Open AccessEscherichia coli ‐associated granulomatous colitis in dogs treated according to antimicrobial susceptibility profiling
Author(s) -
Manchester Alison C.,
Dogan Belgin,
Guo Yongli,
Simpson Kenneth W.
Publication year - 2020
Publication title -
journal of veterinary internal medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.356
H-Index - 103
eISSN - 1939-1676
pISSN - 0891-6640
DOI - 10.1111/jvim.15995
Subject(s) - medicine , escherichia coli , antimicrobial , colitis , antibiotics , microbiology and biotechnology , doxycycline , meropenem , gastroenterology , antibiotic resistance , biology , biochemistry , gene
Background Eradication of intramucosal Escherichia coli correlates with remission of periodic acid‐Schiff‐positive E coli ‐associated granulomatous colitis (GC). Treatment failures attributed to multidrug resistant (MDR) bacteria necessitate alternative approaches. Hypothesis/objectives Determine clinical outcome of E coli ‐associated GC in dogs treated based on antimicrobial susceptibility profiling and characterize E coli phylogeny and resistance mechanisms. Animals Twenty Boxers and 4 French Bulldogs with E coli ‐associated GC. Methods Culture, antimicrobial susceptibility profiling, and molecular characterization of E coli were performed and response to treatment was evaluated. Results Initial biopsy sample culture yielded fluoroquinolone‐sensitive (FQ‐S) E coli from 9/24 dogs and fluoroquinolone‐resistant (FQ‐R) E coli from 15/24. All but 1 FQ‐R E coli were MDR with susceptibility to macrophage‐penetrating antimicrobials restricted to carbapenems in 13/15 dogs. Of 22/24 treated based on susceptibility profiling, 8/9 FQ‐S dogs had complete initial clinical response (CR) during fluoroquinolone (FQ) treatment, whereas 9/13 FQ‐R dogs had complete or partial response (PR) during meropenem or doxycycline treatment. In 5/9 FQ‐S and 12/13 FQ‐R dogs with follow‐up ≥3 months, CR was sustained in 5/5 FQ‐S (median, 25 months; range, 4‐46) whereas 6/12 FQ‐R had long‐term CR (median, 59 months; range 15‐102), 4/12 PR (median, 19 months; range, 5‐65), and 2/12 had no response (NR). Four dogs with long‐term follow‐up died within 4 years of diagnosis, including 2 euthanized for refractory colitis. Escherichia coli were genetically diverse. Fluoroquinolone resistance was associated with mutations in gyrA and parC , with plasmid‐mediated resistance less common. Conclusions and Clinical Importance Antimicrobial treatment guided by susceptibility profiling was associated with positive long‐term outcomes in >80% of cases. Fluoroquinolone‐resistance was widespread and not clonal. Further study is required to optimize treatment for dogs with MDR E coli ‐associated GC.