Pyocyanin

Abstract

Pyocyanin, a pigment naturally produced by most Pseudomonas aeruginosa strains and noted to have a role in the wellbeing of the organism and its pathogenicity, was studied for its role as an inhibitor of bacterial growth and biofilm formation of many clinical bacterial isolates. The organisms included in the study were 33isolates of 11 different bacterial species. The results showed that most of the Gram-positive isolates from the 3species included in the study: Staphylococcus aureus, Staphylococcus saprophyticus and Enterococcus fecal is were inhibited at low concentrations of pyocyanin. The results varied for the Gram-negative organisms tested. Whereas the growth of the Escherichia coli, Citrobacter koseri, Enterobacter cloacae and A. baumannii isolates was clearly inhibited even by low concentrations of pyocyanin, the growth of Klebsiella pneumonia, Proteus mirabilis and Morganella morganii was not affected even by higher concentrations of pyocyanin. The methanol extract of the pigment was highly effective in preventing the biofilm forming ability of all S. saprophyticus, A. baumannii, E. cloacae and K. pneumoniae isolates, 3 of the 4 P. mirabilis isolates and 2 of the 5 E. coli isolates. All the other isolates tested, also showed a moderate antibiofilm activity This study revealed that pyocyanin has a powerful inhibitory effect on the bacterial growth and/or biofilm forming ability of the numerous clinically significant isolates tested, a characteristic that can prove valuable in developing new drugs for the treatment and prevention of different bacterial infections, once its safety for regular use has been assessed.