You might want to wash your hands after touching money in your wallet.
Researchers at New York University's Dirty Money project found 3,000 types of bacteria on dollar bills they got from a Manhattan bank. Most were harmless, but some bills had bacteria containing antibiotic resistant genes like MRSA.
Bills collected in the winter were most likely to have bacteria that can cause pneumonia, which suggests that money may have a part in the spread of illness. Acne-causing bacteria was the most abundant species found.