A comparative study on the in-vitro antimicrobial activity of Bacillus subtilis supertanant versus standard treatment (Co-trimoxazole) on methicillin-resistant staphylococcus aureus (MRSA)

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Clinical Pharmacology


Methicillin-resistant staphylococcus aureus, Anti-Infective Agents, Bacillus subtilis, Trimethoprim, Sulfamethoxazole Drug Combination


This study compared the antimicrobial property of Bacillus subtilis supertanant and co-trimoxazole against methicillin-resistant straphylococcus aureaus (MRSA). Specifically, this study compared the zones of inhibitions of both substances on Mueller-Hinton Agar (MHA), with the B. subtilis supernatant as a test group and the co-trimoxazole as the positive control group. The B. subtilis was cultured in nutrient broth and was mixed with glycerol and centrifuged at 6k rpm for 30 min, and 20µl were placed on blank antibiotic discs. The Co-trimoxazole was made from a dissolved tablet with a concentration of 1µl/µl, and 25µl of the solution was placed on black antibiotic discs. The antibiotic discs were placed on MRSA cultured on MHA. The results revealed that the B. subtilis supernatant's zone of inhibition was not comparable to that of Co-trimoxazole. Heteroresistance phenomena, where in a certain number of bacteria from one culture exhibit a range of susceptibilities to an antibiotic, by MRSA towards B. subtilis was observed. The findings may help future studies regarding the antibiotic properties of B. subtilis on MRSA in developing new drugs.

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