Identifying antimicrobial resistance genes of human clinical relevance within Salmonella isolated from food animals in Great Britain

Abstract

Salmonella isolated from livestock was shown to harbour antimicrobial resistance genes although no or little resistance to third-generation cephalosporins or ciprofloxacin, respectively, was detected. The preponderance in pigs of multidrug-resistant Salmonella Typhimurium makes it important to introduce control measures such as improved biosecurity to ensure that they do not pass through the food chain and limit human therapeutic options.

Evaluation of an Expanded Microarray for Detecting Antibiotic Resistance Genes in a Broad Range of Gram-Negative Bacterial Pathogens

“…For testing on the microarray, bacteria were cultivated overnight at 37°C on Luria-Bertani agar plates, and then a loopful of bacteria was lysed and DNA from the lysed cells was quantified using a nanodrop apparatus and labeled in a linear multiplex reaction using all primers (i.e., primers described previously [4,8] and the new primers [shown in Table S1 in the supplemental material]). The amplified labeled mix was added to the microarrays for hybridization to all probes present on AMR06 (i.e., probes described previously [4,8]and the new probes [shown in Table S1 in the supplemental material]), with signals from the hybridization duplex read on an ArrayMate apparatus (Alere Technologies, Jena, Germany) using IconoClust software, as already described (standard version; Inverness Technologies, Jena, Germany) (8). Mean signal intensities of three replicate spots per probe were used for analysis.…”

“…Resistance genes for which probes were validated in this study are indicated in bold font. All other probes had been validated previously (4,8).…”

“…In particular, conventional or real-time PCR, single-gene sequencing, or in situ hybridization usually detects only a few resistance genes simultaneously. Microarrays, however, offer the potential for simultaneous detection of large numbers of resistance genes, allowing prediction of an isolate's repertoire of resistances to multiple antibiotic classes (4)(5)(6)(7).…”

“…We previously developed a microarray that detected 51 resistance genes in Escherichia coli and Salmonella and facilitated epidemiological studies (4,8). Its coverage included genes that conferred acquired resistance to a range of antimicrobials of clinical importance as well as two integrase genes associated with class 1 and class 2 integrons and not just those genes encoding ␤-lactamases (6).…”

Antimicrobial resistance, class 1 integrons, and horizontal transfer in Salmonella isolated from retail food in Henan, China

“…The increasing prevalence of multidrug resistance among Salmonella and resistance to clinically important antimicrobial agents has also been an emerging problem in China and other countries [7,8]. The spread of antimicrobial resistance potential in Salmonella is mainly attributed to integrons, which are genetic elements capable of capturing and transferring resistance genes among bacteria [9].…”