Evaluation of the impact of polyclonal infection and heteroresistance on treatment of tuberculosis patients

Kamakoli, Mansour Kargarpour; Sadegh, Hamid Reza; Farmanfarmaei, Ghazaleh; Masoumi, Maryam; Fateh, Abolfazl; Javadi, Gholamreza; Jamnani, Fatemeh Rahimi; Vaziri, Farzam; Siadat, Seyed Davar

doi:10.1038/srep41410

Cited by 36 publications

(20 citation statements)

References 22 publications

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“…On the other hand, molecular assays may not be sensitive enough to detect drug-resistant subpopulations (heteroresistance) at the critical 1% proportion level (10% for PZA) defining clinical resistance (17,18,23). The magnitude of mixed and polyclonal infections among TB patients is relatively unknown, although recent studies clearly showed that heteroresistance occurs frequently (ϳ20% to 45%) in specific TB populations and that it may also have a negative impact on the treatment outcome (24)(25)(26).…”

Section: Discussionmentioning

confidence: 99%

Non- pncA Gene-Mutated but Pyrazinamide-Resistant Mycobacterium tuberculosis: Why Is That?

2017

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Pyrazinamide (PZA) is a key component for the effective treatment of drug-susceptible and PZA-susceptible multidrug-resistant (MDR) tuberculosis (TB). gene mutations are usually detected in a clear majority (>90%) of PZA-resistant strains but obviously not in all. Rapid and reliable PZA drug susceptibility testing (DST) is critical whenever PZA is to be used in a treatment regimen, not least for the treatment of MDR TB. In this study, we selected 26 PZA-resistant isolates reported to carry a wild-type gene. To confirm resistance, susceptibility testing was repeated using 100 mg/liter and 200 mg/liter PZA for all the 26 isolates and Sanger sequencing was repeated on the 18 isolates that remained PZA resistant. Apart from the eight isolates initially misclassified as PZA resistant, the retests identified three factors responsible for the phenotype-genotype discrepancy: or mutations identified by whole-genome sequencing (WGS) ( = 7), heteroresistance ( = 8), and mixed populations with ( = 3). Additionally, we performed WGS on 400 PZA-susceptible isolates and 15 consecutive MDR clinical isolates. Of the 400 PZA-susceptible isolates, only 1 harbored a nonsynonymous mutation (Thr87Met), whereas a nonsynonymous mutation was found in 17 isolates. None of these isolates carried a nonsynonymous mutation, while all 15 of the MDR isolates harbored a nonsynonymous mutation. Our findings indicate that it is necessary to consider the occurrence of mutations in PZA-resistant isolates, as well as heteroresistance, for the development and evaluation of new molecular techniques to ensure high-quality DST performance. The identification of nonsynonymous mutations in both PZA-susceptible and PZA-resistant isolates also implies that further studies are needed in order to determine the role of in PZA resistance.

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Section: Discussionmentioning

confidence: 99%

Non- pncA Gene-Mutated but Pyrazinamide-Resistant Mycobacterium tuberculosis: Why Is That?

2017

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“…The sub-culturing of isolates for MB7H10 and MYCTB plate DST may have caused changes in the sample strain population from the original sample used for DST in presence of hetero-resistance [ 18 ]. Studies have indicated hero-resistance to affect DST results from the sub-cultured strains [ 19 , 20 ], however, this is expected to be minimal given the low prevalence of hetero-resistance. This is one of the few studies which have compared LJ and MB7H10 DST with MYCOTB plate and our findings are vital for future studies and recommendations.…”

Section: Discussionmentioning

confidence: 99%

Agreement of Middle brook 7H10 with Lowenstein Jensen and accuracy of the Sensititre MYCOTB plate using either method as a reference standard for Mycobacterium tuberculosis first line drug susceptibility testing

