EXPERIMENTAL LOBAR PNEUMONIA DUE TO PENICILLIN-SUSCEPTIBLE AND PENICILLIN-RESISTANT STREPTOCOCCUS-PNEUMONIAE IN IMMUNOCOMPETENT AND NEUTROPENIC RATS - EFFICACY OF PENICILLIN AND TEICOPLANIN TREATMENT

Lobar pneumonia models were established in rats by intratracheal inocu lation of either penicillin-susceptible (immunocompetent model) or pen icillin-resistant (immunocompetent and neutropenic models) Streptococc us pneumoniae, Untreated animals maintained a relatively high bacteria l load in the lungs but only occasionally developed bacteraemia or ple urisy, The infection was rarely fatal in immunocompetent rats, but imm unocompromised rats frequently died, Treatment im with 10,000 IU/kg of procaine penicillin G (12 h after infection then bid for 3 days) or w ith a single iv dose of 5 or 10 mg/kg of teicoplanin significantly red uced lung bacterial loads of rats infected with the penicillin-suscept ible strain. Against the penicillin-resistant strain, teicoplanin disp layed a significant activity regardless of the immununological status of the animals, Penicillin G significantly reduced lung bacterial load of the penicillin-resistant strain only in immunocompetent rats and a t a higher dose than needed in treatment of the penicillin-susceptible infection. The experimental models described here could be suitable f or studying the efficacy of antibacterial agents against pulmonary inf ections caused by penicillin-susceptible and penicillin-resistant S. p neomoniae strains.