Do you mean the wick inside the tank?
Bacteria is everywhere in the air, worrying about if it lands on the expanded wicks more than it does on the floral foam as found in humidifiers like Hydras and Cigar Oasis units is kind of pointless. Wicks have to be changed periodically, as does the floral foam in those other units, it's just a fact of life. You can extend the length of time between changes by keeping things clean and using distilled water.
A number of high end humidification systems have been successfully using tanks with wicks for decades. Habitat Monitor, Bob Stabell's (Aristocrat humidors) Set-and-Forget, Avallo Accumonitor, to name a few.
I was speaking of what generation control head with the photo, the new tanks and wicks are no different from the old tanks aside from the clear lids so you can see the water level.