| Abstract: |
Athymic nude mice infected with Corynebacterium bovis typically exhibit transient hyperkeratotic dermatitis. Our vivarium experienced an increased incidence of disease characterized by persistent skin lesions and increased mortality, leading to this study. For detection of infection, skin and buccal swab methods showed comparable sensitivities in nude mice. Various prevention, treatment, and eradication strategies were evaluated through clinical assessment, microbiology, and histopathology. In experimentally naïve athymic nude mice, a 2-wk course of prophylactic amoxicillin-containing diet (1200 ppm amoxicillin; effective dose, 200 mg/kg) was ineffective at preventing infection or disease. There was also no significant difference in disease duration or severity in athymic nude mice that received amoxicillin diet or penicillin-streptomycin topical spray (penicillin, 2500 U/mL; streptomycin, 2500 μg/mL). Prolonged treatment with 4 or 8 wk of amoxicillin diet cleared only a small number of athymic nude mice that had subclinical C. bovis infections. Antibiotic sensitivity of C. bovis isolates demonstrated a small colony isolate with less susceptibility to all antibiotics compared with a large colony isolate. Resistance did not appear to develop after prolonged treatment with amoxicillin. Provocation testing by administration of cyclophosphamide (50 mg/kg IP every 48 to 72 h for 90 d) to subclinically infected athymic nude mice resulted in prolonged clinical disease that waxed and waned without progression to severe disease. Our findings suggest that antibiotic prophylaxis and treatment of clinical disease in experimentally naïve mice is unrewarding, eradication of bacterial infection is difficult, and severe disease associated with C. bovis is likely multifactorial. Copyright 2011 by the American Association for Laboratory Animal Science. |
| Keywords: |
controlled study; treatment outcome; disease course; histopathology; drug efficacy; nonhuman; mouse; animals; mice; animal tissue; mus; skin biopsy; prevalence; animal experiment; administration, topical; cyclophosphamide; bacteria (microorganisms); hyperkeratosis; mus musculus; skin; anti-bacterial agents; disease severity; nude mouse; mice, nude; nucleotide sequence; long term care; disease duration; dermatitis; administration, oral; rna 16s; bacterium culture; bacterium identification; antibiotic sensitivity; antibiotic prophylaxis; heart surgery; bacterium isolation; sampling; streptomycin; blood culture; eradication therapy; amoxicillin; skin diseases, bacterial; provocation test; penicillin g; animals, laboratory; corynebacterium; corynebacterium bovis; rodent diseases; veterinary drug; asymptomatic infection; bacterium colony; buccal swab; cardiocentesis; corynebacterium infection; skin scrape; skin swab; corynebacterium infections; penicillins
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