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This study aimed at detecting the presence of antibiotic-resistant Gram-negatives in samples of meals delivered at the University General Hospital of Palermo, Italy. Antibiotic resistant Gram negatives were isolated in July—September 2007 ffrom cold dishes and food contact surfaces and utensils. Bacterial strains were submitted to susceptibility test and subtyped by random amplification of polymorphic DNA (RAPD). Forty-six of 55 (83.6%) food samples and 14 of 17 (82.3%) environmental swabs were culture positive for Gram negative bacilli resistant to at least one group of antibacterial drugs. A total of 134 antibiotic resistant strains, 51 fermenters and 83 non-fermenters, were recovered. Fermenters and non-fermenters showed frequencies as high as 97.8% of resistance to two or more groups of antibiotics and non fermenters were 28.9% resistant to more than three groups. Molecular typing detected 34 different profiles among the fermenters and 68 among the non-fermenters. Antibiotic resistance was very common among both fermenters and non-fermenters. However, the wide heterogeneity of RAPD patterns seems to support a prominent role of cross-contamination rather than a clonal expansion of a few resistant isolates. A contribution of commensal Gram negatives colonizing foods to a common bacterial resistance pool should not been overlooked.

Ionizing radiation is widely used as treatment technique for food preservation. It involves among others reduction of microbial contamination, disinfestations, sprout inhibition and extension of shelf life of food. However, the commercialization of irradiated food requires the availability of reliable methods to identify irradiated foodstuffs. In this paper, we present results on the application to irradiated chicken of this method, based on the detection, in muscle and skin samples, of the peaks of ions 98 Da and 112 Da, in a ratio approximately 4:1, typical of radiation induced 2-dodecylcyclobutanones (2-DCB). Aim of the work was also to study the time stability of the measured parameters in samples irradiated at 3 and 5 kGy, and to verify the efficacy of the treatment from a microbiological point of view. Our results show that, one month after irradiation at 3 kGy, the method is suitable using the skin but not the muscle, while the measured parameters are detectable in both samples irradiated at 5 kGy. The microbial population was substantially reduced even at 3 kGy. © 2007 Elsevier Ltd. All rights reserved.

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°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°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°C were used to characterize the isolate at the species level. The MICs of vancomycin and teicoplanin were 64 μg/mL and 1 μg/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).