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  • Genomic and in vitro pharmacodynamic analysis of rifampicin resistance in multidrug‐resistant canine Staphylococcus pseudintermedius isolates
Title: Genomic and in vitro pharmacodynamic analysis of rifampicin resistance in multidrug‐resistant canine Staphylococcus pseudintermedius isolates
BackgroundAntimicrobial resistance is a growing concern in canineStaphylococcus pseudintermediusdermatitis. Treatment with rifampicin (RFP) is considered only in meticillin‐resistant and multidrug‐resistantS. pseudintermedius(MDR‐MRSP). Hypothesis/ObjectivesTo determine an optimal RFP dosing for MDR‐MRSP treatment without induction of RFP resistance and identify causal mutations for antimicrobial resistance. Methods and materialsTime–kill assays were performed in a control isolate and three MDR‐MRSP isolates at six clinically relevant concentrations [32 to 1,024 × MIC (the minimum inhibitory concentration)]. Whole‐genome resequencing and bioinformatic analysis were performed in the resistant strains developed in this assay. ResultsThe genomic analysis identified nine antimicrobial resistance genes (ARGs) in MDR‐MRSP isolates, which are responsible for resistance to seven classes of antibiotics. RFP activity against all four isolates was consistent with a time‐dependent and bacteriostatic response. RFP resistance was observed in six of the 28 time–kill assays, including concentrations 64 × MIC in MDR‐MRSP1 isolates at 24 h, 32 × MIC in MDR‐MRSP2 at 48 h, 32 × MIC in MDR‐MRSP3 at 48 h and 256 × MIC in MDR‐MRSP3 at 24 h. Genome‐wide mutation analyses in these RFP‐resistant strains discovered the causal mutations in the coding region of therpoBgene. Conclusions and clinical relevanceA study has shown that 6 mg/kg per os results in plasma concentrations of 600–1,000 × MIC ofS. pseudintermedius. Based on our data, this dose should achieve the minimum MIC (×512) to prevent RFP resistance development; therefore, we recommend a minimum daily dose of 6 mg/kg for MDR‐MRSP pyoderma treatment when limited antibiotic options are available.  more » « less
Award ID(s):
1928770
PAR ID:
10387612
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  ;  ;  ;  
Publisher / Repository:
Wiley-Blackwell
Date Published:
Journal Name:
Veterinary Dermatology
Volume:
32
Issue:
3
ISSN:
0959-4493
Format(s):
Medium: X Size: Article No. 219
Size(s):
Article No. 219
Sponsoring Org:
National Science Foundation
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