IngentaConnect DEVELOPMENT OF ANTIBIOTIC RESISTANCE IN ESCHERICHIA COLI FROM DOG...

Abstract:

Introduction:

Antibiotic resistance develops in human patients in the intensive care unit (ICU) with increased duration of stay. The major selection factor is the use of antimicrobial agents. The hypothesis tested in this study was that antimicrobial resistance in fecal E. coli isolated from dogs increased with increased length of stay in the ICU. Methods:

E. coli were isolated from rectal swabs collected on days 0 (D0, day of admission to the ICU), 3 (D3), 6 (D6), and 9 (D9) from all dogs housed in the ICU for 3 or more days. The E. coli were tested for resistance to nalidixic acid, enrofloxacin, cephalothin, cefoxitin, cefotaxime, ceftiofur, trimethoprim-sulfa, chloramphenicol, gentamicin, tetracycline, ampicillin and amoxicillin/clavulanate. Thirty-two patients were included in the study, 17 with D0-D3 and 15 with D0-D6 E. coli isolates. Five E. coli strains were isolated each sampling day and tested for antimicrobial susceptibility, resulting in a total of 60 outcomes per day per dog. The proportion of positive outcomes (resistance) was calculated for each day up to D6. Univariate ANOVA analysis was used to analyze the data. Results:

The proportion of positive outcomes (resistance) increased from 9.3% on D0 to 14.7% on D3 to 27.9% on D6. Resistance to the frequently used ampicillin increased in a linear manner with increased duration of stay. The proportion of ampicillin-resistant colonies increased from 19.6% on D0 to 39.1% on D3 to 68.7% on D6 (p=0.001). Resistance to the infrequently used amoxicillin/clavulanic acid, also increased significantly (p=0.026) and linearly. The increase in resistance to enrofloxacin was significant (p=0.046); but the increase in resistance to the precursor, nalidixic acid, was highly significant (p=0.020). No change in resistance to gentamicin was found. The remaining antibiotics tested showed an insignificant increase in resistance. Conclusions:

Resistance to antibiotics increased in dogs with duration of stay in the ICU for 3 or more days. This linear trend was most significant with penicillin-based beta-lactams, which are frequently used in the ICU. Consequently, critically ill dogs may be at increased risk for developing opportunistic infections, caused by multi-drug resistant organisms.

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DEVELOPMENT OF ANTIBIOTIC RESISTANCE IN ESCHERICHIA COLI FROM DOGS IN THE INTENSIVE CARE UNIT WITH INCREASED DURATION OF STAY