Cellulitis is an acute bacterial infection of the dermis and subcutaneous tissues. It commonly affects the lower limbs but can occur anywhere on the body. The most common causative organisms are β-haemolytic streptococci and Staphylococcus aureus. Bacteria usually enter through breaks in the skin, such as cuts, ulcers, fissures, insect bites, or wounds. Clinical Features Common clinical features include poorly demarcated skin redness, localized warmth, swelling, and tenderness. Fever, chills, and general malaise may also occur. The affected area may spread over hours to days. Purulent discharge or a fluctuant collection may indicate an abscess, which may require drainage in addition to antibiotic treatment. Diagnosis and Management Diagnosis is primarily based on clinical examination. Routine blood tests and cultures are generally unnecessary in uncomplicated cases but may be indicated in severe infections, unusual exposures, immunocompromised patients, or suspected bloodstream infection. Ultrasound may help identify an abscess when the clinical examination is inconclusive. Treatment depends on the severity of infection, likely causative organisms, drug allergies, local antimicrobial resistance patterns, and individual patient factors. Mild non-purulent cellulitis is usually treated with an appropriate oral antibiotic targeting streptococci. Severe infections or cases involving specific risk factors may require broader-spectrum or intravenous antibiotic therapy. Elevation of the affected limb, treatment of skin breaks, and management of oedema can support recovery. Reassessment is essential if symptoms worsen or fail to begin improving within 48–72 hours after treatment begins. Complications and Red Flags Potential complications include abscess formation, bacteraemia, and, rarely, necrotising soft-tissue infection. The following warning signs require urgent hospital assessment: • Rapid progression of redness or swelling. • Severe pain disproportionate to the clinical findings. • Dusky skin discoloration or the development of bullae. • Confusion, hypotension, or signs of severe systemic toxicity. Conclusion Early recognition and appropriate antibiotic treatment usually lead to recovery. Clinical assessment should distinguish cellulitis from conditions with similar presentations, including venous stasis dermatitis, deep-vein thrombosis, and contact dermatitis, to ensure appropriate management. References • Stevens DL, et al. Practice Guidelines for the Diagnosis and Management of Skin and Soft Tissue Infections: 2014 Update by the Infectious Diseases Society of America. Clinical Infectious Diseases. 2014;59(2):e10–e52. • National Institute for Health and Care Excellence (NICE). Cellulitis and erysipelas: antimicrobial prescribing. NICE Guideline NG141. Educational Note: This article is intended for educational purposes only and does not replace clinical judgement or adherence to local antimicrobial guidelines. Al Mustaqbal University The First University in Iraq