Substantially increased faecal carriage of vancomycin-resistant enterococci in a tertiary Greek hospital after a 4 year time interval

JAC Journal of Antimicrobial Chemotherapy (2004) 54, 251–254 DOI: 10.1093/jac/dkh293 Advance Access publication 26 May 2004 Substantially increased faecal carriage of vancomycin-resistant enterococci in a tertiary Greek hospital after a 4 year time interval D. Sofianou1, S. Pournaras2, M. Giosi1, A. Polyzou1, A. N. Maniatis2 and A. Tsakris3* 1 Received 27 February 2004; returned 14 April 2004; revised 19 April 2004; accepted 21 April 2004 Objectives: In a tertiary Greek hospital with no documented vancomycin-resistant enterococci (VRE) infections, a cross-sectional study was conducted in order to determine the degree of VRE faecal carriage among adult patients hospitalized in high-risk units. Methods: Specimens for the surveillance were collected from separate patients in two periods (January –May 1999 and January –May 2003); 258 specimens were submitted during the first period and 149 during the second period. Results: Three patients (1.2%) were colonized with VRE during the first period, whereas 52 (34.9%) were colonized during the second period. Two VRE isolates of the first period were Enterococcus faecalis and one Enterococcus faecium, whereas those of the second period were E. faecium except for three E. faecalis and two Enterococcus gallinarum. All VRE isolates apart from the two E. gallinarum isolates were positive for the vanA gene. The 48 vancomycin-resistant E. faecium were classified into eight clonal types, one of those predominating with 29 isolates; the remaining included one to nine isolates. The five vancomycin-resistant E. faecalis formed four distinct clonal types. Conclusions: The study reports a substantially higher prevalence of VRE carriage when the surveillance was repeated after a 4 year time interval. Urgent infection control measures are needed to prevent emergence of VRE outbreaks in our hospital setting. Keywords: VRE, surveillance, genotyping Introduction In recent years, enterococcal infections have become a major therapeutic challenge because of their increased incidence and the spread of strains that have acquired resistance to several antimicrobial classes. Strains of vancomycin-resistant enterococci (VRE), causing infections or colonizing hospitalized patients, were first detected in Europe in 19861 and in a short period have become common, mainly in the United States.2 The emergence of nosocomial outbreaks due to VRE has raised serious concerns, and in response, recommendations for preventing the spread of VRE have been developed.3,4 Furthermore, in hospitals where VRE have not yet been recovered from clinical infections, periodic culture surveys of stools or rectal swabs of patients at high risk for VRE infection or colonization are indicated.3 In Greek hospitals, unlike others in the United States and Europe, VRE causing clinical infections have only recently been recognized and outbreaks of vancomycin-resistant Enterococcus faecium and Enterococcus faecalis have been reported from hospitals in the region of Athens.5,6 However, no systematic study has been done to estimate the prevalence of VRE colonization in hospitalized patients. In that respect, a cross-sectional survey was conducted in a tertiary Greek hospital with no documented VRE infections, in order to determine the degree of VRE colonization among hospitalized patients. Materials and methods Study design The study was conducted at Hippokration University Hospital, Thessaloniki, Greece. This is the largest tertiary referral hospital in Northern Greece having 1012 beds (51 with acute facilities) and more than 55 000 admissions each year. Specimens for the study .......................................................................................................................................................................................................................................................................................................................................................................................................................... *Corresponding author. Tel: +30-210-7461494; Fax: +30-210-7461489; E-mail: .......................................................................................................................................................................................................................................................................................................................................................................................................................... 251 JAC vol.54 no.1 q The British Society for Antimicrobial Chemotherapy 2004; all rights reserved. Department of Microbiology, Hippokration University Hospital, Thessaloniki; 2Department of Medical Microbiology, University of Thessalia, Larissa; 3Department of Microbiology, Faculty of Nursing, School of Health Sciences, University of Athens, 123 Papadiamantopoulou Street, 11527 Athens, Greece D. Sofianou et al. were collected in two periods. The first period was from January through May 1999 and the second period from January through May 2003. In the study were included adult patients randomly chosen from those hospitalized for more than 48 h and less than 5 days in eight high-risk units (renal, transplant, oncology and intensive care units). Culture and identification Susceptibility testing For all distinct enterococcal isolates that grew on the screening agar supplemented with 6 mg/L of vancomycin, MICs of vancomycin and teicoplanin were determined by an agar dilution method.8 Interpretative criteria for susceptibility status were those of the NCCLS.8 The Vitek system was used in addition to determine susceptibility to a range of antimicrobials (ampicillin, ciprofloxacin, erythromycin, gentamicin, streptomycin and tetracycline). E. faecalis ATCC 29212 was used for quality control. Isolates for which the vancomycin MIC was >4 mg/L were analysed for the presence of the vanA, vanB, vanC1, vanC2 and vanE gene by PCR using primers and conditions that were described previously.7,9 Pulsed-field gel electrophoresis (PFGE) of SmaIdigested genomic DNA was carried out with a contour-clamped homogeneous electric field apparatus (CHEF DRIII apparatus; Bio-Rad Laboratories, Hemel Hempstead, UK) and banding patterns of the strains were compared visually.10 Ten glycopeptidesensitive E. faecium isolates, which were recovered during the study periods, were also chosen at random and used as controls. Results A total of 258 specimens were submitted from separate patients during the first period and a total of 149 specimens during the second period of the surveillance. At least one enterococcal isolate was obtained from 219 (84.9%) patients during the first period and 132 (88.6%) patients in the second period; from 12 patients, two distinct enterococcal isolates were recovered on the basis that they belonged to different species or had different biochemical or antibiotic resistance profiles. Five different species were identified of (...truncated)