There are several types of bacteria that can be considered "bad" or harmful to the skin, as they can contribute to skin infections and other skin problems. Here are some of the most common types of bad skin bacteria: Staphylococcus aureus: This type of bacteria is commonly found on the skin and can cause a variety of skin infections, including impetigo, folliculitis, boils, and cellulitis. Streptococcus pyogenes: This type of bacteria is responsible for many skin infections, including streptococcal impetigo and cellulitis. Propionibacterium acnes: Although this type of bacteria is normally present on the skin, an overgrowth of P. acnes can contribute to the development of acne. Methicillin-resistant Staphylococcus aureus (MRSA): This is a strain of Staphylococcus aureus that is resistant to many antibiotics and can cause serious skin infections, including boils and abscesses. Pseudomonas aeruginosa: This type of bacteria can cause skin infections, particularly in people with weakened immune systems. It's important to note that not all bacteria are bad, and that some types of bacteria can actually play a positive role in maintaining skin health. However, it's important to maintain good hygiene and to seek prompt medical attention if you develop symptoms of a skin infection, to prevent the growth of harmful bacteria on your skin.