Treating Secondary Infection In A Patient With Severe Tinea Pedis

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Michael Moharan, DPM, Mohamed Abdelmegeed Ahmed, MD, DPM, and Oleg Karpenko, MD, DPM

   The most consistent clinical feature is soggy, wet toe webs and adjacent skin. In the mildest form of pseudomonal infection in the toe web, the affected tissue is damp, softened, boggy and white. The second, third and fourth toe webs are the most common sites of initial involvement. Severe forms may progress to denuded skin and profuse, serous or purulent material. Pseudomonas folliculitis presents with a few to more than 50 urticarial plaques that measure 0.5 to 3 cm in diameter with a central papule or pustule on all skin surfaces other than the head. The rash can be a polymorphous eruption or a mixture of follicular, maculopapular, vesicular or pustular lesions. These lesions often are pruritic. Most clear in seven to 10 days, leaving round spots of red-brown post-inflammatory hyperpigmentation. However, some patients may have recurrent crops of lesions over an extended period of three months.

   Pseudomonas cellulitis presents with a dusky red to bluish or green skin discoloration and purulent discharge. The typical fruity or mouse-like odor has been linked to pseudomonal infection. Vesicles and pustules may occur as satellite lesions. The eruption may spread to cover wide areas and cause systemic manifestations.

Current Insights On Lab Tests And Pseudomonas Infections

The following laboratory results are helpful to confirm a pseudomonal infection.

* Complete blood cell counts reveal leukocytosis with a left shift and bandemia, which indicates the possible presence of toxic granulations or vacuoles.

* Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels may be elevated in infection.

* Metabolic profile reveals any electrolyte abnormalities, the degree of dehydration and worsening renal function.

* Wound and burn cultures can be helpful to identify pseudomonal infections.

* A Wood light examination of a pseudomonal toe web reveals a green-white fluorescence from the elaboration of pyoverdin.

* A computed tomography scan of soft tissue and bone of skin infections may be required to exclude an abscess formation or osteomyelitis.

Key Treatment Considerations

Treatment of Pseudomonas infections entails the use of antimicrobial agents.10 Anti-pseudomonal drug combination therapy (such as a beta-lactam antibiotic with an aminoglycoside) is usually recommended for the initial empiric treatment of a pseudomonal infection, especially for patients with neutropenia, bacteremia, sepsis, severe upper respiratory infection or abscess formation. The choice of antibiotic also depends on the site and extent of infection, and on local antibiotic resistance patterns.

   Reports of more resistant strains of Pseudomonas organisms to the currently used antimicrobials are causing much concern.11 B. cepacia has grown resistant to aminoglycosides, anti-pseudomonal penicillins and most beta-lactam agents. Some strains are variably susceptible to third-generation cephalosporins, ciprofloxacin (Cipro, Bayer), trimethoprim-sulfamethoxazole (Septra, GlaxoSmithKline), ampicillin-sulbactam (Unasyn), chloramphenicol (Neogen) or meropenem (Merrem, AstraZeneca).12

   Since human cases of glanders are rare, limited information is available about antibiotic treatment of the organism in humans. Sulfadiazine has been effective in experimental treatments of animals and humans. B. mallei organisms are usually sensitive to tetracyclines, ciprofloxacin, streptomycin, novobiocin, gentamicin, imipenem (Primaxin, Merck), ceftazidime (Fortaz, GlaxoSmithKline) and sulfonamides. Researchers have reported resistance to chloramphenicol.12 Treatment duration is often prolonged, from one to two months, and clinicians often combine this with surgical drainage.

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man ying leesays: September 23, 2012 at 5:41 am

I have seen patients with Pseudomonas aeruginosa infection secondary to interdigital fungi infection. Instead of using topical cream, I use silver dressing with exudate control ability such as Aquacel Ag or Acticoat with aligiste m, together with oral antibiotics. The infected toe webs dried up, became less swollen and the foot healed up within two weeks.

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