Low Levels of Extensively Drug-resistant Tuberculosis among Multidrug Resistant Tuberculosis Isolates and Their Relationship to Risk Factors: Surveillance in Tehran, Iran; 2006 to 2014

OBJECTIVES: Extensively drug-resistant tuberculosis (XDR-TB) is more expensive and difficult to treat than multidrug-resistant tuberculosis (MDR-TB), and outcomes for patients are much worse; therefore, it is important that clinicians understand the magnitude and distribution of XDR-TB. We conducted a retrospective study to compare the estimated incidence of and risk factors for M/XDR-TB with those of susceptible TB controls. METHODS: Sputum culture and drug susceptibility testing (DST) were performed in patients with known or suspected TB. Strains that were identified as MDR were subjected to DST for second-line drugs using the proportion method. RESULTS: Among 1,442 TB patients (mean age, 46.48 ± 21.24 years) who were culture-positive for Mycobacterium tuberculosis, 1,126 (78.1%) yielded isolates that were resistant to at least one first-line drug; there were 33 isolates (2.3%) of MDR-TB, of which three (0.2%) were classified as XDR-TB. Ofloxacin resistance was found in 10 (0.7%) isolates. Women were 15% more likely than men to yield M/XDR-TB isolates, but this difference was not significant. In a multivariate analysis comparing susceptible TB with X/MDR-TB, only one variable—the number of previous treatment regimens—was associated with MDR (odds ratio, 1.06; 95% confidence interval, 1.14–21.2). CONCLUSION: The burden of M/XDR-TB cases is not sizeable in Iran. Nonetheless, strategies must be implemented to identify and cure patients with pre-XDR-TB before they develop XDR-TB. Our results provide a greater understanding of the evolution and spread of M/XDR-TB in an environment where drug-resistant TB has a low incidence.

[Comparative study of protein profile in Mycobacterium tuberculosis and Mycobacterium bovis with SDS-PAGE method]

Mycobacterium bovine, as the etiology of bovine TB, involves human in some cases and with Mycobacterium tuberculosis are regarded as global health problems. The aim of this study was to extract and compare protein profile of these strains in order to achieve effective biomarkers for diagnosis and the vaccine components. First, the clinical samples were cultured on Lowenstein-Jensen [LJ] medium by the N-acetyl-L-cysteine-sodium hydroxide method and the biochemical tests and antibiotic susceptibility were used. Colonies were grown in the Middlebrook 7H9 medium and, upon harvesting the new colonies, secretory and membrane proteins were extracted by sonication and ammonium sulfate and alcohol precipitation. Concentration was determined by Bradford method and finally the comparison was made through one dimensional electrophoresis. The major discrepancy between two strains of Mycobacterium tuberculosis and Mycobacterium bovis was 45 and 60 KDa bands as well as the zone between 14 and 45 KDa bands of secretory proteins, in the banding separation membrane proteins. Discrepancy in the protein bands of sensitive strains and Mycobacterium bovis seems to be used as an effective protein marker or even a biomarker in distinguishing the sensitive and bovis strains; also similarities can be used for immunization purposes

Effects of protoplast fusion on S-endutoxin production in bacillus thuringiensis Spp. [H14]

In this study, mutant forms of Bacillus thuringiensis spp. israelensis [H14] were produced. These mutants were identified when the cells were cultured on chloramphenicol plates and stained with crystal violet. Protoplasts of the mutants were isolated by enzymatic digestion [lysozyme] of the cell walls at the presence of an osmotic stabilizer. The protoplasts were induced to fuse to each other in the presence of PEG 6000. The frequency of regeneration and recombination was 80% and 2 10-4, respectively. In order to survey the effect of protoplast fusion on production of toxin, anti-serum against pure toxin was raised in rabbit and was used in single radial immunodiffusion. The comparison of -endotoxin concentration between B. thuringiensis fusion and the wild type strains showed that B. thuringiensis fusion has 1.48 time more toxin than wild type