INHIBITION OF BACTERIAL GROWTH BY LIDOCAINE IN PROPOFOL EMULSION
Koçak Z.,Altunkan A.A.,Cýnel Ý.H.,Öztürk C*.,Oral U.
Department of Anesthesiology&Reanimation, Mersin University Medical Faculty,Mersin/TURKEY
(*)Department of Clinical Microbiology, Mersin University Medical Faculty
Introduction:
Propofol emulsion supports bacterial growth and therefore must be prepared for administration in an aseptic manner (2)Lidocaine is frequently added to the solution for painless injection and it was also known to have antimicrobial properties(1,3).In this study we aimed to investigate whether the admixture of lidocaine/propofol and lidocaine alone prevents bacterial growth.
Materials and Methods:
Inhibition of bacteria was determined in each of 4 drug solutions.Four 20 ml samples,%2 lidocaine and propofol emulsion,were formulated as follows:
10mg/ml propofol, 20mg/ml lidocaine, 4mg/ml lidocaine+8mg/ml propofol and 8mg/ml lidocaine+6mg/ml propofol.
These samples were studied for E.Coli,Staf.Aureus and P.Aeruginosa. 2µl of 106 dilution of each bacteria was inoculated in a 50 cc culture tube containing tryptic soybroth media.Then 20 cc drug samples were added to these culture tubes. Each sample was incubated for 4 hours at 37°C in a shaker bath.After 4 hours 0.001cc of each sample was transferred to media(sheep blood agar and Mc Conkey agar).After incubation for 24 hours at 37°C, the number of colonies was counted per plate (colonies/cc)
Results:
Colony counts from the 4 solutions for 3 bacterias as follows:
|
|
E.Coli |
Staf.Aureus |
P.Aeruginosa |
|
10mg/ml propofol |
100.000 |
7000 |
2000 |
|
4mg/ml lidocaine+8mg/ml propofol |
75.000 |
3500 |
no growth |
|
8mg/ml lidocaine+6mg/ml propofol |
50.000 |
2000 |
no growth |
|
20mg/ml lidocaine |
no growth |
no growth |
no growth |
Discussion:
The study shows that propofol strongly supports the growth of E.Coli,Staf.Aureus
and P.Aeruginosa.Lidocaine behaved differently exhibiting markedly bacteriocidal
properties toward all of bacterias. The mechanisms of antimicrobial effect of lidocaine may be due to distruption of transmembrane bioelectrical potentials and the increased pH of propofol/lidocaine
admixture(4,5).
References: