Publication Database

Analysis of macrolide-resistant bovine Mannheimia haemolytica isolates from Germany (2023)

Art

Poster

Autoren

Kostova, V. (WE 7)

Schink, A. - K. (WE 7)

Hanke, D. (WE 7)

Kaspar, H.

Krüger-Haker, H. (WE 7)

Schwarz, S. (WE 7)

Kongress

Tagung der DVG-Fachgruppe Bakteriologie & Mykologie

Berlin, 22. – 24.05.2023

Quelle

Tagung der DVG-Fachgruppe Bakteriologie & Mykologie : 22. bis 24. Mai 2023 — Wissenschaftliche Leitung: Prof. Dr. Stefan Schwarz & Prof. Dr. Marcus Fulde, Berlin Veranstalter und Organisation: DVG Service GmbH, Gießen (Hrsg.)

1. Auflage

Gießen: Verlag der DVG Service GmbH, 2023 — S. 130–132

ISBN: 978-3-86345-666-5

Sprache

Englisch

Verweise

URL (Volltext): https://www.dvg.net/fileadmin/Bilder/DVG/PDF/Gesamtdatei_Tagungsband_Bak-Myk_2023.pdf

Kontakt

Institut für Mikrobiologie und Tierseuchen

Robert-von-Ostertag-Str. 7-13
14163 Berlin
+49 30 838 51843 / 66949
mikrobiologie@vetmed.fu-berlin.de

Abstract / Zusammenfassung

Introduction:
Mannheimia haemolytica plays an important role in the pathogenesis of multifactorial bovine respiratory tract infections, which are often treated
with macrolides. Recent data from the national resistance monitoring program GERM-Vet showed that since 2009 macrolide-resistant bovine M.
haemolytica isolates were found at increasing percentages. The aims of this study were (i) to further define the macrolide resistance phenotypes of
the isolates and (ii) to determine the genetic basis of the multidrug-resistance (MDR) phenotype of one selected isolate.

Material and Methods:
A total of 19 macrolide-resistant bovine M. haemolytica isolates from GERM-Vet 2008 – 2020 were included in the study. Antimicrobial susceptibility testing (AST) was carried out according to CLSI standards. In order to obtain a closed genome, one isolate was selected for a hybrid assembly
of Illumina MiSeq and Oxford Nanopore MinION reads.

Results:
Minimal inhibitory concentrations (MICs) for macrolides (particularly: erythromycin, tilmicosin, tulathromycin, gamithromycin, tildipirosin) were determined. All isolates were either resistant or had elevated MICs for one or a combination of the tested macrolides. Isolate Mh190176 showed resistance to ilmicosin, tulathromycin, gamithromycin and tildipirosin and elevated MICs for erythromycin. In addition, it was resistant to penicillin, ampicillin, florfenicol, tetracycline and showed elevated MICs for gentamicin, streptomycin, kanamycin and sulfisoxazole. Sequence analysis revealed the presence of a 9226 bp plasmid harboring two copies of a blaROB-1 gene. The resistance genes erm(T), mef(C), mph(G), floR, catA3, aac(3)-IIa, aph(3’’)-Ib, aph(3’)-Ia-like, tet(Y)-like and sul2 were identified in a 69571 bp ICE Tn7406-like mobile genetic element (MGE).

Conclusions:
Macrolide-resistant respiratory tract pathogens severely limit therapeutic options, and the presence of the macrolide resistance genes erm(T), mef(C), and mph(G) in a MGE along with a variety of other resistance genes may further limit treatment options in the future. The simultaneous occurrence of plasmid-borne β-lactamase genes and the ICE Tn7406-like MGE in Mh190176, renders the isolate already resistant to regularly used florfenicol, penicillins, tetracycline and macrolides. Thus, pathogen isolation and subsequent AST are strongly recommended when treating bovine respiratory tract infections.