RESUMO
BACKGROUND AND OBJECTIVES: Some Nontuberculous Mycobacteria (NTM) can occasionally infect the human population and cause infections having symptoms similar to tuberculosis (TB). This study tried to provide updated data about the frequency and diversity of NTM species. MATERIALS AND METHODS: Suspicious samples of Mycobacterium tuberculosis (MTB) with both positive results in Ziehl-Neelsen (ZN) staining and Löwenstein-Jensen medium culturing were evaluated during January 2016 and December 2018 in Gorgan, Iran. After determination of MTB isolates by the growth rate, pigmentation status, the niacin test, and the insertion sequence 6110 (IS6110) PCR assay, other unknown isolates (presumably NTM) were detected by the 16S rDNA sequencing method and drawing the phylogenetic tree. Based on the patients' demographic information, their risk factors were also assessed. RESULTS: Among 226 culture-positive samples, obtained from 2994 individuals with suspected symptoms of TB, the analyses found 12 (5.3%) NTM and three Mycobacterium caprae isolates. Mycobacterium simiae (6/12) was the most prevalent NTM species. The average nucleotide similarity value was 98.2% ± 3.7. In comparison to patients with MTB (211 confirmed cases), other mycobacterium infections were more common in patients over 65 years old (Odd ratio (95% convenience interval): 2.96 (0.69 - 12.59), P = 0.14). CONCLUSION: Although the NTM species has a small portion in TB suspected patients, their prevalence has increased, mainly in elderly patients. Moreover, M. simiae was the most prevalent NTM species in our region. Therefore, identification of common species in each region is recommended and clinicians should pay more attention to them in each region.
RESUMO
BACKGROUND AND OBJECTIVES: Tuberculosis (TB) is still responsible for a wide range of deaths worldwide. Beijing genotype is one of the most important and virulent strains in Mycobacterium tuberculosis. This study was designed for determination Beijing genotypes of M. tuberculosis in Golestan province, north of Iran. MATERIALS AND METHODS: In the current descriptive study, 238 clinical MTB isolates, obtained from patients with pulmonary and extra-pulmonary TB in north of Iran, were evaluated. Oligonucleotide primers for the Beijing and non-Beijing genotypes and specific probes for their detection by a real-time PCR method were employed. In addition, an association between the Beijing genotype and possible clinical and demographic factors was evaluated. RESULTS: The method revealed that 33 cases (13.9%) were the Beijing lineage and 205 (86.1%) the non-Beijing genotype. The mean age of patients infected with the Beijing and non-Beijing strains was 37.27 ± 18.3 and 51 ± 21.2 years, respectively; the difference was statistically significant (P = 0.001). In addition, the prevalence of the Beijing strain decreased with age. Patients with a TB infection caused by the Beijing genotype were also more vulnerable to treatment failure. Based on the origin of the samples, the Beijing genotype was more often observed in extra-pulmonary samples compared with Pulmonary ones (P = 0.001). CONCLUSION: The Beijing genotype of MTB is prevalent in our region especially among young people which could indicate the risk of further expansion in the future.
