Comparison of In Vitro Bacterial Susceptibility to Common and Novel Equine Wound Care Dressings.

Simple Summary: Wound care is a challenging part of equine veterinary practice and there are a variety of wound dressings and strategies to manage wounds. Our goal was to ascertain the relative efficacy of honey when compared to common wound dressings as it pertains to reducing bacterial growth. This experiment was performed in a laboratory setting where different species of bacteria were grown in a simulated wound environment. These bacteria were then exposed to medical-grade Manuka honey, local honey, and commercial, food-grade honey as well as other commonly used wound dressings to see how effective each wound dressing was on reducing bacterial growth. Our results showed that polyhexamethylene biguanide (PHMB, a commonly used wound dressing) was best at reducing bacterial growth. Local honey out-performed Manuka and store-bought honeys. Interestingly, the most susceptible type of bacteria was harvested from an actual equine wound when compared to the lab-grown bacteria. We suspect that the complex wound environment plays a large role in determining the efficacy of wound dressings. Our results provide data to practitioners so they can decide how to best manage an infected wound based on the type of bacteria growing. Antimicrobial resistance is becoming a problem of concern in the veterinary field, necessitating the use of effective topical treatments to aid the healing of wounds. Honey has been used for thousands of years for its medicinal properties, but in recent years medical-grade Manuka honey has been used to treat infected wounds. The goal of this study was to determine the relative susceptibility of four common equine wound pathogens to ten different types of antimicrobial agents based on the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The pathogens studied include ATCC lab-acclimated Pseudomonas aeruginosa, Escherichia coli, and methicillin-resistant Staphylococcus aureus and one from an equine sample submitted to the Colorado State Veterinary Diagnostic Laboratory (Streptococcus equi ssp. zooepidemicus (Streptococcus zooepidemicus)). An additional goal of the study was to describe the comparison of bactericidal activity of medical-grade Manuka honey, local honey, and commercial, food-grade honey to other commonly used wound dressings (20% hypertonic saline, silver sulfadiazine cream, PHMB gauze, and PHMB foam). The objective is to provide veterinary practitioners with comparative data on the use of a variety of antimicrobial dressings for inhibiting the growth of common wound bacteria. MIC and MBC for Manuka, store, and local honeys were comparable to those of sterile gauze, sugar, and hypertonic saline. Across bacterial species, local honey proved to have more bactericidal activity when compared to Manuka honey and commercial, food-grade honey. The MIC and MBC for PHMB gauze and foam was consistently at a higher dilution compared to the other antimicrobials. The majority of antimicrobials exhibited stronger inhibitory and bactericidal activity against a Streptococcus zooepidemicus isolate obtained from a wound compared to other bacteria that were ATCC lab-acclimated. Additional research for in vivo applications needs to be done to see whether differences exist in effective wound management. [ABSTRACT FROM AUTHOR]