EAI and LAM with a frequency of 6.9% (2/29) and 3.5% (1/29), respectively. Eight isolates (27.6%) did not match any genotype in the database. The 24-locus MIRU-VNTR showed a high discriminatory power; however, the 15-locus and 12-locus set analyses were more discriminative. Our study revealed a high degree of genetic diversity among drug-resistant MTB isolates, which could be interpreted as the low rate of person-to-person transmission in this region. The 15-locus MIRU-VNTR would be recommended for preliminary genotyping of drug-resistant MTB.

Detection of Five Types of HPV Genotypes Causing Anogenital Warts (Condyloma Acuminatum) Using PCR-Tm Analysis Technology

Objectives

Condyloma acuminatum (CA) is a common sexually transmitted disease caused by human papillomavirus (HPV) infection. We established a high-throughput, simple, low-cost, and accurate HPV-typing assay (polymerase chain reaction-melting temperature [PCR-Tm] analysis) to detect HPV in CA.

Materials and Methods

We detected 280 cervical scraping samples, including positive samples of HPV-6 (26), HPV-11 (12), HPV-16 (22), HPV-42 (18), HPV-43 (25), HPV-multiple (19), HPV- other type (58), and HPV-negative samples (100). All samples were compared by PCR-Tm analysis and a flow fluorescence hybridization assay. Sequencing was used to confirm the results of the PCR-Tm analysis.

Results

PCR-Tm analysis was specific for each genotype (HPV-6, HPV-11, HPV-16, HPV-42, and HPV-43). The sensitivity of the PCR-Tm analysis assay for each genotype was 10³, 10³, 10³, 10³, and 10² copies/reaction, respectively. Most of the 158 samples, including 58 HPV-other type positive and 100 HPV-negative samples tested by the flow fluorescence hybridization assay, were tested negative by PCR-Tm analysis. For the 122 remaining samples, 26 HPV-6, 12 HPV-11, 22 HPV-16, 18 HPV-42, 25 HPV-43, and 19 multiple HPV infections were detected through PCR-Tm analysis. In total, 25 HPV-6, 12 HPV-11, 21 HPV-16, 18 HPV-42, 25 HPV-43, and only 10 multiple HPV infections were detected by the flow fluorescence hybridization assay. The kappa coefficient for the analysis of PCR-Tm analysis and flow fluorescence hybridization assay was 0.940 (P < 0.0001), and the 95% confidence interval of the kappa coefficient was 90.3–97.7%.

Conclusion

PCR-Tm analysis enabled the detection of HPV-6, HPV-11, HPV-16, HPV-42, and HPV-43, including single and multiple infections.

High resolution melting assay as a reliable method for diagnosing drug-resistant TB cases: a systematic review and meta-analysis

BACKGROUND

Tuberculosis (TB) is one of the most contagious infectious diseases worldwide. Currently, drug-resistant Mycobacterium tuberculosis (Mtb) isolates are considered as one of the main challenges in the global TB control strategy. Rapid detection of resistant strains effectively reduces morbidity and mortality of world's population. Although both culture and conventional antibiotic susceptibility testing are time-consuming, recent studies have shown that high resolution melting (HRM) assay can be used to determine the types of antibiotic resistance. In the present meta-analysis, we evaluated the discriminative power of HRM in detecting all drug-resistance cases of TB.

METHODS

A systematic search was performed using databases such as Cochrane Library, Scopus, PubMed, Web of Science, and Google Scholar. Related studies on the effect of HRM in the diagnosis of drug-resistant (DR) TB cases were retrieved by April 2021. We used Meta-Disc software to evaluate the pooled diagnostic sensitivity and specificity of HRM for the detection of each type of drug-resistant cases. Finally, diagnostic value of HRM was characterized by summary receiver operating characteristic (SROC) curve and the area under the curve (AUC) method.

