Successful Treatment of 3 Dogs With Fluoroquinolone-Resistant Escherichia coli Associated Granulomatous Colitis.

Successful resolution of Escherichia coli associated granulomatous colitis (ECGC) is becoming a challenge due to the development of fluoroquinolone resistant E coli, which is associated with poor prognosis. Three dogs presented with signs of chronic colitis and were diagnosed with ECGC. All 3 were initially treated with enrofloxacin and trimethoprim-sulfamethoxazole, without clinical improvement. Despite the fact that culture and susceptibility testing results demonstrate resistance to fluoroquinolone and trimethoprim-sulfamethoxazole, the addition of amikacin fully resolved the clinical signs in all 3 cases. This case series describes the clinical presentation, diagnostic findings, and successful treatment of 3 dogs with fluoroquinolone-resistant ECGC. It suggests an alternative strategy for multidrug-resistance ECGC patients. Further investigations are required to confirm the efficacy of and to determine the molecular mechanisms underpinning the apparent success of aminoglycoside antibiotic combinations for treatment of ECGC.