Multi-drug resistant (MDR) non-typhoidalSalmonella(NTS) is a public health concern globally. This study reports the phenotypic and genotypic antimicrobial resistance (AMR) profiles of NTS isolates from bovine lymph nodes (n = 48) and ground beef (n = 29). Furthermore, we compared genotypic AMR data of our isolates with those of publicly available NTS genomes from Mexico (n = 2400). The probability of finding MDR isolates was higher in ground beef than in lymph nodes:χ²= 12.0, P = 0.0005. The most common resistant phenotypes involved tetracycline (40.3%), carbenicillin (26.0%), amoxicillin-clavulanic acid (20.8%), chloramphenicol (19.5%) and trimethoprim-sulfamethoxazole (16.9%), while more than 55% of the isolates showed decreased susceptibility to ciprofloxacin and 26% were MDR. Conversely, resistance to cephalosporins and carbapenems was infrequent (0–9%). MDR phenotypes were strongly associated with NTS serovar (χ²= 24.5, P<0.0001), with Typhimurium accounting for 40% of MDR strains. Most of these (9/10), carriedSalmonellagenomic island 1, which harbors a class-1 integron with multiple AMR genes (aadA2,blaCARB-2,floR,sul1,tetG) that confer a penta-resistant phenotype. MDR phenotypes were also associated with mutations in theramRgene (χ²= 17.7, P<0.0001). Among public NTS isolates from Mexico, those from cattle and poultry had the highest proportion of MDR genotypes. Our results suggest that attaining significant improvements in AMR meat safety requires the identification and removal (or treatment) of product harboring MDR NTS, instead of screening forSalmonellaspp. or for isolates showing resistance to individual antibiotics. In that sense, massive integration of whole genome sequencing (WGS) technologies in AMR surveillance provides the shortest path to accomplish these goals.

This study evaluates the social performance of monoculture (MC), intensive silvopastoral (ISP), and native silvopastoral (NSP) livestock production systems in the tropical region of southeastern Mexico through a social life cycle assessment (SCLA) approach. The methodological framework proposed by the United Nations Environmental Program/Society of Environmental Toxicology and Chemistry (UNEP/SETAC) (2009) was employed based on a scoring approach with a performance scale ranging from 1 (very poor) to 4 (outstanding). Twelve livestock ranches for calf production were evaluated using 18 impact subcategories associated with the categories “human rights”, “working conditions”, “health and safety”, “socioeconomic repercussions”, and “governance”. The stakeholders evaluated were workers, the local community, society, and value chain actors. The ranches had performance scores between 1.78 (very poor) and 2.17 (poor). The overall average performance of the ranches by production system was 1.98, 1.96, and 1.97 for the MC, ISP, and NSP systems, respectively. The statistical analysis shows that there is no significant difference in the social performance of the livestock production systems. This assessment indicates that the cattle ranches analyzed in Mexico have poor or very poor social performance. The results show that socioeconomic and political contexts exert a greater influence on the social performance of livestock production systems than does their type of technology.

Cattle production in tropical regions has been estimated to account for just over half of cattle worldwide, yet it has not been demonstrated that sufficient similarities in the cattle exist to describe tropical cattle and, even less so, to characterize the meat from these animals. The aim of this review is to investigate the quality and nutrient composition of meat from cattle raised in the Tropics to determine if there is an axiomatic basis that would allow the definition of a concept of “tropical beef”. Tropical beef is the meat obtained from cattle raised in tropical environments, the population of which remains largely uncharacterized. Production systems in the Tropics are highly diverse but converge on the use of indigenous and Bos indicus breeds or Bos indicus-influenced crossbreeds under pasture feeding regimes. While some systems allow cattle to be slaughtered at ≤2 years of age, most often animals are ≥3 years. These production systems generally produce lean, low-yielding carcasses and tough (>46 N), lean (≤3.6% intramuscular fat) meat with a macronutrient composition otherwise similar to beef from animals raised elsewhere (72–74% moisture and 20–24% protein). Fatty acid profiles depend on the breed and production systems, while mineral content is influenced by the environment. Although lean and tough, tropical beef is highly acceptable to the consumers it serves, is culturally and traditionally relevant and, in many countries, contributes to food security. Consolidating the findings from animal and meat science studies in the Tropics has allowed the demonstration of an axiomatic basis defining “tropical beef” as a concept.

