Genetic Organization of Acquired Antimicrobial Resistance Genes and Detection of Resistance-Mediating Mutations in a <i>Gallibacterium anatis</i> Isolate from a Calf Suffering from a Respiratory Tract Infection

oleh: Anne-Kathrin Schink, Dennis Hanke, Torsten Semmler, Nicole Roschanski, Stefan Schwarz

Format: Article
Diterbitkan: MDPI AG 2023-02-01

Deskripsi

<i>Gallibacterium</i> (G.) <i>anatis</i> isolates associated with respiratory diseases in calves and harboring acquired antimicrobial resistance genes have been described in Belgium. The aim of this study was to analyze the genetic organization of acquired resistance genes in the <i>G. anatis</i> isolate IMT49310 from a German calf suffering from a respiratory tract infection. The isolate was submitted to antimicrobial susceptibility testing, and a closed genome was obtained by a hybrid assembly of Illumina MiSeq short-reads and MinION long-reads. Isolate IMT49310 showed elevated MIC values for macrolides, aminoglycosides, florfenicol, tetracyclines, and trimethoprim/sulfamethoxazole. The acquired resistance genes <i>catA1</i>, <i>floR</i>, <i>aadA1</i>, <i>aadB</i>, <i>aphA1</i>, <i>strA</i>, <i>tet</i>(M), <i>tet</i>(B), <i>erm</i>(B), and <i>sul2</i> were identified within three resistance gene regions in the genome, some of which were associated with IS elements, such as IS<i>Vsa5</i>-like or IS<i>15DII</i>. Furthermore, nucleotide exchanges within the QRDRs of <i>gyrA</i> and <i>parC</i>, resulting in amino acid exchanges S83F and D87A in GyrA and S80I in ParC, were identified. Even if the role in the pathogenesis of respiratory tract infections in cattle needs to be further investigated, the identification of a <i>G. anatis</i> isolate with reduced susceptibility to regularly used antimicrobial agents in cases of fatal bovine respiratory tract infections is worrisome, and such isolates might also act as a reservoir for antimicrobial resistance genes.