What Are the Causes of Wound Cellulitis?

Acute cellulitis is an acute, diffuse, suppurative infection of subcutaneous, subfascial, interstitial, or deep loose connective tissue. Common pathogenic bacteria are Staphylococcus aureus, sometimes hemolytic streptococcus, and a few are caused by anaerobic bacteria and E. coli. In recent years, with the development of microbiology and the improvement of detection methods, anaerobic infections and mixed infections have received widespread attention.

Basic Information

English name

acute cellulitis

Visiting department

Emergency Department

Common locations

Loose connective tissue under the skin, subfascia, intermuscular space or deep

Common causes

Staphylococcus aureus, sometimes hemolytic streptococcus, a few are caused by anaerobic bacteria and E. coli.

Common symptoms

Local redness, swelling, heat, pain

Causes of Acute Cellulitis

After skin and mucous membrane damage, loose connective tissue under the skin is caused by bacterial infection. It can also be caused by the direct spread of local purulent infection or by lymphatic or blood transmission. The germs are mostly Staphylococcus aureus, sometimes hemolytic streptococcus, and can also be anaerobic, E. coli, or mixed infections. Cellulitis caused by gram-negative bacteria is occasionally seen in immunodeficiency patients.

Clinical manifestations of acute cellulitis

Local symptoms

The lesion was locally red, swollen, hot, and painful, and rapidly expanded to the surroundings. The red and swollen skin has no obvious boundary with the surrounding normal tissues. The central part is darker and the surrounding color is lighter. Those with shallower infection sites and looser tissues have obvious swelling and diffuse, less painful; when the infection is deep or the tissues are dense, the swelling is not obvious, but the pain is severe.

2. Systemic symptoms

Patients often have systemic symptoms of varying degrees, such as chills, fever, headache, fatigue, and increased white blood cell counts. General deep cellulitis, anaerobic bacteria, and congenital cellulitis caused by aerobic bacteria, systemic symptoms are more obvious, can have chills, high fever, convulsions, delirium and other serious symptoms. Acute cellulitis at the bottom of the mouth, submandibular, and neck can cause edema of the throat and compression of the trachea, causing difficulty breathing and even suffocation. Sometimes inflammation can spread to the mediastinum, causing mediastinitis and mediastinal abscesses.

3. Signs

The lesion was locally red and swollen, with obvious tenderness. Deeper lesions are less marked with local redness and swelling, often only local edema and deep tenderness. Convolutive cellulitis mostly occurs in the perineum and abdominal wounds, and can be checked during examination; loose connective tissue and fascia necrosis, severe edema with progressive skin necrosis, and pus with foul odor.

Acute cellulitis examination

Peripheral blood

(1) WBC count In general infection, WBC count> 10 × 10 ⁹ / L increased. If the white blood cell count is> (20 30) × 10 ⁹ / L, or <4 × 10 ⁹ / L, or immature white blood cells> 0.1%, or toxic particles appear, you should be wary of septic shock and sepsis.

(2) WBC Differential Counts An increase in white blood cell count is often accompanied by an increase in neutrophils.

2. Bacteriological examination

(1) Bacterial culture For patients with multiple and repeated infections, pus can be directly extracted from the abscess for bacterial culture. Positive results are helpful for diagnosis.

(2) Drug sensitivity test While culturing pus bacteria, drug sensitivity test can provide scientific basis for clinical drug treatment.

3. Laboratory inspection

(1) Imaging examination is helpful to judge early diseases and understand the degree of local tissue damage. Type B ultrasound The local tissue structure of the lesion is disordered, the central part shows uneven middle-low echo, the surrounding tissue is edema obvious, and the boundary is unclear. X-rays When the mediastinal abscess is caused by the spread of cellulitis at the floor of the mouth, submandibular, and neck, high-density images of mediastinal widening can be seen. CT examination The surrounding tissue is edema and the center is liquefied. Convoluted cellulitis can be seen with varying degrees of subcutaneous gas accumulation and deep soft tissue emphysema. In a mediastinal abscess, a high-density image of the mediastinum widening can be seen.

(2) Arterial blood gas and pH are helpful for understanding the body's metabolic status and timely finding the acid-base imbalance.

Acute Cellulitis Diagnosis

Clinical manifestations and signs

Diagnosis is based on typical local and systemic manifestations and signs.

