I get this in my shower area, too. I can get rid of it completely for months at a time by spraying/wiping down walls with white vinegar, then wiping but not rinsing surfaces with a saturated solution of borax in water. The slight residue of borax left behind prevents any kind of mold from growing until bathroom moisture eventually rinses the borax away.
This is the most bang you can get for your buck, or for the effort needed. The vinegar is completely non-toxic, but could irritate if inhaled, so be careful. I never spray borax, because it is mildly toxic and can be extremely irritating in the lungs, so just a wet wiping will do the trick. Both ingredients are considerably less toxic or potentially harmful than bleach.