The therapeutic efficacy of Aloe vera gel ointment on staphylococcal pyoderma in dogs

In Vitro/Vivo Mechanisms of Antibacterial Peptide NZ2114 against Staphylococcus pseudintermedius and Its Biofilms

Staphylococcus pseudintermedius is an opportunistic pathogen commonly found in canines, and has garnered escalating interest due to its potential for zoonotic transmission and increasing antimicrobial resistance. However, the excessive use of antibiotics and the characteristic of S. pseudintermedius forming biofilms make treatment challenging. In this study, the in vivo and in vitro antimicrobial activity and mechanisms of action of NZ2114, a plectasin-derived peptide, against S. pseudintermedius were investigated. NZ2114 exhibited potent antibacterial activity towards S. pseudintermedius (minimum inhibitory concentration, MIC = 0.23 μM) with a lower probability of inducing drug-resistant mutations and efficient bactericidal action, which was superior to those of mopirucin (MIC = 0.25-0.5 μM) and lincomycin (MIC = 4.34-69.41 μM). The results of electron microscopy and flow cytometry showed that NZ2114 disrupted S. pseudintermedius' cell membrane, resulting in cellular content leakage, cytoplasmic membrane shrinkage, and, eventually, cell death. The intracellular ROS activity and Alamar Blue detection showed that NZ2114 interferes with intracellular metabolic processes. In addition, NZ2114 effectively inhibits biofilm formation, and confocal laser scanning microscopy further revealed its antibacterial and anti-biofilm activity (biofilm thickness reduced to 6.90-17.70 μm). The in vivo therapy of NZ2114 in a mouse pyoderma model showed that it was better than lincomycin in effectively decreasing the number of skin bacteria, alleviating histological damage, and reducing the skin damage area. These results demonstrated that NZ2114 may be a promising antibacterial candidate against S. pseudintermedius infections.

Biochemical and histopathological changes related to the topical application of Aloe vera ointment for canine pyoderma

Background and Aim:

Pyoderma is common in dogs, and its treatment requires a novel medication rather than antibiotic therapy. This study aimed to determine the biochemical and histopathological changes associated with the topical application of Aloe vera 20% and 40% ointments, compared with gentamicin 0.1% ointment, in dogs suffering from Staphylococcus aureus pyoderma.

Materials and Methods:

Serum and skin samples were collected from a negative control group before inducing pyoderma and from other subdivided groups on the 3^rd, 7^th, 10^th, and 14^th days post-inoculation for biochemical and histopathology examination.

Results:

Serum aspartate aminotransferase, alanine aminotransferase (ALT), urea, and creatinine concentrations were higher in the positive control dogs on the 3^rd day without treatment (DWT) compared with the negative control dogs (p<0.05). Compared with the healthy control dogs, serum zinc concentrations were lower in the positive control group on the 3^rd, 7^th, and 10^th DWT and in dogs treated with A. vera 20% and gentamicin 0.1% ointments on the 3^rd and 7^th days post-treatment (p<0.05). Grossly, skin had erythema, pruritus, and pus-filled pustules of the untreated group. Microscopically, skin showed epidermal necrosis and edema, dermal collagen necrosis, and severe neutrophilic infiltration.

Conclusion:

Compared with A. vera 20% and gentamicin 0.1% ointments, the topical application of A. vera 40% ointment-induced quicker skin healing and decreased the inflammatory changes caused by S. aureus inoculation, based on biochemical and histopathological changes reflective of its curative efficiency. A. vera 40% ointment may be a suitable alternative to antibiotics for the treatment of staphylococcal pyoderma in dogs.