DO INFUSIONS OF MIDAZOLAM AND PROPOFOL POSE AN INFECTION RISK TO CRITICALLY ILL PATIENTS

In order to investigate bacterial contamination of i.v. anaesthetic ag ents, given by infusion to critically ill patients, we have cultured r esidual infusion fluid from infusion syringes, 50 containing midazolam and 50 propofol. The infusions had been prepared with routine aseptic precautions and had been running for between 0.75 and 21.25 h. Only s canty growths of Staphylococcus epidermidis were isolated from seven s yringes (four midazolam and three propofol). Small volume samples were more likely to produce bacterial growth than large volume specimens. Midazolam infusions made up in 5% glucose were more likely to be conta minated than those made up in 0.9% saline. Antibacterial activity was detected in 18 midazolam and one propofol filtrate. Midazolam infusion s inhibited the growth of all seven of the S. epidermidis isolates, wh ereas propofol supported similar rates of multiplication to that obtai ned with control broth medium. The results of this study imply that co ntamination of the infusions probably occurred after they were disconn ected from the patient. Despite the ability of propofol to support mic robial multiplication, we have no evidence to suggest that this is cli nically significant when infusions are prepared with conventional asep tic precautions.