A staph infection is caused by Staphylococcus bacteria, commonly found on the skin or in the nose of healthy individuals. While many strains are harmless, some can cause infections when they enter the body through cuts, abrasions, or medical devices. Staph infections can range from mild skin issues, such as boils, abscesses, or impetigo, to more serious infections affecting the bloodstream, lungs, heart, or bones. Symptoms vary depending on the site of infection and may include redness, swelling, warmth, pain, pus formation, fever, or fatigue. Certain strains, like methicillin-resistant Staphylococcus aureus (MRSA), are resistant to common antibiotics, making infections more difficult to treat and increasing the risk of complications.