RESULTS

Overall 47 studies (4,732 Mtb isolates) met our criteria and were included in the present meta-analysis. Sensitivity, specificity, and AUC of HRM were measured for antibiotics such as isoniazid (93%, 98%, 0.987), rifampin (94%, 97%, 0963), ethambutol (82%, 87%, 0.728), streptomycin (82%, 95%, 0.957), pyrazinamide (72%, 84%, 0.845), fluoroquinolones (86%, 99%, 0.997), MDR-TB (90%, 98%, 0.989), and pan-drug-resistant TB (89%, 95%, 0.973).

CONCLUSIONS

The HRM assay has high accuracy for the identification of drug-resistant TB, particularly firs-line anti-TB drugs. Therefore, this method is considered as an alternative option for the rapid diagnosis of DR-TB cases. However, due to heterogeneity of included studies, the results of HRM assays should be interpreted based on conventional drug susceptibility testing.

A Rapid and Accurate Detection Approach for Multidrug-Resistant Tuberculosis Based on PCR-ELISA Microplate Hybridization Assay

Rapid and accurate diagnosis of multidrug-resistant tuberculosis (MDR-TB) is important for timely and appropriate therapy. In this study, a rapid and easy-to-perform molecular test that integrated polymerase chain reaction (PCR) amplification and a specific 96-well microplate hybridization assay, called PCR-ELISA (enzyme-linked immunosorbent assay), were developed for detection of mutations in rpoB, katG, and inhA genes responsible for rifampin (RIF) and isoniazid (INH) resistance and prediction of drug susceptibility in Mycobacterium tuberculosis clinical isolates. We evaluated the utility of this method by using 32 multidrug-resistent (MDR) isolates and 22 susceptible isolates; subsequently, we compared the results with data obtained by conventional drug susceptibility testing and DNA sequencing. The sensitivity and specificity of the PCR-ELISA test were 93.7% and 100% for detecting RIF resistance, and 87.5% and 100% for detecting INH resistance, respectively. These results were comparable to those yielded by commercially available molecular tests such as the GenoType MTBDRplus assay. Based on the aforementioned results, we conclude that the PCR-ELISA microplate hybridization assay is a rapid, inexpensive, convenient, and reliable test that will be useful for rapid diagnosis of MDR-TB, for improved clinical care.

Investigation of the Rv3065, Rv2942, Rv1258c, Rv1410c, and Rv2459 efflux pump genes expression among multidrug-resistant Mycobacterium tuberculosis clinical isolates

Background

Different resistance mechanisms for multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) have been reported. Although mutations in target genes are the main cause of drug resistance, efflux pumps (Eps) also play an important role in this process. Here, we investigated the overexpression of five putative EP genes plus gene mutations in MDR-TB clinical isolates.

Methods

A total of 27 M. tuberculosis (Mtb) clinical isolates including, 22 MDR and 5 sensitive isolates were analyzed. Minimum inhibitory concentrations (MIC) were determined in the absence and presence of efflux inhibitor. The expression level of 5 EP genes (Rv3065, Rv2942, Rv1258c, Rv1410c, Rv2459) was investigated by quantitative real time PCR (RT-qPCR). DNA sequencing of rpoB, katG, and inhA promoter was done.

Results

Among the 22 MDR-TB isolates, 13 (59.1%) showed significant overexpression (>4-fold) for at least one EP gene. The expression levels of 5 genes were significantly higher (P < 0.05) in MDR-TB isolates than sensitive isolates. The Rv3065 (22.7%), and Rv1410c (18.2%) were found to be the most commonly overexpressed EPs. The observed MICs were as follows: RIF (2 to >128 μg/ml) and INH (2-32 μg/ml). After efflux pump inhibitor exposure, 10/22 (45.45%) isolates showed a decrease in MIC of INH, and 17/22 (77.27%) isolates showed a decrease in MIC of RIF. Of the isolates that overexpressed, 4 isolates lacked mutation in inhA, rpoB, and katG genes and 10 ones lacked mutation in inhA and katG.

Conclusion

The results showed that overexpression of EP genes in Mtb isolates, besides target gene mutations can contribute to the development of MDR phenotype.

