Intestinal Colonization of Vancomycin-Resistant Enterococci

Jeong, Seok Hoon; Lee, Duk Hee; Jeong, Tae Jeon; Jung, Jeong Hae; Kim, Mi Hyang; Koo, Ja Young; Park, Seon Ja

Abstract

BACKGROUND
In the United States, the Centers for Disease Control and Prevention recorded a 20-fold increase in the incidence of vancomycin-resistant enterococci (VRE) associated with nosocomial infections between 1989 and 1991. Although VRE has been reported in Korea since 1992, infections caused by these organisms are still extremely rare in Pusan, Korea. Therefore, a point prevalence culture survey was carried out to investigate the prevalence of intestinal colonization with VRE among patients admitted to Kosin Medical Center, which can predict the appearance of clinical infections with VRE.
METHODS
Between July 1997 and August 1997, stool specimens were obtained from 303 patients. Specimens were placed in bile esculin azide broth containing vancomycin (64 microgram/mL) and aatreonam (60 microgram/mL). Cultures were done for 48 hours at 37degrees C, and turbid solutions were subcultured on blood agar. Minimal inhibitory concentrations (MIC) of vancomycin and teicoplanin to Enterococcus isolates were determined by Etest on Mueller-Hinton agar. For amplification of the vanA, vanB, and vanC genes, polymerase chain reactions were performed.
RESULTS
VRE isolates were isolated from 6 of the patients (2%). Four of them were identified as E. faecium, and 1 was identified as E. avium, and 1 was identified as Enterococcus spp. All of them were highly resistant to vancomycin (MICs >256 microgram/mL), and they were also resistant to teicoplanin (MICs 32-->256 microgram/mL). All of 6 VRE strains carried vanA gene.
CONCLUSION
The colonization of VRE was not infrequent among the patients of a university hospital in Pusan, Korea. Moreover, a large proportion of the colonizing VRE was revealed Enterococcus faecium with vanA gene, which implies quite a possibility of a sudden rising of infections by this organism in the near future. So we propose that the vancomycin susceptibility test should be done for every enterococcal isolate from clinical specimens and the intestinal colonization rate of VRE should be closely monitored at regular intervals for the purpose of surveillance 50 that proper establishment of plans for the prevention of this troublesome pathogen's spread can be promptly made.