Effect of antibiotics on polymorphonuclear neutrophil apoptosis.
OBJECTIVE
To evaluate the effects of various antibiotics-direct and indirect as a result of bacterial killing-on polymorphonuclear neutrophil (PMN) apoptosis.


METHODS
In vitro analysis.


METHODS
Research laboratory.


METHODS
Whole blood collected from healthy human subjects was incubated with and without Klebsiella pneumoniae (1.0 x 10(5) colony-forming units [cfu]/ml) plus ceftazidime 50 microg/ml, gentamicin, ciprofloxacin, trovafloxacin, tetracycline, doxycycline, erythromycin, azithromycin (each 5 microg/ml), or lipopolysaccharide 10 microg/ml. After staining with fluorescein-conjugated annexin V, red blood cells were lysed, and the remaining white blood cells were assessed by flow cytometry with gating on PMNs.


RESULTS
In the absence of K. pneumoniae infection, antibiotic exposure directly decreased PMN apoptosis by 17.8% (range -25.0% to -13.9%, p=0.008) compared with untreated cells. In the presence of K. pneumoniae, all antibiotic treatments, even those with poor in vitro activity for the bacterial isolate, decreased PMN apoptosis by 26.2% (range -38.0% to -17.8%, p<0.001) compared with untreated control cells and by 36.6% compared with untreated (no antibiotic) K. pneumoniae-stimulated cells (range -46.2% to -28.0%, p<0.001).


CONCLUSIONS
All tested antibiotics in clinically relevant concentrations resulted in modest yet consistent decreases in PMN apoptosis. The magnitude of this change increased slightly in the presence of K. pneumoniae infection. In vivo studies are needed to determine whether antibiotic-associated prolongation of PMN survival improves host response to infection.
Healy
Daniel P
DP
College of Pharmacy, University of Cincinnati, OH 45267, USA.
Silverman
Paul A
PA
Neely
Alice N
AN
Holder
Ian Alan
IA
Babcock
George E
GE
D000900:Anti-Bacterial Agents / Q000097:blood / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D004396:Coloring Agents; D005434:Flow Cytometry; D006801:Humans; D066298:In Vitro Techniques; D007711:Klebsiella pneumoniae / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D009504:Neutrophils / Q000187:drug effects* / Q000382:microbiology; D015610:Serum Bactericidal Test; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D000900:Anti-Bacterial Agents; D004396:Coloring Agents; D014409:Tumor Necrosis Factor-alpha