Investigation into infectability and antimicrobial susceptibility of Salmonella spp. isolated from fresh seafood at traditional markets in Ho Chi Minh city

Abstract

In this study, a total of 380 fresh seafood samples (fish, shrimp, squid) were collected randomly at conventional markets of districts in Ho Chi Minh city. Salmonella strains were detected by the traditional method (ISO 6579-1:2017) and conformed by PCR technique (TCVN 8342:2010), serotyping according to ISO/TR 6579-3:2014 and Kirby-Bauer methods evaluated antibiotic resistance's ability. As a result, 85 Salmonella strains were isolated, and the proportion of infection was 22,37% (85/380). The proportion of Salmonella strains that resisted 01 antibiotics was 85,88% (73/85), and 10,59% (09/85) accounted for that of strains that resisted 02 to 05 antibiotics. Also, strains representing resistance towards 06 to 11 antibiotics occupied 4,71% (04/85). Antimicrobial drugs resisted the most were tetracycline 43, 53% (37/85). In contrast, 98,82% (84/85) of Salmonella strains were sensitive to ceftazidime. The proportion of multi-drug resistance was 15,29% (13/85). The familiar combinations of antibiotic resistance were ampicillin, streptomycin, tetracycline, and trimethoprim/sulfamethoxazole (AM, STR, TE, SXT), with 46,15% (6/13). There were six distinguished serovars, including S. Kentucky (05 strains); S. Infantis (02 strains); S. Agona and S. Postdam (01 strain); S. Saintpaul, S. Braenderup (01 strain). 92.31% of serovar detected resistance genes (blaTEM, strA: 53.85%; blaSHV: 7.69%; tetA: 92.31%; tetB: 7.69% and sul1: 23.08%). Three serovars with genotype (blaTEM, strA, tetA, sul1) matched the antibiotic resistance phenotype (AM, STR, TE, SXT), namely S. Kentucky (02) and S. Saintpaul (01), the both isolated from fish samples.