Escherichia coli, Salmonella spp. and Acinetobacter spp. are important human pathogens. Serious infections due to these organisms are usually treated with extended-spectrum cephalosporins (ESCs). However, in the past two decades we have faced a rapid increasing of infections and colonization caused by ESC-resistant (ESC-R) isolates due to production of extended-spectrum-β-lactamases (ESBLs), plasmid-mediated AmpCs (pAmpCs) and/or carbapenemase enzymes. This situation limits drastically our therapeutic armamentarium and puts under peril the human health. Animals are considered as potential reservoirs of multidrug-resistant (MDR) Gram-negative organisms. The massive and indiscriminate use of antibiotics in veterinary medicine has contributed to the selection of ESC-R E. coli, ESC-R Salmonella spp. and, to less extent, MDR Acinetobacter spp. among animals, food, and environment. This complex scenario is responsible for the expansion of these MDR organisms which may have life-threatening clinical significance. Nowadays, the prevalence of food-producing animals carrying ESC-R E. coli and ESC-R Salmonella (especially those producing CTX-M-type ESBLs and the CMY-2 pAmpC) has reached worryingly high values. More recently, the appearance of carbapenem-resistant isolates (i.e., VIM-1-producing Enterobacteriaceae and NDM-1 or OXA-23-producing Acinetobacter spp.) in livestock has even drawn greater concerns. In this review, we describe the aspects related to the spread of the above MDR organisms among pigs, cattle, and poultry, focusing on epidemiology, molecular mechanisms of resistance, impact of antibiotic use, and strategies to contain the overall problem. The link and the impact of ESC-R organisms of livestock origin for the human scenario are also discussed.

中文翻译：

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牲畜的广谱头孢菌素耐药革兰氏阴性菌：人类健康的新问题？

大肠杆菌，沙门氏菌属。和不动杆菌属。是重要的人类病原体。由于这些生物引起的严重感染，通常用广谱头孢菌素（ESC）治疗。然而，在过去的二十年中，由于产生了广谱β-内酰胺酶（ESBLs），质粒介导的AmpC（pAmpCs），因此，由ESC抗性（ESC-R）分离株引起的感染和定植迅速增加和/或碳青霉烯酶。这种情况极大地限制了我们的治疗用武器库，并危及人类健康。动物被认为是耐多药（MDR）革兰氏阴性生物的潜在宿主。在兽医学中大量且不加区分地使用抗生素，促使选择ESC-R大肠杆菌，ESC-R沙门氏菌。以及较少的MDR不动杆菌属。在动物，食物和环境中 这种复杂的情况导致了这些耐多药生物的发展，这可能具有威胁生命的临床意义。如今，携带ESC-R大肠杆菌和ESC-R沙门氏菌的产食动物（特别是产生CTX-M型ESBL和CMY-2 pAmpC的动物）的流行率已达到令人担忧的高水平。最近，牲畜中对碳青霉烯类耐药菌株（即产生VIM-1的肠杆菌科和NDM-1或产生OXA-23的不动杆菌属）的出现甚至引起了更大的关注。在这篇综述中，我们描述了与上述MDR生物在猪，牛和家禽中的传播有关的方面，重点是流行病学，耐药性分子机制，抗生素使用的影响以及遏制整个问题的策略。