Experimental Bacterial Endocarditis in Altitude Rats. III. Effect of Age of Infection on Response to Penicillin

Abstract

Rats were exposed daily to simulated high altitude and then inoculated intraven. with a young broth culture of Streptococcus faecalis. Untreated rats developed a vegetative bacterial endocarditis and renal abscesses and necrosis. Treatment with penicillin instituted within 12 or 20 hrs. after inoculation was highly effective in reducing the mortality and in aborting or preventing the development of cardiac lesions. In the kidney, such early treatment effected an immediate marked reduction in the avg. bacterial count and in the incidence and severity of lesions. However, 4-5 weeks after the cessation of treatment renal lesions were noted in 5 of 7 animals, presumably caused by surviving bacteria. When treatment was delayed until 4.5 days after inoculation, permitting extensive bacterial proliferation and the development of pathological changes, penicillin therapy had a much less favorable effect on mortality, bacterial counts, and the regression of lesions.