What is Ecthyma gangrenosum (a cutaneous manifestation of Pseudomonas aeruginosa infection)?

From the Guidelines

Ecthyma gangrenosum requires immediate treatment with empiric antibacterial therapy, including vancomycin and antipseudomonal antibiotics such as cefepime, a carbapenem, or piperacillin-tazobactam, due to its high mortality rate and association with Pseudomonas aeruginosa and other gram-negative bacteria. The diagnosis of ecthyma gangrenosum is primarily clinical, based on the characteristic appearance of painless erythematous papules that progress to necrotic ulcers with black eschar surrounded by erythema, often in immunocompromised patients such as those with neutropenia or malignancies 1.

Key Considerations

• Ecthyma gangrenosum is a cutaneous vasculitis caused by bacterial invasion of the vessel wall, which can be confirmed by histologic stains of biopsy specimens 1.
• The infection can be caused by various pathogens, including Pseudomonas aeruginosa, other Pseudomonas species, Aeromonas species, Serratia species, and fungi such as Candida and Aspergillus 1.
• Treatment should be aggressive and prompt, with adjustments based on culture results and clinical response, and may require surgical debridement of necrotic tissue in severe cases 1.
• Patients require close monitoring for signs of sepsis and supportive care, including fluid resuscitation and vasopressors, and the underlying cause of immunosuppression should be addressed to prevent recurrence 1.

Management

• Hospitalization and empiric antibacterial therapy with vancomycin plus antipseudomonal antibiotics are recommended for the treatment of ecthyma gangrenosum 1.
• The choice of antibiotic regimen should be based on the suspected pathogen and local resistance patterns, with consideration of the patient's underlying medical conditions and potential allergies 1.
• Combination therapy with an aminoglycoside may be considered for synergistic effect, but should be used cautiously due to the potential for nephrotoxicity and ototoxicity 1.

From the Research

Definition and Causes of Echthyma Gangrenosum

• Echthyma gangrenosum is a rare cutaneous infection that occurs classically in immunocompromised patients with Pseudomonas aeruginosa bacteremia and is associated with a high mortality rate 2.
• The condition can be caused by various pathogens, including Pseudomonas aeruginosa, Enterococcus faecalis, and Escherichia coli 3, 4.
• Echthyma gangrenosum can occur in both immunocompromised and immunocompetent individuals, and is not necessarily connected with septicemia 5.

Clinical Features and Diagnosis

• The clinical features of echthyma gangrenosum include small indurated vesicular papules that progress rapidly to infarcted necrotic areas with surrounding erythema and a typical black eschar 6.
• The condition can be diagnosed based on clinical presentation, laboratory tests, and imaging studies, such as CT scans 3.
• Dermatologists play a key role in the prompt diagnosis of this life-threatening condition, and a thorough understanding of pathogenic mechanisms is critical in selecting an efficacious treatment regimen 2.

Treatment and Management

• Treatment of echthyma gangrenosum typically involves broad-spectrum antibiotics, such as meropenem, amikacin, and linezolid, as well as surgical excision and debridement 3.
• Early recognition and prompt treatment with antipseudomonal antibiotics is vital to reduce morbidity and potential mortality 6.
• The use of intravenous immunoglobulins, anticonvulsants, and red blood cell transfusions may also be necessary in some cases 3.