INHIBITION OF BACTERIAL GROWTH BY LIDOCAINE IN
PROPOFOL EMULSION
Koçak Z.,Altunkan A.A.,Cınel İ.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: