Update on Urinary Tract Infections in Dogs in a Tropical Island and Antimicrobial Susceptibility of Escherichia Coli Isolates for the Period 2010-2016

Abstract

Background: Published information on bacterial urinary tract infection (UTI) in dogs in tropical countries, including the Caribbean is scanty. Monitoring antimicrobial resistance helps in
empirical selection of drugs. The objectives of this study were to examine the diagnostic laboratory records on canine UTI in Grenada for the period of 2009 to 2016, and to identify drugs
which are most likely to be effective.
Methods: Urine samples from 468 dogs suspected of urinary tract infection (UTI) were quantitatively cultured, and the bacterial isolates were identified by phenotypic methods. Antimicrobial susceptibility tests were done using the standard disk diffusion method against 6 or more
drugs.
Results: Of the 150 culture-positive samples, 71.3% were positive for Gram-negative bacterial
UTI, and Escherichia coli (E. coli) were the predominant species. Antimicrobial resistance was
least to enrofloxacin (7.8%) and most to tetracycline (58.7%) when both Gram-negative and
Gram-positive isolates were considered together. With regard to E. coli, none of the 39 isolates
tested were resistant to imipenem, a last-resort drug, but 42% isolates showed resistance to 2
or more classes of drugs, including 2 isolates with multi-resistance to 6 classes of drugs. One
E. coli isolate was resistant to 5 classes of drugs, including resistance to extended spectrum
cephalosporins (ESC), as indicated by resistance to cefotaxime and 4 other cephalosporins.
Conclusions: This study confirms that E. coli is the common bacterial species associated with
UTI in dogs in Grenada, and that resistance is minimal to enrofloxacin when all bacteria are
considered together. However, emerging E. coli with multi-drug resistance to ESC is of concern, and continued monitoring is important for prudent use of antimicrobial drugs, and to detect emerging trends in veterinary medicine, including those of public health significance such
as resistance to ESC, which may be transferred to human pathogens.