title: Antimicrobial susceptibility monitoring of mastitis pathogens isolated from acute cases of clinical mastitis in dairy cows across Europe: VetPath results.
abstract: VetPath is an ongoing pan-European antimicrobial susceptibility monitoring programme collecting pathogens from diseased cattle, pigs and poultry not recently treated with antibiotics. Non-replicate milk samples were collected from cows with acute clinical mastitis in eight countries. Escherichia coli, Staphylococcus aureus and Streptococcus uberis were isolated by standardised methods. Antimicrobial susceptibility was determined in a central laboratory by CLSI broth microdilution methodology; results were interpreted using clinical breakpoints where available. Among E. coli (n=280), resistance to tetracycline (14.3%) and cefapirin (11.1%) were most common. Resistance to other β-lactam antibiotics was absent (ceftiofur) or very low (cefalexin, amoxicillin/clavulanic acid). The MIC90 of enrofloxacin and marbofloxacin was 0.03 and 0.06μg/mL, respectively, with 0.7% of strains displaying a deviating high MIC. Staphylococcus aureus (n=250) were susceptible to most antibiotics tested, although 36.0% were resistant to penicillin G. For other β-lactam antibiotics where a CLSI breakpoint was available, no resistance was detected. Tetracycline resistance was low (5.2%). Streptococcus uberis (n=282) were susceptible to all β-lactam antibiotics, although 29.8% were intermediately susceptible to penicillin G; 18.8% of strains were resistant to erythromycin and 28.7% to tetracycline. This European study shows that bacteria associated with acute clinical mastitis are susceptible to most antibiotics with the exception of penicillin G against S. aureus, and erythromycin and tetracycline against S. uberis. The results of this study should serve as a reference baseline. This work also highlights the urgent need to set additional clinical breakpoints for antibiotics frequently used to treat mastitis.
authors.affiliation: VetPath Study Group, c/o CEESA, 1 Rue Defacqz, Brussels, Belgium; MSD Animal Health, Schwabenheim, Germany.
authors.forename: Valérie
authors.initials: V
authors.lastname: Thomas
authors.affiliation: VetPath Study Group, c/o CEESA, 1 Rue Defacqz, Brussels, Belgium; Bayer HealthCare AG, Animal Health GmbH, Leverkusen, Germany. Electronic address: anno.jong@bayer.com.
authors.forename: Anno
authors.initials: A
authors.lastname: de Jong
authors.affiliation: VetPath Study Group, c/o CEESA, 1 Rue Defacqz, Brussels, Belgium; Zoetis, Zaventem, Belgium.
authors.forename: Hilde
authors.initials: H
authors.lastname: Moyaert
authors.affiliation: VetPath Study Group, c/o CEESA, 1 Rue Defacqz, Brussels, Belgium; Elanco Animal Health, Basingstoke, UK.
authors.forename: Shabbir
authors.initials: S
authors.lastname: Simjee
authors.affiliation: VetPath Study Group, c/o CEESA, 1 Rue Defacqz, Brussels, Belgium; Vétoquinol S.A., Lure, France.
authors.forename: Farid
authors.initials: F
authors.lastname: El Garch
authors.affiliation: LGC, Fordham, UK.
authors.forename: Ian
authors.initials: I
authors.lastname: Morrissey
authors.affiliation: VetPath Study Group, c/o CEESA, 1 Rue Defacqz, Brussels, Belgium; European Animal Health Study Centre (CEESA), Brussels, Belgium.
authors.forename: Hervé
authors.initials: H
authors.lastname: Marion
authors.affiliation: VetPath Study Group, c/o CEESA, 1 Rue Defacqz, Brussels, Belgium; AM Consultant, Saint-Bénigne, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Vallé
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects* / Q000302:isolation & purification*; D002417:Cattle; D062665:Epidemiological Monitoring; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D005060:Europe / Q000453:epidemiology; D008414:Mastitis, Bovine / Q000453:epidemiology / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D013290:Streptococcal Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*
chemical_list: D000900:Anti-Bacterial Agents
keywords: Antimicrobial resistance; Cattle; Minimum inhibitory concentration; Surveillance