| Congresso Brasileiro de Microbiologia 2023 | Resumo: 490-1 | ||||
Resumo:Poultry litter is the main organic residue of poultry farming and is constituted of a mixture of plant substrates, chicken manure, and other veterinary products spilled on chicken shed floors. Due to the richness of nutrients, this material is widely used as an organic fertilizer in agriculture. However, due to the widespread use of veterinary antimicrobials in poultry farming, poultry litter may contain high concentrations of antibiotics and/or antimicrobial-resistant bacteria. These pollutants can be mobilized through soil erosion to water bodies, contributing to the increased selective pressure and spread of antimicrobial resistance genes in the environment. To contribute to elucidating this hypothesis, the aim of this study was to isolate and characterize antimicrobial-resistant bacteria in two horticultural areas with intensive use of poultry litter as organic fertilizer. These horticultural areas are located in the municipality of São José do Vale do Rio Preto, Rio de Janeiro, and four samplings were performed in triplicate: (i) poultry litter from poultry sheds; (ii) cultivable soil fertilized with this organic residue; (iii) rhizosphere soil of Sechium edule (chayote); and (iv) water and sediment from ponds used for irrigation of the agricultural crops. The isolation of antimicrobial-resistant bacterial strains was performed in either CHROMagar culture medium supplemented with sulfamethoxazole or MacConkey culture medium supplemented with cefepime or imipenem. All strains were identified by MALDI-TOF/MS. The presence of the following genes was investigated using PCR: (i) intI1 and intI2, which encode class 1 and 2 integrases, respectively; (ii) sul1 and sul2, which encode resistance to sulfonamides; and (iv) blaCTX-M, blaSHV, blaTEM, blaGES, which encode resistance to β-lactams. In total, 204 strains were isolated, and 138 were identified as belonging to 34 clinically important bacterial genera. Among the sulfamethoxazole-resistant strains, a strain of Citrobacter freundii isolated from the soil sample was detected carrying both sul1 and sul2 genes, while different strains of Pseudomonas sp., isolated from the chayote rhizosphere, carried only the sul1 gene. The sul2 gene was also detected in strains of Pseudomonas sp. and Pseudomonas chlororaphis isolated from soil samples; in strains of Aeromonas sp. and Aeromonas veronii isolated from chayote rhizosphere; and in strains of Proteus mirabilis and Enterococcus faecium isolated from poultry litter samples. One of these strains of P. mirabilis also carries the intI1 gene. Among the cefepime-resistant strains, those belonging to Escherichia coli from poultry litter were positive for both sul2 and blaCTX-M, while Comamonas terrigena and Achromobacter mucicolens strains isolated from sediment and soil were positive only for sul2. At least five Escherichia coli strains carried blaCTX-M and a strain of Ochrobactrum intermedium carried the blaGES gene. The blaGES gene is less frequently described in the environment when compared to the other genes studied here and is usually found in strains from clinical environments. The results of this study lead one to believe strongly in the dissemination of resistant bacteria and antimicrobial resistance genes in different environments of agricultural areas, which may pose a risk to human and animal health. Palavras-chave: Poultry farming, Resistance genes, Organic fertilizer, Chicken manure Agência de fomento:Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES). | |||||