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Introduction Multidrug resistant tuberculosis (MDR-TB) presents a great challenge to public health, especially for developing countries. Some nontuberculous mycobacteria (NTM) cause the similar clinical and radiological characteristics with tuberculosis. We aimed to identify the frequency of NTM infections among subjects who were suspected to have MDR-TB due to lack of response to anti-TB treatment. Methods This retrospective study evaluated patients with suspected MDR-TB due to lack of sputum conversion after 2–3 months therapy with first line anti-TB treatment from 2009 through 2014. Cultures for mycobacteria were performed and identification was done to species level by phenotypic and molecular tests. The outcome of the patients with NTM disease and related risk factors for poor outcome were evaluated. Results Out of 117 consecutive strains isolated from suspected MDR-TB subjects, 35 (30%) strains were identified as NTM by using conventional and molecular approaches. Of these patients with positive NTM cultures, 32 (27%) patients met ATS/IDSA diagnostic criteria. Out of 32, 29 (90%) individuals with confirmed NTM diseases had underlying disorders including 8 subjects with malignancy, 5 with organ transplantations, and 4 with the human immunodeficiency virus. No known underlying disorder was found in 3 (9%) subjects. Treatment outcomes were available for 27 subjects, 17 (63%) of whom were cured and 10 (37%) had poor outcome including 6 (60%) who failed and 4 (40%) who died during treatment. Conclusion The high costs to the patient and society should lead health care providers to consider NTM in all patients suspected of having TB.

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Today Methicillin-Resistant Staphylococcus aureus (MRSA) have acquired multiple resistance to a wide range of antibiotics including aminoglycosides. So, this study was aimed to investigate the rate of aminoglycoside resistance and the frequency of aminoglycoside resistance mediated genes of aac(Ia)-2, aph(3)-IIIa and ant(4')-Ia among MRSA strains. A total of 467 staphylococci isolates were collected from various clinical samples. S. aureus strains were identified by standard culture and identification criteria and investigating of presence of 16S rRNA and nuc genes. Cefoxitin disk diffusion, and oxacillin-salt agar screening methods were used to detect the MRSA strains with subsequent molecular identification for the presence of mecA gene. Antibiotic susceptibility of MRSA strains against aminoglycoside antibiotics was evaluated by using agar disk diffusion method. Multiplex PCR for the presence of aac(Ia)-2, aph(3)-IIIa and ant(4')-Ia encoding genes for aminoglycosides were performed for MRSA strains. From total staphylococci tested isolates, 262 (56.1%) were identified as S. aureus, of which 161 (61.45%) were detected as MRSA and all comprised mecA gene. The resistance pattern of MRSA strains to aminoglycoside antibiotics were: gentamicin 136 (84.5%); amikacin 125 (77.6%); kanamycin 139 (86.3%); tobramycin 132 (82%); and neomycin 155 (96.3%). The frequency of aac(Ia)-2, aph(3)-IIIa, and ant(4')-Ia genes among MRSA strains, were 64%, 42% and 11.8% respectively. In conclusion, as MRSA strains are of great concern in human infections, the results of present study could provide a useful resource for health sectors for choosing appropriate antibiotics for the effective treatment of infections due to MRSA strains.

Pyrazinamide (PZA) is an important first-line drug used for the short-course treatment of tuberculosis in combination with isoniazid and rifampin. It has been reported that mutations in pncA gene correlate well with PZA resistance depending on the geographic area. On the other hand, different genotypes of Mycobacterium tuberculosis show different affinities to acquire resistance-related mutations. To determine the relative significance of various mutations in the pncA gene in Iranian PZA-resistant M. tuberculosis isolates and to analyze the association of different genotypes of M. tuberculosis with PZA resistance, 34 PZA-resistant M. tuberculosis isolates were analyzed for their pncA mutations using direct sequencing. These isolates were genotyped by IS6110 fingerprinting and spoligotyping methods. Mutations in the pncA gene were identified in 24 of 34 of these isolates (70.58%). No mutations were found in 10 PZA-resistant isolates, which implied that alternative mechanisms of resistance existed in these strains. PZA resistance was strongly (41.2%) associated with multidrug-resistant tuberculosis. Genotyping revealed the Central Asian (CAS) and East-African Indian families as the most prevalent families between PZA-monoresistant isolates versus the Beijing and Haarlem families which were the most frequent families between PZA including multidrug-resistant isolates.