Cellulitis is a bacterial skin infection affecting deeper skin layers. It occurs when bacteria, often Staphylococcus or Streptococcus, enter through a break in the skin. Symptoms include a red, swollen, tender area that feels warm. Prompt treatment is crucial to prevent worsening and serious health issues.
How Untreated Cellulitis Progresses
Untreated cellulitis symptoms worsen progressively. The initial redness, warmth, swelling, and tenderness of the affected skin area will expand. The infection can spread rapidly, making the skin more inflamed and painful, with the rash growing quickly.
As the infection advances, the skin may develop a tight, glossy, or stretched appearance. Blisters can form, and individuals might also experience flu-like symptoms such as fever, chills, and fatigue.
Localized Severe Complications
Without appropriate treatment, severe localized complications can develop. Abscesses, pockets of pus under the skin, are common and often require drainage and antibiotics. In more severe cases, untreated cellulitis can lead to tissue death (necrosis), sometimes called necrotizing cellulitis. This can result in open wounds, ulcers, or gangrene, where the affected skin turns black. Such extensive tissue damage often necessitates surgical removal of dead tissue (debridement) to prevent further spread and promote healing.
Systemic Spread and Life-Threatening Outcomes
The most serious consequences of untreated cellulitis occur when the infection extends beyond the skin and enters the bloodstream. This systemic spread can lead to life-threatening conditions. One outcome is bacteremia, the presence of bacteria in the bloodstream, which can be diagnosed through blood cultures.
Bacteremia can progress to sepsis, a life-threatening response causing widespread inflammation. Symptoms of sepsis include fever, rapid heart rate, confusion, low blood pressure, and rapid breathing. It can lead to tissue damage, organ failure, and be fatal if not treated urgently.
Bacteria traveling through the bloodstream can infect distant organs, resulting in other severe conditions. These include osteomyelitis (bone infection) and endocarditis (heart’s inner lining infection). In rare instances, bacteria can reach the brain and spinal cord membranes, causing meningitis. Another rare but severe complication is toxic shock syndrome, a rapid onset condition caused by bacterial toxins, which can lead to organ failure.
Factors Increasing Risk of Severe Outcomes
Several factors increase the risk of severe complications from untreated cellulitis. A compromised immune system, due to conditions like diabetes, HIV/AIDS, or treatments such as chemotherapy and chronic steroid use, makes individuals more vulnerable. High blood sugar in diabetic patients weakens the immune response and promotes bacterial growth.
Pre-existing medical conditions also contribute to a higher risk. Peripheral vascular disease, lymphedema, and chronic venous insufficiency impair blood flow and lymphatic drainage, making it harder for the body to fight infection. These conditions can lead to fluid accumulation and skin changes that predispose individuals to serious infections.
Breaks in the skin barrier provide entry points for bacteria, increasing the likelihood of cellulitis and its progression. These breaches include surgical wounds, cuts, insect bites, or skin conditions such as athlete’s foot, eczema, or shingles. Even minor skin injuries can allow bacteria to enter and establish an infection, especially with underlying risk factors.