학술논문
Antimicrobial Susceptibility and Resistance Mechanisms in Mannheimia haemolytica Isolates from Sheep at Slaughter
Document Type
Academic Journal
Author
Source
Animals (Basel). June 2023, Vol. 13 Issue 12
Subject
Language
English
ISSN
2076-2615
Abstract
Author(s): Julio Alvarez [1,2]; Johan M. Calderón Bernal [1]; Laura Torre-Fuentes [2]; Marta Hernández [3]; Chris E. Pinto Jimenez [4,5]; Lucas Domínguez [1,2]; José F. Fernández-Garayzábal [1,2]; Ana I. Vela [...]
Mannheimia haemolytica is a key bacterial pathogen contributing to important ruminant diseases and accounting for a large proportion of overall antimicrobial use in cattle and sheep. The recent emergence of ovine strains with reduced susceptibility to antimicrobials—which could lead to treatment failure, increased costs of livestock production, and the dissemination of antimicrobial-resistant genes to other bacteria and possibly the environment—is of concern. This study investigated the levels of antimicrobial resistance of M. haemolytica isolated from clinically healthy sheep at slaughter and the genetic bacterial resistance mechanisms. Low levels of phenotypic resistance were detected for most of the antimicrobials tested except for tetracycline (4.3%) and tylosin (89.1%). A few antimicrobial resistance determinants were found in the genome of six out of nine isolates, consisting of genes conferring resistance to tetracyclines (tetH), aminoglycosides (strA), and sulfonamides (sul2), which were sometimes linked to the presence of plasmids but did not always lead to resistance phenotypes. Our results suggest that there is limited resistance in M. haemolytica strains of veterinary origin, but the presence of several resistance genes, some of which were found in mobile genetic elements that play a major role in the dissemination of antimicrobial resistance in members of the Pasteurellaceae family, deserves further consideration. Mannheimia haemolytica is the main pathogen contributing to pneumonic pasteurellosis in sheep. The aim of this study was to investigate the antimicrobial resistance levels in M. haemolytica isolates from the lungs of slaughtered sheep and to examine the genetic resistance mechanisms involved. A total of 256 M. haemolytica isolates, 169 from lungs with pneumonic lesions and 87 from lungs without lesions, were analyzed by the disk diffusion method for 12 antimicrobials, and the whole genome of 14 isolates was sequenced to identify antimicrobial resistance determinants. Levels of phenotypic resistance ranged from
Mannheimia haemolytica is a key bacterial pathogen contributing to important ruminant diseases and accounting for a large proportion of overall antimicrobial use in cattle and sheep. The recent emergence of ovine strains with reduced susceptibility to antimicrobials—which could lead to treatment failure, increased costs of livestock production, and the dissemination of antimicrobial-resistant genes to other bacteria and possibly the environment—is of concern. This study investigated the levels of antimicrobial resistance of M. haemolytica isolated from clinically healthy sheep at slaughter and the genetic bacterial resistance mechanisms. Low levels of phenotypic resistance were detected for most of the antimicrobials tested except for tetracycline (4.3%) and tylosin (89.1%). A few antimicrobial resistance determinants were found in the genome of six out of nine isolates, consisting of genes conferring resistance to tetracyclines (tetH), aminoglycosides (strA), and sulfonamides (sul2), which were sometimes linked to the presence of plasmids but did not always lead to resistance phenotypes. Our results suggest that there is limited resistance in M. haemolytica strains of veterinary origin, but the presence of several resistance genes, some of which were found in mobile genetic elements that play a major role in the dissemination of antimicrobial resistance in members of the Pasteurellaceae family, deserves further consideration. Mannheimia haemolytica is the main pathogen contributing to pneumonic pasteurellosis in sheep. The aim of this study was to investigate the antimicrobial resistance levels in M. haemolytica isolates from the lungs of slaughtered sheep and to examine the genetic resistance mechanisms involved. A total of 256 M. haemolytica isolates, 169 from lungs with pneumonic lesions and 87 from lungs without lesions, were analyzed by the disk diffusion method for 12 antimicrobials, and the whole genome of 14 isolates was sequenced to identify antimicrobial resistance determinants. Levels of phenotypic resistance ranged from