Experimental respiratory tract infection with Klebsiella pneumoniae DT-S in mice: chemotherapy with kanamycin.

Such factors as suspending medium, operating pressure, exposure time, inoculum size, and strain, sex, age, and weight of the animals were examined for their effects on the development of respiratory tract infection with Klebsiella pneumoniae DT-S in mice. The suspending medium was one of the most important factors. Aerosol challenge with a 10(9) colony-forming units per ml resulted in deposition of 10(4) colony-forming units of the organisms in the lung. The numbers of organisms in the lung increased rapidly, and by 30 h, a well-developed pneumonia was apparent. All the mice died within 4 days after infection. The therapeutic effectiveness of single-dose kanamycin regimens decreased markedly with a delay in administration. The effectiveness of multi-dose kanamycin regimens was influenced by the frequency of dosage. Thus a 12-h dosage schedule was superior to a 24-h regimen. Administration of 20 mg of kanamycin per kg at 12-h intervals for 10 days, initiated 30 h after infection, provided a complete cure. The infecting organisms in the lung, trachea, and blood were eradicated by the kanamycin therapy, but those in the nasal cavity were difficult to eliminate.