rifampin and triphenyltetrazolium

A rapid and inexpensive method for the detection of drug resistance in Mycobacterium tuberculosis is essential for the effective control of tuberculosis. The aim of this study was to evaluate a colorimetric method using 2,3,5-triphenyltetrazolium chloride (TTC) for antibiotic susceptibility testing of M. tuberculosis isolates. Eleven multidrug-resistant (MDR) isolates of M. tuberculosis and 12 isolates which were susceptible to rifampicin (RIF) and isoniazid (INH) were used. The test was performed with a critical concentration of 0.2 microg ml(-1) for INH and 2.0 microg ml(-1) for RIF in 7H9GC broth with 0.625 microg TTC ml(-1). Each isolate was inoculated under these conditions and inspected daily for colour changes; the results were obtained after a mean of 4.9 days. The sensitivity and specificity of this method were 100 % and 92 %, respectively, for both antibiotics. Considering the speed, technical ease and cost-effectiveness of this method, the TTC assay is a good alternative method for drug susceptibility testing of M. tuberculosis isolates.

Topics: Antibiotics, Antitubercular; Bacteriological Techniques; Drug Resistance, Multiple, Bacterial; Humans; Isoniazid; Microbial Sensitivity Tests; Mycobacterium tuberculosis; Rifampin; Sensitivity and Specificity; Tetrazolium Salts; Tuberculosis

Rifampicin is an antibacterial agent that is widely used in tuberculosis and leprosy therapy. Interestingly, some experimental studies indicate that rifampicin acts as a hydroxyl radical scavenger and a glucocorticoid receptor activator. In this study, the neuroprotective effect of rifampicin was evaluated after transient and permanent focal cerebral ischemia. Anaesthetized male C57BL/6j mice were submitted to permanent or transient thread occlusion of the middle cerebral artery (MCA). Reperfusion in transient ischemia was initiated 30 min later by thread retraction. Rifampicin or vehicle were applied intraperitoneally before permanent or immediately after 30 min of transient ischemia. Later, 24 h after permanent or transient ischemia, animals were re-anesthetized and decapitated. Brain injury was evaluated by triphenyltetrazolium chloride staining (TTC), terminal transferase biotinylated-dUTP nick end labeling (TUNEL) and cresyl violet staining. A 20-mg/kg sample of rifampicin showed a significant neuroprotection after cerebral ischemia. The number of TUNEL-positive cells in the striatum, where disseminated tissue injury was observed, was also reduced by application of rifampicin as compared with vehicle-treated animals. The present report shows that administration of rifampicin efficiently reduces brain injury after permanent and transient focal cerebral ischemia in mice.

Topics: Animals; Brain Infarction; Brain Ischemia; Cell Count; Cell Survival; Dose-Response Relationship, Drug; Enzyme Inhibitors; In Situ Nick-End Labeling; Infarction, Middle Cerebral Artery; Laser-Doppler Flowmetry; Male; Mice; Mice, Inbred C57BL; Reperfusion; Reperfusion Injury; Rifampin; Tetrazolium Salts