title: In vitro bacterial isolate susceptibility to empirically selected antimicrobials in 111 dogs with bacterial pneumonia.
abstract: OBJECTIVE
  To determine the proportion of airway bacterial isolates resistant to both empirically selected and recently administered antimicrobials, and to assess the impact of inappropriate initial empiric antimicrobials selection on length of hospital stay and survival to discharge in dogs with bacterial pneumonia.
  
  
  METHODS
  Retrospective study.
  
  
  METHODS
  University veterinary teaching hospital.
  
  
  METHODS
  One hundred and eleven dogs with a clinical diagnosis of bacterial pneumonia that had aerobic bacterial culture and susceptibility testing performed from a tracheal wash sample.
  
  
  METHODS
  None.
  
  
  RESULTS
  Overall, 26% (29/111) of the dogs had at least 1 bacterial isolate that was resistant to empirically selected antimicrobials. In dogs with a history of antimicrobial administration within the preceding 4 weeks, a high incidence (57.4%, 31/54) of in vitro bacterial resistance to those antimicrobials was found: 64.7% (11/17) in the community-acquired pneumonia group, 55.2% (16/29) in the aspiration pneumonia group, and 50.0% (4/8) in the other causes of bacterial pneumonia group. No statistically significant association was found between bacterial isolate resistance to empirically selected antimicrobials and length of hospital stay or mortality.
  
  
  CONCLUSIONS
  The high proportion of in vitro airway bacterial resistance to empiric antimicrobials would suggest that airway sampling for bacterial culture and susceptibility testing may be helpful in guiding antimicrobial therapy and recently administered antimicrobials should be avoided when empirically selecting antimicrobials. Although no relationship was found between inappropriate initial empiric antimicrobial selection and length of hospital stay or mortality, future prospective studies using standardized airway-sampling techniques, treatment modalities, and stratification of disease severity based on objective values, such as arterial blood gas analysis in all dogs with pneumonia, would be needed to determine if a clinical effect of in vitro bacterial resistance to empirically administered antimicrobials truly exists or not.
authors.affiliation: Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, PA.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Proulx
authors.forename: Daniel Z
authors.initials: DZ
authors.lastname: Hume
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Drobatz
authors.forename: Erica L
authors.initials: EL
authors.lastname: Reineke
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001419:Bacteria / Q000187:drug effects*; D004283:Dog Diseases / Q000188:drug therapy / Q000382:microbiology*; D004285:Dogs; D024881:Drug Resistance, Bacterial; D008826:Microbial Sensitivity Tests; D018410:Pneumonia, Bacterial / Q000188:drug therapy / Q000382:microbiology / Q000662:veterinary*; D012189:Retrospective Studies
chemical_list: D000900:Anti-Bacterial Agents
keywords: antimicrobial resistance; empirical antibiotics; morbidity; therapeutics