Salmonella Serovars Isolated from Brown Rats (Rattus norvegicus) from Grenada, West Indies: Prevalence and Antimicrobial Susceptibility

Abstract

Aim: The purpose of this study was to estimate the prevalence of Salmonella species and to determine the antimicrobial susceptibility of isolates in brown rats (R. norvegicus) from two parishes (St. George and St David) of Grenada, West Indies. Study Design: Salmonella spp.  was investigated in brown rats from Grenada, West Indies. Place and Duration of Study: Rats were trapped from two parishes: St David and St. George of Grenada, West Indies. Duration of study was from May to July 2017. Methodology: One hundred and seventy rats were trapped from 2 parishes (St. George and St David) of Grenada which have dense human population. The trapping was performed near the human dwellings. After necropsy, intestinal contents were collected and cultured for Salmonella bacteria using enrichment and selective culture techniques. Serotyping of Salmonella isolates was performed at the OIE Salmonella reference laboratory Guelph, Ontario, Canada. Antimicrobial susceptibility of the serovars was tested. Results: Fifteen rats (8.8%) were found positive for Salmonella spp. Five serovars of Salmonella were identified: S. javiana (36.8%); S. panama (26.3%); S. oranienburg and S. montevideo (15.7%) each; and L: Rough (5.2%). S. oranienburg has been isolated for the first time in Grenada. All serovars were found susceptible to 10 antimicrobial drugs; amoxycillin clavulanic acid, ampicillin, Choramphenicol, cephalothin, ciprofloxacin, ceftazidime, acefotaxime, imipenem, gentamycin and neomycin. Resistance of serovars to two antimicrobial drugs (tetracyclin and sulfamethoxazole-trimethaprim) was observed.  Conclusion: All serovars identified in brown rats in Grenada are known pathogens causing serious disease in humans. Presence of Salmonella spp. in rats in a densely human populated area of Grenada may play a role in transmission of Salmonella to humans.