Heterogeneity of Iranian clinical isolates of Mycobacterium fortuitum

The increase of infections caused by nontuberculous mycobacteria [NTM] is receiving increasing attention worldwide. Mycobacterium fortuitum is encountered with increasing frequency in clinical laboratories of Iran. Sequence variation of 48 M. fortuitum clinical isolates, were investigated by sequence analysis of the 16S-23S Internal Transcribed Spacer. Twelve different sequence types [sequevar] were identified by sequence analysis of ITS region. Seven previously described sequevar including MfoA, MfoB, MfoC, MfoD, MfoE, MfoF and MfoG identified. Five novel sequevar namely MfoH, MfoI, MfoJ, MfoK and MfoL that were distinctly different from the previously described sequevar were detected among different clinical strains of M. fortuitum, from Iran. This study showed that the ITS region possesses high discriminatory power between the clinical isolates up to the clonal level. The results also suggest the possibility of the existence of predominant clone of M. fortuitum in affected patients in Iran. The data also point to the conclusion that a large variety of M. fortuitum clone can produce disease although certain clones seem to be predominant

Frequency and molecular characterization of rifampicin-resistance in rpoB region of multiple drug resistance [MDR] isolates from tuberculosis patients in southern endemic region of Iran

The aim of this study was to investigate the frequency, location and type of rpoB gene mutations in Mycobacterium tuberculosis [MTB] collected from patients in the southern endemic region of Iran. Drug susceptibility testing was determined by using the BACTEC system and the center for diseases controls [CDC] standard conventional proportional method. In 29 rifampicin-resistant MTB [85%] isolates, 60 mutations and 13 micro-deletions were identified. Missense mutations produced 23 types of amino acid substitutions. In five rifampicin-resistant MTB isolates [15%] no mutations were found in the core region of the rpoB gene. All silent mutations were localized in codon 507. Most frequent mutations detected in Iranian strains, were found in codons 523 and 526. Five alleles in codon 526 and three alleles occurring in triplets in each of the codons 507, 508, 513 were also found. Thus in Iran the highest frequency of common mutations shared between primary and secondary infections was found to occur in codons 523 and 526

Mutations in codon 315 of the katG gene associated with high-level resistance to isoniazid

The aim of this study was to investigate the significance of mutation in codon 315 of katG gene and its correlation with high-level of resistance to isoniazid, nuclotide and amino acid changes in mycobacterium tuberculosis [MTB] isolates randomly collected from sputums of 42 patients with active pulmonary tuberculosis in different regions of Belarus. Drug susceptibility testing was determined using the CDC standard conventional proportional method. DNA Extraction, katG gene amplification, and DNA sequencing analysis were performed. Six isolates [14%] bearing multi-mutations in three codons [309,315 and 316], 26 Isolates [61.9%] demonstrated multi-mutations in all or two of the above codons, and 8 [19%] were found to have a single mutation in 315. Four types of mutations were identified in codons 315: AGC-ACC [n=36]85%, AGC-AGG [n=1] 2.3%, AGC-AAC [n=2] 4.7%, AGC-GGC [n=1] 2.3%, one type of mutation in 316: GGC-AGC [n=18]41.4%, and four types of mutations in 309: GGT-GGT [n=7]16.1%, GGT-GCT [n=4]9.2%, GGT-GTC [n=3]6.9%, GGT-GGG [n=1]2.7%. In 2 [4.7%] isolates mutations were identified in codons 463, 357, and in codons 454, 357 respectively. MTB in patients from Belarus were found to have high-level resistance to isoniazid in the isolates with mutations in codon 315 [> 10 micro g/mL]

KatG mutation of isoniazid-resistant isolated from tuberculosis patients

The emergence of drug-resistant strains of Mycobacterium tuberculosis [MTB] is an increasing problem in developed and developing countries. The aims of the present study were to identify various types of mutations in katG region from 28 MDR strains isolated from sputum of tuberculosis patients. Twenty-eight rifampin-resistant strains isolated from sputum of patients with active pulmonary tuberculosis were obtained from various geographic regions of Iran. Drug susceptibility was determined by using the BACTEC system. DNA extraction, standard PCR identification, katG gene amplification, DNA sequencing and analysis were done. There was no mutation in 2 strains. In 20 strains, mutation was shown to be in codon 315. Three types of mutations were detected consisting of AGC-ACC [Ser-Thr] [80%], AGC-AGG [Ser-Arg] [5%] and AGC-AAC[Ser-Asn] [15%].Furthermore, one type of mutation was seen in codons 311, 299, and 323. Twelve strains showed one mutation in codon 315 [46%], 7 strains 2 mutations [27%], 5 isolate 3 mutations [19%] and in 2 strains 4 mutations [8%] were observed in different codons. Nine silent mutations was demonstrated in codon 311[GAC1TAC]. This research demonstrated that mutations were mostly seen in codons 315 and 299 indicating resistance to isoniazide