Detection of Isoniazid and Rifampin Resistance in Mycobacterium tuberculosis Clinical Isolates from Sputum Samples by High-Resolution Melting Analysis.

The effective management of multidrug-resistant tuberculosis (MDR-TB) and the need for rapid and accurate screening of rifampin (RIF) and isoniazid (INH)-resistant Mycobacterium tuberculosis (Mtb) isolates are the most fundamental and difficult challenges facing the global TB control. The present study aimed to compare the diagnostic accuracy of high-resolution melting-curve analysis (HRMA) in comparison to multiplex allele-specific PCR (MAS-PCR) and xpert MTB/RIF as well as the conventional drug-susceptibility test (DST) and gene sequencing for the detection of INH and RIF resistance in the Mtb isolates. In the present study, a total of 431 Mtb isolates including 11 MDR (%2.55), 7 INH resistance (%1.62), two RIF resistance (%0.46), and 411 sensitive isolates were phenotypically confirmed. HRMA assay identified katG gene mutations and the mabA-inhA promoter region in 15 of 18 INH-resistant samples and rpoB gene mutations were successfully evaluated in 11 out of 13 RIF-resistant samples. The sensitivity and specificity of the HRMA method were 83.3% and 98.8% for INH and 84.6% and 99% for RIF, respectively. The most common mutation in RIF-resistance-determining region (RRDR) occurred at codon 531 (TCG → TTG)(84.6%) and then at codon 513 (CAA → GTA)(7.6%) and 526 (CAC → TAC) (7.6%), which resulted in the amino-acid changes. Also, 88.8% of INH-resistant samples had mutations in the katG gene and the mabA-inhA promoter region, of which the highest mutation occurred at codon 315 (AGC → ACC) of the katG gene. In conclusion, all these results indicated that the sensitivity and specificity of the HRM method were increased when the katG gene and the mabA-inhA promoter region were used as a target.

Genotyping of Mycobacterium tuberculosis complex isolated from humans and animals in northeastern Iran.

The objective of this study was to genotype Mycobacterium tuberculosis complex isolated from humans and cattle in northern Iran. Over the course of one year, a total of 120 human and 21 cattle isolates were tested using region of difference (RD)-based polymerase chain reaction (PCR) and mycobacterial interspersed repetitive unites-variable number tandem repeats (MIRU-VNTR). In M. tuberculosis, out of 120 isolates investigated, the most common genotype detected was NEW-1 (53.3%), followed by CAS/ Delhi (24.1%), Haarlem (5%), Beijing (4.16%), Uganda I (4.16%), S (3.3%), Ural (0.83%), TUR (0.83%), Uganda II (0.83%), Lam (0.83%) and Cameroon (0.83%). The HGDI rate was 0.9981 and the clustering rate was 10.83. Of the isolates, QUB26 had the highest allele diversity (h: 0.76), while the loci Mtub29 and MIRU24 had the lowest (h: 0). In M. Bovis, out of 123 collected tissue samples, 21 (17%) grew on culture media. The HGDI rate was 0.71 and clustering rate was 85.7%. The locus ETRC had the highest allele diversity (h: 0.45). The findings of this study suggest that there is high genetic diversity among M. tuberculosis isolates in Khorasan Razavi Province, which is consistent with similar results from other studies in other provinces in Iran and neighboring countries. This indicates that the prevalent genotypes in this study are spreading in the Middle East region. Furthermore, considering that M. Bovis isolates were identified in two clusters, it seems that all of them have a common origin and are circulating among the livestock farms in the province.

Prevalence of Diabetes Mellitus and its Related Factors in Patients with Tuberculosis.

BACKGROUND: Considering the high prevalence of tuberculosis (TB) in developing countries and the fact that comorbidity with diabetes mellitus (DM) imposes a higher burden on the society, this study was carried out to assess the prevalence of diabetes and its related factors in patients with TB in Mashhad, Iran. METHODS: In this study, we enrolled 405 patients over the age of 18 who had been diagnosed with TB between the years 2015 and 2016 according to the documents of the ministry of health. The participants were selected randomly from five health center domains based on the stratified sampling method. The patients were screened for diabetes according to HbA1c over 6.5% or a fasting blood sugar (FBS) level over 126 mg/dL at different time points and the patient's self-report of having DM. RESULTS: The mean age of participants was 51.14±20.52 (19-92 years). The prevalence of DM in patients with TB was 21.2%, of whom 3.5% were newly diagnosed. Among potential factors, age with OR=3.786 (1.183, 12.113), body mass index with OR=9.149 (3.182, 26.302), nationality with OR=2.149 (1.122, 4.117) and TB type with 3.328 (1.44, 7.689) were associated with DM in patients with TB. CONCLUSION: The prevalence of DM in our study was higher than that observed in other countries. Our study showed associated factors like age, body mass index, and TB type to be very important. Also, the prevalence of DM was different in patients with different nationality.

Co-infection of long-standing extensively drug-resistant Mycobacterium tuberculosis (XDR-TB) and non-tuberculosis mycobacteria: A case report.

We report a 69-years-old Iranian HIV negative male patient, with long-standing pulmonary tuberculosis (eleven years) co-infected with non-tuberculosis mycobacteria. Despite of initiation of first line anti-tuberculosis therapy after diagnosis the patient poorly respond because of low compliance with anti-TB treatment. After several incomplete treatments the smear was still positive and thus drug susceptibility tests were performed on isolated organism which revealed that the organisms was resistant not only against isoniazid and rifampin but also against Ofloxacin (OFX), Capreomycin (CAP), p-aminosalicylic acid (PAS), ethionamide (ETH), Kanamycin (KAN), ciprofloxacin (Cip), amikacin (AMK) and cycloserine (CYC). Persistence and resistance of infection had led us to do more investigation using molecular methods, which revealed co-infection with Non-tuberculosis mycobacteria (NTM). The patient is still alive with cough and shortness of breath.