In Vivo Bioluminescence Imaging To Evaluate Systemic and Topical Antibiotics against Community-Acquired Methicillin-Resistant Staphylococcus aureus-Infected Skin Wounds in Mice

Department of Medicine, Division of Dermatology, David Geffen School of Medicine at University of California, Los Angeles (UCLA), Los Angeles, California 90095, USA.
Antimicrobial Agents and Chemotherapy (Impact Factor: 4.48). 12/2012; 57(2). DOI: 10.1128/AAC.01003-12
Source: PubMed


Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) frequently causes skin and soft-tissue infections, including impetigo, cellulitis, folliculitis, and infected wounds and ulcers. Uncomplicated CA-MRSA skin infections are typically managed in an outpatient setting with oral and topical antibiotics and/or incision and drainage whereas complicated skin infections often require hospitalization, intravenous antibiotics, and sometimes surgery. The aim of this study was to develop a mouse model of CA-MRSA wound infection to compare the efficacy of commonly used systemic and topical antibiotics. A bioluminescent USA300 CA-MRSA strain was inoculated into full-thickness scalpel wounds on the backs of mice and digital photography/image analysis and in vivo bioluminescence imaging were used to measure wound healing and the bacterial burden. Subcutaneous vancomycin, daptomycin and linezolid similarly reduced the lesion sizes and bacterial burden. Oral linezolid, clindamycin and doxycycline all decreased the lesion sizes and bacterial burden. Oral trimethoprim/sulfamethoxazole decreased the bacterial burden but did not decrease the lesion size. Topical mupirocin and retapamulin ointments both reduced the bacterial burden. However, the petrolatum vehicle ointment for retapamulin, but not the polyethylene glycol vehicle ointment for mupirocin, promoted wound healing and initially increased the bacterial burden. Finally, in type 2 diabetic mice, subcutaneous linezolid and daptomycin had the most rapid therapeutic effect compared with vancomycin. Taken together, this mouse model of CA-MRSA wound infection, which utilizes in vivo bioluminescence imaging to monitor the bacterial burden, represents an alternative method to evaluate the preclinical in vivo efficacy of systemic and topical antimicrobial agents.

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Available from: Romela Irene Silva Ramos, Nov 23, 2014
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    • "Thus, these models are not always reproducible or sustainable because of the leakage and spread of the bacteria from the inoculated tissues. Indeed, in previous studies the bacterial growth was observed for periods ranging from only 12 hours to a maximum of 7 days [3], [8], [18], [26]. In models of osteomyelitis and joint infection, skin ulcers resulting from bacterial leakage from the inoculation site to surrounding tissues are often observed, making such models unstable and poorly reproducible. "
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