AAC Accepted Manuscript Posted Online 30 March 2015 Antimicrob. Agents Chemother. doi:10.1128/aac.00513-15 Copyright 2015, American Society for Microbiology. All Rights Reserved. 1 2 Decrease of vancomycin resistance in Enterococcus faecium from bloodstream infections in Italy from 2003 to 2013 3 4 Maria Del Grosso 1 *, Tommi Kärki 2, 3, Fortunato Paolo D Ancona 2, Annalisa Pantosti 1 5 6 7 8 9 1 Department of Infectious, Parasitic and Immune-mediated Diseases; 2 National Centre of Epidemiology, Surveillance and Health Promotion, Istituto Superiore di Sanità, Rome, Italy; 3 European Programme for Intervention Epidemiology Training (EPIET), European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden 10 11 12 13 14 15 Running title: Vancomycin-resistant enterococci in Italy 16 17 *Address correspondence to Maria Del Grosso, maria.delgrosso@iss.it 18
19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 Vancomycin-resistant enterococci (VRE) are multi-drug resistant nosocomial pathogens that emerged in the 1990 s, likely in association with increased use of glycopeptides (vancomycin and teicoplanin) in the clinical setting. In Europe, the emergence of VRE was also ascribed to the use of the glycopeptide avoparcin as a growth-promoter in farm animals. The evidence of an animal reservoir of VRE induced the EU Commission to ban the use of avoparcin in 1997 (1); this measure led to a rapid decrease of VRE in animals and food of animal origin (2, 3). In 2011 less than 1% of the enterococci isolated in the EU from broilers or pigs were VRE (4). Here we report the decreasing trend of VRE in bloodstream infections in Italy between 2003 and 2013. Data about VRE were collected through the project AR-ISS, a sentinel surveillance of antibiotic resistance (http://www.simi.iss.it/antibiotico_resistenza.htm) that provides Italian data to the European Surveillance of Antibiotic Resistance EARS-Net (5). In addition, laboratories send VRE isolates, on a voluntary basis, to the national reference laboratory for molecular characterization (6). Between 2003 and 2013, 8601 Enterococcus spp. blood isolates were reported to AR-ISS. Of these, 62.6% (5384/8601) were Enterococcus faecalis and 37.4% (3217/8601) were Enterococcus faecium. The proportion of VR-E faecium was 24.1% in 2003, decreased steadily in the subsequent years to reach 4.3% in 2009, and remained between 4 and 6% until 2013. The proportion of VR-E. faecalis was 1.5% in 2003, and over the years remained stable ranging between 1.3% and 3.5% (Figure 1). The decreasing trend of VR-E. faecium was confirmed analyzing the 20 laboratories that participated in the surveillance throughout the whole period: the proportion decreased from 22.0% (24/109) in 2003 to 4.5% (8/179) in 2013. The molecular characterization of 69 VR-E. faecium showed that vana was the most common vancomycin resistant determinant throughout the years, with only 14% of the isolates carrying vanb. By Pulsed Field Gel Electrophoresis, the majority of the isolates examined (36/54, 66.7%) appeared related (7). On the basis of Multi Locus Sequence Typing (http://www.mlst.net/), this group of isolates, all resistant to ampicillin, included genetic lineages (ST78 and ST202 obtained in 2006, and ST17 obtained in 2012) that are constituents of the so-called
45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 Clonal Complex 17 (http://eburst.mlst.net), an E. faecium subpopulation successfully adapted to the hospital environment (8) and already circulating in Italy (6). The decrease of vancomycin resistance in E. faecium is in contrast with the stability of aminopenicillin resistance (from 80% in 2003 to 82% in 2013) and high-level gentamicin resistance (from 44% in 2003 to 59% in 2013) observed in Italy over the same time span (5), and with the increasing trend of antibiotic resistance in other bacterial species under surveillance (5). Although no data on antibiotic consumption in hospitals are available before 2011, it is unlikely that the decrease of VRE in Italy is attributable to a decreased use of glycopeptides. It is possible that we are witnessing the late indirect effect of avoparcin withdrawal in farm animals that has led to a decreased circulation of VRE in animals (4) and in food of animal origin in European countries including Italy (9). The decreased colonization in animals is potentially associated to a decreased colonization of healthy people and to a decreased number of VRE infections. Although we cannot rule out that other factors might have contributed to this decrease, we suggest that both clinical and veterinary antibiotic use are drivers of vancomycin resistance, and therefore policies of prudent antibiotic use should be applied to both areas. 60 61 62 63 64 65 Acknowledgements The authors wish to thank the collaborators of the Italian laboratories participating in the Italian antibiotic resistance surveillance project AR-ISS. This work was partially supported by the Italian Ministry of Health (CCM). 66 67 68 69 70 References 1. EuropeanCommission Press-Release-ip/97/71. 1997. Ban on the antibiotic "Avoparcin" in animal feed. http://europa.eu/rapid/press-release_ip-97-71_en.htm.
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95 96 97 9. Pesavento G, Calonico C, Ducci B, Magnanini A, Lo Nostro A. 2014. Prevalence and antibiotic resistance of Enterococcus spp. isolated from retail cheese, ready-to-eat salads, ham, and raw meat. Food Microbiol 41:1-7. 98 99
100 Figure Legend 101 102 Figure 1. Trends of VR-E. faecalis and VR-E. faecium in years 2003-2013 in Italy. 103 104 105 106 107 % VRE 30 25 20 E. faecalis E. faecium 15 10 5 108 109 0 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 Figure 1