Antimicrobial resistance in salmonella enterica isolated from dogs and cats in northern and northeastern Thailand

Abstract

Antimicrobial resistance (AMR) is One Health issue involved in humans, animals and environment and a unified One Health approach is required to contain this problematic issue. However, data on AMR in companion animals is limited. Dogs and cats are popular pet animals and are known to carry many bacterial pathogens that are of public health importance, including Salmonella. This study aimed to identify serovars of Salmonella and phenotypically and genetically characterize AMR in Salmonella isolated from dogs and cats in Northern and Northeastern Thailand. A total of 178 S. enterica isolates from dogs (n= 159) and cats (n= 19) collected between 2015 – 2018 were included. Seventy-seven serovars were identified, of which serovars Weltevreden (9.6%), Stockholm (9.0%), and Typhimurium (7.3%) were most common. The majority of the isolates (34.3%) were multidrug resistant. Only one ESBL-producing isolate (i.e., serovar Stockholm) was identified and the isolate carried blaTEM-1 and blaCTX-M55. Of all plasmid-mediated quinolone resistance genes tested, only qnrS (10.1%) was detected. Plasmid replicon types found were IncA/C (0.6%), N (1.1%) IncFIIA (28.7%), IncHI1 (2.2%), and IncI1 (3.4%). IncFIIA was most prevalent (51 isolates, 28.7%). Based on the pMLST typing scheme, the plasmids were assigned to 5 different STs including IncA/C-ST6, IncH1-ST16, IncI1-ST60, IncI1-ST101, and IncI1-ST136, of which ST 16, of IncHI1 plasmid was the novel plasmid STs. Subtyping F-type plasmids using the RST scheme revealed 4 different combinations of replicons including S1:A-:B- (n=4), S1:A-:B22 (n=2), S3:A-:B- (n=1), and S-:A-:B47 (n=1). The findings highlight the role of household dogs and cats as carriers of AMR Salmonella enterica strains with R plasmid and AMR determinants. These Salmonella strains may spread to humans and environment and promote the wide distribution of AMR.