Of 52 culture positive urine samples from dogs in Grenada for six years (2004 through 2009) 65.5% of isolates were Gram-negative bacteria, with E. coli as the predominant species, followed by Proteus mirabilis, and Pseudomonas aeruginosa. Other Gram-negative isolates included Klebsiella pneumoniae, Acinetobacter anitratus, and Serratia plymuthica. Among the Gram-positive isolates, Staphylococcus intermedius was the most common species, followed by S. aureus, coagulase-negative staphylococci, and enterococci. Sensitivity results obtained with 6 antibiotics showed least resistance to enrofloxacin, the rate being 19% for all isolates together. More than two-thirds of isolates were resistant to tetracycline. For Gram-positive isolates, resistance to cephalothin was even less than that against enrofloxacin, with a rate of only 13%. Overall resistance to amoxicillinclavulanic acid was 36%. The most common drug used for treatment of urinary tract infections in Grenada has been amoxicillin-clavulanic acid, followed by enrofloxacin.

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.