Staphylococcus aureus, or S. aureus, is a bacterium that normally lives on the skin and mucous membranes, especially in the mouth and nose. Most of the time, it does not harm the body.
However, when the immune system is weakened or there is an open wound, this bacterium can multiply. It may then enter the bloodstream and cause sepsis, a serious body-wide infection and inflammatory response.
An S. aureus infection can range from a mild infection, such as folliculitis, to a more serious infection, such as endocarditis, when bacteria are present in the heart. Because of this, symptoms can vary from skin redness to muscle pain and bleeding.
Treatment for S. aureus infection should follow a doctor’s guidance and the bacterium’s antibiotic susceptibility profile. Antibiotics such as oxacillin or nafcillin are usually recommended.
Main symptoms
The main symptoms of S. aureus infection are:
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Pain at the site
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Swelling and redness of the skin
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Abscesses and blisters
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High fever, when the infection reaches the bloodstream
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Muscle pain, in some cases
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Headache
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Shortness of breath, when the infection reaches the lungs
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Nausea and vomiting, when the infection reaches the gastrointestinal system
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Abdominal pain and diarrhea, when the bacterium reaches the intestine
Depending on how severe the infection symptoms are, the person may need to be hospitalized and, in some cases, placed in isolation until the infection is treated.
How transmission occurs
Staphylococcus aureus bacteria can naturally be found in the body, especially on the skin, in the mouth, and in the nose, without causing any signs or symptoms. However, in some cases, they can enter the body through wounds and cause signs and symptoms of infection, especially when they reach the bloodstream and multiply.
Diseases caused by Staphylococcus aureus
The main diseases that can be caused by Staphylococcus aureus are:
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Folliculitis, which is characterized by small pus-filled blisters and skin redness caused by bacterial growth at the site
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Infectious cellulitis, in which S. aureus penetrates the deeper layer of the skin, causing pain, swelling, and intense skin redness
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Septicemia, or septic shock, which is a body-wide infection characterized by the presence of bacteria in the bloodstream and can affect several organs
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Endocarditis, which is a disease that affects the heart valves due to the presence of bacteria in the heart
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Osteomyelitis, which is a bone infection caused by bacteria and can occur when the bone is directly contaminated through a deep cut, fracture, or prosthetic implant, for example
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Pneumonia, which is a respiratory disease that causes difficulty breathing and can occur when bacteria affect the lungs
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Toxic shock syndrome or scalded skin syndrome, which is a skin disease caused by toxins produced by Staphylococcus aureus, leading to skin peeling
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Food poisoning, which can occur after eating contaminated foods, especially processed meats, that contain toxins produced by S. aureus
People with weakened immune systems due to cancer, autoimmune diseases, or infectious diseases, as well as people who have had burns, wounds, or surgery, are more likely to develop Staphylococcus aureus infections.
For this reason, it is important to wash your hands well and take the proper precautions in hospital settings to help prevent infections caused by this bacterium, in addition to eating foods that support the immune system.
Confirming a diagnosis
Diagnosis is made by isolating the bacterium in a microbiology laboratory using a biological sample. The doctor requests the sample based on the person’s symptoms, and it may include urine, blood, saliva, or wound drainage.
After the bacterium is isolated, an antibiotic susceptibility test is performed to identify the microorganism’s sensitivity profile and determine the best antibiotic to treat the infection.
If symptoms of S. aureus infection are present, schedule an appointment with the nearest doctor so an evaluation can be performed and the need for treatment can be assessed:
Treatment for S. aureus
Treatment for S. aureus is usually determined by the doctor based on the type of infection and the patient’s symptoms. The doctor should also consider whether there are other related infections, assess which infection poses the greatest risk to the patient, and decide which one should be treated most urgently.
Based on the antibiotic susceptibility test result, the doctor can indicate which antibiotic is likely to be most effective against the bacterium. Treatment is usually done with oxacillin or nafcillin for 7 to 10 days.
Methicillin-resistant Staphylococcus aureus
Methicillin-resistant Staphylococcus aureus, also known as MRSA, is very common mainly in hospitals, making this bacterium one of the main causes of hospital-acquired infections.
Methicillin is an antibiotic developed to fight beta-lactamase-producing bacteria. Beta-lactamases are enzymes produced by some bacteria, including S. aureus, as a defense mechanism against certain classes of antibiotics. However, some strains of Staphylococcus aureus, especially those found in hospitals, have developed resistance to methicillin and do not respond to treatment with this antibiotic.
Therefore, infections caused by MRSA are usually treated with antibiotics such as vancomycin, daptomycin, or linezolid for 7 to 10 days, or according to medical guidance.