Cellulitis

Original Editors - Students from Bellarmine University's Pathophysiology of Complex Patient Problems project.

Top Contributors - Kacie McClendon, Elaine Lonnemann, Erica Shelley, Kim Jackson, Lucinda hampton, Fasuba Ayobami, 127.0.0.1, Vidya Acharya, Claire Knott, Evan Thomas, WikiSysop and Karen Wilson

Introduction

Severe case of cellulitis

Cellulitis is a common infection of the dermis and subcutaneous tissues. Cellulitis typically presents with pain, erythema, oedema, and warmth. Cellulitis is not transmitted by person-to-person contact as the epidermis is not involved. If correctly identified and treated promptly with appropriate antibiotic treatment is usually resolves.

Etiology

Cellulitis and lymphedema

The skin is a protective barrier that stops normal skin flora and other microbial pathogens reaching the subcutaneous tissue and lymphatic system. If a skin breakage occurs normal skin flora and other bacteria can enter the dermis and subcutaneous tissue, leading potentially to an acute infection affecting the deep dermis and subcutaneous tissue. Cellulitis most commonly results from infection with group A beta-hemolytic streptococcus (i.e., Streptococcus pyogenes).

Risk factors for cellulitis include: skin injuries; surgical incisions; intravenous site punctures; fissures between toes; insect and animal bites; other skin infections; patients with comorbidities such as diabetes mellitus, venous insufficiency, peripheral arterial disease, and lymphedema.

Epidemiology

Cellulitis is relatively common, occurring often in middle-aged and older adults. Men and women, have a similar incidence of cellulitis. There are approximately 50 cases per 1000 patient-years

Pathophysiology

Cellulitis takes place after the skin is disrupted and microorganisms invade the subcutaneous tissues. Most commonly the infective agent is beta-haemolytic streptococci (most often) or staphylococcus aureus (including methycillin-resistant).

Clinical Presentation

A classic presentation of cellulitis: poorly demarcated erythema 

Typical symptoms of cellulitis include acute poorly demarcated and spreading erythema along with pain, swelling, and warmth. Commonly affects a lower limb but can occur on any area of skin or underlying subcutaneous tissue. Regional lymphadenopathy and lymphangitis may be present alongside systemic features such as fevers and rigors.

Examination

Patients with cellulitis will reveal an affected skin area typically with a poorly demarcated area of erythema. The erythematous area is often warm to the touch with associated swelling and tenderness to palpation. The patient may present with constitutional symptoms of generalized malaise, fatigue, and fevers.

• Ask for a complete history of the presenting illness, focusing on the context in which the patient noticed the skin changes or how the cellulitis began to occur.
• It is essential to ask patients if they: recently traveled, experienced any trauma or injuries, have a history of intravenous drug use, and/or have had insect or animal bites to the affected area.
• A complete and thorough past medical history should additionally be conducted to evaluate for possible chronic medical conditions that predispose patients to cellulitis, such as diabetes mellitus, venous stasis, peripheral vascular disease, chronic tinea pedis, and lymphedema. Diabetes Mellitus is one of most common comorbidities among those hospitalized for acute bacterial infections including cellulitis. Following a cellulitis infection, those with diabetes require a longer course of antibiotic therapy and are more likely to have an outpatient follow-up visit..
• Inspected area to look for any area of skin breakdown. The area should be demarcated with a marker to monitor for continuous spread. The area should be palpated to feel for fluctuance that could indicate the formation of a possible abscess.
• Gently palpate the affected area, be sure to note any presence of warmth, tenderness, or purulent drainage.
• Cellulitis can present on any area of the body, but most often affects the lower extremities. It is rarely bilateral. 
• In lower extremity cellulitis, careful examination between interspaces of the toes should take place.
• Check for proper sensation and verify pulses are intact to monitor closely for compartment syndrome.
• Note if there are developing vesicles, bullae, or the presence of peau d'orange and lymphadenopathy.

Diagnosis

Cultures is most commonly diagnosed by history and physical examination alone. Two of the four criteria (warmth, erythema, edema, or tenderness) are needed for diagnosis.

Medical Management

Patients presenting with mild cellulitis and no systemic signs of infection require antibiotics. The duration of oral antibiotic therapy should be for a minimum duration of 5 days.

• Hospitalization for systemic antibiotics may be requires for patients with systemic signs of infection, have failed outpatient treatment, are immunocompromised, exhibit worsening erythema, are unable to tolerate oral medications, or have cellulitis overlying or near an indwelling medical device.
• It is beyond a physiotherapists scope to know the individual antibiotics and best choices. The pharmacist ideally will have a board specialty in infectious disease to assist and work with the clinician on the best antibiotic selection.

Physical Therapy Management

While there is lack of evidence that discusses specific physical therapy interventions for cellulitis, therapists should be aware of the signs and symptoms in order to refer the patient appropriately. Physical therapists should have awareness of risk factors and various causes of cellulitis, in addition to signs and symptoms.
Modalities that physical therapists can use for a patient with cellulitis include

• Rest and elevation of the affected limb is important and can help alleviate pain.
• The application of cool, wet, sterile bandages is also recommended for pain relief, and ice can be used as well.

Preventative Measures: Compression stockings; Exercise promotion and specific exercises eg calf pumps whilst standing in lines etc.; Educate patient re the importance of maintaining good hand hygiene and adequately clean any future abrasions in their skin.

Differential Diagnosis

Many and include:

• Necrotising soft tissue infections
• Deep vein thrombosis
• Myriad of non-infective erythematous rashes
• Dermatitis
• Thermal injury

Complications

Without prompt diagnosis and treatment, cellulitis could lead to several complications. Cellulitis that leads to bacteremia, endocarditis, or osteomyelitis will require a longer duration of antibiotics and possibly surgery. Cellulitis can spread systemically through the lymphatics and blood stream, which can lead to further complications. If cellulitis does spread systemically through one of these systems, it can cause flu-like symptoms such as fever, rigors, nausea, and vomiting. Though rare, there is a risk for severe sepsis, gangrene, or necrotizing fasciitis if cellulitis spreads systemically and is left untreated.

Prognosis

Overall, cellulitis has a good prognosis

• If promptly diagnosed cellulitis with correct antibiotic treatment, patients can expect to notice an improvement in signs and symptoms within 48 hours.
• Annual recurrence of cellulitis occurs in about 8 to 20% of patients, with overall reoccurrence rates reaching as high as 49%
• Recurrence is preventable with prompt treatment of cuts or abrasions, proper hand hygiene, as well as effectively treating any underlying comorbidities.
• There is approximately an 18% failure rate with initial antibiotic treatment.

Resources

A video link by dermatologist Dr. Noah Craft MD, PhD, DTMH discusses Cellulitis from the provider point of view and includes case studies, differential diagnosis, and treatment approaches.