{"id":22577,"date":"2020-12-15T15:35:41","date_gmt":"2020-12-15T15:35:41","guid":{"rendered":"https:\/\/todaysveterinarypractice.com\/?p=22577"},"modified":"2022-07-06T18:57:29","modified_gmt":"2022-07-06T18:57:29","slug":"treating-canine-superficial-pyoderma-in-the-era-of-antimicrobial-resistance","status":"publish","type":"post","link":"https:\/\/navc.sitepreview.app\/todaysveterinarypractice.com\/dermatology\/treating-canine-superficial-pyoderma-in-the-era-of-antimicrobial-resistance\/","title":{"rendered":"Treating Canine Superficial Pyoderma in the Era of Antimicrobial Resistance"},"content":{"rendered":"

Canine superficial pyoderma, also called bacterial folliculitis<\/i>, is one of the most common problems veterinarians face, and the increasing prevalence of staphylococcal antimicrobial resistance poses a new challenge to treatment. Failure to recognize staphylococcal antimicrobial resistance frequently results in ineffective empiric therapeutic choices and protracted clinical disease. In addition, concern exists regarding potential transmission of antimicrobial-resistant strains among animals and humans. <\/span><\/p>\n

The rise of antimicrobial resistance requires veterinarians to shift their approach in treating bacterial skin infections, particularly in regard to the use and selection of systemic antimicrobials. Specific antimicrobial guidelines and clinical consensus on treating bacterial skin infections have been developed by the International Society for Companion Animal Infectious Diseases (ISCAID, <\/span>iscaid.org<\/span><\/a>) and the World Association for Veterinary Dermatology (WAVD, <\/span>wavd.org<\/span><\/a>) to help veterinarians adequately diagnose and treat pyoderma, using judicious antimicrobial therapy to prevent bacterial resistance.1,2<\/sup> To treat canine pyoderma successfully, it is important to recognize its clinical signs, confirm the infection, and identify and treat any underlying cause to help prevent pyoderma recurrence. <\/span><\/p>\n

Bacteria that Cause Superficial Pyoderma<\/h2>\n

Staphylococcus pseudintermedius<\/i>\u00a0is the most common cause of superficial pyoderma in dogs. Other less commonly identified gram-positive bacteria include Staphylococcus schleiferi<\/i>, Staphylococcus aureus, Staphylococcus xylosus, Staphylococcus epidermitis<\/i>, and Streptococcus <\/i>species. <\/i>Gram-negative bacteria such as Pseudomonas aeruginosa <\/i>and Corynebacterium <\/i>species are rarely identified.1<\/sup><\/span><\/p>\n

Antimicrobial Resistance<\/h2>\n

Antimicrobial resistance occurs when bacteria can survive in the presence of antimicrobials designed to kill them or stop their growth. One of the most important factors leading to the emergence of antimicrobial-resistant bacteria is the use and misuse of antimicrobial therapy. Therefore, reduction of the overall use of antimicrobials in veterinary medicine, especially systemic antimicrobials, can help reduce antimicrobial resistance. <\/span><\/p>\n

Multidrug-resistant (MDR) bacteria are bacteria that demonstrate in vitro resistance to at least 3 antimicrobial classes. The term methicillin-resistant staphylococcus<\/i> (MRS) refers to any Staphylococcus <\/i>species that is resistant to oxacillin; that is, it demonstrates in vitro resistance to all <\/span>\u03b2<\/span>-lactam antimicrobials, including all cephalosporins, penicillins (including potentiated amoxicillin), and carbapenem antimicrobials. When an MRS expresses resistance to at least 2 additional antimicrobial classes, it is also referred to as MDR.<\/span><\/p>\n

Clinical Signs<\/h2>\n

Clinical signs of canine superficial pyoderma typically include erythematous papules and pustules (<\/span>FIGURE 1<\/b><\/span>), which are usually associated with hair follicles. Pustules are quite short lived and not always identified during examination. Successively, scaling, crusts, and epidermal collarettes (FIGURE<\/b><\/span><\/span>\u00a02<\/b><\/span>) are often present. Multifocal areas of hypotrichotic or alopecic patches (moth-eaten alopecia; FIGURE<\/b><\/span><\/span>\u00a03<\/b><\/span>) can also be seen, most commonly in short-coated breeds. Clinical signs cannot differentiate susceptible from resistant infections.<\/span><\/p>\n

\"\"<\/a>

Figure 1. Papules and pustules on the inguinal and medial thigh area of a dog.<\/p><\/div>\n

\"\"<\/a>

Figure 2. Epidermal collarettes on the ventral abdomen of a dog.<\/p><\/div>\n

\"\"<\/a>

Figure 3. Moth-eaten alopecia on the dorsum of a dog.<\/p><\/div>\n

Diagnosis<\/h2>\n

The first step in treating superficial pyoderma properly is to confirm the diagnosis. The diagnosis includes recognition of the typical clinical signs, the exclusion of other similar conditions, and confirmation via skin cytology, plus or minus bacterial culture and susceptibility testing.3<\/sup> This approach helps prevent inappropriate use of antimicrobial therapy for skin diseases that are not associated with pyoderma. <\/span><\/p>\n

Differential Diagnosis<\/h3>\n

Other causes of folliculitis and pustular disease should be considered, including demodicosis, dermatophytosis, sterile pustular diseases such as pemphigus foliaceus (FIGURE<\/b><\/span><\/span>\u00a04<\/b><\/span>), and sterile neutrophilic or eosinophilic pustulosis. Appropriate diagnostic tests, such as skin scrapings, trichogram, fungal culture, and skin biopsy, should be performed to rule out these conditions.<\/span><\/p>\n

\"\"<\/a>

Figure 4. Generalized pemphigus foliaceus mimicking superficial pyoderma in a dog.<\/p><\/div>\n

Skin Cytology<\/h3>\n

Skin cytology is the most important diagnostic test for canine pyoderma; however, it is still underused. Before antimicrobials are administered, the diagnosis of superficial pyoderma needs to be supported by cytologic findings demonstrating coccoid bacteria, often associated with inflammatory cells (typically degenerate neutrophils) and, when present, bacteria phagocytosis (FIGURE<\/b><\/span><\/span>\u00a05<\/b><\/span>). Cytology is also very important for identification of co-infection with other microorganisms such as Malassezia pachydermatis <\/i>and, less commonly, rod-shaped bacteria.<\/span><\/p>\n

\"\"<\/a>

Figure 5. Skin cytology from a dog with superficial pyoderma demonstrating degenerate neutrophils and intracellular (blue arrow) and extracellular (orange arrow) cocci bacteria.<\/p><\/div>\n

Bacterial Culture and Susceptibility Testing<\/h3>\n

Bacterial culture and susceptibility testing is a very important diagnostic tool for identification of the bacteria involved and selection of appropriate antimicrobial therapy (<\/span>BOX 1<\/b><\/span>), especially when considering systemic antibiotics. The need for this test has increased with the emergence of MDR infections in veterinary medicine. Ideally, samples should be taken from pustules. If pustules are not present, samples may be collected from exudate beneath crusts, epidermal collarettes, and, if needed, from papules (by rupturing the papules with a 22-gauge needle). There is no current indication that use of antimicrobials affects isolation of causative bacteria in canine superficial pyoderma; therefore, samples may be collected for culture whenever indicated, regardless of administration of antimicrobials.<\/span><\/p>\n

BOX 1 When to Perform Bacterial Culture and Sensitivity Testing<\/div>
<\/p>\n