Prevalence, Serovar, and Antimicrobial Resistance of Nontyphoidal <i>Salmonella</i> in Vegetable, Fruit, and Water Samples in Ho Chi Minh City, Vietnam

Abstract

In this study, we investigated the prevalence, serovar distribution, and antimicrobial resistance pattern of <i>Salmonella</i> isolates from vegetable, fruit, and water samples in Ho Chi Minh City, Vietnam. <i>Salmonella</i> was detected in 75% (30/40), 57.1% (12/21), 17.5% (28/160), and 2.5% (1/40) of river water, irrigation water, vegetable, and ice water samples, respectively. However, no <i>Salmonella</i> was isolated from 160 fruit and 40 tap water samples examined. A total of 102 isolates obtained from 71 samples belonged to 34 different serovars, of which <i>Salmonella</i> Rissen was the most prevalent, followed by <i>Salmonella</i> London, <i>Salmonella</i> Hvittingfoss, and <i>Salmonella</i> Weltevreden. Certain <i>Salmonella</i> serovars such as Newport, Rissen, and Weltevreden were isolated from both vegetable and water samples. Antimicrobial resistance was most commonly observed against tetracycline (35.3%), followed by chloramphenicol (34.3%), ampicillin (31.4%), trimethoprim/sulfamethoxazole (23.5%), and nalidixic acid (10.8%). Of 102 isolates analyzed, 52 (51%) showed resistance to at least 1 antimicrobial class whereas 27 (26.5%) showed multidrug resistant (MDR) phenotype, being resistant to at least three different classes of antimicrobials. Determination of the presence and type of β-lactamase genes showed the cooccurrence of <i>bla</i>_TEM-1 and <i>bla</i>_CMY-2 in one <i>Salmonella</i> Agona isolate from a river water sample. Taken together, these data indicated that both environmental water and vegetables were contaminated with <i>Salmonella</i>, including MDR strains, and that environmental water used in irrigation might have been the source of <i>Salmonella</i> contamination in the vegetables.