Publikationsdatenbank

Characterization of equine Staphylococcus aureus isolates with reduced oxacillin susceptibility (2019)

Art

Poster

Autoren

Scholtzek, Anissa D. (WE 7)

Klein, Katja-Sophia (WE 17)

Stöckle, Sabita D. (WE 17)

Eichhorn, Inga (WE 7)

Walther, Birgit

Feßler, Andrea T. (WE 7)

Hanke, Dennis (WE 7)

Gehlen, Heidrun (WE 17)

Lübke-Becker, Antina (WE 7)

Schwarz, Stefan (WE 7)

Kongress

8th Symposium on Antimicrobial Resistance in Animals and the Environment

Tours Val de Loire - France, 01. – 03.07.2019

Quelle

8th Symposium on Antimicrobial Resistance in Animals and the Environment : Abstracts book : 1-3 July 2019 — UMR 1282 Infectiologie et Santé Publique Institut National de la Recherche Agronomique (Hrsg.)

France: INRA Science & Impact, 2019 — S. 129

Sprache

Englisch

Verweise

URL (Volltext): https://symposium.inrae.fr/arae2019/Abstract-Book

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

Background and objectives:
Resistance among staphylococci, especially to oxacillin, is a major threat in human and veterinary medicine. Besides antimicrobial resistance, there is the concern of increasing biocide resistance [1]. Therefore, Staphylococcus aureusisolates with reduced susceptibility to oxacillin were characterized and tested for their resistance properties.

Materials and methods:
In total, 19clinical S. aureusisolates with reduced susceptibility to oxacillin (minimum inhibitory concentrations (MICs) of 0.5mg/L to ≥4mg/L [VITEK]), originating from 17 equine patients, were collected from 2015 to 2017. Whole genome sequencing was performed using the Illumina MiSeq platform. Multilocus sequence types, spatypes and antimicrobial resistance genes were deduced from the obtained sequences. We performed antimicrobial susceptibility testing to 31 agents by broth microdilution [2]. Comparative susceptibility testing to the biocides benzalkonium chloride (BAC), glutardialdehyde (GLU) and chlorhexidine (CHX) was carried out bybroth macrodilution [3] and broth microdilution.

Results:
The isolates belonged to two different sequence types (STs), ST1 (n=3) and ST1660 (n=16). The spatyping revealed spatype t127 for all ST1 isolates, spatype t3043 for 14 ST1660 isolates and spatypes t549 and t2484 for single ST1660 isolates. The phylogenetic analysis revealed identities of 99.6-99.9% for the genome sequences within both sequence types. Between the sequence types ST1 and ST1660 the core genome showed an identity of 98-98.4%. All isolates were negative for the genesmecA andmecC. Antimicrobial susceptibility testing classified all isolates as multi-resistant (penicillins via blaZ, gentamicin and kanamycin via aacA-aphD, and trimethoprimviadfrG(ST1) or dfrS1(ST1660)). The ST1 strains were additionally resistant to the combination sulfamethoxazole/trimethoprim, to tetracycline via thetet(L) gene and harbored also the kanamycin/neomycin resistance geneaadD. The biocide MICs of the clinical isolates were: BAC:0.000125 –0.0005%, GLU:0.125 –0.5%, CHX:0.00006 –0.00025%. The results between broth macrodilution and broth microdilution differed only one to two dilution steps. The reference strain S. aureusATCC®6538, tested for comparative reasons, showed comparable results to previous studies [3, unpublished observations].

Conclusion:
The clinical S. aureusisolates belonged to two different sequence types, ST1 and ST1660, and had different resistance profiles. The two biocide susceptibility testing methods provided comparable results.