MRSA cellulitis

MRSA cellulitis is a spreading bacterial infection of the deeper skin layerscaused by methicillin-resistant Staphylococcus aureus. It appears as a warm, red, swollen patch with no clear border, and can spread rapidly to surrounding tissue. It needs prompt antibiotic treatment and urgent assessment if fever or red streaks develop.

The hallmark of cellulitis is a red, swollen, warm patch of skin that expands over hours or days. The border is usually blurred, and the skin may feel tight or shiny. The area is often tender and can be painful to touch or move. In some cases small blisters form, or the skin develops a dimpled or greyish appearance if deeper tissue is involved.

Cellulitis often develops around a break in the skin — a cut, insect bite, surgical wound, or an existing abscess. It can occur anywhere on the body but is most common on the legs, arms, and face.

Abscess: an abscess is a localised pocket of pus with a soft centre. Cellulitis is a broader, spreading infection of the skin layers. The two often occur together: a boil or abscess can be surrounded by cellulitis.

Erysipelas: this is a more superficial infection with a sharply raised, bright red border. Cellulitis is deeper and has a less defined edge.

Venous eczema / dermatitis: this can also cause redness and swelling of the legs, but it is usually itchy rather than painful, and the skin is not warm. A clinician can distinguish the two and treat infection if present.

• People with skin breaks: cuts, ulcers, eczema, athlete's foot, insect bites, or surgical wounds
• People with diabetes, obesity, poor circulation, or weakened immune systems
• Those who have had MRSA before or carry MRSA in the nose or skin
• Older adults and people who inject drugs

Diagnosis is usually clinical, based on the appearance and history. A swab or sample from any abscess or wound helps confirm MRSA and guide antibiotic choice. Blood tests are reserved for people with fever, systemic symptoms, or signs of sepsis.

Antibiotics are the main treatment. Outpatient options for suspected MRSA cellulitis include clindamycin, doxycycline, trimethoprim-sulfamethoxazole, or minocycline. The exact choice depends on local resistance, allergies, and severity. A typical course lasts 5 to 14 days.

Hospital treatment is needed for severe cellulitis, facial involvement, fever or sepsis, rapidly spreading redness, failure to improve on oral antibiotics, or significant underlying disease. Intravenous vancomycin, daptomycin, or linezolid are commonly used in hospital.

Drainage of any associated abscess is essential. Antibiotics alone cannot clear a walled-off pocket of pus.

Self-care includes elevating the affected limb to reduce swelling, keeping the skin clean and dry, marking the edge of redness to monitor spread, and completing the full antibiotic course.

• Fever, chills, or feeling generally unwell
• Red streaks spreading from the red area
• Rapidly spreading redness or severe pain
• Cellulitis on the face, around the eye, or on the hand
• Confusion, shortness of breath, or low blood pressure