El objetivo fue estimar la frecuencia de contaminación, diversidad de serotipos y tipificación por multilocus (MLST) de Salmonella enterica (SE) en linfonodos y carne molida de bovino. Para ello, se analizaron 1545 muestras provenientes de 400 canales bovinas. El muestreo incluyó linfonodos superficiales (LNS) y profundos, carne molida magra y con grasa, obtenidas en estación cálida (abril-julio) y fría (septiembre-diciembre) durante 2017 y 2018. Los aislamientos puros se sometieron a secuenciación completa del genoma. Con estos datos, se realizó la predicción in silico de serotipos y del perfil de MLST. En total, se obtuvieron 78 aislamientos de SE (5% del total de muestras analizadas). La frecuencia de contaminación se asoció con el tipo de muestra (2=23.7, P<0.0001) y con la época del año (2=20.3, P<0.0001), siendo mayor en LNS (9.7%) y en estación cálida (7.0%). Los serotipos predominantes fueron Anatum y Reading (n=23 cada uno), Typhimurium (n=11) y London (n=9). El perfil de MLST de cepas de los serotipos Typhimurium (ST 19 y 34) y Kentucky (ST 198) se ha reportado previamente en aislamientos involucrados en casos clínicos. Se concluye que los linfonodos y la carne molida de res son reservorios de SE de importancia en salud pública, especialmente durante los meses cálidos del año. Por tanto, es necesario establecer medidas encaminadas a prevenir la diseminación, a lo largo de la cadena productiva, de las cepas asociadas con animales aparentemente sanos.

Se determinó la frecuencia de contaminación con Salmonella enterica (SE) en la carne molida de res que se comercializa en ocho capitales estatales del centro de México (n = 115), así como el fenotipo y genotipo de resistencia a antimicrobianos (RAM) de los aislamientos obtenidos. Se detectó SE en 48/115 muestras, con tasas variables de contaminación (10-80 %) por zona geográfica (c2 = 24.2, P = 0.0021). Se obtuvieron 116 aislamientos y se observó circulación de serotipos implicados en salmonelosis humana en México (Agona, Anatum, Infantis, Newport, Derby, Give y Typhimurium). La resistencia fue más frecuente en tetraciclina (39.7 %), cloranfenicol (37.9 %), estreptomicina (37.1 %), trimetoprima-sulfametoxazol (31.0 %) y ampicilina (28.4 %), moderada en azitromicina (14.7 %), escasa en cefalosporinas (2.6-3.4 %) y nula en carbapenémicos, mientras que 38.8 % de los aislamientos fue multi-drogo resistente (MDR). Los genomas secuenciados portaban alelos de resistencia contra aminoglucósidos (aadA, aac, aph), beta-lactámicos (bla-CARB, bla-PSE, bla-TEM, bla-CTX-M, bla-CMY), fenicoles (floR), inhibidores de la vía del folato (sul, dfrA), fluoroquinolonas (qnrAB, oqxAB), tetraciclinas (tetABM) y macrólidos: mph(A) y lnu(F). Se concluye que la carne bajo estudio es reservorio de SE con preocupantes fenotipos de MDR y que el patógeno ha adquirido genes de RAM contra antibióticos usados en medicina humana y veterinaria. El auge de resistencia contra azitromicina es particularmente alarmante y no se había reportado hasta el momento. Se requieren estudios más amplios para una mejor caracterización de la RAM en las poblaciones de SE asociadas con bovinos.