Ethambutol resistance of indigenous Mycobacterium tuberculosis isolated from human patients

Abstract

The present study was conducted to find out the ethambutol resistance pattern of indigenous isolates of Mycobacterium tuberculosis from Tuberculosis diagnosed human patients. A total of 172 specimens were collected from six different sources and comprised of 84.9% sputum, 10.5% pus and 4.7% bronchial washings. There were 70.9% males and 29.1% females with 84.30% pulmonary and 15.69% extrapulmonary tuberculosis. The Mycobacterium tuberculosis isolates collected from primary culture were further studied to determine their pattern and level of resistance. The inoculums were prepared using 0.5 Mac Farland turbidity standards. Five different concentration of ethambutol were used in Lowenstein Jensen (LJ) medium i.e. 2µg/ml, 4µg/ml, 6µg/ml, 8µg/ml and 10µg/ml for sensitivity testing. Data showed 10 (5.8%) resistant and 162 (94.2%) sensitive Mycobacterium tuberculosis out of total 172 clinical isolates. The growth was not inhibited at 1 st (2µg/ml) and 2 nd (4µg/ml) drug levels, while growth of 50% isolates inhibited at 3 rd level (6µg/ml), 30% inhibited at 4 th level (8µg/ml) and 20% at 5 th level (10µg/ml).The last three levels are above the therapeutic index and not recommended in actual clinical practice. It is thus conceivable to explore some other more effective chemotherapeutic agents, modify combinations or find more effective procedures to stop morbidity and mortality due to ethambutol resistant Mycobacterium tuberculosis.

Emergence of Potential Superbug Mycobacterium Tuberculosis , Lessons from New Delhi Mutant-1 Bacterial Strains

“…Several studies including our group have reported incidences of Rifampin resistant Mycobacterium in clinical isolates. (32)(33)(34)(35) Interestingly, the 96 % of the Mycobacterium tuberculosis clinical isolates screened were found to have in 81 bp core region of rpoB gene, which encodes for the beta subunit of RNA polymerase. (36) Missense mutations in codons 513, 526, or 531 resulted in high level Rifampin resistance; whereas amino acid changes at position 514 or 533 usually resulted in low levels of Rifampin resistance.…”

“…(35) Our group has found that about 90% of rifampinresistant clinical isolates in the South Asia were also resistant to ethambutol and isoniazid. (34,37) This may lead us to hypothesize that rifampin resistance could be mediated through a surrogate genetic marker, such as Class I integron that have been found to confer multidrug resistance in other bacterial strains, indicating that second and third line anti-tubercular drugs to which these isolates may be susceptible would also be rendered useless by subsequent anti-tubercular therapy. However, several investigators have also reported that many INH resistant clinical isolates may have small deletions or insertion mutations.…”

“…However, several investigators have also reported that many INH resistant clinical isolates may have small deletions or insertion mutations. (37)(38)(39) (42,43) Streptomycin resistant Mycobacterium tuberculosis: Streptomycin is another first-line antitubercular drug that binds to 16S rRNA of the 30S subunit of the bacterial ribosome, thus interfering with the binding of formyl-methionyltRNA to 30S subnit. This leads to the inhibition of the protein synthesis in the Mycobacterium tuberculosis.…”

“…It is presumed that these structural changes detrimentally change enzyme function, thereby altering conversion of PZA to its bioactive form. (34,46) Ethambutol resistant Mycobacterium tuberculosis: Ethambutol is another important bactericidal first line antitubercular drug. This agent has been proposed to be an arabinose analog; the specific target is likely to be an arabinosyl transferase, presumably a functionally important site.…”

Anti-Mycobacterium tuberculosis activity of fungus Phomopsis stipata

“…Among the infected individuals in the world, about eight million a year develop active TB and nearly two million die (33). Advancements in health care facilities offered a goal to eradicate tuberculosis (TB) by the end of the 20th century, but it reemerged because of the global resistance against antitubercular drugs (22). The advent multidrug resistance (MDR), extensive drug resistance (XDR) infection, concerns health authorities around the world, especially in developing countries, where the situation is more severe.…”