Abstract
Background: Staphylococcus pseudintermedius is the main bacterial cause of skin and soft tissue (SSTI) infections in companion animals, particularly dogs. The emergence of methicillin-resistant strains (MRSP), many times associated with a multidrug resistance phenotype is a public health concern.
Objective: To evaluate efflux, a resistance mechanism still poorly characterized in S. pseudintermedius, as a contributor to biocide and fluoroquinolone resistance.
Methods: Susceptibility to the efflux pump substrates ethidium bromide (EtBr), tetraphenylphosphonium bromide (TPP) and ciprofloxacin (CIP) was evaluated by MIC determination for 155 SSTI-related S. pseudintermedius isolated from companion animals. EtBr and TPP MIC distributions were analyzed and used to estimate cut-off (COWT) values. The effect of the efflux inhibitors (EIs) thioridazine and verapamil on MICs was assessed. Real-time fluorometric EtBr accumulation assays were performed with/without glucose and/or EIs.
Results: Applying the estimated COWT value for TPP revealed the presence of a non-wild type population towards TPP with increased efflux. Characterization of this efflux activity showed that it is strain-specific and glucose-dependent. Resistance to fluoroquinolones was mainly linked to target gene mutations, yet a contribution of efflux to ciprofloxacin resistance levels could not be ruled out.
Conclusion: This study describes the relevance of efflux-mediated resistance in S. pseudintermedius, particularly to biocides, and provides the methodological basis for further studies on efflux activity in this important veterinary pathogen.
Funding: Project BIOSAFE funded by FEDER/FCT (Portugal), Grant LISBOA-01-0145- FEDER-030713, PTDC/CAL-EST/30713/2017. Further support by FCT to GHTM (UID/04413/2020) and (CM) UI/BD/151061/2021.
Objective: To evaluate efflux, a resistance mechanism still poorly characterized in S. pseudintermedius, as a contributor to biocide and fluoroquinolone resistance.
Methods: Susceptibility to the efflux pump substrates ethidium bromide (EtBr), tetraphenylphosphonium bromide (TPP) and ciprofloxacin (CIP) was evaluated by MIC determination for 155 SSTI-related S. pseudintermedius isolated from companion animals. EtBr and TPP MIC distributions were analyzed and used to estimate cut-off (COWT) values. The effect of the efflux inhibitors (EIs) thioridazine and verapamil on MICs was assessed. Real-time fluorometric EtBr accumulation assays were performed with/without glucose and/or EIs.
Results: Applying the estimated COWT value for TPP revealed the presence of a non-wild type population towards TPP with increased efflux. Characterization of this efflux activity showed that it is strain-specific and glucose-dependent. Resistance to fluoroquinolones was mainly linked to target gene mutations, yet a contribution of efflux to ciprofloxacin resistance levels could not be ruled out.
Conclusion: This study describes the relevance of efflux-mediated resistance in S. pseudintermedius, particularly to biocides, and provides the methodological basis for further studies on efflux activity in this important veterinary pathogen.
Funding: Project BIOSAFE funded by FEDER/FCT (Portugal), Grant LISBOA-01-0145- FEDER-030713, PTDC/CAL-EST/30713/2017. Further support by FCT to GHTM (UID/04413/2020) and (CM) UI/BD/151061/2021.
| Original language | English |
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| Publication status | Published - 21 Apr 2023 |
| Event | 6º Congresso Nacional de Medicina Tropical - IHMT, Lisboa, Portugal Duration: 20 Apr 2023 → 21 Apr 2023 https://6cnmt.admeus.pt/?page=43 |
Conference
| Conference | 6º Congresso Nacional de Medicina Tropical |
|---|---|
| Abbreviated title | 6º CNMT |
| Country/Territory | Portugal |
| City | Lisboa |
| Period | 20/04/23 → 21/04/23 |
| Internet address |
