Moisture and water will always exist in your shower and/or tub. It’s the perfect breeding ground for mold. Here are some simple tips to keep mold from spreading:
Add a bathroom exhaust fan that is properly vented to outside of the home (not into attic space).
Keep exhaust fan on for at least 10 minutes after shower has ended (timers can be added by an electrician).
Add a dehumidifier to reduce the humidity levels in your bathroom.
Keep your shower and/or tub clear of any standing water and clean regularly with anti-microbial bathroom cleaner.