RESUMO
The use of heavy metals in economic and social development can create an accumulation of toxic waste in the environment. High concentrations of heavy metals can damage human and animal health, lead to the development of antibiotic resistance, and possibly change in bovine microbiota. It is important to investigate the influence of heavy metals in food systems to determine potential harmful effects environmental heavy metal contamination on human health. Because of a mining dam rupture, 43 million cubic meters of iron ore waste flowed into the Doce river basin surrounding Mariana City, Brazil, in 2015. Following this environmental disaster, we investigated the consequences of long-term exposure to contaminated drinking water on the microbiome and resistome of dairy cattle. We identified bacterial antimicrobial resistance (AMR) genes in the feces, rumen fluid, and nasopharynx of 16 dairy cattle 4 years after the environmental disaster. Cattle had been continuously exposed to heavy metal contaminated water until sample collection (A) and compared them to analogous samples from 16 dairy cattle in an unaffected farm, 356 km away (B). The microbiome and resistome of farm A and farm B differed in many aspects. The distribution of genes present in the cattle's nasopharynx, rumen, and feces conferring AMR was highly heterogeneous, and most genes were present in only a few samples. The relative abundance and prevalence (presence/absence) of AMR genes were higher in farm A than in farm B. Samples from farm A had a higher prevalence (presence) of genes conferring resistance to multiple drugs, metals, biocides, and multi-compound resistance. Fecal samples had a higher relative abundance of AMR genes, followed by rumen fluid samples, and the nasopharynx had the lowest relative abundance of AMR genes detected. Metagenome functional annotation suggested that selective pressures of heavy metal exposure potentially skewed pathway diversity toward fewer, more specialized functions. This is the first study that evaluates the consequences of a Brazilian environmental accident with mining ore dam failure in the microbiome of dairy cows. Our findings suggest that the long-term persistence of heavy metals in the environment may result in differences in the microbiota and enrichment of antimicrobial-resistant bacteria. Our results also suggest that AMR genes are most readily detected in fecal samples compared to rumen and nasopharyngeal samples which had relatively lower bacterial read counts. Since heavy metal contamination has an effect on the animal microbiome, environmental management is warranted to protect the food system from hazardous consequences.
RESUMO
ABSTRACT: The objective of this study was to determine the frequency and factors associated with the occurrence of seropositivity for Leptospira spp. in goat herds in the state of Sergipe, Brazil, on the basis of the analysis of 675 samples collected from 41 properties in 2013-2014. Analysis of anti-Leptospira spp. antibodies revealed that 25.74% goats (194) were seropositive and that 90.24% (37) of the properties had at least one infected goat. The most prevalent serogroup was Icterohaemorrhagiae (85.57%); although, the study animals were reactive to other serogroups: Australis (5.15%), Pomona (3.61%), Sejroe (3.09%), and Pyrogenes (2.58%) had titers ≤400 in 96.91% of cases. The origin of the water source [still water source (OR=3.86)] was associated with seropositivity. Results reflected the importance of adopting appropriate management practices for herds in Sergipe.
RESUMO: O objetivo deste estudo foi determinar a frequência e os fatores associados à soropositividade para Leptospira spp. em caprinos do Estado de Sergipe, Nordeste do Brasil, utilizando 675 animais de 41 propriedades no período de 2013 e 2014. A frequência de positividade entre os animais foi de 25,74% (194), e em 90,24% (37) das propriedades houve pelo menos um animal soropositivo. O sorogrupo reagente predominante foi o Icterohaemorrhagiae (85,57%), com presença também de animais reagentes para Australis (5,15%), Pomona (3,61%), Sejroe (3,09%) e Pyrogenes (2,58%) com títulos ≤400 em 96,91% dos casos. A origem da água fornecida (água parada) (OR=3,86) foi o fator associado à presença de caprinos positivos. Ressalta-se a importância da adoção de práticas de manejo adequadas nos rebanhos caprinos sergipanos.