Performance of the MeltPro MTB Assays in the Diagnosis of Drug-Resistant Tuberculosis Using Formalin-Fixed, Paraffin-Embedded Tissues

OBJECTIVES

The MeltPro MTB assays for detection of resistance to antituberculosis (TB) drugs perform well in genotypic drug susceptibility testing (DST) of clinical samples, but their effectiveness with formalin-fixed, paraffin-embedded (FFPE) tissues is unknown.

METHODS

FFPE tissues were obtained from 334 patients with TB. Susceptibility to rifampicin (RIF), isoniazid (INH), and fluoroquinolones was examined using the MeltPro MTB assays, with Xpert MTB/RIF (Xpert) and/or phenotypic DST (pDST) results as references. Samples with discordant results were analyzed by multiplex polymerase chain reaction-targeted amplicon sequencing (MTA-seq).

RESULTS

With pDST as the reference, the MeltPro MTB assays sensitivity for RIF, INH, levofloxacin (LVX), and moxifloxacin (MXF) was 95.00%, 96.00%, 100%, and 100%, respectively, and the specificity was 95.15%, 95.92%, 94.69%, and 89.92%, respectively. Concordance was 99.08% between the MeltPro MTB and Xpert (κ = 0.956) for RIF and 95.12% (κ = 0.834), 95.93% (κ = 0.880), 95.12% (κ = 0.744), and 90.24% (κ = 0.367) between the MeltPro MTB and pDST for RIF, INH, LVX, and MXF, respectively. MTA-seq confirmed the discordancy between the MeltPro MTB and pDST for 26 (89.66%) of 29 samples.

CONCLUSIONS

The MeltPro MTB assays rapidly and efficiently predict Mycobacterium tuberculosis resistance to the main first- and second-line anti-TB drugs in FFPE tissues.

Rapid screening of UPB1 gene variations by high resolution melting curve analysis

The present study aimed to analyze gene mutations in patients with β-ureidopropinoase deficiency and establish a rapid detection method for β-ureidopropinoase (UPB1) pathogenic variations by high resolution melting (HRM) analysis. DNA samples with known UPB1 mutations in three patients with β-ureidopropinoase deficiency were utilized to establish a rapid detection method for UPB1 pathogenic variations by HRM analysis. Further rapid screening was performed on two patients diagnosed with β-ureidopropinoase deficiency and 50 healthy control individuals. The results showed that all known UPB1 gene mutations can be analyzed by a specially designed HRM assay. Each mutation has specific HRM profiles which could be used in rapid screening. The HRM method could correctly identify all genetic mutations in two children with β-ureidopropinoase deficiency. In addition, the HRM assay also recognized four unknown mutations. To conclude, the results support future studies of applying HRM analysis as a diagnostic approach for β-ureidopropinoase deficiency and a rapid screening method for UPB1 mutation carriers.

Systematic Review of Mutations Associated with Isoniazid Resistance Points to Continuing Evolution and Subsequent Evasion of Molecular Detection, and Potential for Emergence of Multidrug Resistance in Clinical Strains of Mycobacterium tuberculosis

Molecular testing is rapidly becoming an integral component of global tuberculosis (TB) control. Uncommon mechanisms of resistance escape detection by these platforms and undermine our ability to contain outbreaks. This article is a systematic review of published articles that reported isoniazid (INH) resistance-conferring mutations between September 2013 and December 2019. The genes katG, inhA, and fabG1, and the intergenic region oxyR'-ahpC were considered in this review. Fifty-two articles were included that described 9,306 clinical isolates (5,804 INH resistant [INH^r] and 3,502 INH susceptible [INH^s]) from 31 countries. The three most frequently mutated loci continue to be locus 315 of katG (katG315; n = 4,271), locus -15 of inhA (inhA-15; n = 787), and locus -8 of inhA (inhA-8; 106). However, the diagnostic value of inhA-8 is far lower than previously thought, as it only appears in 25 (0.4%) of the INH^r isolates lacking the first two mutations. I catalogued 45 new loci (29 katG, nine inhA, and seven ahpC) associated with INH resistance and identified 59 loci (common to this and previous reviews) as a reliable basis for molecular diagnostics. Including all observed mutations provides a cumulative sensitivity of 85.6%. In 14.4% of resistant isolates, no mechanism of resistance was detected, making them likely to escape molecular detection, and in the case of INH monoresistance, likely to convert to multidrug-resistant TB (MDR-TB). Integrating the information cataloged in this study into current diagnostic tools is essential for combating the emergence of MDR-TB, and its exclusion can lead to an unintended selection against common mechanisms and to diversifying evolution. Observation of many low-frequency resistance-conferring mutations points to an advantage of whole-genome sequencing (WGS) for diagnostics. Finally, I provide five recommendations for future diagnostic platforms.

