Objective—To assess the prevalence and patterns of
antimicrobial resistance among Escherichia coli
strains isolated from the urine of women with cystitis
or pyelonephritis and from fecal samples from dogs
and healthy humans.
Sample Population—Escherichia coli isolates from
82 women with cystitis, 170 women with pyelonephritis,
45 dogs, and 76 healthy human volunteers.
Procedure—Susceptibility to 12 antimicrobial agents
was determined by means of disk diffusion testing as
specified by the NCCLS.
Results—Overall, the 4 most common antimicrobial
resistance patterns were resistance to ampicillin, sulfisoxazole,
trimethoprim, and trimethoprim-sulfamethoxazole
(n = 45 [12% of all isolates]); ampicillin
alone (33 [9%]); ampicillin and sulfisoxazole (29 [8%]);
and sulfisoxazole alone (14 [4%]). None of the isolates
were resistant to ceftazidime, ciprofloxacin, nitrofurantoin,
or piperacillin-tazobactam. Resistance was
significantly more common and extensive among isolates
from women with cystitis or pyelonephritis than
among isolates from healthy humans or dogs.
Resistance was least common among isolates from
dogs. The only resistance phenotype that was more
common among canine isolates than human isolates
was resistance to sulfisoxazole alone.
Conclusions and Clinical Relevance—Results suggest
that dogs are unlikely to be an important external reservoir
of antimicrobial-resistant E coli strains causing infections
in humans. On the contrary, the data suggest that dogs
conceivably could acquire resistant E coli strains from
humans. ( J Am Vet Med Assoc 2004;225:368–373)