Isopropyl alcohol (2-propanol) can be used as disinfectant.
For increasing concentration of it in water, the effect as disinfectant increases, and then decreases again.
Typical concentrations for use as disinfectant seem to be 60-75% isopropyl alcohol in water.
Wikipedia: Isopropyl alcohol - Medical mentions membrane pores of bacteria that will not open without water.
That does not feel like the full explanation to me; I expect there are bacteria with membrane pores of diverse kind. Does 100% isopropyl alcohol not disinfect at all - or just more slowly? What abour the effect on other pathogens?