Fifty-nine isolates of Salmonella enterica subsp. enterica (S. enterica) isolated from indigenous vegetables, ‘selom’ (Oenanthe stolonifera) associated with 13 different serovars were obtained from Chemistry Department of Malaysia. The isolates encompass the common serovar, Salmonella enterica subsp. enterica serovar Weltevreden (S. Weltevreden) (39%) and Salmonella enterica subsp. enterica serovar Agona (S. Agona) (8.5%). Frequencies of the other 11 Salmonella serovars were ranged from 1.7% to 5.1%. All isolates were characterized by Enterobacterial Repetitive Intergenic Consensus-Polymerase Chain Reaction (ERIC-PCR), random amplified polymorphic DNA (RAPD), plasmid profiling and antimicrobial susceptibility testing. The results demonstrated ERIC-PCR, RAPD and composite analysis of both are suitable typing methods for S. enterica by demonstrating good discriminative ability and can be utilize as a rapid approach of comparing S. enterica isolates for epidemiological investigation. From this study, ERIC-PCR is exhibited lower discriminatory power when compare with RAPD. On the other hand, plasmid profiles yielded 32 profiles with molecular size ranging from 1129 bp to 17911 bp. Thirteen antimicrobial agents were included in this study and all isolates showed 100% (59/59) resistant to erythromycin and showed Multiple Antimicrobial Resistance (MAR) indexes ranging from 0.08 to 0.68. Dendrogram generated from antimicrobial resistance profiling exhibited poor discriminatory capability at serovar level. Although poultry still remain as the common reservoir for multidrug resistant (MDR) Salmonella. The isolation of 13 Salmonella serovars from selom that showed high MDR in this study is alarming. These results supported the notion that indigenous vegetable (selom) are gaining more antimicrobial resistance and could be potential health hazards.
Caenorhabditis elegans (C. elegans) have been widely used as an infection model for mammalian related pathogens with promising results. The bacterial factors required for virulence in non-mammalian host C. elegans play a role in mammalian systems. Previous reported that Salmonella found in vegetable and poultry meat could be potential health hazards to human. This study evaluated the pathogenicity of various serovars of Salmonella enterica (S. enterica) that recovered from local indigenous vegetables and poultry meat using C. elegans as a simple host model. Almost all S. enterica isolates were capable of colonizing the intestine of C. elegans, causing a significant reduction in the survival of nematodes. The colonization of Salmonella in C. elegans revealed that the ability of S. enterica in killing C. elegans correlates with its accumulation in the intestine to achieve full pathogenicity. Using this model, the virulence mechanisms of opportunistic pathogenic S. enterica were found to be not only relevant for the interactions of the bacteria with C. elegans but also with mammalian hosts including humans. Hence, C. elegans model could provide valuable insight into preliminary factors from the host that contributes to the environmental bacterial pathogenesis scenario.