The effects of midazolam, droperidol, fentanyl, and alfentanil on phagocytosis and killing of bacteria by polymorphonuclear leukocytes in vitro.

Polymorphonuclear leukocytes (PMNL) make an outstanding contribution to the defence against invading bacteria. We studied the effects of midazolam, droperidol, fentanyl, and alfentanil on phagocytosis and killing of Staphylococcus aureus and Escherichia coli by PMNL in vitro. Using a method described by Eggleton et al., PMNL were isolated from venous blood samples obtained from ten volunteers. The fluorescence microscopic method mentioned by Bellinati-Pires et al. was used to examine phagocytosis and killing. Whereas both midazolam and droperidol caused a significant inhibition of phagocytosis as well as bactericidal activity, fentanyl and alfentanil did not influence these PMNL functions. In order to find out whether midazolam and droperidol are able to intensify perioperative bacterial infections in vivo as well, additional clinical studies should be conducted.