Acquisition and persistence of antimicrobial-resistant bacteria isolated from dogs and cats admitted to a veterinary teaching hospital.
OBJECTIVE
To assess antimicrobial resistance among bacteria isolated from dogs and cats admitted to a veterinary teaching hospital (VTH), determine the incidence of acquisition of and frequency of persistent colonization by antimicrobial-resistant organisms among these animals, and identify risk factors associated with these variables.


METHODS
Prospective longitudinal study.


METHODS
622 dogs and 92 cats admitted to a VTH and expected to stay ≥ 48 hours.


METHODS
Samples were collected with rectal and nasal or oropharyngeal swabs at admission and discharge. Isolates of enterococci, staphylococci, and Escherichia coli were tested for antimicrobial resistance via microbroth dilution methods. A subset of isolates was analyzed with pulsed-field gel electrophoresis and multilocus sequence typing. Significant trends in proportions of organisms with antimicrobial resistance over the 3-year study period were assessed.


RESULTS
The proportion of staphylococci with antimicrobial resistance increased, whereas the proportion of E coli with resistance decreased, over time; resistance among enterococci was more variable. For 506 dogs with paired admission and discharge samples, multidrug-resistant (MDR) E coli was acquired by 40 (8%) and methicillin-resistant Staphylococcus aureus (MRSA) was acquired by 7 (1.4%); hospitalization for > 3 days was significantly associated with both variables. Most (5/7 isolates) acquired MRSA was of sequence type (ST) 5.


CONCLUSIONS
Extended hospitalization was associated with increased risk of acquiring MDR E coli or MRSA, although few animals acquired MRSA. It is unclear whether associations were confounded by illness severity or use of infection control measures. Additionally, MRSA of ST5, which has been associated with small animal medicine, was the most commonly acquired MRSA in this study.
Center for Comparative Epidemiology, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824.
Elizabeth
E
Hamilton
John M
JM
Kruger
William
W
Schall
Matthew
M
Beal
Shannon D
SD
Manning
John B
JB
Kaneene
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects* / Q000235:genetics; D001424:Bacterial Infections / Q000382:microbiology / Q000662:veterinary*; D002371:Cat Diseases / Q000382:microbiology*; D002415:Cats; D004283:Dog Diseases / Q000382:microbiology*; D004285:Dogs; D024901:Drug Resistance, Multiple, Bacterial; D005260:Female; D006762:Hospitals, Animal / Q000592:standards*; D008297:Male; D010802:Phylogeny
D000900:Anti-Bacterial Agents