Effect of different concentrations of acridine orange on selected gram positive and gram-negative organisms

Abstract

This investigation determined the effect of different concentrations of Acridine Orange (AO) on selected Gram positive and Gram negative organisms. Twenty (20) clinical isolates of multidrug-resistant strains that included Staphylococcus aureus (5;25%), Escherichia coli (6;30%) Pseudomonas aeruginosa (5;25%) and Klebsiella species (4;20%), were obtained from the Department of Medical Microbiology, Irrua Specialist Teaching Hospital, Irrua, Edo State, Nigeria. The differences in drug susceptibility profiles of the isolates before and after AO-curing, were evaluated and compared. In comparison, Staphylococcus aureus strains 1, 2 & 4; E.coli strain 1; P. aeruginosa strain 1&4, and Klebsiella species strains 1&3 showed statistically significant differences (P<0.05) in curing rates unlike Staphylococcus aureus strain 3 and E. coli strains 5&6 (P>0.05). E. coli strains 2&5, P. aeruginosa strains 2&3, and Klebsiella species strain 4, showed sensitivity to a minimum of one antibiotic and a maximum of two to the three concentrations of AO used, while Staphylococcus aureus strain 5, E.coli strain 3 and Klebsiella species strain 2, showed complete resistance to all the antibiotics used. Overall, curing was achieved in 25%, 35% and 75% of the 50ug/ml, 75ug/ml and 100ug/ml AO-treated isolates respectively; depicting the concentration dependent curing potential of Acridine Orange.