SummaryPulmonary clearance forStaphylococcus aureushas been examined in two inbred strains of mice with some hereditary alterations resembling cystic fibrosis (CF). These mice were mice with abnormal electrolyte metabolism (DBA/2J-Cri), mice with spontaneous pneumonitis (C57BL/6J-bgJ), and mice without any CF-like alterations (BALB/c).The methods used to produce pulmonary infection were essentially those of Laurenzi and associates adapted as needed for mutant mice. The animals mentioned above were exposed to a finely divided aerosol suspension of a coagulase-positive strain ofS. aureusin phosphate buffer.Immediately after the exposure, half of the animals were killed, and the remaining half were killed 4 hr later. In each experimental unit the mice killed immediately after the exposure were as similar as possible to the mice killed 4 hr later with respect to genotype, age, and sex; some were siblings.The uncleared bacteria (UBR) in 4 hr were 0.20 for the mice without any CF-like alterations (BALB/c) and the C57BL/6J-bg, bg/bggenotypes; 0.28 for C57BL/6J-ftg, +/? genotypes; 0.50 for the DBA/2J-cri, +/? genotypes; and 0.56 forcri/crimice.The number of viable staphylococci found immediately after the aerosol exposure (Co) in the C57BL/6J-bgstrain is significantly lower than the Co of the BALB/c (P< 0.05) and DBA/2J-cristrain (P< 0.01). The latter two did not differ from each other.There was no sex difference with respect to the UBR and Co data. The DBA/2J-cristrain of mice, where thecrimutation first appeared, has a decreased capacity for clearance ofS. aureusby the lung. Together with the other CF-like alterations of thecrimutation, namely failure for the reabsorption of Na+by the parotid duct, high level of Na+in the fur, and CF abnormal serum factor activity in the scrum ofcri/crimice, we suggest that the cribriform degeneration mouse mutant may provide a potential animal model for studying CF.SpeculationThe finding of a mouse mutation with electrolyte alterations and CF-like abnormal scrum activity, similar to the activity found in CF children, in an inbred strain of mice with a decreased bacterial clearance by the lungs, makes these mice very useful for CF studies.