Salmonellosis is a common subclinical infection in pigs and therefore apparently healthy animals may represent a reservoir of antibiotic-resistant Salmonella for humans. This study estimates and characterizes resistance to two classes of antimicrobials considered of the highest priority within the critically important antimicrobials for humans, i.e. colistin (CR) and 3^rd generation cephalosporins (3GC), on a collection of Salmonella isolates from pigs from two periods: between 2008-09, when colistin was massively used; and in 2018, after three years under a National Plan against Antibiotic Resistance. Prevalence of CR was low (6 out of 625; 0.96%; 95%CI: 0.44-2.1) in 2008-09 and associated mostly to the mcr-1 gene, which was detected in four S. 4,5,12:i:- isolates. Polymorphisms in the pmrAB genes were detected in a S. 9,12:-:- isolate. No CR was detected in 2018 out of 59 isolates tested. Among 270 Salmonella isolates considered for the assessment of resistance to 3GC in the 2008-2009 sampling, only one Salmonella Bredeney (0.37%; 95%CI: 0.07-2.1) showed resistance to 3GC, which was associated with the bla_CMY-2 gene (AmpC producer). In 2018, six isolates out of 59 (10.2%; 95%CI: 4.7-20.5) showed resistance to 3GC, but only two different strains were identified (S. 4,12:i:- and S. Rissen), both confirmed as extended-spectrum β-lactamases (ESBL) producers. The bla_CTX-M-3 and bla_TEM-1b genes in S. 4,12:i:- and the bla_TEM-1b gene in S. Rissen seemed to be associated with this resistance. Overall, the prevalence of CR in Salmonella appeared to be very low in 2008-2009 despite the considerable use of colistin in pigs at that time, and seemed to remain so in 2018. Resistance to 3GC was even lower in 2008-2009 but somewhat higher in 2018. Resistance was mostly coded by genes associated with mobile genetic elements. Most serotypes involved in these antimicrobial resistances displayed a multidrug resistance pattern and were considered zoonotic.

沙门氏菌病是猪中常见的亚临床感染，因此显然健康的动物可能代表着人类对抗生素具有抗药性的沙门氏菌。这项研究估计并表征了对人类至关重要的重要抗微生物剂中的两类抗微生物剂的耐药性，即大肠杆菌素（CR）和^第三代头孢菌素（3GC）对来自两个时期的猪的沙门氏菌分离物的收集：在2008-09年间，大肠粘菌素大量使用；并在《国家抗抗生素抵抗计划》三年后的2018年。在2008-09年，CR的患病率较低（625个中的6个； 0.96％； 95％CI：0.44-2.1），且大部分与mcr-1相关基因，在四个S中检测到。4,5,12：i：-分离株。在S. 9,12：-：-分离物中检测到了pmrAB基因的多态性。在2018年检测的59种分离株中未检测到CR。在2008-2009年抽样中考虑用于评估对3GC耐药性的270株沙门氏菌中，只有1株沙门氏菌（0.37％; 95％CI：0.07-2.1）显示出对3GC的耐药性，这与bla _CMY-2基因相关（AmpC制作人）。在2018年，6分离出的59（10.2％; 95％CI：4.7-20.5），以表明3GC阻力，但只有两个不同的菌株进行鉴定（小号4,12：I： -和。小号。Rissen），都被确认为超光谱β-内酰胺酶（ESBL）的生产者。S.中的bla _CTX-M-3和bla _TEM-1b基因。4,12：i：-和S中的bla _TEM-1b基因。里森似乎与这种抵抗有关。总体而言，沙门氏菌中CR的患病率尽管那时猪中大肠粘菌素的使用量很高，但在2008-2009年间似乎仍然很低，并且在2018年似乎仍然如此。对3GC的抗性在2008-2009年甚至更低，但在2018年则有所提高。与移动遗传元件相关的基因。与这些抗药性有关的大多数血清型均表现出多药耐药性，被认为是人畜共患病。