Ms
Johanna Jahnen
(Institute of Microbiology and Epizootics, Centre for Infection Medicine, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany; Veterinary Centre for Resistance Research (TZR), Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany)
Human (n=64) and equine (n=29) Staphylococcus aureus isolates of the clonal complexes 1 and 1660 were investigated for their phenotypic biocide susceptibility, biocide resistance genes and efflux capacity. Broth microdilution was performed for benzalkonium chloride (BAC), octenidine, polyhexanide and chlorhexidine. Whole genome sequences were screened for qac genes, which were confirmed by PCR in 26 isolates. Increased efflux activity was determined by evaluating fluorescence emitted by ethidium bromide accumulated in the cells. For this, cartwheel assays were performed for the qac positive isolates and one qac negative control. Real time fluorometry was performed for eight isolates. Two control strains were included in both assays. Biocide susceptibility testing revealed unimodal distributions. For BAC, minimum inhibitory concentrations (MICs) of 1.25-5µg/mL were detected. Of the 24 isolates with a BAC MIC of 5 19 carried qacA, four qacC and one qacC S99L. Two of the 19 isolates with a MIC of 2.5 were qacC positive. The cartwheel assays showed increased efflux activity in 18 qacA and all seven qacC positive isolates. Real time fluorometry confirmed this for the selected isolates. Within the qacC positive isolates, the isolate carrying the qacC mutation S99L showed lower efflux activity for both methods. To investigate the effect of the efflux activity on the isolates’ BAC susceptibility, susceptibility testing with efflux inhibitors will be performed.
Keywords
Biocide susceptibility, Efflux, Staphylococcus aureus
| Registration ID |
OHS25-71
|
| Professional Status of the Speaker |
PhD Student
|
| Junior Scientist Status |
Yes, I am a Junior Scientist.
|
Ms
Johanna Jahnen
(Institute of Microbiology and Epizootics, Centre for Infection Medicine, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany; Veterinary Centre for Resistance Research (TZR), Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany)
Ms
Marta Leal
(Global Health and Tropical Medicine, GHTM, LA-REAL, Instituto de Higiene e Medicina Tropical, IHMT, Universidade NOVA de Lisboa, Lisbon, Portugal)
Dr
Sofia Santos Costa
(Global Health and Tropical Medicine, GHTM, LA-REAL, Instituto de Higiene e Medicina Tropical, IHMT, Universidade NOVA de Lisboa, Lisbon, Portugal)
Prof.
Isabel Couto
(Global Health and Tropical Medicine, GHTM, LA-REAL, Instituto de Higiene e Medicina Tropical, IHMT, Universidade NOVA de Lisboa, Lisbon, Portugal)
Dr
Chirstiane Cuny
(Robert Koch Institute, Wernigerode, Germany)
Dr
Wolfgang Witte
(Robert Koch Institute, Wernigerode, Germany)
Dr
Ralf Ehricht
(Leibniz Institute of Photonic Technology (IPHT), Jena, Germany; InfectoGnosticsResearch Campus, Jena, Germany; Institute of Physical Chemistry, Friedrich-Schiller University, Jena, Germany)
Dr
Stefan Monecke
(Leibniz Institute of Photonic Technology (IPHT), Jena, Germany; Institute of Physical Chemistry, Friedrich-Schiller University, Jena, Germany; Institute for Medical Microbiology and Virology, Dresden University Hospital, Dresden, Germany)
Dr
Dennis Hanke
(Institute of Microbiology and Epizootics, Centre for Infection Medicine, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany; Veterinary Centre for Resistance Research (TZR), Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany)
Mrs
Tanja Ahrens
(Institute of Microbiology and Epizootics, Centre for Infection Medicine, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany; Veterinary Centre for Resistance Research (TZR), Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany)
Prof.
Stefan Schwarz
(Institute of Microbiology and Epizootics, Centre for Infection Medicine, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany; Veterinary Centre for Resistance Research (TZR), Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany)
Dr
Andrea T. Feßler
(Institute of Microbiology and Epizootics, Centre for Infection Medicine, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany; Veterinary Centre for Resistance Research (TZR), Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany)
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