Antimicrobial resistance in Honduran salmonella and in Escherichia coli recovered from cattle in the U.S.

Date

2019-12

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Abstract

Characterization of pathogenic bacteria in the food chain in developing countries is necessary to address antimicrobial resistance from a perspective One Health. Hence, the main objective of the first study is to understand antimicrobial resistant of Salmonella isolates from a developing country that has not implemented systematic surveillance to access and control the emergence and spread of antimicrobial resistance. This investigation covered the phenotypic antimicrobial resistance of Salmonella isolates recoverd at different points of the food chain in Honduras. Sequence data of the Salmonella isolates were intenagated to describe antimicrobial resistance genes associated and obdenued phenotypic resistance. In this study, some Salmonella isolates were resistant to antibiotics of critically importance to human health (ie. macrolide, fluroquinolones, and third-generation cephalosporins). The horizontally transferable genes blaCMY, and qnr, as well non-transferable mutations in topoisomerase genes such as parC and gyrA were detected by whole genome sequencing, and were associated with phenotypic resistance. This study provides insights into the extent of antimicrobial resistance in Honduras, filling gap of important knowledge of this global threat in developing countries. The second study investigated the sample-desolate-level prevalence and antimicrobial resistance of Escherichia coli isolated from U.S. beef cattle fecal samples. Healthy cattle are a major reservoir of E. coli which can lead to higher contamination rates of pathogenic bacteria in beef products. Resistance to antibiotics has also been observed. One of the most important classes of antibiotics are β-lactams, which are primarly used to treat Gram-negative bacteria infections. Escherichia coli resistant to β-lactam antibiotics have been observed in cattle, and this is mainly conferred by extended spectrum β-lactamase (ESBL) and AmpC β-lactamase producing bacteria. Therefore, the objective was to estimate the sample and isolate level prevalence of E. coli and its antimicrobial resistant patterns, detectAmpC and ESBL producers. Feces were inoculated into Buffered Peptone Water and plated onto MacConkey agar without supplementation (MAC), and onto MacConkey agar with 1 mg/L cefotaxime (MACctx), and onto MacConkey agar with 0.5 mg/L ciprofloxacin (MACcip). E. coli was recovered from isolate level in 88% (66/75) on MAC, 60% (45/75) on sample level MACctx, and 53% (40/75) of MACcip. Presumptive E. coli subjected to antimicrobial susceptibility analysis suggested AmpC/ESBL produced (1/66) E. coli from MAC, (45/45) E. coli from MACctx, and (10/40) E. coli from MACcip. Resistance to critically important antimicrobials was detected.

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Keywords

Antimicrobial resistance, AmpC beta lactamase, Critically important, Escherichia coli, Extended spectrum beta lactamase, Honduras, Salmonella

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