Sneakers and shoes do end up getting the the brunt of it all. Not only are you sweating in them, but they provide a “chamber” of sorts for this bacteria to manifest and fester – leading to smelly odors. The first step you can take is practicing preventative measures. If you know your feet tend to get smelly, make sure you always have clean feet and clean socks. To take it further, try using a powder or spray such as Odor Eaters. If the shoe odor is already present, try using some tried and true baking soda.
If it’s your shoes that need the cleaning, the first step would be to remove the excess dirt both from inside and outside the shoe using a shoe brush or a tooth brush. After mixing a small amount of detergent and water, dip either the same or a different brush into the mixture and clean the affected areas. Go over the outside of the shoe with a sponge and then air dry.