Abstrait

Antimicrobial efficacy of pyocyanin produced by Pseudomonas aeruginosa against multi-drug resistant microorganisms

Mostafa M.El-Sheekh, S.M.El-Sabbagh,M.M.Gharieb, W.T.Hamza

The antibiotic sensitivity test revealed that some bacteria were multipleresistant to 3-8 antibiotics. The most effective drugs were amoxycillin, ciprofloxacin and nitrofurantoin. Yeasts exhibited different levels of sensitivity to the tested antibiotics. The addition of different stress factors enhanced the synthesis of pyocyanin by Pseudomonas aeruginosa. Maximum incriment of the pigment production was attained by adding ganoderma extract (159.7 µg ml-1 after 6 hrs) representing 254 %. A high antibacterial activity of pyocyanin against the testedGrampositive bacteria. Streptococcus pneumoniae was the most affected and it showed largest zones at different concentrations of pyocyanin (1:1 and 1: 0.2 v/v). Gram negative bacteria showed lower sensitivity to pyocyanin thanGram-positive bacteria. Thus, E. coli and Salmonella typhi were the only affected isolates by different concentrations of pyocyanin. Whereas, Klebsiella pneumoniae, P. aeruginosa and Shigella flexneri were resistant to all pyocyanin extracts. Candida tropicalis was susceptible to pyocyanin extracted by chloroformat 1:0.2 (v/v) than Saccharomyces servisiae which was more susceptible to pyocyanin at 1:0.5 (v/v). The antifungal effect of pyocyanin was recorded as inhibition zones ranged from 14 to 19 mm.