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Effect of clindamycin on the intracellular bactericidal capacity of human peritoneal macrophages
C W de Fijter1, H A Verbrugh, H C Heezius
1Department of Internal Medicine, Free University Hospital, Amsterdam, The Netherlands.
Abstract:
Survival and growth of bacteria within peritoneal macrophages has been implicated as a cause of recurrence and relapse of Staphylococcus epidermidis peritonitis during peritoneal dialysis. We studied the effect of orally administered clindamycin (known to enter and concentrate in phagocytes) on the intracellular killing of S. epidermidis by human peritoneal macrophages. Clindamycin (300 mg qid) was taken for one day by eight CAPD patients. Peritoneal macrophages were isolated from the effluents and their capacity to phagocytose and kill S. epidermidis was measured. In effluents containing clindamycin, the macrophages showed better uptake (32 vs 17%, P less than 0.01) and intracellular killing (70 vs 42%, P less than 0.01) of S. epidermidis compared with control after 1 h incubation. After 18 h S. epidermidis within peritoneal macrophages incubated with clindamycin, showed a further decrease in viability (-0.33 decrease in log cfu/ml). In contrast, control phagocytes allowed numbers of S. epidermidis to increase over 18 h (+1.46 increase in log cfu/ml; P less than 0.01 compared to clindamycin). Antibiotics with the ability to suppress intracellular bacterial growth should be studied for treatment of CAPD-related S. epidermidis peritonitis.
Insights
Clindamycin enhances the ability of peritoneal macrophages to kill Staphylococcus epidermidis, reducing bacterial survival within these cells. This suggests clindamycin may be effective in treating peritonitis related to continuous ambulatory peritoneal dialysis.
Area of Science:
- Microbiology
- Immunology
- Nephrology
Background:
- Bacterial survival within macrophages contributes to relapsing Staphylococcus epidermidis peritonitis in peritoneal dialysis patients.
- Understanding intracellular bacterial killing is crucial for effective peritonitis treatment.
Purpose of the Study:
- To investigate the effect of oral clindamycin on the intracellular killing of Staphylococcus epidermidis by human peritoneal macrophages.
- To assess clindamycin's impact on bacterial uptake and survival within macrophages.
Main Methods:
- Eight continuous ambulatory peritoneal dialysis (CAPD) patients received oral clindamycin (300 mg qid) for one day.
- Peritoneal macrophages were isolated from patient effluents.
- Macrophage phagocytosis and intracellular killing of S. epidermidis were measured in the presence and absence of clindamycin.
Main Results:
- Clindamycin significantly increased S. epidermidis uptake (32% vs 17%) and intracellular killing (70% vs 42%) by macrophages.
- After 18 hours, clindamycin-treated macrophages showed decreased bacterial viability (-0.33 log cfu/ml).
- Control macrophages showed increased bacterial growth (+1.46 log cfu/ml) over 18 hours.
Conclusions:
- Clindamycin enhances peritoneal macrophage function against S. epidermidis.
- Antibiotics that suppress intracellular bacterial growth warrant further study for CAPD-related S. epidermidis peritonitis treatment.