Role of horizontal transfer of the transposon Tn1546 in the nosocomial spread of vanA vancomycin-resistant enterococci at a tertiary care hospital in Korea.
OBJECTIVE
To investigate the epidemiologic characteristics of vancomycin-resistant enterococci (VRE) infection.


METHODS
An epidemiologic description by means of chromosomal DNA fingerprinting and transposon typing.


METHODS
A 2,200-bed tertiary care hospital in Korea.


METHODS
First VRE isolates were obtained from patients hospitalized from April 1997 to December 2001.


METHODS
The van genotypes of isolates were identified by means of multiplex polymerase chain reaction (PCR). The macrorestriction patterns of chromosomal DNA were determined by pulsed-field gel electrophoresis (PFGE). The transposon Tn1546 was typed by means of 2 sets of long PCR restriction fragment-length polymorphism analysis, which were ClaI restriction of a 10.4-kb region from orf1 to vanZ and DdeI restriction of a 4.4-kb region from vanR to vanX.


RESULTS
VRE isolates were recovered from 215 patients. All were vanA genotype. PFGE analysis of the 215 isolates showed 172 types, including 21 clusters composed of 64 isolates and 151 types of as many isolates. Each type was composed of 2-10 isolates; the isolates within each PFGE cluster were detected within a 10-month period and mostly shared a transposon type. Transposon typing classified 169 strains into 15 types and 158 strains belonged to 4 major transposon clusters. Each of these 4 transposon clusters was isolated from patients treated in 5-22 different wards during a 31-52 month period and consisted of 9-80 PFGE types. Each of the other 11 types were found in only one strain.


CONCLUSIONS
Our findings suggest that the horizontal transfer of Tn1546 has a major role in the nosocomial spread of vanA VRE. Clonal spread of VRE seemed to contribute to short-term dissemination in limited areas.
Yoo
Soo Jin
SJ
Department of Laboratory Medicine, University of Ulsan College of Medicine and Asan Medical Center, Seoul, Korea.
Sung
Heungsup
H
Cho
Young-Uk
YU
Kim
Mi-Na
MN
Pai
Chik Hyun
CH
Kim
Yang Soo
YS
D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology*; D016172:DNA Fingerprinting; D004251:DNA Transposable Elements / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D016983:Enterococcus / Q000235:genetics*; D022761:Gene Transfer, Horizontal; D014644:Genetic Variation; D016908:Gram-Positive Bacterial Infections / Q000453:epidemiology / Q000382:microbiology*; D006801:Humans; D007723:Korea; D016133:Polymerase Chain Reaction; D020713:Vancomycin Resistance / Q000235:genetics*
D004251:DNA Transposable Elements