Understanding Cellulitis: Causes, Symptoms, and Management

Introduction

Cellulitis is a common bacterial skin infection. It poses a high global burden, leading to millions of cases annually with substantial economic loss and hospitalizations. It is very important to diagnose and treat cellulitis early to prevent hospitalizations and severe life-threatening complications.

What is Cellulitis?

Cellulitis is a bacterial infection of the skin and adjacent tissue, usually occurring due to a break in the skin from an injury, insect bite, cut, wound, or poor skin health. It typically presents with four clinical signs:

Dolor (Pain): Discomfort experienced due to inflammation.
Calor (Heat): Warmth felt in the infected area.
Rubor (Redness): Visible redness indicating inflammation.
Tumor (Swelling): Puffiness that accompanies the infection.

Causes of Cellulitis

Cellulitis usually begins after a break in healthy skin, such as a cut, injury, or bite, through which bacteria can enter the skin and subcutaneous tissue. Common bacteria responsible for cellulitis are Staphylococcus and Streptococcus. These entry points break the barrier created by the skin, allowing microbes to enter the subcutaneous tissue or bloodstream.

Risk Factors for Developing Cellulitis

Various risk factors increase the likelihood of developing cellulitis:

Skin injuries: Cuts, scrapes, and other skin damage.
Recent cellulitis: A history of cellulitis significantly increases the risk of recurrence, especially in people with obesity, limb edema, and other skin conditions.
Chronic skin conditions: Conditions that compromise skin integrity.
Weakened immune system: Individuals with compromised immunity are more vulnerable.
Specific health conditions: Diabetes and obesity can exacerbate risks.
Lymphedema: People with this condition are at higher risk of cellulitis.

Signs and Symptoms of Cellulitis

Local skin signs:

Redness: Erythema and its progression as a sign of infection.
Swelling: Puffy appearance of the skin.
Tenderness: Pain upon touch in the affected area.
Warmth: Localized rise in temperature.
Skin appearance: Tight, glossy, stretched skin may indicate cellulitis.
Blisters and fluid-filled vesicles: Additional localized symptoms.
Skin dimpling: Lumpy or pitted surface as an indicator.

Generalized or systemic signs:

Fever and chills as indicators of infection spreading.
Myalgias: Muscle pain as a symptom.
Nausea and vomiting: Potential systemic effects from infection.

Diagnosis of Cellulitis

Cellulitis is typically diagnosed through physical examination by an experienced and qualified doctor. Additional tests may include:

Complete Blood Count (CBC) to assess severity.
C-reactive protein (CRP) to measure inflammation levels in the body.
Liver and Renal Function Tests (LFT and RFT) for comprehensive assessment.
Skin cultures for confirming bacterial infection.

Management of Cellulitis

Standard treatment approaches for cellulitis include antibacterial management. It is commonly caused by gram-positive bacteria, specifically Staphylococcus and Streptococcus. In individuals with comorbid conditions or weakened immune systems, additional culprits could be gram-negative bacteria. In such cases, skin culture is always advised to prevent devastating complications.

Antibiotics: Use of oral or intravenous antibiotics for infection management.
NSAIDs: Anti-inflammatory drugs can be used for symptomatic relief along with other supportive management.
Limb elevation: Importance of elevating affected limbs to reduce swelling.
Compresses: Use of hot or cold compresses for symptomatic relief.

Complications of Untreated Cellulitis

If not treated or treated improperly, cellulitis can lead to severe complications:

Severe sepsis: A life-threatening response to infection.
Necrotizing fasciitis: Fast-spreading infection requiring urgent surgical attention.
Gangrene: Tissue death due to lack of blood flow or infection, which may require amputation.
Risk of death: Death is possible if not treated on time, especially in individuals with compromised immune systems, leading to Multiorgan Dysfunction Syndrome (MODS) and death due to various complications.

Importance of Healthy Skin

Skin acts as the first line of defense against microbial invasion through the following mechanisms:

Physical barrier: The epidermis is the outermost layer of skin, which is strong and waterproof, preventing microorganism entry. Keratin is a protein in skin cells that strengthens the skin barrier against invasions.
Skin Surface Conditions: Dry, salty, and acidic environment discourages bacterial growth.
Shedding of Dead Skin Cells: Regular process that removes attached microorganisms.
Chemical Defense mechanisms: Antimicrobial Peptides (AMP) are naturally produced compounds that inhibit or kill invading microorganisms. Sebum is an acidic, waxy substance secreted by the skin that further prevents bacterial growth.
Importance of the Skin Microbiome: Our skin is home to a diverse community of microbes, including viruses, fungi, and bacteria, collectively known as the skin microbiome, which competes against invading bacteria to inhibit their growth.

Case Presentation

A 52-year-old male presented in the outpatient department with a complaint of pain and swelling in his right foot for one week. He has no comorbid complications and denies any bite or injury over the affected foot. He was taking treatment from a local practitioner.

Examinations and findings:

General physical examination was normal.
Local examination of the right foot revealed a local rise in temperature, redness, edema, and local tenderness. The skin over the area of redness appeared glossy, stretched, and shiny. These local symptoms were enough for the diagnosis of cellulitis.

Image 1. Showing Cellulitis of right foot. Note the area of redness which is swollen, streatched and shiny.

Management:

The patient was advised to maintain proper hygiene, elevate the limb, and apply ice packs for no more than 5 minutes while elevating the limb three times a day to relieve pain and swelling.
Antibiotics were prescribed to inhibit/kill the bacteria.
NSAIDs were prescribed for symptomatic relief.

Conclusion

Cellulitis is a bacterial infection of the skin and subcutaneous tissue caused by a break in the skin. Patients with compromised immune systems are more susceptible to developing cellulitis and should take extra care of their skin, especially in the lower limbs and other hidden areas. It is important for readers to seek medical attention for suspicious skin infections.