Purpose: Examine AMR and characterize environmental strains of V. parahaemolyticus isolated from two British Columbia geographic areas between 1998 and 2011.
Methods: In total, 85 V. parahaemolyticus strains isolated from the Department of Fisheries and Oceans Statistical Area (SA) 13-15 (n=24) and SA 14-08 (n=61) were selected for analysis. AMR phenotypes were determined by disc diffusion assay using a panel of 20 antimicrobial agents. All strains were screened for the presence of toxin genes (tdh, trh) by multiplex PCR.
Results: Of the 85 V. parahaemolyticus isolates analyzed, two (2%) possessed tdh and/or trh. The prevalence of resistance to specific antimicrobials between 2007 and 2011 at SA 13-15 were: ampicillin, 92%; sulfisoxazole, 83%; cephalothin, 17%; and streptomycin, 8%. Compared to isolates collected between 1998 and 2001 (n=12), resistance to streptomycin increased while a decrease was seen for cephalothin and sulfisoxazole. The prevalence of AMR among isolates originating from SA 14-08 between 2008 and 2011 (n=38) are as follows: ampicillin, 100%; sulfisoxazole, 89%; cephalothin, 29%; piperacillin, 5%; streptomycin, 5%; and gentamicin, 3%. Compared to isolates collected between 1998 and 2000 (n=23), increased resistance to ampicillin, piperacillin, streptomycin, and gentamicin were noted while a decrease was observed for cephalothin and sulfisoxazole.
Significance: Although overall levels of AMR were low, isolates resistant to four or more antibiotics were only observed between 2008 and 2011. Reasons for this, however, are not currently understood and further study is required to gain additional insight.