Molecular epidemiology of vancomycin-resistant enterococci in  Singapore.
OBJECTIVE
To characterise the mechanism of glycopeptide resistance, genetic relatedness, and pathogenicity factors in isolates of vancomycin-resistant enterococci (VRE) in Singapore.


METHODS
A total of 292 Enterococcus faecium and 17 Enterococcus faecalis were isolated from humans, and five E. faecium, two Enterococcus durans, two Enterococcus flavescens, one Enterococcus casseliflavus, and one Enterococcus gallinarum from chickens. The mechanism of glycopeptide resistance and pathogenicity factors were studied by PCR and the genetic relatedness determined by pulsed-field gel electrophoresis (PFGE), multi-locus variable number tandem repeat analysis (MLVA), and Tn1546 analysis.


RESULTS
There were five outbreak clones among the vancomycin-resistant E. faecium with one clone predominant. Four of the clones were vanB positive, and only one clone carried vanA. All outbreak clones were esp gene positive. Sporadic human isolates and chicken isolates were vanA positive and did not contain any pathogenicity genes. The situation was reversed in vancomycin-resistant E. faecalis where almost all isolates were vanA positive.


CONCLUSIONS
Most VRE in Singapore is hospital associated with a small number of clones of esp-positive vanB E. faecium responsible for the majority of isolates.
Koh
Tse H
TH
Department of Pathology, Singapore General Hospital, Singapore. koh.tse.hsien@sgh.com.sg
Low
Beng S
BS
Leo
Nicholas
N
Hsu
Li-Yang
LY
Lin
Raymond T P
RT
Krishnan
Prabha
P
Chan
Douglas
D
Nadarajah
Maheswari
M
Toh
Say L
SL
Ong
Keng H
KH
D000818:Animals; D002645:Chickens / Q000382:microbiology; D004196:Disease Outbreaks; D016983:Enterococcus / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D005798:Genes, Bacterial / Q000235:genetics*; D005838:Genotype; D016908:Gram-Positive Bacterial Infections / Q000453:epidemiology* / Q000382:microbiology; D008826:Microbial Sensitivity Tests; D012846:Singapore / Q000453:epidemiology; D014640:Vancomycin / Q000494:pharmacology*; D020713:Vancomycin Resistance / Q000187:drug effects*
D014640:Vancomycin