ABSTRACT
This article reports our experience with the BACTEC 460 TB system in the past five years and its performance characteristics and its advantages over the conventional LJ medium for mycobacterial culture. Clinical specimens (3597) from patients suspected to have tuberculosis were submitted for mycobacterial culture between May 2000 and August 2005 and were processed using the BACTEC 460 TB system. Pulmonary samples were 1568 while the extra pulmonary samples were 2029. BACTEC achieved detection of 681 (18.93%) M. tuberculosis cases (499- pulmonary, 182- extrapulmonary) with a recovery time shorter by 13.2 days compared to conventional method, while 577 (84.7%) were non-tuberculosis mycobacteria. Automated systems can have a great impact and thrust on an early diagnosis of tuberculosis allowing an early and appropriate management of the patient and thereby a better disease outcome.
Subject(s)
Automation , Bacteriological Techniques/instrumentation , Culture Media , Humans , Mycobacterium/isolation & purification , Mycobacterium tuberculosis/isolation & purification , Tuberculosis/diagnosis , Tuberculosis, Pulmonary/diagnosisABSTRACT
Mycolic acids are important components having a significant role in maintaining the rigidity of mycobacterial cell wall. They could also be the barrier for penetration of certain drugs into the bacterial cell. A novel in vitro model system was established for assessing the effect of Ciproflaxacin on mycolic acid metabolism in pathogenic mycobacteria M. Kansasii (which has similar mycolic acid pattern to that from M. leprae) and the effect of norfloxacin in M. intracellulare. These test mycobacteria were exposed in their midlogarithmic phase of growth to 0.5, 1, 2, 3, 4, 5 and 6 micrograms ml of ciprofloxacin and norfloxacin respectively for 1, 2 and 24 hours. Ciprofloxacin completely inhibited the synthesis of mycolates in M. kansasii at 3, 4 and 5 micrograms/ml; whereas norfloxacin exhibited its maximum inhibitory action on mycolic acids in M. intracellulare at 6 micrograms/ml for all the durations of exposure. Inhibition of mycolates directly correlated with bacterial viability which was estimated by colony forming units. The effect of quinolones on mycolic acid metabolism appears to be direct and not secondary to DNA gyrase. The results obtained from this study and our previous findings show that mycolic acid metabolism is affected by various groups of drugs, whose primary sites of activity may be different. The findings of the present study may have significant therapeutic implications in leprosy and other mycobacterial diseases.
Subject(s)
Ciprofloxacin/pharmacology , Nontuberculous Mycobacteria/drug effects , Mycobacterium/drug effects , Mycobacterium avium Complex/drug effects , Mycolic Acids/metabolism , Norfloxacin/pharmacologyABSTRACT
In this study, the ATP content of M. leprae exposed to various antimicrobial agents has been measured to evaluate its usefulness in drug sensitivity screening. Purified M. leprae suspensions from human biopsies have been incubated at 30 degrees C in a modified Dubos medium in the presence of different concentrations of various drugs viz., Rifampicin, Ethionamide, Ethambutol, Cycloserine, Dapsone, Clofazimine, Erythromycin and Tetracycline. ATP levels were estimated at 0, 7 days, 14 days of incubation by the procedures modified and standardised at this laboratory. ATP decay was accelerated by ethionamide, rifampicin, clofazimine, dapsone, erythromycin and to a lesser extent by cycloserine, whereas ethambutol and tetracycline did not have any significant effect. The rate of decay depended on the concentrations of these drugs. ATP assay promises to be a useful system for in vitro drug sensitivity screening against M. leprae isolated from patients.