Detection and homology analysis on metalloβlactamases gene in clinically isolated gramnegative bacteria

Abstract:

ObjectiveTo investigate the detection of IMP and VIM metalloβlactamases (MβLs) genes in clinically isolated gramnegative bacteria as well as  bacterial resistance to  βlactam antimicrobial  agents.  Methods113 clinically isolated  bacteria were performed antimicrobial susceptibility testing by KirbyBauer method , drugresistant genes IMP and VIM were detected by polymerase chain reaction (PCR) , PCR products were sequenced  and aligned with BLAST software.  ResultsVIM gene was detected in 1 Pseudomonas fluorescens strain , IMP gene was detected in 15 strains , they were Klebsiella pneumoniae (n=6) ， Acinetobacter baumannii (n=3)， Escherichia coli (n=2)， Ralstonia pickettii (n=1)， Pseudomonas aeruginosa (n=1)， Citrobacter amalonaticua (n=1)，and Enterobacter cloacae (n=1).  BLAST results showed that VIM gene was VIM2 subtype, similarity with gene bank was 99%; all IMP genes were IMP1 subtype，which were highly homologous , similarity was 98%-99%.  Resistant rates of IMP positive strains to  ceftriaxone，cefotaxime,   cefoxitin，aztreonam and imipenem  were all significantly higher than negative strains (all P<0.05). ConclusionIMP genes of different strains are highly homologous, all are IMP1 type, indicating that  IMP genes are highly transmissible and can spread among different species of bacteria. IMP genes are related with resistance of β-lactam antimicrobial agents.