The in vitro effects of cetyltrimethylammonium naproxenate on oral and pharyngeal microorganisms of various ecological niches

The purpose of this study was to determine the in vitro susceptibility to c etyltrimethylammonium naproxenate for various aerobic and anaerobic micro-o rganisms responsible for oral and pharyngeal diseases by assessing the mini mum inhibitory concentrations (MICs) and minimum bactericidal concentration s (MBCs) or minimum fungicidal concentrations (MFCs) and by determining kil l-times. The MICs of cetyltrimethylammonium naproxenate for 46 tested strai ns (25 reference strains and 21 clinical isolates) ranged from 8 to 500 mu g/ml. The MIC was found to be 31.25 mu g/ml for 36% of the reference strain s. Even lower MIC values (15.63 mu g/ml) were observed for some anaerobic s trains, for Haemaphilus influenzae and for Candida tropicalis. MIC and MBC values corresponded for the majority of strains tested while the MFC for C. tropicalis and C. albicans was much higher. Only 9.5% of the clinical isol ates gave a MIC value of 31.25 mu g/ml. Enterococcus faecalis, Streptococcu s pyogenes and Staphylococcus aureus showed MIC at 62.5 mu g/ml. The MIC an d MBC values among the isolates were comparable, while the MFC value for th e yeasts was greater. A concentration of 125 mu g/ml of cetyltrimethylammon ium naproxenate inhibited the growth of all bacteria, except Enterobacteria ceae and Pseudomonaceae, and yeasts. Cetyltrimethylammonium naproxenate sho ws very rapid kill-time for S. sanguis (0 "), and rapid (15 ") for S. pyoge nes, S. dysgalactiae and S. mutans and for Moraxella catarrhalis, while a l onger kill-time was necessary for the other microbes tested.