VanB-vanC1 Enterococcus gallinarum, Italy.

To the Editor: We report detecting a vanB determinant in Enterococcus gallinarum in poultry in Italy. High-level vanA-mediated glycopeptide resistance has been described for E. gallinarum and E. casseliflavus (1-4), and vanB-mediated vancomycin resistance has been frequently described for E. faecalis and E. faecium. However, vanB-mediated resistance in isolates of E. gallinarum has been described only in sporadic nosocomial cases of infection or colonization (5,6).

In January 2005, a study of contamination by foodborne organisms in slaughtered broiler carcasses was conducted in Sicily. To detect glycopeptide-resistant enterococci (GRE), each carcass was placed in a bag with 100 mL sterile buffered peptone water and shaken vigorously for 60 sec. After overnight incubation at 37[degrees]C, 0.5 mL rinsate was added in duplicate to 5 mL ethyl violet azide broth (Oxoid, Basingstoke, United Kingdom) with 4 mg/L vancomycin. Broth cultures were further incubated at 37[degrees]C for 48 h, and 0.1 mL aliquots were spread onto duplicate plates of VRE (commercial denomination product, Oxoid) agar.

A vancomycin-resistant isolate of E. gallinarum was identified in a carcass from a broiler farm in eastern Sicily. The biochemical tests of API 20 Strep (bioMerieux, Marcy l'Etoile, France) and motility test at 30[degrees]C were used to characterize the isolate at the species level. The MICs of vancomycin and teicoplanin were 64 [micro]g/mL and 1 [micro]g/mL, respectively. The isolate was subjected to a multiplex polymerase chain reaction followed by an endonuclease cleavage of amplicons by MspI (Invitrogen, Carlsbad, CA, USA) as previously described (7) to detect van gene determinants; this process demonstrated a simultaneous presence of vanC1 and vanB determinants.

E. gallinarum and the other motile enterococci are thought to infrequently cause infection. However, the recent involvement of vanC1-vanA E. gallinarum in person-to-person spread in a long-term-care facility (8) and in an intensive care unit (2), along with identification of vanC1-vanB isolates in some patients treated with prolonged courses of glycopeptides (5,6), suggests reassessment of their possible pathogenic role.

For the first time, 1 isolate of E. gallinarum has been found harboring the vanB gene in poultry. Our findings confirm that E. gallinarum can capture the genetic determinants of high-level glycopeptide resistance, probably under selective pressure conditions that do not permit survival of a host organism with constitutive low-level resistance (3). Previous studies have demonstrated that E. gallinarum can transfer these determinants to E. faecium by conjugation (2).

The role of food animals as reservoirs of GRE and the causes of their persistently high prevalence in poultry carcasses in some European countries are being investigated (9). Moreover, the public health risk associated with consumer exposure to GRE when handling raw animal foods is poorly understood. In Europe, the food chain is thought to be the major source of GRE since avoparcin was used as a food additive for animals until the European Union ban in 1997. Previous studies in Italy showed that avoparcin withdrawal successfully reduced GRE contamination of poultry meat products (10). However, our finding, 7 years after the European Union ban, highlights that resistance genotypes in motile enterococci should be closely monitored (11).

Caterina Mammina, * Anna Maria Di Noto, ([dagger]) Antonella Costa, ([dagger]) and Antonino Nastasi ([double dagger])

* Universita degli Studi, Palermo, Italy; ([dagger]) Istituto Zooprofilattico Sperimentale della Sicilia, Palermo, Italy; and ([double dagger]) Universita degli Studi, Florence, Italy

References

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(2.) Corso A, Faccone D, Gagetti P, Togneri A, Lopardo H, Melano R, et al. First report of vanA Enterococcus gallinarum dissemination within an intensive care unit in Argentina. Int J Antimicrob Agents. 2005;25:51 6.

(3.) Dutka-Malen S, Blaimont B, Wauters G, Courvalin P. Emergence of high-level resistance to glycopeptides in Enterococcus gallinarum and Enterococcus casseliflavus. Antimicrob Agents Chemother. 1994;38:1675-7.

(4.) Foglia G, Del Grosso M, Vignaroli C, Bagnarelli P, Varaldo PE, Pantosti A, et al. Molecular analysis of Tn1546-like elements mediating high-level vancomycin resistance in Enterococcus gallinarum. J Antimicrob Chemother. 2003;52:772-5. Erratum in: J Antimicrob Chemother. 2003;52:887.

(5.) Liassine N, Frei R, Jan I, Auckenthaler R. Characterization of glycopeptide-resistant enterococci from a Swiss hospital. J Clin Microbiol. 1998;36:1853-8.

(6.) Schooneveldt JM, Marriott RK, Nimmo GR. Detection of a vanB determinant in Enterococcus gallinarum in Australia. J Clin Microbiol. 2000;38:3902.

(7.) Patel R, Uhl JR, Kohner P, Hopkins MK, Cockerill FR. Multiplex PCR detection of vanA, vanB, vanC-1, and vanC-2/3 genes in enterococci. J Clin Microbiol. 1997;35:703 7.

(8). Kapala M, Armstrong-Evans M, Willey BM, Berntson A, Nusinowitz S, Low DE. Clonal dissemination of Enterococcus gallinarum (Egal) in Long Term Care Facility (LTCF). 38th Interscience Conference on Antimicrobial Agents and Chemotherapy. San Diego, California, 1998. Abstract no. 34.

(9.) Borgen K, Sorum M, Wasteson Y, Kruse H. VanA-type vancomycin-resistant enterococci (VRE) remain prevalent in poultry carcasses 3 years after avoparcin was banned. Int J Food Microbiol. 2001;64: 89-94.

(10.) Del Grosso M, Caprioli A, Chinzari P, Fontana MC, Pezzotti G, Manfrin A, et al. Detection and characterization of vancomycin-resistant enterococci in farm animals and raw meat products in Italy. Microb Drug Resist. 2000;6:313-8.

(11.) Toye B, Shymanski J, Bobrowska M, Woods W, Ramotar K. Clinical and epidemiological significance of enterococci intrinsically resistant to vancomycin (possessing the vanC genotype). J Clin Microbiol. 1997;35:3166-70. Erratum in: J Ciin Microbiol. 1998;36:1469.

Address for correspondence: Caterina Mammina, Dipartimento di Igiene e Microbiologia "D'Alessandro," Universita degli Studi, Via del Vespro 133, I-90127 Palermo, Italy; fax: [phone]; email: [e-mail]