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Background: One of the most important causes of death due to tuberculosis is drug resistant Mycobacterium tuberculosis. Rifampin is one of the most important drugs that are commonly used for treatment of tuberculosis. Mutations in rpoB gene of Mycobacterium tuberculosis cause rifampin drug resistant. The aim of this study was to investigate the type and frequencies of the mutation in this region in Mycobacterium tuberculosis isolated from patients in Tehran.

 Materials and methods: In this experimental study, 50 patients who did not respond to 6- month chemotherapy with anti- tuberculosis drugs were selected and tested for resistance to this drug. Patients’ sputum were obtained and cultured on Lowenstein-Jensen solid medium. After susceptibility testing, DNA of resistant strains was extracted and rpoB gene was amplified with PCR. Results were analyzed by computer using DNAMAN program.

 Results: 14 cases had mutations in this region of Mycobacterium tubrculosis. However, 6 isolates (30%) had no mutation in this part of the genome. The most frequent mutations occurred in codons 531(40%) and 515 (20%). We report mutation of codon 515 for the first time. Mutations in codons 526 (10%) and 510 (15%) were found.

Conclusion: Mutation in codon 515 probably shows the different pattern of mutation in Tehran. Our data indicate 6 isolates without mutation in the 81bp region. According to this study, resistance to rifampin may have non genetic and genetic causes on genes outside of 81bp region.

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Background: There is high prevalence of pencicllinase producing Neisseria gonorrhoeae and antibiotic resistance in numerous areas of the world. The aim of this study was to investigate drug resistance of gonococci.

Material and methods: In this cross-sectional descriptive study, vaginal discharge of 126 patients visited for vaginal discharge or suprapubic pain or admitted for periodic examination in Azad University hospitals were studied. Direct smear and gram stain of vaginal discharge was prepared and it was cultured into Tyer-Marthin media. Sensitivity to antibiotics was evaluated in positive cultures.

Results: Direct smear and gram staining of cervical discharge revealed 48 (38.1%) gram negative kidney shaped diplococci, but in selective media, only 12 (9.5%) Nesseria gonorrhoeae was detected. From 12 strains of Neisseria gonorrhoeae, 8 (66.6%) were resistant to penicillin, 8 (66.6%) to spectinomycin and 8 (66.6%) to co-trimoxazol, but neither of specimens were resistant to ceftriaxone.

Conclusion: Direct smear of vaginal discharge isn't enough for proper diagnosis of Neisseria gonorrhoeae and it should be confirmed by culture. Ceftriaxone is the best choice for treatment of gonococcal infections, but there is resistance to spectinomycin, co-trimoxazol and penicillin.

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Background: Nickel-titanium (nitinol) can be used in various biomedical prosthetic devices. Microorganism adhesion properties of nitinol may be decreased by oxidizing agents and surface heat treatment. In this study, we compared the microorganism adhesion and cytotoxic effects of the thin film and bulk form of nitinol.
Materials and methods: In this analytical comparative study, thin film and bulk forms of nitinol were treated by microorganism suspension in different culture flasks. Adherence activity of these forms was studied by electron microscopy. The number of microorganisms was counted before and after adoption to the surface of alloy.
Results: On the thin film, a decrease rate of 14% for Ecoli, 44% for P.aeroginosia, 30.1%for S.aureus, 22% for B.cereus and 6.4% for C.albicans were noticed. In the bulk form, decrease rate of cells were 39% for E.coli, 62% for P.aeroginosa, 61.9% for S.aureus, 49% for B.cereus and 31% for C.albicans. There found lower decrease rate of cells of thin film compared with the bulk form (mean decrease rate of 39% for thin film and 62% for bulk form P value<0.05).
Conclusion: The thin film of nitinol has less cytotoxic effects in comparison with the bulk form. The lower adherence activity of the thin film can be attributed to smoothness and better biocompatibility of the thin film. This may be a promising alloy for development of medical prosthetic devices.