The role of veterinary medicine in the development of antimicrobial resistance has been highly debated over the past decade; however, specific information on the current situation in small companion animals is scarce (Prescott et al. 2002). Veterinary medical laboratories have access to an extensive amount of patient data. As bacterial urinary tract infection is a common infectious disease in canine practice (Bartges 2004), we retrospectively reviewed bacterial culture results of canine urine samples over a 3-year period. Results were obtained from 7437 urine samples submitted between January 2010 and December 2012 to AML-Medvet laboratory (Antwerp, Belgium) for culture and susceptibility testing, according to CLSI standards (except for cephalexin, where EUCAST 3.0 guidelines were applied); 20.2% demonstrated a positive result (>10,000 CFU/mL), with Escherichia coli, Proteus mirabilis, Enterococcus species and Staphylococcus (pseud)intermedius being the most commonly isolated pathogens. These findings correspond to published data (Cohn et al. 2003, Ball et al. 2008). There was good overall in vitro susceptibility to amoxicillin-clavulanic acid and cephalexin, two frequently prescribed antimicrobial drugs in dogs (Wayne et al. 2011) (Table 1). Amoxicillin is generally accepted as empirical treatment; nevertheless the present data show that there are a significant number of amoxicillin-resistant strains, emphasizing the importance of bacterial culture and susceptibility testing.

Table 1. Susceptibility of the most frequently isolated bacteria from canine urine samples (2010 to 2012)
Bacteria isolated from urine% of totala (n=7437)% urine WBC count >22/μL% urine WBC count ≤22/μL% urine WBC count unknownSusceptibilityc
  1. a

    AMP Ampicillin, AMC Amoxicillin-clavulanic acid, LEX Cephalexin, ENR Enrofloxacin, MAR Marbofloxacin, TE Tetracycline, SXT Trimethoprim-sulphamethoxazole

  2. b

    % occurrence of named bacterial pathogens. Totals do not equal 100; less common species are not included

  3. c

    % of pathogens susceptible to drugs in vitro (according to CLSI standards)

Escherichia coli63·665·518·016·571·088·092·083·487·581·084·3
Proteus mirabilis16·359·025·515·566·795·592·977·084·561·7
Enterococcus species6·653·533·612·992·692·658·640·236·2
Staphylococcus (pseud)intermedius3·472·010·018·096·194·098·030·092·2


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