Peer-reviewed veterinary case report
New antibiotic combos tested against dog ear infections in the lab
By Chan, Wei Yee et al.·Published in Veterinary dermatology·2020·School of Animal and Veterinary Sciences, Australia·View original on PubMed →
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Original publication title: In vitro antimicrobial activity of narasin and monensin in combination with adjuvants against pathogens associated with canine otitis externa.
- Species:
- dog
Plain-English summary
A study tested combinations of two antibiotics, narasin and monensin, with other substances to see if they could help treat ear infections in dogs caused by bacteria like Staphylococcus and Pseudomonas. The results showed that using narasin with Tris-EDTA or disodium EDTA worked well against these bacteria, while combining monensin with N-acetylcysteine (NAC) significantly lowered the amount of monensin needed to be effective. These findings suggest that these combinations could be a new way to tackle tough ear infections in dogs.
People also search for: dog ear infection treatment · narasin for canine otitis · monensin and NAC for dog infections
Abstract
BACKGROUND: The emergence of antimicrobial resistance represents a serious human and animal health risk. Good antimicrobial stewardship is essential to prolong the lifespan of existing antibiotics, and new strategies are required to combat infections in man and animals. HYPOTHESIS/OBJECTIVES: To determine the in vitro interaction of ionophores (narasin or monensin) with antimicrobial adjuvants (N-acetylcysteine (NAC), Tris-EDTA or disodium EDTA) against bacterial strains representing pathogens associated with canine otitis externa (OE). ANIMAL/ISOLATES: American Type Culture Collection (ATCC) strains Staphylococcus aureus 29213, Pseudomonas aeruginosa 27853 and P. aeruginosa biofilm producer PAO1, and a clinical isolate of Proteus mirabilis from a case of canine OE were tested. METHODS AND MATERIALS: A 2D microdilution checkerboard method was used, allowing calculation of fractional inhibitory concentration index (FICI), dose reduction index (DRI) and plotting of isobolograms. RESULTS: The combination of narasin with either Tris-EDTA or disodium EDTA produced additive effects (FICI = 0.75) against P. aeruginosa ATCC 27853 and P. aeruginosa biofilm producer ATCC PAO1. An additive effect (FICI = 0.53-0.75) was found against S. aureus ATCC 29213 when narasin or monensin were combined with NAC. The highest DRI (32-fold) was found with monensin/NAC where the MIC of monensin was reduced from 4 to 0.125 μg/mL. CONCLUSIONS AND CLINICAL IMPORTANCE: The combination of narasin with Tris-EDTA or disodium EDTA is a promising strategy to inhibit the intrinsic resistance elements of Gram-negative bacteria. These novel combinations potentially could be useful as a multimodal approach to treat mixed infections in canine OE.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/31710159/