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To evaluate the ability of the EmulSiv™ filter (EF) to remove extrinsic microbial contaminants from propofol. Aliquots of Staphylococcus aureus (S. aureus), Candida albicans (C. albicans), Klebsiella pneumoniae (K. pneumoniae), Moraxella osloensis (M. osloensis), Enterobacter agglomerans (E. agglomerans), Escherichia coli (E. coli), Serratia marcescens (S. marcescens), Moraxella catarrhalis (M. catarrhalis), Haemophilus influenzae (H. influenzae) and Campylobacter jejuni (C. jejuni) were inoculated into vials containing 20 mL of sterile propofol. The unfiltered inoculated propofol solutions served as controls. Ten millilitres and 20 mL samples of the inoculated propofol were filtered through the EF. All solutions were then subplated onto three culture plates using a precision 1 μL calibrated platinum loop and incubated. The number of colony forming units (CFU) were counted. Data were analyzed using a one-sample t test, and a P value of less than 0.05 was selected as the level of statistical significance. The EF was able to completely remove CFU of S. aureus, C. albicans, K. pneumoniae, M. osloensis, E. agglomerans, E. coli, S. marcescens, and M. catarrhalis (P < 0.05). A small number of H. influenzae CFU were able to evade filtration in both the 10 mL and 20 mL samples. C. jejuni CFU were able to evade filtration in only the 10 mL sample. The EF removes the majority of microbial contaminates from propofol with the exception of H. influenzae and C. jejuni. Although the EF is capable of removing most of the microbial contamination produced by H. influenzae and C. jejuni, a few CFU are capable of evading filtration. Consequently, even the use of a filter capable of removing microbial contaminants is not a substitute for meticulous aseptic technique and prompt administration when propofol is used.

Propofol emulsion supports bacterial growth.Extrinsic contamination of propofol has been implicated as an etiological event in postsurgical infections. When added to propofol, local anesthetics (e.g., lidocaine) alleviate the pain associated with injecting it. Because local anesthetics have antimicrobial activity, we determined whether lidocaine would inhibit microbial growth by comparing the growth of four microorganisms in propofol and in mixtures of propofol and lidocaine. Known quanta of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans were inoculated into solutions of 1% propofol, 0.2% lidocaine in propofol, 0.5% lidocaine in propofol, 0.5% lidocaine in isotonic sodium chloride solution, and 0.9% isotonic sodium chloride solution. All microorganisms were taken from stock cultures and incubated for 24 h. Growth of microorganisms in each solution was compared by counting the number of colony-forming units grown from a subculture of the solution at 0, 3, 6, 12 and 24 h. Propofol supported the growth of E. coli and C. albicans. Propofol maintained static levels of S. aureus and was bactericidal toward P. aeruginosa. The addition of 0.2% and 0.5% lidocaine to propofol failed to prevent the growth of the studied microorganisms. The effect of 0.5% lidocaine in isotonic sodium chloride solution did not differ from the effects of isotonic sodium chloride solution alone. We conclude that lidocaine, when added to propofol in clinically acceptable concentrations, does not exhibit antimicrobial properties. Implications: Local anesthetics such as lidocaine have antimicrobial activity. Propofol supports the growth of bacteria responsible for infection. Bacteria were added to propofol and propofol mixed with lidocaine. The addition of lidocaine to propofol in clinically relevant concentrations did not prevent the growth of bacteria. The addition of lidocaine to propofol cannot prevent infection from contaminated propofol. (Anesth Analg 1999;88:209-12)