Distribution of Class B and Class A β-Lactamases in Clinical Strains of Pseudomonas aeruginosa: Comparison of Phenotypic Methods and High-Resolution Melting Analysis (HRMA) Assay

Background

There are various phenotypic methods for identifying class B and class A β-lactamase enzymes in Pseudomonas aeruginosa. The purpose of this study was to compare the sensitivity and specificity of different phenotypic methods with HRMA assay to detect β-lactamase-producing P. aeruginosa strains.

Methods

Eighty-eight of P. aeruginosa isolates were collected from different specimens. Conventional double-disk test (DDT) and EDTA-imipenem microbiological (EIM) were performed to detect ESBL and MBL-producing strains, respectively. Meanwhile, the Modified Hodge test and Carba-NP test were performed on all carbapenem-resistant strains. HRMA method and sensitivity and specificity of primers were determined based on the melt curve temperature range. In all comparisons, PCR was considered as the gold standard.

Results

Of the 402 isolates collected from different clinical specimens, 88 isolates of P. aeruginosa were identified. However, 43 strains were (48.88%) ESBL-producing, and 7 strains (7.95%) were MBL-producing. Also, using the Modified Hodge test and Carba-NP method, 11 (12.5%) and 19 (21.59%) strains were carbapenemase-producing, respectively. The results of the HRMA test revealed that genes coding for bla _SHV, bla _TEM, bla _KPC, bla _IMP, bla _VIM, and bla _GES were detected in 44.31%, 22.72%, 13.63%, 14.7%, 5.6%, and 2.27% of P. aeruginosa isolates. Nonetheless, for bla _KPC and bla _GES genes, sensitivity and specificity of the Carba-NP test were 90.47%, 94.87%, and 83.36%, 94.80%, respectively. However, sensitivity and specificity of MHT was 91.66%, 98.70%, and 77.77%, 96.42%, respectively. For bla _SHV and bla _TEM genes, sensitivity and specificity of DDT were 95.55%, 95.55%, and 86%, 83.50%, respectively. However, sensitivity and specificity of EMI were 77.77%, 97.59%, and 91.66%, 97.43% for bla _VIM and bla _IMP, respectively.

Conclusion

The HRMA is a powerful, accurate, closed-tube, rapid method for detecting β-lactamase genes in P. aeruginosa. The high sensitivity and specificity of this method, along with phenotypic tests, play a useful role in increasing the predictive value of clinical reports.

Development of high-resolution melting curve analysis in rapid detection of vanA gene, Enterococcus faecalis, and Enterococcus faecium from clinical isolates

Background

High-resolution melting analysis (HRMA) is a novel molecular technique based on the real-time PCR that can be used to detect vancomycin resistance Enterococcus (VRE). The purpose of this study was to identify VRE species with HRMA in clinical isolates.

Results

Out of 49 Enterococcus isolates, 11 (22.44%) E. faecium isolates and 19 (38.77%) E. faecalis isolates were detected. Average melting temperatures for divIVA in E.faecalis, alanine racemase in E.faecium, and vanA in VRE strains were obtained as 79.9 ± 0.5 °C, 85.4 ± 0.5 °C, and 82.99 ± 0.5 °C, respectively. Furthermore, the data showed that the HRMA method was sensitive to detect 10⁰ CFU/ml for the divIVA, alanine racemase, and vanA genes. Also, out of 49 Enterococcus spp., which were isolated by HRMA assay, 8 isolates (16.32%) of E. faecium and 18 isolates (36.73%) of E. faecalis were detected. The vanA gene was reported in 2 isolates (25%) of E. faecium and 9 isolates (50%) of E. faecalis.

