Establishing a canine superficial pyoderma model

Canine Models of Inflammatory Skin Diseases and Their Application in Pharmacological Research

The purpose of this article is to provide an overview of existing pharmacological models of canine dermatitis. Canine models of dermatitis have contributed significantly to our current understanding of the pathology of dermatitis and to the development of corresponding pharmacological interventions. Specifically, canine atopic dermatitis (AD) is reviewed here, as it is one of the most common inflammatory skin diseases in dogs. Canine AD also shares clinicopathological features with human AD, making the dog a natural and optimal model for human disease. Thus, pharmacological models of canine AD may be uniquely applicable to human pharmacological research. In this article, particular attention is dedicated to relevant in vivo, in vitro, and ex vivo models of canine AD, skin barrier defect models, pruritus models, and skin immunology models. Additionally, models of superficial pyoderma and food allergy are also discussed. With understanding of findings from canine models, researchers can select the most salient features for future pharmacological drug development. © 2023 Wiley Periodicals LLC.

Bacteriocins Revitalize Non-Effective Penicillin G to Overcome Methicillin-Resistant Staphylococcus pseudintermedius

The rise of antibiotic-resistant bacteria is among the biggest challenges in human and veterinary medicine. One of the major factors that contributes to resistance is use of frontline clinical antibiotics in veterinary practices. To avoid this problem, searching for antimicrobials aimed at veterinary applications is becoming especially important. Thiopeptide micrococcin P1 and leaderless peptide EntEJ97s are two different bacteriocins that are very active against many gram-positive bacteria; however, sensitive bacteria can rapidly develop resistance towards those bacteriocins. To overcome this problem, we searched for synergy between those bacteriocins and conventional antibiotics against methicillin-resistant Staphylococcus pseudintermedius (MRSP): a common pathogen in animal skin infections. The two bacteriocins acted synergistically with each other and with penicillin G against MRSP clinical isolates in both planktonic and biofilm assays; they also prevented resistance development. The therapeutic potential was further validated in a murine skin infection model that showed that a combination of micrococcin P1, EntEJ97s and penicillin G reduced cell-forming units of MRSP by 2-log10 CFU/g. Taken together, our data show that a combination of bacteriocins with conventional antibiotics can not only prevent resistance development but also pave the way to revitalize some old, less useful antibiotics, such as penicillin, which by itself has no effect on methicillin-resistant pathogens.

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.

Methicillin-resistant Staphylococcus pseudintermedius synthesizes deoxyadenosine to cause persistent infection

Methicillin-resistant Staphylococcus pseudintermedius (MRSP) is an emerging zoonotic pathogen of canine origin that causes an array of fatal diseases, including bacteremia and endocarditis. Despite large-scale genome sequencing projects have gained substantial insights into the genomic landscape of MRSP, current knowledge on virulence determinants that contribute to S. pseudintermedius pathogenesis during human or canine infection is very limited. Using a panel of genetically engineered MRSP variants and a mouse abscess model, we here identified the major secreted nuclease of S. pseudintermedius designated NucB and adenosine synthase A (AdsA) as two synergistically acting enzymes required for MRSP pathogenesis. Similar to Staphylococcus aureus, S. pseudintermedius requires nuclease secretion along with the activity of AdsA to degrade mammalian DNA for subsequent biosynthesis of cytotoxic deoxyadenosine. In this manner, S. pseudintermedius selectively kills macrophages during abscess formation thereby antagonizing crucial host immune cell responses. Ultimately, bioinformatics analyses revealed that NucB and AdsA are widespread in the global S. pseudintermedius population. Together, these data suggest that S. pseudintermedius deploys the canonical Nuc/AdsA pathway to persist during invasive disease and may aid in the development of new therapeutic strategies to combat infections caused by MRSP.

Draft Genome Sequence of Staphylococcus pseudintermedius Strain 13-13613, Isolated from a Case of Canine Pyoderma

Here, we report the draft genome sequence of Staphylococcus pseudintermedius strain 13-13613, isolated from a case of canine pyoderma. The draft genome contains 2,533,486 bp in 570 contigs.

Efficacy study of a topical treatment with a plant extract with antibiofilm activities using an in vivo model of canine superficial pyoderma

BACKGROUND

Canine pyoderma is a common skin infection caused predominantly by staphylococcal bacteria. Because of increasing rates of antimicrobial resistance in bacterial isolates, there is an urgent need for alternative or supplementary treatment options. W16P576, a Water Extract of Complex Mix of Edible Plants (WECMEP), has shown in vitro activity against a variety of bacteria, including Staphylococcus pseudintermedius. A canine model of pyoderma was developed which allows in vivo testing of antimicrobial agents in a controlled environment.

OBJECTIVE

To evaluate the antibacterial efficacy of topical application of W16P576 in a model of canine pyoderma.

ANIMALS

Nine laboratory housed beagle dogs.

METHODS AND MATERIALS

In an evaluator-blinded cross-over study with an eight week washout period, dogs were treated topically twice daily with W16P576 WECMEP or its vehicle, starting three days before bacterial challenge. On the day of challenge, each dog was treated with two concentrations of a clinical S. pseudintermedius strain on opposite sides of the body. Topical treatment was continued for 11 days and lesions of pyoderma were evaluated and scored for 14 days.

RESULTS

All dogs developed lesions consistent with bacterial pyoderma. Lesion scores were generally higher on the side inoculated with a higher concentration of bacteria. Treatment with W16P576 significantly reduced lesion development and hastened resolution of lesions, compared to placebo.

CONCLUSION

Topical application of W16P576 markedly reduced lesion development in this proof of principle study. Clinical trials are warranted to estimate benefits for dogs with naturally occurring pyoderma under field conditions.

Staphylococcus pseudintermedius Surface Protein L (SpsL) Is Required for Abscess Formation in a Murine Model of Cutaneous Infection

Staphylococcus pseudintermedius is the leading cause of pyoderma in dogs and is often associated with recurrent skin infections that require prolonged antibiotic therapy. High levels of antibiotic use have led to multidrug resistance, including the emergence of epidemic methicillin-resistant clones. Our understanding of the pathogenesis of S. pseudintermedius skin infection is very limited, and the identification of the key host-pathogen interactions underpinning infection could lead to the design of novel therapeutic or vaccine-based approaches for controlling disease. Here, we employ a novel murine cutaneous-infection model of S. pseudintermedius and investigate the role of the two cell wall-associated proteins (SpsD and SpsL) in skin disease pathogenesis. Experimental infection with wild-type S. pseudintermedius strain ED99 or a gene-deletion derivative deficient in expression of SpsD led to a focal accumulation of neutrophils and necrotic debris in the dermis and deeper tissues of the skin characteristic of a classical cutaneous abscess. In contrast, mice infected with mutants deficient in SpsL or both SpsD and SpsL developed larger cutaneous lesions with distinct histopathological features of regionally extensive cellulitis rather than focal abscessation. Furthermore, comparison of the bacterial loads in S. pseudintermedius-induced cutaneous lesions revealed a significantly increased burden of bacteria in the mice infected with SpsL-deficient mutants. These findings reveal a key role for SpsL in murine skin abscess formation and highlight a novel function for a bacterial surface protein in determining the clinical outcome and pathology of infection caused by a major canine pathogen.