AmpC Enzyme Genes and β-Lactamases Genes for Multi-resistant Acinetobacter baumannii in Nanjing

OBJECTIVE To study the current status of the AmpC enzyme and β-lactamases genes for multi-resistant Acinetobacter baumannii isolates in clinic in Nanjing.METHODS The samples of 20 multi-resistant A.baumannii isolates were collected from Jul 2007 to Oct 2007 from the patients in hospitals of Nanjing.To determine the sensitivity to the 11 antibacterials by using a broth induction method,and two kinds of AmpC enzyme genes and eighteen kinds of β-lactamases genes of multi-resistant A.baumannii analyzed by polymerase chain reaction(PCR).RESULTS In all of the 20 A.baumannii isolates,the AmpC genes of chromosome type were found in 14 isolates(70.0%),there were the AmpC genes of plasmid type in 1 isolate(5.0%),the TEM genes in 12 isolates(60.0%),the SHV genes in 1 isolate(5.0%),CTX-M-1 genes in 2 isolates(10.0%),OXA-23 genes in 1 isolate(5.0%),and OXA-24 genes in 1 isolate(5.0%),respectively.The OXA-24 genes from No.9 isolate was the type of OXA-72 after DNA sequencing.The amino acid sequence translated by AmpC genes of chromosome type from No.16 and No.17 isolates was the new subtype.CONCLUSIONS The A.baumannii has not only TEM,VEB,GES,IMP,VIM,OXA-10 and OXA-23 genes,but also the type of chromosome and plasmid of AmpC,SHV,CTX-M-1 and OXA-24 genes in Nanjing.It is the first time that activity of AmpC enzyme and the genotype of chromosome and plasmid of AmpC enzyme for matching are tested at the same time.