Introduction
Pseudomonas aeruginosa infections remain challenging because of more patients with chronic disease and weakened immune systems and antibiotic resistance. In particular, pseudomonas septicemia is an alarming complication that can be treated efficiently only if diagnosed early. A distinguishing feature to diagnose pseudomonas septicemia is a distinctive skin lesion known as ecthyma gangrenosum. Recognition of this lesion by physicians helps in earlier diagnosis and more promising treatment of pseudomonas septicemia.
What Is Ecthyma Gangrenosum?
Ecthyma gangrenosum (EG) is a serious cutaneous condition caused by hematogenous seeding by Pseudomonas aeruginosa septicemia. There is a high risk of fatality when there is systemic spread. Escherichia coli has little effect on EG. It is more common in immune-compromised patients but rarely occurs in healthy individuals. When it affects healthy individuals there is a history of viral infection, on antibiotic therapy or neutropenic.
Who Is Affected With Ecthyma Gangrenosum?
Ecthyma gangrenosum affects both males and females of all age groups. About 60 % to 75 % of patients with ecthyma gangrenosum are immunocompromised individuals. Predisposing conditions of ecthyma gangrenosum are neutropenia, leukemia, malnutrition, diabetes mellitus, multiple myeloma, and extensive burn wounds.
How Does Ecthyma Gangrenosum Occur?
Weakened immunity predisposes to Pseudomonas infections or other pathogens. These pathogens break down the protective skin and mucous layer allowing the infectious organisms to enter the body. When these bacteria invade the walls of arteries and veins through the cut skin, it can result in ecthyma gangrenosum. The lesion can occur by direct inoculation into the skin or through the blood vessels (septicemia). These pathogens damage the blood vessels and their surrounding structures, decreasing the blood supply. This initially causes redness, swelling, pus formation, and bleeding resulting in skin necrosis with ulcer and scab formation.
Ecthyma gangrenosum is chiefly caused by Pseudomonas aeruginosa but may be seen in other bacterial, fungal, and viral infections as follows:
Multi-drug resistance of Pseudomonas aeruginosa may be due to decreased permeability, antibiotic flow pumps, antibiotic inactivating mechanisms, and antibiotic target site mutations.
What Are the Clinical Features of Ecthyma Gangrenosum?
Ecthyma gangrenosum starts as painless, round, red patches in the skin with pus formation. Next, it forms a blister that tends to bleed. When the blister bleeds, there is a peripheral spread of the toxins causing black or gray, scabby gangrenous ulcers with a red halo. An initial lesion transforms into a necrotic ulcer within 12 hours. Ecthyma gangrenosum commonly affects the anogenital area and armpits but can appear anywhere in the body. Rare sites include arms, legs, trunk, and face.
How Is Ecthyma Gangrenosum Diagnosed?
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Initial evaluation includes blood cultures, wound cultures, urinalysis, chest radiograph, complete blood count, comprehensive metabolic panel, C-reactive protein, and HIV testing for general bacterial analysis and sensitivity testing.
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Procalcitonin and lactate levels are essential to diagnose sepsis.
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In a Wood lamp test, Pseudomonas aeruginosa appears as green fluorescence.
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A deep skin biopsy specimen of 4 mm or 5 mm depth is taken, and a histopathologic examination is done to eliminate other infectious causes.
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A second skin biopsy specimen is taken to obtain bacterial cultures and sensitivity testing. The culture also investigates the presence of yeast, fungus, and mycobacteria.
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Needle aspiration of a suspicious lesion should be done.
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Excisional or punch biopsies are performed in misleading cases.
How Is Ecthyma Gangrenosum Treated?
When ecthyma gangrenosum is present, the physician should know the associated pseudomonas septicemia. Ecthyma gangrenosum requires early diagnosis and suitable antibiotics treatment.
Antibiotic Therapy -
Broad-spectrum antibiotics therapy should be initiated before obtaining blood and wound cultures. Piperacillin with an Aminoglycoside should be started immediately. Initial empiric therapy includes,
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Antipseudomonal beta-lactams antibiotics – Piperacillin, Tazobactam.
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Third-generation cephalosporins - Cefepime.
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Fluoroquinolones – Levofloxacin.
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Carbapenems - Imipenem.
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Aminoglycosides.
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Aztreonam.
Antibiotics should be adjusted when antibiotic sensitivity is present. Combination therapy should be suggested in high-risk individuals with neutropenia and septic shock. In case of fungal infection in the bloodstream, systemic antifungal therapy should be prescribed. Commonly used antifungal drugs are Itraconazole or Fluconazole, with or without Amphotericin B.
Surgical Therapy -
Incision and drainage of abscesses are vital to control the source of infection. For necrotic skin lesions, forceful debridement and tissue grafting may be required for lesions greater than 10 cm. Surgically excising the necrotic lesions or abscesses is essential. In high fatality patients with sepsis or neutropenia, an intensive care setting with constant monitoring is required.
What Are the Lesions That Resemble Ecthyma Gangrenosum?
Other conditions with similar clinical features are,
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Autoimmune vasculitides.
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Vasopressor-induced necrosis.
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Warfarin-induced skin necrosis.
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Disseminated intravascular coagulation (DIC).
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Necrolytic migratory erythema.
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Livedoid vasculopathy.
What Is the Prognosis for Ecthyma Gangrenosum?
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When ecthyma gangrenosum is associated with sepsis, the prognosis is poor and leads to death.
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When ecthyma gangrenosum does not involve bacteremia, the mortality rate is as low as 8 %.
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The immunosuppressive state and the presence of neutropenia determine the prognosis and mortality rate of ecthyma gangrenosum.
What Are the Complications of Ecthyma Gangrenosum?
The complications of ecthyma gangrenosum include;
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Cellulitis.
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Erysipelas.
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Lymphangitis.
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Gangrene.
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Lymphadenitis.
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Bacteremia.
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Permanent scarring.
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Rarely, post-streptococcal glomerulonephritis.
Ecthyma gangrenosum is a life-threatening infection that can result in septic shock.
Conclusion
Ecthyma gangrenosum is a severe skin condition related to Pseudomonas aeruginosa septicemia. It is common in immuno-compromised patients and with poor prognosis. In patients with systemic signs of sepsis, ecthyma gangrenosum should be suspected when pustules, dark red induration, and mainly when necrotic ulcer on the skin is present. Early diagnosis and treatment are essential in managing Pseudomonas septicemia. Treatment includes antibiotic therapy, local debridement, and supportive medical care.
