Abstract:

Objective To investigate the resistance mechanism of Enterobacter aerogenes to carbapenems. Methods Sixteen isolates of carbapenem-resistant Enterobacter aerogenes were collected, and modified Hodge test was used to screen the strains producing carbapenemase. PCR amplification and gene sequencing were employed to detect and verify the resistance-associated gene. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was adopted to analyze the outer membrane porin of the strains. Results Modified Hodge test revealed that all the 16 strains of Enterobacter aerogenes produced carbapenemase. PCR amplification and gene sequencing indicated that all the 16 strains of Enterobacter aerogenes possessed KPC-2 gene, but did not carry IMP-1, IMP-2, VIM-1, VIM-2, NDM-1, OXA-1 and OXA-9 carbapenemase gene. SDS-PAGE demonstrated that Omp36 porin was absent in 5 of the 16 strains of Enterobacter aerogenes. Conclusion The major resistance mechanism of 16 strains of Enterobacter aerogenes to carbapenem may be associated with the expression of KPC-2 cabarpenemase accompanied with the absence of Omp36 porin in some strains.

Key words: Enterobacter aerogenes, resistance mechanism, carbapenemase gene, outer membrane porin