Comparison of Culture-Based Methods for Identification of Colonization with Methicillin-Resistant and Methicillin-Susceptible Staphylococcus aureus in the Context of Cocolonization.

Two screening methods to detect staphylococcal colonization in humans were compared. Direct plating to CHROMagar (BD Diagnostics) was compared to a broth preenrichment followed by plating to Baird-Parker agar. The broth-enrichment method was comparable to CHROMagar for methicillin-resistant Staphylococcus aureas (MRSA) detection, but the enrichment method was optimum for recovery of coagulase-positive Staphylococcus spp.

Longitudinal Evaluation of the Skin Microbiome and Association with Microenvironment and Treatment in Canine Atopic Dermatitis.

Host-microbe interactions may play a fundamental role in the pathogenesis of atopic dermatitis, a chronic relapsing inflammatory skin disorder characterized by universal colonization with Staphylococcus species. To examine the relationship between epidermal barrier function and the cutaneous microbiota in atopic dermatitis, this study used a spontaneous model of canine atopic dermatitis. In a cohort of 14 dogs with canine atopic dermatitis, the skin microbiota were longitudinally evaluated with parallel assessment of skin barrier function at disease flare, during antimicrobial therapy, and post-therapy. Sequencing of the bacterial 16S ribosomal RNA gene showed decreased bacterial diversity and increased proportions of Staphylococcus (S. pseudintermedius in particular) and Corynebacterium species compared with a cohort of healthy control dogs (n = 16). Treatment restored bacterial diversity with decreased proportions of Staphylococcus species, concurrent with decreased canine atopic dermatitis severity. Skin barrier function, as measured by corneometry, pH, and transepidermal water loss also normalized with treatment. Bacterial diversity correlated with transepidermal water loss and pH level but not with corneometry results. These findings provide insights into the relationship between the cutaneous microbiome and skin barrier function in atopic dermatitis, show the impact of antimicrobial therapy on the skin microbiome, and highlight the utility of canine atopic dermatitis as a spontaneous nonrodent model of atopic dermatitis.

Evaluation of Clostridium novyi-NT spores in dogs with naturally occurring tumors.

OBJECTIVE: To establish the maximum tolerated dose of Clostridium novyi-NT spores in tumor-bearing dogs and evaluate spore germination within tumors and tumor response. ANIMALS: 6 client-owned dogs. PROCEDURES: A standard dose-escalation study was planned, with maximum tolerated dose defined as the highest dose at which 0 or 1 of 6 dogs had dose-limiting toxicoses (DLT). Dogs received 1 dose of C. novyi-NT spores i.v.. Toxicoses were graded and interventions performed according to specific guidelines. Grade 3 or higher toxicosis or any toxicosis combination that substantially affected patient status was considered DLT. Clinical response was measured by use of response evaluation criteria in solid tumors at 28 days. RESULTS: The first 2 dogs had DLT. The dose was decreased. Two of the next 4 dogs had DLT; therefore, dose administration was stopped because the study endpoint had been reached. The most common toxicosis was fever (n = 6 dogs). Two dogs developed abscesses (1 within a nasal carcinoma and 1 splenic abscess) attributable to C. novyi-NT infection; both required surgical intervention. Clostridium novyi-NT was cultured from 1 of 6 tumors. Five dogs were available for response assessment (4 had stable disease; 1 had progressive disease). CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that C. novyi-NT can germinate within tumors of dogs. Toxicosis, although common and sometimes severe, was manageable with treatment. Further studies in dogs with superficial tumors may allow for continued dose escalation and provide information for use in clinical trials in veterinary and human oncology.

Methicillin-resistant Staphylococcus aureus-associated dermatitis in a Congo African grey parrot (Psittacus erithacus erithacus).

A 2-year-old DNA-sexed female Congo African grey parrot (Psittacus erithacus erithacus) was evaluated for self-trauma of the feathers and skin of the tail base for a duration of more than 1 year. All rectrices and tail coverts were missing, the skin of the tail base was thickened and ulcerated, and the uropygial gland was swollen. Results of a complete blood cell count revealed relative monocytosis and basophilia. Survey radiographs showed truncation and lysis of the caudal vertebrae and pygostyle. Results of biopsy and bacterial culture of the tail base lesions revealed an ulcerative bacterial dermatitis positive for staphylococcal cassette chromosome mec (SCCmec) type IV (community-acquired) methicillin-resistant Staphylococcus aureus (MRSA). The bird was treated with oral trimethoprim-sulfamethoxazole, meloxicam, fluoxetine, topical lidocaine gel, and hydrotherapy. One month later, tail feather regrowth was evident; however, follow-up over 2 years found continued self-trauma to the rectrices in spite of repeated skin biopsies negative for MRSA or other bacteria. It is unknown if the MRSA cultured from this bird was commensal or acquired from either the environment or humans to which the bird was exposed.