Staphylococcus bacteria grow white, yellow or orange colonies that look like a bunch of grapes. Some species cause conditions characterized by a pus discharge, some produce toxins destructive to cells, and some cause a common type of food poisoning. All are contagious. Staphylococcus aureus is commonly found on skin and mucus membranes, and does not normally cause serious illness. However, methicillin-resistant forms of staphylococcus aureus can be dangerous.
Boils, or furuncles, are round, pus-filled skin nodules that result from infection with staphylococcus aureus bacteria. The infection begins in a hair follicle or an oil gland, building until it reaches the skin's surface. Boils are common in children, those with poor hygiene and those with impaired immune systems.
Impetigo is a childhood illness characterized by painful fluid-filled blisters that ooze and crust. Sores may form anywhere on the body, but often cluster around the nose and mouth. Cellulitis affects deep skin tissues, causing redness, swelling and inflammation. Fever, chills and body aches may accompany the infection. According to the National Institutes of Health, cellulitis can be serious and even deadly, requiring prompt medical attention.
Some staphylococcus bacteria can survive in salt, high heat and the absence of moisture. These organisms can be transmitted in contaminated food. The onset of symptoms occurs within a few hours of eating, and may include nausea, vomiting, abdominal cramps and diarrhea; symptoms typically last 24 to 72 hours. Children and the elderly are vulnerable to dehydration and more severe illness.
Toxic shock syndrome caused by toxins produced by staphylococcus bacteria is rare, and is usually linked to surgical infections, super-absorbent tampons and contraceptive sponges. The onset of illness is sudden and may be fatal.
Bacteremia, or blood poisoning, is characterized by a persistent fever. This serious infection can invade internal organs or surgically implanted devices. Septic arthritis can result when staph bacteria travel from other parts of the body and invade one or more joints, most often the knee.
Methicillin-resistant staphylococcus aureus is what's commonly referred to as a "superbug." Due to over-use and misuse of antibiotic medications, some strains of staph are hard to kill with drugs that used to work against them. Treatment is often difficult and expensive. According to the CDC, in 2005 there were 94,360 MRSA infections in the United States, resulting in 18,650 deaths.
Healthcare-acquired MRSA is a pathogen that strikes mostly nursing home residents, dialysis patients and others with weakened immune systems. Another strain called community-acquired MRSA affects otherwise healthy persons in the general population. It is spread by close contact, such as between members of sports teams or families. According to the Mayo Clinic, community-acquired MRSA can cause boils that require surgical drainage, soft tissue infections and a serious type of pneumonia.