Clinical disease, when apparent, is generally limited to lesions of the skin and adnexal structures, although ophthalmitis, conjunctivitis, and mastitis have also been reported. Lesions are characterized by suppurative inflammation. Natural infection of rats with P. pneumotropica could compromise research involving the skin. Transmission is direct, and entry into the body is via breaks in normal barriers. A variety of clinical presentations have been reported in rats and mice.
Lesions are more severe in immunocompromised hosts.
In addition, rats inapparently infected during nonsterile surgical procedures are less active in open-field testing. Infected rats have alterations in the fibrinogen level in plasma, the glucose level in serum, total leukocyte counts, and wound histology scores. The hallmark of S. aureus infection is suppurative inflammation, with abscess formation in virtually any organ. Most commonly, infection occurs in the skin and subcutaneous tissues, but it may also be found in the upper airways, lungs, conjunctiva, and other tissues. Immunity to S. aureus is primarily via complement-mediated killing by neutrophils.