Adaptation and development of a new method for measuring antibiotic and dye accumulation in Acinetobacter baumannii

[摘要] Acinetobacter spp. are nosocomial pathogens, commonly associated with opportunistic infections such as pneumonia, urinary tract and skin and soft tissue infections, particularly in intensive care units and in military casualties returning from Iraq and Afghanistan. Their propensity to acquire resistance determinants and over-express existing resistance genes allows them to avoid eradication by antibiotics and biocides. A common cause of multidrug resistance is innate and over-production of efflux pumps. This study aimed to establish a method to distinguish between isolates that demonstrate different levels of efflux and to apply the method to study defined efflux pump mutants. MICs of a range of antibiotics were determined against clinical isolates representative of resistant and susceptible isolates commonly found causing infection in Singapore hospitals and specific pump deletion mutants. A Hoechst 33342 accumulation assay was developed and used to compare efflux in the clinical isolates and pump deletion mutants and data were compared with those from ethidium bromide and norfloxacin accumulation assays. Measurement of accumulation of H33342, with supporting ethidium bromide accumulation data, showed a significant difference in the efflux activity of specific pump deletion mutants compared with the parental strain. Data obtained in this study support previous work carried out with other strains and isolates of A. baumannii and provide an insight into the contribution of RND systems AdeFGH and AdeIJK to MDR in clinical isolates commonly found in Singapore hospitals.

[发布机构] University:University of Birmingham;Department:School of Immunity and Infection

[关键词] Q Science;QR Microbiology