Antimicrobial Drug Resistance and Molecular Typing ofSalmonella entericaSerovar Rissen from Different Sources

Abstract

Salmonella enterica serovar Rissen is one of the most common serovars found in pigs and pork products in different countries, including Spain. However, information on the molecular bases of antimicrobial drug resistance and the population structure of Salmonella Rissen from different sources in Spain is limited. The present study focused on 84 isolates collected in Spain from pig and beef carcasses, foods and clinical samples associated with sporadic cases of gastroenteritis, and one outbreak. The majority of the isolates were resistant to tetracycline (73.8%), mainly conferred by tet(A). Resistances to streptomycin (aadA1-like, aadA2, and strAB), sulfonamides (sul1, sul2, and sul3), trimethoprim (dfrA1-like and dfrA12), ampicillin (blaTEM-1-like), and chloramphenicol (cmlA1-like) were also detected, with frequencies ranging from 12% to 20.2%. Most of the identified genes were carried by integrons, including three class 1 integrons of the sul1 type, a class 1 integron of the sul3 type, and the class 2 integron of Tn7. Two sul1 integrons, the sul3 integron, and the class 2 integron are first reported in Salmonella Rissen. Typing of the isolates with XbaI pulsed-field gel electrophoresis detected a major clone, which was circulating in humans and animals during the past decade, and was responsible for the outbreak. The obtained results are relevant for food safety and public health.

Multidrug-Resistant Salmonella enterica Serovar Rissen Clusters Detected in Azores Archipelago, Portugal

“…The fact that the Azores archipelago is composed by nine small islands with livestock as one of the major economic resources reinforces this possibility. Another detected cluster containing a PT isolate and a Spanish isolate (cluster D) seems to suggest the existence of either a S. enterica serovar Rissen strain already circulating within the Iberian Peninsula, as a result of intensive trade of live pigs and pork between Portugal and Spain [17], or a discrete phenomenon, as only two cases were detected. Also, these isolates present the resistance genes sul1, dfrA12, and aadA2, mirroring what has been previously reported [17].…”

“…In Portugal, only 31 cases of human salmonellosis caused by S. enterica serovar Rissen were identified in a 12-year period (2000-2012) [9]. However, this is one of the most commonly reported serovars in pigs and pork, in several European and Asian countries [10][11][12][13][14][15][16][17]. This serovar has also been isolated less frequently from other sources, namely, beef, chicken, and seafood [14,15,18,19].…”

The European Union summary report on trends and sources of zoonoses, zoonotic agents and food‐borne outbreaks in 2015

“…A recent study demonstrated the high frequency of resistance and multidrug‐resistance among S . Rissen isolates obtained from different sources and mainly from pigs (Garcia‐Fierro et al., ). Moreover, the authors described a successful clone of S .…”

“…Moreover, the authors described a successful clone of S . Rissen that is circulating among humans, pigs and other sources in the Iberian Peninsula and in other countries (Garcia‐Fierro et al., ).…”

“…Another serovar associated with the pig chain is S. Rissen and it accounted for 25.6% of serotyped pig isolates in Spain. A recent study demonstrated the high frequency of resistance and multidrug-resistance among S. Rissen isolates obtained from different sources and mainly from pigs (Garcia-Fierro et al, 2016). Moreover, the authors described a successful clone of S. Rissen that is circulating among humans, pigs and other sources in the Iberian Peninsula and in other countries (Garcia-Fierro et al, 2016).…”