et al. 2018

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IntroductionAlthough Sensititre Mycobacterium tuberculosis (MYCOTB) plate offers both drug susceptibility testing (DST) and minimum inhibitory concentration (MIC) results, it has not been evaluated against both Lowenstein Jensen (LJ) and Middlebrook 7H10 (MB7H10) DST methods at standard critical concentrations.Materials and methodsWe analyzed 76 M. tuberculosis isolates consisting of 54 isolates from the Uganda National TB drug resistance survey done December 2009–February 2011 and 22 isolates from the World Health Organization External Quality Assessment panel for the year 2011. All isolates were tested for LJ, MB7H10 and MYCOTB plate based DSTs for streptomycin, isoniazid, rifampicin and ethambutol anti-tuberculosis drugs. The agreement of MB7H10 with LJ and accuracy of MYCOTB plate using either LJ-DST or MB7H10 as a reference standard were determined.ResultsThe agreement (kappa) of MB7H10 with LJ was; 0.687 for rifampicin, 0.498 for isoniazid, 0.275 for streptomycin and 0.082 for ethambutol which as almost similar when compared with MYCOTB plate. The sensitivity (95% confidence interval; CI) of MYCOTB plate when LJ was used as a reference standard was higher for streptomycin 87.5% (81.6–98.4) followed by isoniazid 75.9% (65.1–95.6) and rifampicin 73.1% (52.2–88.4). When MB7H10 was used as reference standard, the sensitivity of MYCOTB plate improved significantly; isoniazid 96.2% (80.3–99.9), rifampicin 94.0 (83.4–98.7) and 93.8% (69.7–99.8). There was good agreement between MYCOTB plate and MB7H10; 1.00 for ethambutol, 0.959 for streptomycin, 0.915 for rifampicin and 0.778 for isoniazid.ConclusionsThe performance of the two culture-based reference standards for phenotypic first-line drug susceptibility testing methods, LJ and MB7H10, varied much even with acceptable MYCOTB plate MICs. There was acceptable agreement and accuracy of MYCOTB plate for drug susceptibility testing when MB7H10 was used as reference standard than with LJ-DST. Results from MIC information makes the MYCOTB plate more suitable for guiding clinicians on the choice of the most appropriate TB treatment regimen as well as limits of detection for TB drug resistance.

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“…Our recent studies have shown that the rate of polyclonal infections in clinical specimens is more than 50 percent in our region [ 9 – 11 ]. With this background, Spoligotyping was performed on clinical specimens and their respective cultures, and interesting results were obtained.…”

Section: Main Textmentioning

confidence: 99%

“…MIRU-VNTR is the best and most widely used method for identifying mixed infections in TB [ 8 ]. Several studies have used MIRU-VNTR to diagnose mixed infections in clinical specimens and this method has been successful in detecting the mixed infections [ 9 – 11 ]. But a recent article suggests that mixed infections in clinical specimens can disrupt direct genotyping and challenge the Spoligotyping technique [ 3 ].…”

Section: Introductionmentioning

confidence: 99%

Challenge in direct Spoligotyping of Mycobacterium tuberculosis: a problematic issue in the region with high prevalence of polyclonal infections

et al. 2018

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ObjectiveBased on our recent studies the prevalence of polyclonal infection in tuberculosis clinical specimens is more than 50% in Tehran, Iran. With this background, Spoligotyping was performed on clinical specimens and their respective cultures, and we examined whether mixed infections interfere with the results or not.ResultsBased on the Spoligotyping pattern, among the fourteen patients, 57.1% had different genotypes in clinical samples and their respective cultures. These discrepant patterns were suggestive of polyclonal infections in clinical samples with possible overlapping Spoligotype patterns. We propose that in societies with high mixed infections (e.g. Iran), direct Spoligotyping on clinical samples can be controversial.

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Evaluation of the impact of polyclonal infection and heteroresistance on treatment of tuberculosis patients

Cited by 36 publications

References 22 publications

Non- pncA Gene-Mutated but Pyrazinamide-Resistant Mycobacterium tuberculosis: Why Is That?

Non- pncA Gene-Mutated but Pyrazinamide-Resistant Mycobacterium tuberculosis: Why Is That?

Agreement of Middle brook 7H10 with Lowenstein Jensen and accuracy of the Sensititre MYCOTB plate using either method as a reference standard for Mycobacterium tuberculosis first line drug susceptibility testing

Challenge in direct Spoligotyping of Mycobacterium tuberculosis: a problematic issue in the region with high prevalence of polyclonal infections

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