Antimicrobial Resistance in Bacteria from Swiss Veal Calves at Slaughter

Abstract

Bacteria with antimicrobial resistance can be transferred from animals to humans and may compromise antimicrobial treatment in case of infection. To determine the antimicrobial resistance situation in bacteria from Swiss veal calves, faecal samples from 500 randomly selected calves originating from 129 farms were collected at four big slaughterhouses. Samples were cultured for Escherichia coli, Enterococcus sp. and Campylobacter sp. and isolated strains were tested for antimicrobial susceptibility to selected antimicrobial agents by the minimal inhibitory concentration technique using the broth microdilution method. From 100 farms, data on farm management, animal husbandry and antimicrobial treatments of the calves were collected by questionnaire. Risk factors associated with antimicrobial resistance were identified by logistic regression. In total, 467 E. coli, 413 Enterococcus sp. and 202 Campylobacter sp. were isolated. Of those, 68.7%, 98.7% and 67.8%, respectively, were resistant to at least one of the tested antimicrobial agents. Resistance was mainly observed to antimicrobials frequently used in farm animals. Prevalence of resistance to antimicrobials important for human treatment was generally low. However, a rather high number of quinupristin/dalfopristin-resistant Enterococcus faecium and ciprofloxacin-resistant Campylobacter sp. were detected. External calf purchase, large finishing groups, feeding of milk by-products and administration of antimicrobials through feed upon arrival of the animals on the farm significantly increased the risk of antimicrobial resistance at farm level. Participation in a quality assurance programme and injection of a macrolide upon arrival of the animals on the farm had a protective effect. The present study showed that veal calves may serve as a reservoir for resistant bacteria. To ensure food safety, veal calves should be included in the national monitoring programme for antimicrobial resistance in farm animals. By improving farm management and calf husbandry the prevalence of resistance may be reduced.

Use of colistin-containing products within the European Union and European Economic Area (EU/EEA): development of resistance in animals and possible impact on human and animal health

“…A recent review supports that colistin resistance among Enterobacteriaceae from poultry and swine is low in many European countries [54]. In veal calves, the evolution of multidrug resistance is of major concern [98], yet colistin resistance in this production system is extremely low, if not absent [99]. E. coli from broilers are increasingly becoming MDR [100], but colistin resistance reports remain scarce and limited to some broiler meat samples (2.1%; n = 328) [59].…”

Risk factors for antimicrobial resistance in fecal Escherichia coli from preweaned dairy calves

“…Young calves are an exception; they often harbor E. coli resistant to multiple antimicrobials (DeFrancesco et al, 2004;Sato et al, 2005;SVARM, 2006). Resistant isolates of E. coli from calves may therefore be a significant source of resistance genes for other bacteria in the vicinity (Donaldson et al, 2006;Di Labio et al, 2007).…”

Global Epidemiology of Campylobacter Infection

“…For example, in a study by Di Labio and colleagues, investigation of antimicrobial resistance in 202 Campylobacter isolates from Swiss veal calves showed 67.8% of isolates to be resistant to at least one of the agents tested (396). Importantly, resistance mainly corresponded to antimicrobial agents that were utilized in the farming processes.…”