Pulmonary infection due to disruption of the pharyngeal bacterial flora by antibiotics in hamsters.

An animal model was used to determine the effect of oxacillin on the pharyngeal bacterial flora and the relationship of this flora to pneumonia. The pharyngeal bacterial flora of 68 healthy Golden Syrian hamsters was determined. A quantitative comparison between Streptococci and Escherichia, Proteus, Klebsiella and Enterobacter from 70 hamsters was made before and at 4, 24, 48 and 72 hours after oxacillin administration. Lung cultures were positive in 22 of 25 hamsters, yielding K pneumoniae type 1 most frequently. Lung histology from 25 hamsters revealed bronchopneumonia. Intestinal postmortem cultures of treated and untreated animals were similar. The importance of throat cultures in diagnosing pneumonia and the value of the hamster model to study the effect of other antibiotics on the temporary flora are demonstrated.