Contribution of efflux pumps in fluroquinolone resistance in multi-drug resistant nosocomial isolates of Pseudomanas aeruginosa from a tertiary referral hospital in north east India.

Background: Pseudomonas aeruginosa is one of the leading opportunistic pathogen and its ability to acquire resistance against series of antimicrobial agents confi ne treatment option for nosocomial infections. Increasing resistance to fl uroquinolone (FQ) agents has further worsened the scenario. The major mechanism of resistance to FQs includes mutation in FQs target genes in bacteria (DNA gyrase and/or topoisomerases) and overexpression of antibiotic effl ux pumps. Objective: We have investigated the role of effl ux pump mediated FQ resistance in nosocomial isolates of P. aeruginosa from a tertiary referral hospital in north eastern part of India. Materials and Methods: A total of 234 non-duplicate, consecutive clinical isolates of P. aeruginosa were obtained from a tertiary referral hospital of north-east India. An effl ux pump inhibitor (EPI), carbonyl cyanide m-chlorophenylhydrazone (CCCP) based method was used for determination of effl ux pump activity and multiplex polymerase chain reaction (PCR) was performed for molecular characterisation of effl ux pump. Minimum inhibitory concentration (MIC) reduction assay was also performed for all the isolates. Results and Conclusion: A total number of 56 (23%) have shown effl ux mediated FQ resistance. MexAB-OprM effl ux system was predominant type. This is the fi rst report of effl ux pump mediated FQ resistance from this part of the world and the continued emergence of these mutants with such high MIC range from this part of the world demands serious awareness, diagnostic intervention, and proper therapeutic option.

Effect of sealing on the incorporation of pyrene in goat erythrocyte ghosts – Α fluorescence study.

The incorporation of pyrene within the membrane interior of goat erythrocyte ghost has been estimated from its fluorescence spectrum. The excimer to monomer fluorescence intensity ratio of embedded pyrene is a function of the fluidity of its environment and the magnitude of its incorporation. Our study shows that this ratio is considerably less (30%) in a pre-sealed ghost than in the non-sealed ghost revealing that the site of incorporation of the probe is indeed the hydrophobic interior of the membrane; as in the later case, the probe has access to the membrane interior from both sides of the membrane. Our study on kinetics of molecular exchange indicates a very fast (of the order of seconds) transfer rate of pyrene from probed to unprobed erythrocyte ghosts through the aqueous phase rather than actual fusion of the membranes.