Antibiotic Susceptibilities And Pheno/genotype Analysis Of Ocular Isolates Of Pseudomonas Aeruginosa

Abstract

Abstract: : Purpose: Infection of the human eye by Pseudomonas aeruginosa can result in permanent decrease in vision if not successfully treated. The aim of this study was to determine the antibiotic resistance patterns and pheno/genotypes in ocular isolates of P. aeruginosa. Methods: 23 ocular isolates of P. aeruginosa were included in the study. The susceptibilities of each strain to 11 antibiotics were examined by the standard disk–diffusion method. After co–incubation of test strains with human corneal epithelial cells, bacterial cytotoxicity was measured quantitatively using a cytotoxicity assay kit and bacterial invasion was quantified by gentamicin survival assay. Bacterial serotypes were examined using a P. aeruginosa antisera kit. Genotyping for detection of toxin genes exoU and exoS was performed using polymerase chain reaction. Results: 47% of isolates were resistant to b–lactam antibiotics. 10% were resistant to aminoglycosides and 4% resistant to fluoroquinolones except ofloxacin, to which 26% isolates showed resistance. 30% of isolates (7/23) showed multiple drug resistance (MDR). Among the MDR strains, 57% (4/7) were categorized as highly cytotoxic with toxin gene exoU and serotype E. 29% of MDR strains (2/7) were neither cytotoxic nor invasive, and possessed toxin gene exoS. 14% of MDR isolates (1/7) were invasive and contained gene exoS. Conclusions: The results suggest that the MDR rate is relatively high in ocular isolates of P. aeruginosa. The MDR in ocular P. aeruginosa may be more associated with strains having cytotoxicity and exoU gene, and belonging to serotype group E.

Keywords: antibiotics/antifungals/antiparasitics • Pseudomonas • bacterial disease