The antibiogram of pyocyanin-producing laboratory and environmental Pseudomonas aeruginosa isolates

Abstract

T

The high incidence of Pseudomonas–borne infections and difficulty associated with treating these infections is very worrisome. Pseudomonas has often been implicated in wound and hospital borne infections. Nevertheless, it’s an organisms of pharmaceutical importance, producing a metabolic product with potentials for development of newer medicines. The study evaluated the antibiotic susceptibility profile of P. aeruginosa isolates that produced pyocyanin. Twelve P. aeruginosa were isolated from soil and laboratory samples and identified using selected cultural and biochemical tests. Pure isolates were subjected to antibiotic profiling using the Kirby-Bauer disk diffusion method. The isolates were fermented using formulated broth medium containing some selected salts for enhanced pyocyanin production. Fermentation products were subjected to centrifugation and the supernatant filtered using appropriate Whatman filter paper. All the isolates showed a positive reaction to oxidase, citrate and catalase tests whereas, a negative reaction was observed for indole test. Their biochemical reaction in combination with their microscopic features confirmed these isolates to be Pseudomonas aeruginosa. A 100 % (12/12) level of resistance was recorded for all the isolates against ceftazidime, cefuroxime, augmentin and nitrofurantoin while 99.9 % (11/12) resistance was recorded against cefixime. Other antibiotics tested such as gentamicin, ofloxacin and ciprofloxacin were active [100 % (12/12)] against all the test isolates with varying inhibition zones recorded. All the isolates that were at least multidrug resistant also produced pyocyanin a virulence factor. This explains high prevalence of Pseudomonas aeruginosa and prolonged infections.