(i) Corynebacterium kutscheri.
Corynebacterium kutscheri is a gram-positive bacillus that infects both mice and rats. Transmission is fecal-oral. The oral cavity and large intestine most commonly serve as reservoir sites for a latent carrier stage. Natural infections are usually subclinical and are revealed only by the immunosuppressive effects of certain drugs, experimental manipulations, or other infectious agents. Clinical signs in rats, when present, usually include dyspnea with abnormal lung sounds, weight loss, humped posture, and anorexia. Hematogenous spread occurs in both species and accounts for abscess formation in various organs. In rats, abscesses commonly develop in the lungs and extend to the pleura, while in mice, abscesses occur more often in the kidneys and liver. Strain differences in colonization sites and susceptibility have been reported. C57BL/6 and B10.BR/SgSn mice are among the more resistant strains, while Swiss, BALB/cCr, and A/J are among the more susceptible strains. Strain susceptibility may reflect differences in the efficiency of mononuclear phagocytes or cytokine responses. Experimental procedures that cause immunosuppression of rats or mice
may result in the unwanted development of active C. kutscheri infection, which could compromise a variety of studies, including those of the respiratory system.
