In vitro and in vivo effects of subinhibitory concentrations of clindamycin on experimental Klebsiella pneumoniae sepsis.

We studied the effect of subinhibitory doses of clindamycin on the course of experimental Klebsiella pneumoniae sepsis. Wistar rats were injected intraperitoneally with an inoculum containing 5 x 10(6) colony-forming units of K. pneumoniae resistant to clindamycin (minimum inhibitory concentration greater than 128 micrograms/ml) and then distributed to receive clindamycin 10 mg/kg/day or placebo for 10 days. All animals were bacteremic at 3 h. When the magnitude of bacteremia was compared, no difference was seen during the first 24 h; however, by 72 h the clindamycin-treated group had a significant decrease in the number of colony-forming units per milliliter blood (p less than 0.01). The mortality rate showed a tendency to decrease in the treated group (0%) as compared with the control group (30%). By 120 h, 3 of the 9 (33%) surviving animals from the control group were still bacteremic versus 0 of 11 (0%) in the clindamycin-treated group. These results suggest that subinhibitory clindamycin therapy can improve bacterial clearance and survival during the course of experimental K. pneumoniae sepsis.