title: Ceftiofur susceptibility of Streptococcus equi subsp zooepidemicus isolated from horses in North America between 1989 and 2008.
abstract: In vitro activity of ceftiofur and six other antimicrobial agents was assessed for 516 Streptococcus equi subsp zooepidemicus isolates collected from horses with lower respiratory tract infections in North America in 2007 and 2008 and 239 equine S. equi subsp zooepidemicus isolates received from US and Canadian veterinary diagnostic laboratories between 1989 and 2007. The lowest concentration of ceftiofur inhibiting the growth of 90% of the isolates (MIC90) was 0.12 microg/ml for both groups of isolates. The Clinical and Laboratory Standards Institute susceptible breakpoint set for ceftiofur against this organism is a minimal inhibitory concentration value of ≤ 0.25 microg/ml. The MIC90 values remained consistent for isolates collected over 19 years.
authors.affiliation: Microbial Research Inc., Fort Collins, CO 80524, USA.
authors.forename: Donald
authors.initials: D
authors.lastname: Bade
authors.forename: Gary
authors.initials: G
authors.lastname: Sibert
authors.forename: John
authors.initials: J
authors.lastname: Hallberg
authors.forename: Ellen
authors.initials: E
authors.lastname: Portis
authors.forename: Joseph
authors.initials: J
authors.lastname: Boucher
authors.forename: Lawrence
authors.initials: L
authors.lastname: Bryson
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002511:Cephalosporins / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D006734:Horse Diseases / Q000382:microbiology*; D006736:Horses; D008826:Microbial Sensitivity Tests; D009656:North America / Q000453:epidemiology; D012141:Respiratory Tract Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary; D013290:Streptococcal Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D018502:Streptococcus equi / Q000187:drug effects* / Q000302:isolation & purification*; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D002511:Cephalosporins; C053503:ceftiofur