Clinical characteristics and molecular epidemiology of carbapenem- resistant Acinetobacter baumannii infections at Shenzhen People's Hospital during an 8-year period

Abstract

To investigate the clinical features, mechanism of resistance and molecular epidemiology of carbapenem-resistant Acinetobacter baumannii (CRAB) infections at Shenzhen People's Hospital during an 8-year period. A. baumannii isolates were recovered from nosocomial infections patients at this hospital from 2002 to 2009. The minimum inhibitory concentrations (MICs) of antimicrobial agents against A. baumannii isolates were detected by agar dilution method. Polymerase chain reaction (PCR) and DNA sequencing were used to examine the carbapenemase genotype among CRAB. All isolates were typed by pulse field gel electrophoresis (PFGE). Clinical cases of CRAB infections were retrospectively analyzed according to Chinese experts' consensus on diagnosis, treatments, preventions and controls of Acinetobacter baumannii infections in China. A total of 87 cases of CRAB nosocomial infections were diagnosed in this study. The most prominent infections caused by CRAB was lung infections, followed by bloodstream infections, wound infections and abdominal infections, accounting for 69.0%, 8.0%, 8.0% and 6.9% of 87 cases, respectively. Approximately 80.5% (70/87) of CRAB isolated from intensive care unit (ICU). A sharp increase of CRAB infections (42/87) occurred in 2009, with the majority of pulmonary infections (34/42). Genotyping by PFGE found eight distinct PFGE patterns among 87 isolates of CRAB. The prominent CRAB clone A, carrying a blaOXA-58-like carbapenemase gene, had been prevalent from 2002 to 2006 at this hospital. The CRAB clone C, harboring a blaOXA-23-like carbapenemase gene, as well as clone A became the prominent clones during 2007 to 2008. The CRAB clone D, carrying a blaOXA-23-like carbapenemase gene, replaced clone A and C, and became the dominant clone in 2009. The spread of the CRAB clone D harboring a blaOXA-23-like gene causes a rapid increase of CRAB infections at this hospital during 2009.