The molecular epidemiological study of colistin-only-sensitive strains in multi-drug resistant Acinetobacter baumannii.

This paper reported the epidemiology of the colistin-only-sensitive Acinetobacter baumannii (COS-AB) in a tertiary teaching hospital in China. We analyzed the clinical data of 136 COS-AB isolates from June 2004 to May 2005 and collected 66 A. baumannii isolates in which 33 strains were COS-AB, and the rest were non-COS-AB. Random amplified polymorphic DNA (RAPD) analysis (primer ERIC2 and 272) showed that all COS-AB were identical, while pulsed-field gel electrophotesis (PFGE) analysis showed two separate genotypes of these COS-AB which were distinctly different from that of non-COS-AB. The COS-AB from burn wards showed the identical PFGE pattern which was distinguished from the genotype of COS-AB in other departments, mainly surgical systems. The cross-infection was severe and strict methods of disinfection and sterilization should be implemented. Meanwhile, the epidemiology of COS-AB in environment and patients should be closely monitored. The PFGE analysis is a reliable method of A. baumannii typing.