Conclusions

This study demonstrated that using the HRMA method, we can detect E. faecium, E. faecalis, and the vanA gene with high sensitivity and specificity.

Molecular identification of mutations conferring resistance to rifampin, isoniazid and pyrazinamide among Mycobacterium tuberculosis isolates from Iran

Here, we aimed to determine the susceptibility of 70 Mycobacterium tuberculosis isolates obtained from different regions of the country to 8 anti-tuberculosis (anti-TB) drugs and possible underlying mechanisms causing resistance to rifampin, isoniazid, and pyrazinamide. The susceptibility of 70 isolates of M. tuberculosis to anti-TB drugs was tested using proportion method. Strains showing resistance to the first line anti-TB drugs were subjected to PCR amplification and sequencing of the rpoB, katG, ahpC, pncA genes, inhA promoter and oxyR-ahpC intergenic regions to detect resistance conferring mutations. Overall, 77.1% and 77.1% of isolates were resistant to at least one of the tested first- and second-line drugs, respectively. Within the rpoB gene the highest rate of mutation was found in codons 531(450) (56.3%), and 533(452) (12.5%). Also, codons 315 (42.4%) of katG, positions -48, -72 and -77 of oxyR-ahpC (total= 3, 9.1%) and -15 of inhA promoter region (33.3%) were the most altered positions in isoniazid resistant isolates. Only a single mutation was detected for pncA among resistant isolates. High prevalence of resistance to essential anti-TB drugs among M. tuberculosis strains isolated from retreated tuberculosis cases is alarming issue necessitating immediate action to prevent the spread of drug resistant isolates in the country.

Phenotypic and genotypic characterization of levofloxacin- and moxifloxacin-resistant Mycobacterium tuberculosis clinical isolates in southern China

Background

Levofloxacin (LVX) and Moxifloxacin (MXF) are the cornerstones for treatment of multidrug-resistant tuberculosis (MDR-TB). China is one of the highest MDR- and fluoroquinolones (FQ)-resistant TB burdens countries. DNA gyrase encoded by gyr genes is the main target of FQ in Mycobacterium tuberculosis (MTB). The prevalence and molecular characterization of LVX- and MXF-resistant MTB strains from southern China were examined in this study.

Methods

Drug susceptibility testing (DST) of 400 MTB clinical isolates was evaluated by proportion method on Löwenstein-Jensen (LJ) medium against ten drugs. The sequencing of entire gyrA and gyrB genes and multiplex PCR were performed to distinguish the prevalence of mutant types in Beijing and non-Beijing genotypes.

Results

Three hundred and twenty-one out of four hundred (80.25%) drug-resistant isolates (resistant > one drug) were categorized as 83/321 (25.80%) MDR, 174/321 (54.20%) pre-XDR and 64/321 (19.93%) XDR-MTB. Overall, 303/400 (75.75%) LVX- and 292/400 (73.00%) MXF-resistant (R) MTB strains were identified. Two hundred seventy-one out of three hundred and three (89.43%) resistant strains carried mutations in gyrA and 91/303 (30.03%) in gyrB. Interestingly, 18 novel mutations were detected in gyrA and gyrB genes. Mutations at (A90, D94) and (T500, G510, G512) frequently existed in QRDR(s) of gyrA and gyrB respectively in 286/400 (71.50%) LVX^RMXF^R strains. The novel mutations in- and out-side the QRDR of gyrA (L105R, A126E, M127K, D151T, V165A) and gyrB (D461H, N499S, G520A) increased the sensitivity and consistency of genotypic tests. Notably, 25 LVX^RMXF^R strains were found with unknown resistance mechanisms.

Conclusions

Mutations in QRDR(s) were concomitantly associated with Beijing and non-Beijing genotypes. The prevalence of resistance and cross-resistance between LVX and MXF in MTB isolates from southern China was immensely higher than other countries. Our valuable findings provide the substantial implications to improve the reliability of genotypic diagnostic tests relying on potential resistance conferring mutations in entire gyr genes.