Resistance to cephalosporins and carbapenems in gram-negative bacteria isolated from swine, soil, and wastewater of a pig production unit

• Ano de defesa: 2021
• Autor(a) principal: Oliveira, Rúzivia Pimentel
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa; Microbiologia Agrícola
• Palavras-chave em Português: Resistência Microbiana a Medicamentos; Suínos; Resistência beta-Lactâmica; Microbiologia Agrícola
• Link de acesso: https://locus.ufv.br//handle/123456789/31433; https://doi.org/10.47328/ufvbbt.2021.244

Some antibiotics of veterinary importance belong to the same class and share the same mechanisms of action of antibiotics used for humans such as carbapenems, which can trigger the selection and spread of multidrug resistant bacteria from animals to the environment through waste and wastewater. The objective of this study was to evaluate the co-occurrence of genetic determinants conferring resistance to cephalosporins and carbapenems in Gram-negative bacteria isolated from finishing pigs, soil and wastewater from a swine production unit. For this, the different isolates obtained were characterized for the presence of genes encoding extended spectrum beta-lactamases (ESBL) and/or carbapenemases. After an initial screening in selective MacConkey agar supplemented with ceftiofur (8 mg/L), 77 isolates were obtained from the rectal swabs of finishing pigs, in addition to 58 isolates from soil and 52 isolates from wastewater, both collected from environments of the production unit. Susceptibility was evaluated against carbapenems (meropenem and imipenem) and cephalosporins of 1st (cefazolin), 3rd (cefotaxime and ceftriaxone) and 4th (cefepime) generations. The results indicated that 70 % of the isolates from all environments were resistant to imipenem and 20 % to meropenem. Regarding susceptibility to cephalosporins, more than 90 % of the swine and wastewater isolates and more than 81 % of the soil isolates were resistant to at least one of the cephalosporins tested. The highest frequencies of resistance to cephalosporins were observed in bacterial isolates from wastewater, with 95.5 % showing resistance to cefazolin, ceftriaxone and cefepime, and 90.9 % to cefotaxime. In addition to the resistance profile, genes associated with resistance to beta-lactams were identified, including blaCTX-M, blaVIM and blaIMP. Approximately 85 % of the isolates from the three environments carried at least one resistance determinant. The blaVIM gene was the most frequent among isolates from soil and wastewater, while blaCTX-M was the most frequent gene in pig isolates, corroborating the hypothesis that genetic determinants of resistance to cephalosporins and carbapenems coexist in Gram-negative bacteria isolated from swine, soil and wastewater. Furthermore, the results suggest the existence of cross-resistance between cephalosporins and carbapenems through resistance determinants between the three environments. Keywords: Antibiotic resistance. Food-producing animals. ESBL. Swine. Cross-resistance.