Characterization of Acinetobacter clinical isolates

Members of the genus Acinetobacter are typical opportunistic bacterial pathogens that can survive for a long term even on inanimate surfaces. Acinetobacter species have natural and acquired antibiotic resistance mechanisms that provide resistance against a broad range of antimicrobial agents. Between April 2010 and March 2011, 6 clinical Acinetobacter sp. strains were isolated from expectoration or aspiration sputum samples in a local medical treatment-type hospital in Osaka prefecture. The antibiotic susceptibility breakpoint test showed that all the 6 isolates were ciprofloxacin-resistant. Strain AHU-70, which was identified as A.baumannii by 16S rRNA sequencing and polymerase chain reaction detection of the blaOXA-51-like gene, showed high levels of resistance to ciprofloxacin by the minimum inhibitory concentration (MIC) test. Preliminary research in Japan, based on nationwide susceptibility surveillance of ciprofloxacin against A.baumannii isolates showed that approximately 90% of the isolates were ciprofloxacin-susceptible. Given these results, further strain level identification of isolates is required to determine whether resistance to ciprofloxacin is an overall trait of these bacteria in the sampled local area or is restricted to a specific strain within particular hospitals