engleski

Evaluation of effectiveness of chemical disinfectants on the growth of Francisella novicida-growing amoebae

Francisella tularensis is a highly infectious, gram-negative intracellular bacterium and the causative agent of tularemia. The bacteria has been isolated from more than 250 wild species including protozoa cells. Our previous study have shown that infection of amoebae by F. novicida, surprisingly, did not enhance the infectivity of Francisella. Since the organisms is very virulent and persists in the environment for years it is important to determine the efficacy of disinfectants, when used to inactivate this biological agent. Our previous results have shown that disinfectants, 5 % of Asepsol has bactericide effect on F. novicida while 0.2% Bigvasan and 1% Descocid only reduce the number of bacterial colonies. In this study, we further investigated the effectiveness of three disinfectants (0.2%, 0.5% and 1.0% Bigvasan and Descocid as well as 1%, 2% and 5% Asepsol eko) on decontamination of F. novicida after growing of the bacterium in Acanthamoeba castellanii for 48 hours. Our results showed that Asepsol (1%, 2% and 5%) and 1% Descocid completely inhibited bacterial growth, regardless the time of exposure (10 sec, 5, 10 and 15 minutes). The efficacy of Bigvasan and Descocid was concentration and time of the exposure dependent, on the Francisella-growing amoebae. Surprisingly, in comparison to previous results, F. novicida in growing amoebae are more sensitive to decontamination by 1% of Descocid and 0.2 % of Bigvasan. We can conclude that among tested disinfectants, Asepsol eko, even at four time’s lower concentrations than manufacturer-recommended, exhibits the best bactericidal activity against F. novicida-growing amoeba.

Francisella, disinfectants

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