Association between Handling of Pet Treats and Infection with Salmonella enterica Serotype Newport Expressing the AmpC β-Lactamase, CMY-2

Abstract

Resistance to the extended-spectrum cephalosporins can occur in Salmonella species via the production of extended-spectrum and AmpC ␤-lactamases. We describe human infections with Salmonella enterica serotype Newport phage type 14 strains resistant to ceftazidime (CAZ) and cefoxitin (FOX) related to the handling of pet treats containing dried beef. These strains were isolated from five patients in Calgary, Alberta, Canada, during 2002 and were compared to a strain cultured from a commercial pet treat present at the property of one of the patients. The strains were resistant to FOX, CAZ, cefpodoxime, ampicillin, and chloramphenicol; intermediate resistant to ceftriaxone and cefotaxime; and sensitive to the aminoglycosides, ciprofloxacin, cefepime, and imipenem. Isoelectric focusing, multiplex PCR, and sequencing of the amplicons showed that all strains produced the plasmid-encoded AmpC ␤-lactamase, CMY-2. Restriction analysis of plasmid DNA following transformation demonstrated that bla CMY-2 was encoded on an approximately 140-kb plasmid. Pulsed-field gel electrophoresis showed the human and pet treat Salmonella strains to be highly related. This study is the first to implicate the transfer of multidrug-resistant Salmonella species through the handling of commercial pet treats containing animal products. In addition to documenting the first cases of human infection caused by CMY-2-producing S. enterica serotype Newport strains in Canada, this study illustrates the necessity of rapid and accurate laboratory-based surveillance in the identification of novel types of antimicrobial resistance.

Scientific Opinion on the public health risks of bacterial strains producing extended-spectrum β-lactamases and/or AmpC β-lactamases in food and food-producing animals

“…Outbreaks of CMY-2 producers due to clonal expansion of S. Heidelberg caused by imported live animals, meat consumption and unpasteurized dairy products were described in the EU and the US Folster et al, 2009;Zhao et al, 2008). Human infections by S. Newport lineage II comprises most of MDR-AmpC clones of this serotype, which are linked to ST45 (and single locus variant ST116) and associated with consumption of cattle, bovine, and horse meat or pets treats (Espie and Weill, 2003;Harbottle et al, 2006;Pitout et al, 2003;Sangal et al, 2010). In 1984, a strain of S. Newport with resistance to cephalosporins originating in cattle in the USA, was traced through the food chain to humans (Holmberg et al, 1984).…”

Joint Opinion on antimicrobial resistance (AMR) focused on zoonotic infections

“…In relation to human infection and domestic pets, a study in Canada, found an association between handling pet treats containing dried beef and human infection with S. Newport expressing the ampC β-lactamase CMY-2, which confers resistance to third-generation cephalosporins (Pitout, JD et al, 2003). No salmonellas were recovered from stools taken from the pets receiving these treats in affected households; salmonella isolates from affected human patients were highly related to an isolate recovered from one of the commercial pet treats.…”

“…In Australia, ornamental fish tanks have been identified as reservoirs for MDR S. Paratyphi variant Java (= S. Java) (Levings, RS et al, 2006). Although not strictly from pets, in Canada MDR S. Newport associated with pet treats has caused infections in both humans and dogs (Pitout, JD et al, 2003). Although infections with quinolone-resistant Salmonella associated with contact with domestic pets appear to be uncommon, concern has been expressed about the possibility of pet animals acting as reservoirs of antimicrobial-resistant Salmonella, including quinolone-resistant strains, particularly as antimicrobials, including FQs, are used commonly in small animal veterinary practices.…”

Detection of Salmonella spp. from zoo animals in Iran, determination of serovars, antibiotic susceptibility and genotyping by RAPD-PCR

“…Non-typhoidal Salmonella serotypes are transferred to humans through food products of animal origin. Other sources include direct or indirect animal contact at homes, veterinary clinics, pet products, zoological gardens and farm environments (Friedman et al, 1998;Neera et al, 2000;Campbell et al, 2001;Pitout et al, 2003). In addition, transmission of Salmonella between production animals and wildlife is probable (Pitout et al, 2003).…”