Distribution and transmission characteristics of thirty-five dual genotype vancomycin-resistant Enterococcus faecium carrying both vanA and vanM in an intensive care unit

Abstract

Objective To investigate the distribution and transmission characteristics of vancomycin-resistant Enterococcus faecium (VREF) carrying both vanA and vanM in the intensive care unit. Methods VREF strains were isolated from patients in the intensive care unit of Jinshan Hospital, Fudan University in Shanghai from 2013 to 2017. Antimicrobial susceptibilities of the VREF strains to nine antibiotics, including vancomycin, teicoplanin, linezolid and chloromycetin, were tested by broth microdilution method. Multiple polymerase chain reaction (PCR) was used for van genotyping and pulsed field gel electrophoresis (PFGE) was used for homology analysis. Results Thirty-five strains were mainly isolated from urine (16 strains), blood (11 strains), feces (five strains), bile (two strains) and pleural effusion (one strain). All the strains (100.00%) were resistant to vancomycin, ampicillin and levofloxacin, but only 40.00% were resistant to teicoplanin. All the strains were sensitive to linezolid. The results of van genotyping showed that 33 (94.3%) strains belonged to vanA and vanM dual genotype VREF, and the other two were vanA type VREF. PFGE results showed that 35 strains could be divided into 14 PFGE patterns, and seven out of 10 strains isolated in 2014 were identical and the other three belonged to three different PFGE patterns. Conclusions A dual genotype VREF carrying both vanA and vanM has been emerging and spreading in the intensive care unit of Jinshan Hospital, Fudan University in Shanghai. Key words: Enterococcus faecium; Vancomycin; Drug resistance; Genes; Genotype