In this study, antibiotic resistance and major
phenol and genotypes of non-
typhoid Salmonella spp. from riversheds in Taiwan were examined. In 236 water samples tested, 54 (22.9%) contained Salmonella spp. Fifteen Salmonella serovars were identified from the Salmonella isolates, and some common serovars are associated with
infections of human and livestock, including Albany (27.8%), Newport (14.8%), Bareilly (13.0%), Derby (11.1%), and Typhimurium (7.4%). Various environmental factors may also affect the presence and proportion of different serovars in the receiving waters. In contrast, serovars with narrower range of hosts, e.g., Dublin, were rarely detected. The Salmonella isolates were subjected to eight
antibiotics for drug resistance, and 51.9% of the samples were resistant to at least one tested
antibiotics.
Tetracycline and
sulfadiazine were the two most ineffective
antibiotics against the Salmonella isolates, and the results were indicative of long-term
antibiotics abuse as fodder supplements in animal husbandry. The more commonly detected serovars such as Albany, Derby, and Typhimurium were also more likely to be resistant to multiple
antibiotics. Finally, a significant correlation was observed between resistance to
chloramphenicol and the resistance gene
cmlA, suggesting that the resistance genotypes could persist in the environment even long after prohibition of the
drug use. The high prevalence of
antibiotic-resistant Salmonella spp. infers elevated
infection risks that must be further examined.