2. Laboratory inspection

Elevated white blood cell counts and cytology of pus can help diagnose.

3. Imaging examination

It is helpful to judge the degree of infection and pathogenic bacteria.

Differential diagnosis of acute cellulitis

Erysipelas

Infection caused by hemolytic streptococci invading the skin and reticulum. The local manifestations were dark red plaques, which faded after finger pressure, the skin was slightly edema, the edges were slightly raised, and the boundaries were clear. The infection spreads rapidly, but does not purulent, rarely has tissue necrosis, and is prone to recurrent attacks. Repeated lower limb authors may have subcutaneous lymphatic obstruction.

2. Necrotizing fasciitis

Often mixed aerobic and anaerobic infections. Urgent onset, severe systemic symptoms, but local symptoms are not obvious. The infection spreads rapidly along the fascia, with massive necrosis of the fascia and subcutaneous tissue. Patients often have anemia and toxic shock. Ulcers and thin pus can be seen on the skin. A variety of bacteria can grow in the pus culture.

3. Gas gangrene

Gas-producing cellulitis should be distinguished from gas gangrene, which has severe trauma before the disease, often deep and muscular, with injured limbs or physical dysfunction; wound secretions have a certain smell. A pus smear test can roughly distinguish the germ morphology.

Acute Cellulitis Complications

Toxic shock

Systemic inflammatory response syndrome may occur, manifested as high fever or hypothermia, heart rate> 90 beats / minute, shortness of breath or hyperventilation, PaCO ₂ 12 × 10 ⁹ / L or <4 × 10 ⁹ / L, or immature White blood cells> 0.1%.

2. Sepsis

A sudden chill followed by a high fever of 40 ° C to 41 ° C, or a low temperature. Abnormal consciousness, thin pulse, liver and spleen can be enlarged, jaundice or subcutaneous bleeding in severe cases.

Acute Cellulitis Treatment

Local treatment

(1) When there is no local fluctuation in the early stage of drug application , 50% magnesium sulfate can be used as a local wet and hot compress, or external application with golden powder.

(2) The early application of ultraviolet and infrared rays in physical therapy can promote the limitation of the abscess and reduce inflammation; diuretic methods such as ultrashort wave and microwave can be selected after the pus is discharged to promote local blood circulation, granulation tissue growth, and accelerate wound healing.

(3) Incision and drainage Once an abscess has formed, it should be incision and drainage. For cellulitis at the bottom of the mouth and submandibular, if the short-term active anti-infective treatment is not effective, the decompression should be cut early to prevent laryngeal edema from compressing the trachea and causing asphyxia. Cellulitis of the fingers should also be decompressed early to prevent phalanx necrosis. For convoluted cellulitis, extensive incision and drainage should be made, necrotic tissue should be removed, and the wound should be washed with 3% hydrogen peroxide solution. If there is a large amount of subcutaneous tissue necrosis, skin can be transplanted to promote healing after the necrotic tissue is shed.

2. Systemic treatment

(1) Anti-shock therapy For patients with septic shock, positive fluid replacement and volume expansion should be given to improve microcirculation and corresponding symptomatic treatment. Pay close attention to the patient's urine output, blood pressure, heart rate, and peripheral circulation. Intravenous infusion of dopamine is effective for hypotensive patients.

(2) The whole body supportive therapy guarantees the patient to rest adequately. Those with severe infections should appropriately strengthen nutrition, supplement calories and protein, and input fresh blood or plasma in an appropriate amount. Human blood gamma globulin can enhance patients' ability to resist infection.

(3) Application of antibiotics Antibiotics are one of the most important measures for the treatment of cellulitis. The principle of use is to select targeted and sensitive drugs according to the results of bacterial culture and drug sensitivity tests. Before the results of drug susceptibility are available, a relatively targeted broad-spectrum antibiotic can be selected based on a pus smear test. For Staphylococcus aureus and Streptococcus infection, penicillin and sulfamethoxazole are preferred. In severe cases, cephalosporins are used; amikacin is used for gram-negative bacteria, because it has few drug-resistant strains, and the clinical effect is also good; for anaerobic infections, metronidazole is listed as a treatment for anaerobic infections. Drug of choice.

Prognosis of acute cellulitis

If there are no serious complications, the prognosis is good after active and standardized treatment. Those with low immunity and diabetic patients may have recurrence.