scholarly journals Fluoroquinolone susceptibility in first-line drug-susceptible M. tuberculosis isolates in Lima, Peru

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Alvaro Schwalb ◽  
Rodrigo Cachay ◽  
Ericka Meza ◽  
Tatiana Cáceres ◽  
Amondrea Blackman ◽  
...  
Keyword(s):  
Susceptibility Testing ◽  
Critical Concentration ◽  
Drug Susceptibility ◽  
Drug Susceptibility Testing ◽  
First Line ◽  
Viable Option ◽  
Time Points ◽  
Line Drug

Abstract Objective To determine at two distinct time points the prevalence of resistance to ofloxacin (OFX), the representative class drug of fluoroquinolones (FQs), in M. tuberculosis isolates susceptible to first-line drugs. Results There were 279 M. tuberculosis isolates from the two cohorts (2004–2005: 238 isolates; 2017: 41 isolates) that underwent OFX drug-susceptibility testing (critical concentration: 2 µg/ml). Of 238 isolates in Cohort 1, no resistance to OFX was detected (95% CI 0–0.016); likewise, in Cohort 2, no resistance to OFX was detected in 41 isolates (95% CI 0–0.086). Our findings suggest that FQ use remains a viable option for the treatment of first-line drug-susceptible TB in Peru.

scholarly journals Molecular Detection of Mutations Associated with First- and Second-Line Drug Resistance Compared with Conventional Drug Susceptibility Testing of Mycobacterium tuberculosis

2011 ◽  
Vol 55 (5) ◽  
pp. 2032-2041 ◽  
Author(s):  
Patricia J. Campbell ◽  
Glenn P. Morlock ◽  
R. David Sikes ◽  
Tracy L. Dalton ◽  
Beverly Metchock ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Mycobacterium Tuberculosis ◽  
Dna Sequencing ◽  
Susceptibility Testing ◽  
Drug Susceptibility ◽  
Drug Susceptibility Testing ◽  
Second Line ◽  
First Line ◽  
Content Type ◽  
Line Drug

ABSTRACTThe emergence of multi- and extensively drug-resistant tuberculosis is a significant impediment to the control of this disease because treatment becomes more complex and costly. Reliable and timely drug susceptibility testing is critical to ensure that patients receive effective treatment and become noninfectious. Molecular methods can provide accurate and rapid drug susceptibility results. We used DNA sequencing to detect resistance to the first-line antituberculosis drugs isoniazid (INH), rifampin (RIF), pyrazinamide (PZA), and ethambutol (EMB) and the second-line drugs amikacin (AMK), capreomycin (CAP), kanamycin (KAN), ciprofloxacin (CIP), and ofloxacin (OFX). Nine loci were sequenced:rpoB(for resistance to RIF),katGandinhA(INH),pncA(PZA),embB(EMB),gyrA(CIP and OFX), andrrs,eis, andtlyA(KAN, AMK, and CAP). A total of 314 clinicalMycobacterium tuberculosiscomplex isolates representing a variety of antibiotic resistance patterns, genotypes, and geographical origins were analyzed. The molecular data were compared to the phenotypic data and the accuracy values were calculated. Sensitivity and specificity values for the first-line drug loci were 97.1% and 93.6% forrpoB, 85.4% and 100% forkatG, 16.5% and 100% forinhA, 90.6% and 100% forkatGandinhAtogether, 84.6% and 85.8% forpncA, and 78.6% and 93.1% forembB. The values for the second-line drugs were also calculated. The size and scope of this study, in numbers of loci and isolates examined, and the phenotypic diversity of those isolates support the use of DNA sequencing to detect drug resistance in theM. tuberculosiscomplex. Further, the results can be used to design diagnostic tests utilizing other mutation detection technologies.

scholarly journals Overcoming the Challenges of Pyrazinamide Susceptibility Testing in Clinical Mycobacterium tuberculosis isolates

2021 ◽  
Author(s):  
Simone Mok ◽  
Emma Roycroft ◽  
Peter R Flanagan ◽  
Lorraine Montgomery ◽  
Emanuele Borroni ◽  
...  
Keyword(s):  
Sanger Sequencing ◽  
Susceptibility Testing ◽  
Critical Concentration ◽  
Drug Susceptibility ◽  
Rapid Identification ◽  
Drug Susceptibility Testing ◽  
Whole Genome ◽  
Testing Methods ◽  
First Line ◽  
Phenotypic Susceptibility

Pyrazinamide (PZA) is one of the first-line agents used for the treatment of tuberculosis. However, current phenotypic PZA susceptibility testing in the BACTEC MGIT 960 system is unreliable and false resistance is well documented. Rapid identification of resistance-associated mutations can confirm the phenotypic result. This study aimed to investigate the use of genotypic methods in combination with phenotypic susceptibility testing for confirmation of PZA resistant M. tuberculosis isolates. Sanger sequencing and/or whole genome sequencing were performed to detect mutations in pncA, rpsA, panD and clpC1. Isolates were screened for heteroresistance, and PZA susceptibility testing was performed in the BACTEC MGIT 960 system using a reduced inoculum to investigate false resistance. Overall, 40 phenotypically PZA resistant isolates were identified. Of these, PZA resistance was confirmed in 22/40 (55%) isolates by detecting mutations in pncA, rpsA and panD genes. 16/40 (40%) isolates were found to be susceptible using the reduced inoculum method (i.e. false resistance). No mutations were detected in two PZA resistant isolates. False resistance was observed in isolates with MICs close to the critical concentration. In particular, EAI strains (lineage 1) appeared to have an elevated MIC that is close to the critical concentration. While this study illustrates the complexity and challenges associated with PZA susceptibility testing of M. tuberculosis, we conclude that a combination of genotypic and phenotypic drug susceptibility testing methods is required for accurate detection of PZA resistance.

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