Epidemiological Characterization Of Carbapenem-resistant Acinetobacter Baumanii In ChongQing

BackgroundAcinetobacter baumannii is a nonfermenting gram-negative aerobic coccobacillus,belong to Conditional pathogen.It usually relate with respiratory infection, urinary tract infection,meningitis,peritonitis on inpatient,especially patient in ICU and patient with severely immunocompromised.With the clinical application of various kinds of invasive operation,such as breathing machines,and the wide use of antibiotics,glucocorticoid and immunosuppressants,the clinical detection rate of Acinetobacter baumannii continues to rise.As the clinical wide use of antibiotics,acinetobacter baumannii produces a wide range of inherent and acquired antibiotic resistance,appears multidrug resistance and even the outbreak of pandrug resistance.The transmission of CRBA cloning strains is an important reason of hospital infection by acinetobacter baumannii increased in Chinese hospitals.ObjectiveTo investigate the antibiotic resistance of nosocomial infection by Acinetobacter baumannii in our hospital in2009,and analysis the outbreak of Carbapenem-resistant Acinetobacter baumannii and the genotype of OXA-carbapenemases.MethodsAntimicrobial susceptibility testing was performed using broth micro dilution on272strains of A. baumannii isolated from our hospital in2009according to the NCCLS guidelines for MIC testing. The homology of102strains of Carbapenem-resistant A. baumannii (CRAB) in2009was studied by PFGE, cluster sequence types(STs) was analyzed with MLST, the genotype of OXA-carbapenemases (OXA-51-like,OXA-23-like, OXA-24-like,OXA-58-like) was detected by a novel multiplex polymerase chain reaction (PCR).ResultsThe drug resistance rate of A. baumannii to common antimicrobial agents increased year by year,the resistance rate to Minocycline、 Doxycycline、polymyxin B was lowest,resistance to Carbapenems raised faster.PFGE results show that there was outbreak of A/B/C cloning strains in ICU,and scattered during2009.ST238was the most prominent STs in the main cloning strans. In102strains of Carbapenem-resistant A. baumannii,71.6%of strains produced carbapenemases which were confirmed as OXA-23by multiplex PCR, and84.3%of strains produced OXA-51carbapenemases, only2strains produced OXA-24carbape nemases,3strains produced OXA-58carbapenemases,66%of strains produced two or more OXA carbapenemases.ConclusionThere was outbreak of A/B/C cloning strains in ICU in a teaching hospital, and ST238was the most prevalent STs, OXA-23carbape nemases are the most popular genotypes. Because of high resistance rate of antibiotics especially Carbapenems and Treatment options against the prevalent strain infections seem to be limited. So, strict adherence to a variety of infection control measures are typically required for prevent ting the outbreak. meanwhile, research to assess the clinical usefulness of various investigational agents should be encouraged.