Staphylococcus bacteria, often simply called “staph,” are a common type of germ found on the skin and in the nose. While staph bacteria are typically harmless, certain conditions can allow them to cause infections. There are over 30 different types, or “strains,” of Staphylococcus bacteria, but only a few are commonly associated with human illness.
Common Strains and Their Characteristics
Among the various Staphylococcus strains, Staphylococcus aureus is the most significant human pathogen. This bacterium is commonly found in the nose of about 30% of healthy adults and on the skin of about 20%. Staphylococcus aureus can lead to a wide range of infections, from minor skin issues to more severe, life-threatening conditions if it enters the bloodstream or internal organs.
One type of S. aureus is methicillin-resistant Staphylococcus aureus (MRSA), which has developed resistance to several common antibiotics. This resistance makes MRSA infections more challenging to treat compared to other staph infections. MRSA is a significant public health concern, frequently encountered in healthcare settings, but also increasingly prevalent in community-acquired infections.
In contrast, methicillin-sensitive Staphylococcus aureus (MSSA) refers to S. aureus strains that remain susceptible to standard antibiotics. While MSSA infections are generally easier to treat, both MRSA and MSSA can cause similar types of infections and present with comparable symptoms. The key difference lies in their antibiotic susceptibility, which determines the appropriate treatment approach.
Another strain, Staphylococcus epidermidis, is a common bacterium found on human skin and mucous membranes. This species typically acts as a harmless commensal organism, meaning it lives on the body without causing disease. However, S. epidermidis can become an opportunistic pathogen, particularly in individuals with weakened immune systems or those with implanted medical devices like catheters or prosthetic joints. Its ability to form biofilms on artificial surfaces is a major factor in these device-related infections, making them difficult to treat.
Recognizing Staph Infections
Staph infections often manifest on the skin. Common skin infections include boils, which are painful, red lumps filled with pus that develop in hair follicles or oil glands, often appearing under the arms or around the groin or buttocks. Impetigo, a contagious and often painful rash, typically features large blisters that may ooze fluid and form a honey-colored crust. Cellulitis involves deeper layers of the skin, causing redness, swelling, and pain on the surface, sometimes accompanied by oozing sores.
While skin infections are the most frequent presentation, staph bacteria can also cause more serious internal infections if they enter the body, such as through a cut or wound. These can include bloodstream infections (bacteremia), which may lead to fever and low blood pressure. Staph can also cause pneumonia, an infection of the lungs, or osteomyelitis, a bone infection characterized by pain, swelling, warmth, and redness in the affected area, along with fever. Infections of heart valves (endocarditis) and joints (septic arthritis) are also possible, though less common than skin infections.
It is important to seek medical attention if a suspected staph infection worsens or spreads quickly, if it persists for more than a week, or if it is accompanied by a fever or significant pain. Individuals with weakened immune systems, such as those who have had an organ transplant or are undergoing chemotherapy, should also consult a healthcare provider promptly if they suspect a staph infection. Red streaks radiating from a wound or severe pain also require immediate medical attention.
Treatment and Prevention
Antibiotics are the primary treatment for staph infections, but the specific type of antibiotic prescribed depends on the infecting strain. For MSSA infections, specific antibiotics are commonly used, while MRSA infections often require different antibiotics. Completing the full course of antibiotics as prescribed, even if symptoms improve, is important to ensure the infection is fully eradicated and to help prevent the development of antibiotic resistance.
In addition to antibiotics, drainage is often necessary for localized staph infections like abscesses or boils. A healthcare provider may make a small incision to drain the accumulated pus, which can significantly aid in the healing process. This procedure often accompanies antibiotic therapy to effectively treat the infection.
Preventing staph infections involves good hygiene and careful wound care. Regular handwashing with soap and water for at least 20 seconds, or using an alcohol-based hand sanitizer when soap and water are unavailable. Keeping cuts, scrapes, and other open wounds clean and covered with sterile bandages until they heal helps prevent bacteria from entering the body. Avoiding the sharing of personal items like towels, washcloths, razors, clothing, and athletic equipment can also reduce the spread of staph bacteria. Regularly washing clothes and bedding at the warmest temperature recommended by the fabric’s label also helps to eliminate any lingering bacteria.