Pseudomonas skin infections
Infection of the skin or soft tissues by Pseudomonas aeruginosa or other Pseudomonas species tend to be serious and complex because these bacteria are both invasive and toxigenic.
What causes Pseudomonas skin infections?
Pseudomonas aeruginosa can be commonly found on the skin, especially in the axillary and anogenital regions. However, healthy people do not normally develop Pseudomonas infection. Pseudomonas is considered to be opportunistic and more frequently causes disease in those who are immunocompromised.
Pseudomonas can be easily transmitted from hospital workers to their patients in absence of proper hand hygiene and is responsible for approximately 10% of all nosocomial infections.
Who is at risk for Pseudomonas skin infections?
Patients at higher risk for this infections include those with:
- Intravenous catheter
- Indwelling urinary catheter
What are the signs and symptoms of a Pseudomonas skin infection?
Signs and symptoms of Pseudomonas infection can vary widely depending upon the site of the infection, but can include:
- Erythematous (red) lesions that can be haemorrhagic or necrotic
- Deep abscess
- Subcutaneous nodules
- Necrotising fasciitis
- Black or purple discoloration or eschar (in case of infected thermal burns)
What are the different types of Pseudomonas skin infections?
Pseudomonas skin infections include:
- Puncture wounds of the foot. These can frequently become infected with Pseudomonas species and the patient will present with drainage with a sweet, fruity-smelling discharge. Cellulitis and osteomyelitis are common complications.
- Thermal burn wounds. If eschar is present, Pseudomonas bacteria can populate beneath this protected layer. It can often result in bacteraemia (bacteria in the blood stream), a complication with a high mortality rate.
- Chronic leg ulcers. Colonisation with Pseudomonas is recognised by malodorous greenish superficial crust.
- Spa pool folliculitis. This Pseudomonas infection is acquired in inadequately chlorinated hot tubs. Patients present with itchy follicular papules and pustules on any part of the body submerged in the tub.
- External otitis. This is the most common form of Pseudomonas infection of the ear and is most commonly found in the tropics: patients present with pain, swelling and redness of the external portions of the ear as well as purulent discharge. Malignant external otitis is more serious. This affects diabetic patients and can cause severe pain and damage to the cranial nerve.
- Ecthyma gangrenosum. Patients with ecthyma gangrenosum are frequently neutropaenic. They develop erythematous, ulcerated, purple or black skin lesions in the axillary, inguinal or anogenital areas.
- Chronic paronychia and onycholysis. Greenish discolouration may be due to colonisation by Pseudomonas.
What are the complications from Pseudomonas skin infections?
The most common complication of a Pseudomonas skin or soft tissue infection is bacteraemia; this usually comes from contaminated intravenous fluids, drugs or antiseptics used during placement of an intravenous line.
How are Pseudomonas skin infections diagnosed?
Pseudomonas infections are suspected on physical examination when there is a a greenish or blackish, fruity-smelling discharge. They are confirmed by laboratory studies of cultures taken from the affected area.
What are the treatments for Pseudomonas skin infections?
Treatment is based on the site of the Pseudomonas infection and its severity. It may include:
- Irrigation with a 1% acetic acid solution in cases of otitis media along with topical polymyxin B, colistin, or fluoroquinolones in cases of a more severe infection
- Debridement of necrotic tissue and/or drainage of abscesses as an adjuvant to antibiotic therapy
- Amputation of affected limb (in rare cases).