Ecthyma gangrenosum is more common in immunocompromised patients with pseudomonas aeruginosa sepsis. Skin lesions can also occur in the diaper areas and perineum of healthy infants receiving antibiotics.
Pseudomonas aeruginosa is an aerobic Gram-negative bacillus, is widely present in moist natural environments, mainly in the soil, water, and intestines of few persons, and can also temporarily parasitize the anus, genitals, armpits, and external auditory canal. Under normal circumstances, its growth is inhibited by Gram-positive cocci, generally nonpathogenic. However, the bacterium can quickly reproduce in the burns, ulcers, and moist skin, causing skin infections. Systemic infections usually occur in persons with low immunity, such as patients whose normal microflora being inhibited by antibiotics or glucocorticoids, tumor patients, patients with granulocytopenia caused by various causes, patients with immunodeficiency caused by chronic wasting diseases, frail old adults, and malnourished infants. If a healthy person is immersed in water for a long time, the infection of the bacteria can also occur. The bacteria can also cause nosocomial infections by contamination of hospital bedpans and sheets, and has become one of the main pathogens of nosocomial infections in recent years.
Studies have shown that the pathogenicity of the bacteria is mainly caused by the secreted exotoxin, and the collagenase, elastase, and phospholipase secreted by the bacteria are involved in the disease. A typical strain produces two pigments of blueish green pyocyanin and yellowish green pyoverdin.
Systemic pseudomonas aeruginosa infection can cause sepsis, and patients present with fever, jaundice, splenomegaly, pneumonia, urinary tract infection, and meningitis. Cutaneous pseudomonas aeruginosa infection often occurs in the persistently moist lesion sites, especially on the periumbilical and burned surfaces of infants, as well as in macerated toes, external auditory canal, and auricle.
Signs and Symptoms
Typical lesions are erythema or purple erythema initially, with tenderness, developing into milky white, intense, clustered vesicles or pustules, surrounded by narrow pink or purplish red halos, rapidly evolving into hemorrhagic necrotic bullae, forming round ulcers after rupture, with black necrotic center, with bluish green pus on the surface, with odor. Skin lesions are more common in the armpits, perineum, buttocks, and calves.
In addition to ecthyma gangrenosum, pseudomonas aeruginosa sepsis can be seen in cellulitis, vesicles, papules, macules, maculopapular rashes, plaques, nodules, and other rashes. Skin lesions often occur in the trunk, and patients are generally in poor condition. Under severe conditions, hypothermia, hypotension, and coma can occur.
On the basis of typical skin lesions, vesicles, necrosis, and green pus, diagnosis is not difficult. Gram-negative bacilli found in the pus smears or pseudomonas aeruginosa seen in the pus or blood cultures can assist in the definitive diagnosis.
Severe patients with pseudomonas aeruginosa sepsis should be immediately injected with effective antibacterial drugs. It is recommended to use a combination of one of aminoglycosides plus one of antipseudomonal penicillins, such as amikacin, gentamicin, or tobramycin plus piperacillin or carbenicillin. Ceftazidime, ciprofloxacin and ofloxacin have antibacterial effects against pseudomonas aeruginosa. However, due to increased drug resistance, severe patients require combination treatment. The choice of antibiotics should be guided by the susceptibility test. In patients with myelodysplastic syndrome, granulocyte-macrophage colony-stimulating factor is used to stimulate the proliferation and differentiation of bone marrow precursor cells, which is a beneficial adjuvant therapy.
Topical effective antibacterial drugs are preceded by cleans of the skin lesion in 1% acetic acid solution. Silver sulfadiazine solution or cream, 0.1% polymyxin, or gentamicin solution can be selected. Surgical debridement may be necessary for deep necrosis.