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Efficacy of pyocyanin produced by Pseudomonas aeruginosa as a topical treatment of infected skin of rabbits

Mohamed M.Gharieb, Mostafa M.El-Sheekh, Sabha M.El-Sabbagh, Walaa T.Hamza

Pseudomonas aeruginosa produced the maximum amount of pyocyanin pigment (64.90 µg/ml) after 5 days of incubation in liquid peptone water medium. In vitro antimicrobial activity of the purified pyocyanin was demonstrated by agar well diffusion test. Gram positive bacteria were more susceptible to the antibiotic action of pyocyanin than Gramnegative bacteria. Thus, the Gram negative bacteria; E. coli and Salmonella typhi were the only affected isolates by the original extract of pyocyanin (1: 0.5 v/v). Whereas, Klebsiella pneumoniae was only affected at twenty folds of the original concentration. P. aeruginosa and Shigella flexneri were resistant to pyocyanin at all concentrations. Gram positive bacteria were more susceptible to P. aeruginosa pyocyanin (MICs 0.06 mg/ml) than Gram negative bacteria. Fungi that were non-susceptible to pyocyanin at original concentration (1 : 0.5 v/v), were affected when the concentration of pyocyanin increased to twenty fold of the original pigment extract. Thus, the inhibition zones of fungal growth reached 19mm. The minimum inhibitory concentrations of pyocyanin against the affected bacteria and fungi ranged from 0.06 to 1.2 mg/ml. In an animal model, pyocyanin was applied topically to treat wounded skin of rabbits which infected with S. aureus, K. pneumoniae or C. albicans.Maximumhealing and hair growing of the pyocyanin treated area of rabbit skin was observed after 14 -20 days in all cases compared to the untreated infected control.