title: Type B Chloramphenicol Acetyltransferases Are Responsible for Chloramphenicol Resistance inRiemerella anatipestifer, China.
abstract: Riemerella anatipestifercauses serositis and septicaemia in domestic ducks, geese, and turkeys. Traditionally, the antibiotics were used to treat this disease. Currently, our understanding ofR. anatipestifersusceptibility to chloramphenicol and the underlying resistance mechanism is limited. In this study, thecatgene was identified in 69/192 (36%)R. anatipestiferisolated from different regions in China, includingR. anatipestiferCH-2 that has been sequenced in previous study. Sequence analysis suggested that there are two copies ofcatgene in this strain. Only both two copies of thecatmutant strain showed a significant decrease in resistance to chloramphenicol, exhibiting 4 μg/ml in the minimum inhibitory concentration for this antibiotic, but not for the singlecatgene deletion strains. Functional analysis of thecatgene via expression inEscherichia coliBL21 (DE3) cells andin vitrosite-directed mutagenesis indicated that His79 is the main catalytic residue of CAT inR. anatipestifer. These results suggested that chloramphenicol resistance ofR. anatipestiferCH-2 is mediated by thecatgenes. Finally, homology analysis of types A and B CATs indicate thatR. anatipestifercomprises type B3 CATs.
authors.affiliation: Research Center of Avian Diseases, College of Veterinary Medicine of Sichuan Agricultural UniversityChengdu, China; Key Laboratory of Animal Disease and Human Health of Sichuan ProvinceChengdu, China.
authors.forename: Li
authors.initials: L
authors.lastname: Huang
authors.affiliation: Research Center of Avian Diseases, College of Veterinary Medicine of Sichuan Agricultural UniversityChengdu, China; Key Laboratory of Animal Disease and Human Health of Sichuan ProvinceChengdu, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Yuan
authors.affiliation: Key Laboratory of Animal Disease and Human Health of Sichuan ProvinceChengdu, China; Institute of Preventive Veterinary Medicine, Sichuan Agricultural UniversityChengdu, China.
authors.forename: Ma-Feng
authors.initials: MF
authors.lastname: Liu
authors.affiliation: Key Laboratory of Animal Disease and Human Health of Sichuan ProvinceChengdu, China; Institute of Preventive Veterinary Medicine, Sichuan Agricultural UniversityChengdu, China.
authors.forename: Xin-Xin
authors.initials: XX
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Animal Disease and Human Health of Sichuan ProvinceChengdu, China; Institute of Preventive Veterinary Medicine, Sichuan Agricultural UniversityChengdu, China.
authors.forename: Ming-Shu
authors.initials: MS
authors.lastname: Wang
authors.affiliation: Research Center of Avian Diseases, College of Veterinary Medicine of Sichuan Agricultural UniversityChengdu, China; Key Laboratory of Animal Disease and Human Health of Sichuan ProvinceChengdu, China.
authors.forename: Ren-Yong
authors.initials: RY
authors.lastname: Jia
authors.affiliation: Key Laboratory of Animal Disease and Human Health of Sichuan ProvinceChengdu, China; Institute of Preventive Veterinary Medicine, Sichuan Agricultural UniversityChengdu, China.
authors.forename: Shun
authors.initials: S
authors.lastname: Chen
authors.affiliation: Key Laboratory of Animal Disease and Human Health of Sichuan ProvinceChengdu, China; Institute of Preventive Veterinary Medicine, Sichuan Agricultural UniversityChengdu, China.
authors.forename: Kun-Feng
authors.initials: KF
authors.lastname: Sun
authors.affiliation: Key Laboratory of Animal Disease and Human Health of Sichuan ProvinceChengdu, China; Institute of Preventive Veterinary Medicine, Sichuan Agricultural UniversityChengdu, China.
authors.forename: Qiao
authors.initials: Q
authors.lastname: Yang
authors.affiliation: Key Laboratory of Animal Disease and Human Health of Sichuan ProvinceChengdu, China; Institute of Preventive Veterinary Medicine, Sichuan Agricultural UniversityChengdu, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Research Center of Avian Diseases, College of Veterinary Medicine of Sichuan Agricultural UniversityChengdu, China; Key Laboratory of Animal Disease and Human Health of Sichuan ProvinceChengdu, China.
authors.forename: Xiao-Yue
authors.initials: XY
authors.lastname: Chen
authors.affiliation: Research Center of Avian Diseases, College of Veterinary Medicine of Sichuan Agricultural UniversityChengdu, China; Key Laboratory of Animal Disease and Human Health of Sichuan ProvinceChengdu, China.
authors.forename: An-Chun
authors.initials: AC
authors.lastname: Cheng
authors.affiliation: Research Center of Avian Diseases, College of Veterinary Medicine of Sichuan Agricultural University Chengdu, China.
authors.forename: De-Kang
authors.initials: DK
authors.lastname: Zhu
keywords: Riemerella anatipestifer; antibiotics resistance; chloramphenicol acetyltransferase; homologous recombination; site-directed mutagenesis