NTU Undergraduates' research April 2014 - Biosciences | Page 50

NOTTINGHAM TRENT UNIVERSITY
SCHOOL OF SCIENCE AND TECHNOLOGY
NIALL RITCHIE -- N0303499
A STUDY OF THE ANTIBACTERIAL EFFICACY OF BENZALKONIUM CHLORIDE AND POTASSIUM
SORBATE PRESERVATIVES ON BACILLUS SUBTILIS, ESCHERICHIA COL MG1655 AND
PSEUDOMONAS AERUGINOSA POA1 IN LIQUID PHARMACEUTICAL PRODUCTS AND RAW IN
VARYING CONCENTRATIONS.
ABSTRACT

The use of preservatives in liquid pharmaceutical formulations is of significant prevalence in the
pharmaceutical industry. Used in order to prevent contamination and/ or spoilage by
microorganisms, preservatives are selected on a product individual basis to convey specific
antimicrobial properties based on the route of administration or the product’s composition. The aim
of this study was to observe the antibacterial efficacy of the preservatives benzalkonium chloride
(BAK) in Optrex multi-action eye wash, potassium sorbate (PS) in Omega3 vitamin liquid and in the
varying concentrations of the raw preservatives in PBS solution against three representative bacteria:
Bacillus subtilis (laboratory stock), Escherichia coli MG1655 leu::Tn10 and Pseudomonas aeruginosa
POA1. Results showed significant resistance to BAK by B. subtilis and strong antibacterial effects
against both gram-negative species’. Increased resistance to PS was observed in both gram-negative
species, with P. aeruginosa displaying proliferation in the raw PBS solutions. B. subtilis displayed the
greatest sensitivity to PS in all forms. PS was found have increased efficacy in-product when
compared to that of the raw PBS solutions. Results served to highlight the variable resistance of
gram-positive and gram-negative bacteria to antimicrobial agents such as preservatives.