The next time you walk into a hospital room, beware! It could be contaminated with drug-resistant bacteria, which can easily infect you, and cause deadly conditions like pneumonia and meningitis.

Researchers at the University of Maryland School of Medicine tested freshly cleaned hospital rooms for drug-resistant bacteria.

The result? If the last patient who had been in the room had a drug-resistant bacterial infection, the room was covered in it. Everywhere from the floor, to the bed rails, to drawer handles.

Most hospital cleaning products are powerful enough to kill those germs. But the problem is that a worker has to decontaminate every square inch of a room. If they don’t, the moment a hospital worker, visitor, or patient touches a dirty surface, it quickly gets spread around. And experts warn that since the deadly bacteria can survive on surfaces for months, it could potentially infect hundreds of future patients per room, sparking a fatal outbreak.

Now, you may be tempted to go on do-it-yourself bleach duty the next time you hit the hospital. But that could backfire big time.

Experts say that your cleaning products could clash with hospital cleaning products, and cause toxic fumes. And even interfere with some kinds of medical equipment.

The fix: Before you walk into a hospital room, ask the nurse if it’s been properly sterilized for bacteria. If not, then request a new one.