Absence of carriage of glycopeptide-resistant enterococci by at-risk hospitalised patients in Malta

Abstract

In a recent article in Clinical Microbiology and Infection, Cordeiro et al. [1Cordeiro JCR Silbert S Reis AO Sader HS Inter-hospital dissemination of glycopeptide-resistant Enterococcus faecalis in Brazil.Clin Microbiol Infect. 2004; 10: 260-262Abstract Full Text Full Text PDF PubMed Scopus (15) Google Scholar] described the interhospital dissemination of glycopeptide-resistant enterococci (GRE) in Brazil. These organisms are isolated mainly from patients in intensive care, transplant and oncology units, and this has been attributed particularly to the use of combination antimicrobial therapy involving vancomycin and anti-anaerobe agents, coupled with prolonged hospitalisation [2Donskey CJ Chowdhry TK Hecker MT et al.Effect of antibiotic therapy on the density of vancomycin resistant enterococci in the stool of colonised patients.N Engl J Med. 2000; 343: 1925-1932Crossref PubMed Scopus (532) Google Scholar, 3Rao GG Ojo F Kolokithas D Vancomycin-resistant grampositive cocci: risk factors for faecal carriage.J Hosp Infect. 1997; 35: 63-69Abstract Full Text PDF PubMed Scopus (41) Google Scholar]. GRE have a major impact on the management of patients and wards [4Hospital Infection Control Practices Advisory Committee.Recommendation for preventing the spread of vancomycin resistance.Infect Control Hosp Epidemiol. 1995; 16: 105-113Crossref PubMed Scopus (523) Google Scholar], and gastrointestinal colonisation with GRE is difficult to eradicate once it is established [5Chia JKS Nakata MM Park SS Lewis RP McKee B Use of bacitracin therapy for infection due to vancomycin-resistant Enterococcus faecium.Clin Infect Dis. 1995; 21: 1520Crossref PubMed Scopus (47) Google Scholar, 6Whitman MS Pitsakis PG DeJesus E Osborne AJ Levison ME Johnson CC Gastrointestinal tract colonisation with vancomycin-resistant Enterococcus faecium in an animal model.Antimicrob Agents Chemother. 1996; 40: 1526-1530PubMed Google Scholar]. There have been no previous reports of GRE in Malta, which is an island in the Mediterranean with a population of 450 000. This contrasts with other countries in the region, where the prevalence of GRE in blood culture isolates has been reported to reach 2% [7AnonymousEuropean Antimicrobial Resistance Surveillance System Newsletter. National Institute of Public Health and the Environment, Bilthoven, The Netherlands2002Google Scholar]. Glycopeptide use (predominantly teicoplanin) in Malta is common because of the high prevalence of methicillin-resistant Staphylococcus aureus infections in St Luke's Hospital, which is the only tertiary care hospital (with 900 beds, including a 13-bed intensive care unit) on the island. In order to establish whether the at-risk population in this hospital harboured GRE, a 4-month screening programme, concentrating on the intensive care unit, was performed in June to September 2002. In total, 310 rectal swabs were taken from 300 patients and inoculated into VRE broth (Oxoid, Basingstoke, UK) supplemented with meropenem (Oxoid) 1 mg/mL and colistin sulphate (Pharmax, Bexley, UK) 7.5 mg/L (to suppress the growth of meropenem-resistant Pseudomonas aeruginosa). Control experiments demonstrated that this broth supported the growth of the standard strains Enterococcus faecalis NCTC 12201 (vanA+), E. faecalis ATCC 33186 (glycopeptide-susceptible) and Enterococcus faecium ATCC 51559 (vanA+). Following incubation at 37°C for 16 h, the broths were streaked on to VRE agar (Oxoid) supplemented with meropenem 0.5 mg/L and vancomycin (Oxoid) 6 mg/L. Following incubation at 37°C for 24-48 h, putative enterococci were identified to the species level with the API STREP system (bioMérieux, Marcy l'Etoile, France), and susceptibilities to vancomycin and teicoplanin were determined with Etests (AB Biodisk, Solna, Sweden). Only one isolate of GRE was recovered during the 4-month screening period. This isolate was identified as E. faecium (vancomycin MIC >32 mg/L; teicoplanin MIC 32 mg/L) and was shown by PCR to carry the vanA gene. The patient was a poultry farm worker and was screened on the first day following admission to the intensive care unit. The patient was not receiving any antimicrobial therapy and had no previous history of prolonged hospitalisation. Interestingly, the presence of GRE in Europe has been linked to the use of avoparcin in animal husbandry [8Bonten JM Willems R Weinstein RA Vancomycin-resistant enterococci: why are they here, and where do they come from?.Lancet Infect Dis. 2001; 1: 314-325Abstract Full Text Full Text PDF PubMed Scopus (318) Google Scholar]. Avoparcin was used in poultry farms in Malta until August 1999, when its importation was banned, but residual stocks may well remain at some farms. GRE are now found worldwide, but these results confirmed that the prevalence of GRE within St Luke's Hospital remains negligible. Since St Luke's is the only tertiary hospital on the island, it seems that the prevalence of GRE in Malta is considerably lower than that reported in many other European countries. We gratefully acknowledge the assistance of the staff of the Infection Control and Health Information Units, and financial support from the Malta Health Division.