Chitosan and its derivative water soluble Chitosan oligosaccharide are used in a variety of applications in pharmaceutical preparations. In this study, 2 wild (ATCC 15729 and PAO1) and 2 mutant strains (PT121 and PT149) of P. aeruginosa are investigated for drug-drug interactions in vitro. 10 antimicrobial agents (antibiotics) are combined with different degree of deacetylated Chitosans and Chitosan oligosaccharide. All the chitosans show synergistic activity with sulfamethoxazole, a sulfonamide antimicrobial agent. It is interesting to observe that the MIC value for the MexEF-OprN overexpressing mutant strain of P. aeruginosa is 5 fold higher than the other strains under investigation suggesting a possible role of this efflux pump in Sulfamethoxazole efflux. The findings suggest on the use of chitosans as enhancing agent in combination with antibiotics in pharmaceutical preparations.

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Chitosan and its derivative water soluble chitosan oligosaccharide are used in a variety of applications in pharmaceutical preparations. In this study, 2 wild (ATCC 15729, PAOl) and 2 mutant strains (PT121, PT149) of Pseudomonas aeruginosa and one strain of MRSA Staphylococcus aureus (ATCC43300) are investigated for drug-drug interactions in vitro. Ten antimicrobial agents (antibiotics) are combined with different degree of deacetylated chitosans and chitosan oligosaccharide. All the chitosans exhibit synergistic activity with sulfamethoxazole against all P. aeruginosa strains. Chitosan oligosaccharide-sulfamethoxazole and high molecular weight chitosan-sulfamethoxazole combination are more effective than other chitosan preparations against S. aureus. Microscopic studies of bacteria cell membrane show evidence of the collapse of membrane integrity after treating with the combined drugs. This suggests the membrane disruption function of the chitosan and disruption of cell membrane synthesis function of sulfamethoxazole act synergistically. In conclusion, chitosan and chitosan oligosaccharide are effective against both gram-negative and gram-positive bacteria in combination with sulfamethoxazole.