Annals of Clinical Microbiology, The official Journal of the Korean Society of Clinical Microbiology


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Antimicrobial Resistance and Occurrence of Virulence Factors in Enterococci Isolated from Patients with Bacteremia and Urinary Tract Infection

Original article

Annals of Clinical Microbiology (Ann Clin Microbiol) 2006 December Volume 9, Issue 2, pages 77-83.

Antimicrobial Resistance and Occurrence of Virulence Factors in Enterococci Isolated from Patients with Bacteremia and Urinary Tract Infection

Wee Gyo Lee1, Il Joong Park1, Ji Young Huh2, Eui-Chong Kim2, Kyungwon Lee3, Mi-Na Kim4, Chulhun L. Chang5, Sunjoo Kim6, Young Uh7, Insoo Rheem8, Gyoung Yim Ha9, and Hye Soo Lee10
Department of Laboratory Medicine1, Ajou University School of Medicine, Suwon; Department of Laboratory Medicine2, Seoul National University College of Medicine; Department of Laboratory Medicine3, Yonsei University College of Medicine; Department of Laboratory Medicine4, University of Ulsan College of Medicine, and Asan Medical Center, Seoul; Department of Laboratory Medicine5, Pusan National Uinversity School of Medicine, Busan; Department of Laboratory Medicine6, Gyeongsang University College of Medicine, Jinju; Department of Laboratory Medicine7, Yonsei University Wonju College of Medicine, Wonju; Department of Laboratory Medicine8, Dankook University College of Medicine, Chunan; Department of Laboratory Medicine9, Dongguk University College of Medicine, Gyungju; and Department of Laboratory Medicine10, Chonbuk National University College of Medicine, Chonju, Korea


Background: Enterococci have become increasingly predominant as causative agents of nosocomial infections. Infections due to multi-drug resistant enterococci have drawn increasing attention during the past two decades. The purpose of the present study was to evaluate the occurrence of virulence factors and antimicrobial resistance in enterococci isolated from patients with bacteremia or urinary tract infection. 

Methods: A total of 209 strains of enterococi (102 Enterococcus faecalis and 107 E. facium) isolated during 8 months of 2005 were collected from 10 university hospitals in Korea. Disk diffusion susceptibility tests were performed using Mueller-Hinton agar. The antimicrobial resistance genes and virulence factors were determined using PCR. 

Results: In E. faecalis, the rate of resistance to ciprofloxacin, tetracycline, and quinupristindalfopristin was 27.4%, 83.3%, and 85.2%, respectively; no isolates were resistant to ampicillin, vancomycin, teicoplanin, or linezolid. In E. faecium, the rate of resistance to ampicillin, ciprofloxacin, tetracycline, vancomycin, and teicoplanin was 86.9%, 87.9%, 8.4%, 19.6%, and 6.5%, respectively; no strains were resistant to quinupristin-dalfopristin or linezolid. All the E. faecalis strains tested were found to harbor multiple virulence factors, but E. faecium strains were generally without virulence factors except esp. The prevalence of the esp gene was significantly higher in enterococci isolated from urinary tract infection than in those from bacteremia. 

Conclusion: A similar pattern of resistance to antimicrobial agents and prevalence of virulence factors was observed in both the enterococci isolated from bacteremia and urinary tract infection. Our study indicates that host factors are more likely than bacterial properties to influence the development of bacteremia. (Korean J Clin Microbiol 2006;9(2):77-83)


Enterococci, Virulence factor, Enterococcal surface protein