Vancomycin-resistant Enterococcus faecalis in Serbia.

To the Editor: First isolated in France (1), vancomycin-resistant enterococci (VRE) have become pathogens of major importance, particularly in the United States (2). Infections due to VRE are still uncommon in most European countries (3). We report the first isolation of high-level vancomycin-resistant Enterococcus faecalis in Serbia.

A 55-year-old woman was admitted to the Clinic for Cardiovascular Diseases, Belgrade, on April 1, 2002, for aortobifemoral bypass surgery. Three weeks after she was admitted to the hospital, an infection developed in the surgical wound and treatment with trimethoprim-sulfamethoxazole (160/800 mg q 12 h) was empirically introduced. Bacteriologic analysis of the wound swab sample showed a methicillin-resistant strain of Staphylococcus aureus, a multiresistant strain of Acinetobacter sp., a commonly susceptible strain of Enterococcus sp., and a VRE strain. According to the results of susceptibility testing, imipenem (1 g q 6 h) was added to the patient's treatment protocol. VRE were not isolated from subsequent wound samples or ally other sample submitted for microbiologic analysis. The patient was discharged at the end of the 14-day treatment period.

The isolate was identified as E. faecalis by biochemical characterization, as recommended by Facklam and Collins (4) and confirmed by API 20 Strep (bioMerieux, Marcy-l'Etoile, France). Susceptibility testing, performed by the disk diffusion method, showed that the isolate was resistant to vancomycin, teicoplanin, gentamicin, streptomycin, tetracycline, and ciprofloxacin, while susceptible to ampicillin, amoxicillin, amoxicillin and clavulanic acid, and imipenem. Resistance to vancomycin, teicoplanin, gentamicin, and streptomycin was confirmed by the broth dilution method, according to the National Committee for Clinical Laboratory Standards (NCCLS) recommendations (5). The obtained MICs were 256 [micro]g/mL for vancomycin, 64 [micro]g/mL for teicoplanin, >4,000 [micro]g/mL for gentamicin, and >2,000 [micro]g/mL for streptomycin. This phenotype, with high-level resistance to vancomycin and teicoplanin, is typical for the vanA genotype (2). The strain was subsequently genotyped by pulsed-field gel electrophoresis, using previously described methods (6). The presence of the vanA gene was confirmed by polymerase chain reaction assay, according to a previously described procedure (7). E. faecium EF228 was used as the positive control.

The enterococci are among the most frequent causes of nosocomial infections, particularly in intensive care units, and present a major therapeutic challenge (2). While the emergence of VRE strains in the United States is probably associated with extensive use of vancomycin, the occurrence of VRE in Europe is possibly due to application of avoparcin (glycopeptide analog) as a growth promoter in animal husbandry (3). However, avoparcin has not been used in Serbia, and vancomycin application has been restricted to hospitalized patients and quite limited due to its high cost. Thus, emergence of VRE strains in Serbia has not been likely.

The origin of this VRE isolate is unknown: the strain may have been imported or may have originated from the hospital environment. The first prospective pan-European VRE surveillance study (January-April 1997) showed VanA-VRE strains in only eight European countries, with isolates numbering from one to four per country (3). No epidemiologic relations were established among the VanA isolates, and only 2 out of 18 isolates (11%) were identified as E. faecalis (3). Since our patient-ease had no history of travel outside Serbia, we assumed that the VRE isolate originated from the hospital environment. However, a study investigating the occurrence of VRE strains in Belgrade, the capital of Serbia, detected no such isolates in five different hospitals (8). Although the study did not analyze samples from the Clinic for Cardiovascular Diseases, it did include samples from the Clinic for General Surgery, which is located within the same building. The susceptibility of 191 isolates of enterococci to vancomycin was tested by agar dilution method according to NCCLS recommendations. Of the 191 isolates, 159 were classified as susceptible and 32 as intermediately susceptible.

This report of the first isolation of VRE in Serbia, as well as the previously shown presence of enterococci displaying intermediary susceptibility to vancomycin, provides the rationale for future active screening for VRE in hospital environments in the region.

References

(1.) Leclercq R, Derlot E, Duval J, Courvalin P. Plasmid-mediated resistance to vancomycin and teicoplanin in Enterococcus faecium. N Engl J Med 1988;319:157-61.

(2.) Cetinkaya Y, Falk P, Mayhall CG. Vancomycin-resistant enterococci. Clin Microbiol Rev 2000;13:686-707.

(3.) Schouten MA, Hoogkamp-Korstanje JA, Meis JF, Voss A. Prevalence of vancomycin-resistant enterococci in Europe. Eur J Clin Microbiol Infect Dis 2000;19:816-22.

(4.) Facklam RR, Collins MD. Identification of Enterococcus species isolated from human infections by a conventional test scheme. J Clin Microbiol 1989;27:731-4.

(5.) National Committee for Clinical Laboratory Standards. Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically. Approved standard M7-A4. Wayne (PA): National Committee for Clinical Laboratory Standards; 1997.

(6.) Donabedian S, Chow JW, Shlaes DM, Green M, Zervos MJ. DNA hybridization and contour-clamped homogeneous electric field electrophoresis for identification of enterococci to the species level. J Clin Microbiol 1995;33:141-5.

(7.) Clark NC, Cooksey RC, Hill BC, Swenson JM, Tenover FC. Characterization of glycopeptide-resistant enterococci from U.S. hospitals. Antimicrob Agents Chemother 1993;37:2311-7.

(8.) Dakic I, Vukovic D, Stepanovic S, Kalezic I, Svabic-Vlahovic M. Enterococci isolated in Belgrade hospitals: the resistance to vancomycin. In: Abstract book of the 9th International Congress on Infectious Diseases, Buenos Aires, Argentina, 2000 April 10-13; p. 213.

Branka Stosovic, * Srdjan Stepanovic, ([dagger]) Susan Donabedian, ([double dagger]) Tanja Tosic, * and Milica Jovanovic *

* Institute of Infectious and Tropical Diseases "Dr Kosta Todorovic," Belgrade, Serbia; ([dagger]) University of Belgrade School of Medicine, Belgrade, Serbia; and ([double dagger]) William Beaumont Hospital, Royal Oak, Michigan, USA

Address for correspondence: Srdjan Stepanovic, Institute of Microbiology and Immunology, University of Belgrade School of Medicine, Dr Subotica 1, 11000 Belgrade, Serbia; fax: [phone]; email: stepan@ afrodita.rcub.bg.ac.yu