Treating Secondary Infection In A Patient With Severe Tinea Pedis

Author(s): 
Michael Moharan, DPM, Mohamed Abdelmegeed Ahmed, MD, DPM, and Oleg Karpenko, MD, DPM

   Dried exudate or a green stain (caused by pyoverdin) may be present on socks or toenails. Pseudomonas folliculitis presents as cutaneous lesions any time from eight hours to five days or more (mean incubation period is 48 hours) after using a contaminated whirlpool, home hot tub, water slide, physiotherapy pool or contaminated loofah sponge. Malaise and fatigue may occur during initial days of the eruption. Fever (uncommon) is low grade when present. Localized cellulitis can occur as a secondary infection of tinea of the toe webs or groin. It may also be triggered by bedsores, stasis ulcers or burns. Localized cellulitis can also occur in grafted areas or under the foreskin of the penis.
Maceration or occlusion of these skin lesions leads to secondary infection. Deep erosions and tissue necrosis may occur before one correctly diagnoses the condition.

   Severe pain is highly characteristic of an evolving infection. The hallmark lesions resulting from pseudomonal wound infections are multifocal with dark-brown to black or violaceous discoloration of the burn eschar. This is accompanied by edema and hemorrhagic necrosis.

   Ecthyma gangrenosum lesions are multiple noncontiguous ulcers or solitary ulcers. These lesions begin as isolated, red, purpuric macules that become vesicular, indurated and eventually, bullous or pustular. The bullae may be hemorrhagic but contain little if any pus. Lesions can remain localized or more often can extend over several centimeters. The central area of these lesions becomes hemorrhagic and necrotic. Then the lesion denudes to form a gangrenous ulcer with a gray-black eschar and erythematous halo. Although lesions can occur anywhere, they occur mainly in the gluteal and perineal regions (57 percent), the extremities (30 percent), the trunk (6 percent) and the face (6 percent).5

   These skin lesions heal slowly. Patients with septicemia have associated signs that include elevated temperatures, chills, hypotension, tachycardia and tachypnea. In chronic paronychia, the skin around the nail becomes pale, red, painful and swollen. A small amount of pus may occasionally emanate from beneath the proximal nail fold. The nail plate turns green-black, which is characteristic of pseudomonal infections. The condition causes little discomfort or inflammation.

   This presentation is often confused with subungual hematoma. A Pseudomonas-infected toe web presents as a thick, white, macerated scale with a green discoloration.

   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.

Comments

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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