In vitro evaluation of the susceptibility of Acinetobacter baumannii isolates to antiseptics and disinfectants: comparison between clinical and environmental isolates

BACKGROUND: This study aims to assess the susceptibility of Acinetobacter baumannii isolates to the antiseptics and disinfectants commonly used, and to the non-approved product. METHODS: This is a prospective study carried out from February to August 2015, in the Bacteriology department of Mohammed V Military Teaching hospital of Rabat on A.baumannii isolates collected from colonized and/or infected patients and environmental samples. The antiseptics and disinfectants susceptibility testing was assessed using the micromethod validated in our department. The antiseptics and disinfectants studied were: 70% ethyl alcohol, chlorhexidine, povidone-iodine, didecyldimethylammonium chloride and a commercial product which was presented as a hospital disinfectant (non-registered product). RESULTS: Povidone-iodine, 0.5% chlorhexidine digluconate, 70% ethyl alcohol and didecyl dimethyl ammonium chloride in combination with N- (3-aminopropyl) -N-dodecylpropane-1, 3-diamine were effective against all the 81 A.baumannii isolates tested, and their logarithmic reduction ≥ 5 were observed in 100% of the isolates in their undiluted form. The strains isolated from patients were more resistant than environmental strains: at a dilution of ½ for 70% ethyl alcohol (37.77% vs 11.11%, p = 0.007) and at a dilution of 1/10 (100% vs 69.44%, p < 0.001) for povidone iodine. The non-registered product was ineffective with a resistance rate of 96.29% at a dilution of 1/50, 45.67% at a dilution of 1/10 and 13.58% in its purest form. CONCLUSION: Our study revealed the effectiveness of the main disinfectants and antiseptics used in Morocco; three antiseptics tested were effective in their purest form against the 81 A.baumannii isolates. Regarding disinfectants, our results showed an efficacy of didecyl dimethyl ammonium at the recommended use concentration and in its purest form. This study emphasizes the need for using disinfectants and antiseptics in dilutions recommended by the manufacturer because the insufficient dilutions of these products are not effective. Our findings also demonstrated an inefficiency of the non-registered product against A.baumanii isolates. However, the non-registered products should be prohibited.