vanA and vanB Incorporate into an Endemic Ampicillin-Resistant Vancomycin-Sensitive Enterococcus faecium Strain: Effect on Interpretation of Clonality

Abstract

Clonal spread and horizontal transfer in the spread of vancomycin resistance genes were investigated. Multiplex PCR, pulsed-field gel electrophoresis (PFGE), hybridization of enterococcal plasmids with the vanA and vanB probes, and sequencing of a fragment of vanB were used in the analysis. Before May 1996, 12 vancomycin-resistant Enterococcus faecium (VRE) isolates were found in Finland. Between May 1996 and October 1997, 156 VRE isolates were found in the Helsinki area. Between December 1997 and April 1998, fecal samples from 359 patients were cultured for VRE. One new case of colonization with VRE was found. During the outbreak period, 88% (137 of 155) of the VRE isolates belonged to two strains (VRE types I and II), as determined by PFGE. Each VRE type I isolate possessed vanB, and five isolates also had vanA. Of the 34 VRE type II isolates, 27 possessed vanA and 7 possessed vanB. Fifteen of 21 (71%) ampicillin-resistant, vancomycinsensitive E . faecium (VSE) isolates found during and after the outbreak period in one ward were also of type II. Two VSE type II isolates were found in the hospital before the outbreak in 1995. By PFGE, the three groups (vanA, vanB, or no van gene) of type II shared the same band differences with the main type of VRE type II with vanA. None of the differences was specific to or determinative for any of the groups. Our material suggests that vanA and vanB incorporate into an endemic ampicillin-resistant VSE strain.

Isolation of Tn1546-like elements in vancomycin-resistant Enterococcus faecium isolated from wood frogs: an emerging risk for zoonotic bacterial infections to humans

“…However, a possibility of the presence of VanB could not be eliminated in these bacteria. Previous studies have reported the presence of both VanA and VanB in the same isolate (Suppola et al 1999). The VanA phenotype expressing high-level Vn and Tp resistance is carried on Tn1546-like elements (Derlot and Courvalin 1991;Arthur et al 1996;Garnier et al 2000).…”

Recommendations for the successful control of a large outbreak of vancomycin-resistant Enterococcus faecium in a non-endemic hospital setting

“…Most likely, therefore, they were introduced to the study hospital shortly before first detection. Acquisition of vanA genes has been described in ARE [29]. Hospital-wide surveillance for more than four years found no evidence for repeated introduction of these two epidemic STs into the hospital from the environment, but they were detected in other hospitals between 2012 and 2017.…”

Genetic methods for detection of antimicrobial resistance

“…However, the ever growing subtypes within the vanD‐group has already emphasized the need for consensus D‐primers (14A). VanA and VanB‐phenotypes are the most commonly encountered forms and clinically the most important due to their epidemic appearance in the clinical setting (159, 167). (i) The VanA‐type of resistance is characterised by inducible high‐level resistance to both vancomycin and teicoplanin.…”