Antibiotic resistance and associated resistance determinants in different Salmonella enterica serovars isolated from pigs in Argentina

Abstract

Background and Aim: Salmonellosis is one of the most common foodborne diseases in the world, and the increasing antibiotic resistance in Salmonella enterica subsp. enterica recovered from food animals constitutes an important risk from a One Health approach. This study aimed to characterize antibiotic resistance and some of its associated resistance determinants in different S. enterica serovars isolated from pigs in Argentina. Materials and Methods: A retrospective study was conducted on Salmonella strains isolated between 2011 and 2015 from pigs in the Pampean region of Argentina. The antimicrobial susceptibility patterns to 21 antimicrobials and some antibiotic resistance determinants were characterized in 55 Salmonella isolates, representing 58 farms. Results: We identified 56% (n=30) of the strains as multidrug-resistant, where resistance to tetracycline (62%, n=34), ampicillin (53%, n=29), nalidixic acid (53%, n=29), chloramphenicol (33%, n=18), and trimethoprim-sulfamethoxazole (31%, n=17) was most common. The wide range of resistance to ampicillin correlates with the presence of TEM type β-lactamases in the strains. However, high susceptibility was found in the new generation of β-lactams. Fluoroquinolone resistance is a major concern. Most strains with decreased susceptibility to ciprofloxacin showed gyrA mutations and plasmid-mediated quinolone resistance gene qnrB. Conclusion: Here, we identified broad resistance to some antibiotics frequently used in human therapeutics and several easily transferable resistance mechanisms that could endanger public health.

Characterization of Salmonella spp. in a tertiary hospital during 2019-2021 in Nanjing, China: Focusing on the clonal dissemination of Salmonella Enteritidis ST11

“…The high frequency of resistance to ampicillin and ampicillin/sulbactam in our study was similar to the previous reports from China [27,29], Italy [28], and Argentina [30], suggesting that ampicillin and ampicillin/sulbactam should be carefully prescribed for clinical treatment of infections caused by such strains. In addition, resistance to sulfamethoxazole/trimethoprim in our study was lower than those in previous domestic and foreign studies [29][30][31][32], however, relatively higher than those of other studies [33,34]. The reason may lie on the regional or strain difference.…”

“…Fortunately, the observed frequencies of resistance to monocyclic β-lactam antibiotics (aztreonam) and third and fourth generation cephalosporins were lower when compared to data from other studies [27,29,31]. Luckily, the distribution of MDR strains in our study was lower than reports in Argentina [30], Iran [37], Philippine [38], USA [33,39], and parts of China [31,35], indicating that the third-and fourth-carbapenems could be still effective for the clinical therapy of Salmonella infections.…”

Molecular Characteristics of Salmonella Spp. Responsible for Bloodstream Infections in a Tertiary Hospital in Nanjing, China, 2019-2021

“…Fortunately, the observed frequencies of resistance towards aztreonam, third-and fourth-generation cephalosporins were lower than those previously reported. 20,25 Additionally, the distribution of MDR strains observed in this study was lower than that reported in Argentina, 24 the USA, 26 and China. 20 This suggests that the third-and fourth-generation cephalosporins may still be effective for the clinical treatment of Salmonella infections in our hospital.…”

“…22,23 Further, the high frequency of resistance to ampicillin and ampicillin/sulbactam is similar to previous studies. 24 Thus, these antibiotics should be cautiously prescribed for the clinical treatment of infections caused by these strains. Fortunately, the observed frequencies of resistance towards aztreonam, third-and fourth-generation cephalosporins were lower than those previously reported.…”