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

   After one week of physical therapy, the patient went on vacation. During this time, he swam and walked barefoot. After vacation, the patient came back to the clinic with the complaints of severe pain, swelling and drainage from the wound of the right foot. The Wood’s lamp test was negative and we obtained a wound culture, which was positive for Pseudomonas aeruginosa. To rule out an abscess of the right foot, we sent the patient for magnetic resonance imaging (MRI) of the right foot. To rule out neoplasm, we recommended a periodic acid Schiff (PAS) stain with histopathology.

   The PAS results were positive for orthokeratotic hyperkeratosis and negative for fungus. The MRI demonstrated chronic phlegmon with no signs of abscess.

   The treatment consisted of moxifloxacin (Avelox, Bayer) PO for P. aeruginosa, local wound care with application of Burow's solution to reduce inflammation and piroxicam for pain management. We successfully treated the patient for severe foot infection but due to his non-adherence to follow-up, it was hard to obtain the final results of our treatment.

Understanding The Prevalence And Impact Of Pseudomonas

Pseudomonas is a strictly aerobic gram negative bacterium. Pseudomonal species have been found in water, plants, soil and animals. P. aeruginosa colonization occurs in more than 50 percent of humans and Pseudomonas aeruginosa are considered the most common pseudomonal species.5

   Pseudomonas is a clinically serious and opportunistic pathogen, usually causing nosocomial infections.6 These organisms also exhibit innate resistance to many antibiotics and can develop new resistance after exposure to antimicrobial agents.

   P. aeruginosa rarely causes disease in healthy people. Most infections occur in compromised hosts, such as those with disrupted physical barriers to bacterial invasion like macerated skin, ulcers, burn injuries, intravenous lines, urinary catheters, dialysis catheters, endotracheal tubes and impaired immune systems that one may encounter in patients with. HIV, hypogammaglobulinemia, cystic fibrosis, complement deficiency and iatrogenic immunosuppression.7

   According to data from the Centers for Disease Control and Prevention (CDC) National Nosocomial Infections Surveillance System of 2004, P. aeruginosa is the leading cause of intensive care unit-related pneumonia and osteochondritis.8 It is the second most common gram-negative organism, responsible for 9 percent of all nosocomial bacterial and fungal isolates. P. aeruginosa is the fourth most common cause of surgical site infections and hospital-acquired gram-negative rod bacteremia.8

What You Should Know About Secondary Infections Caused By Pseudomonas

Children have a higher risk than adults to pseudomonal osteochondritis infections following puncture wounds of the foot.9 Older patients are more susceptible to pseudomonal bone and joint infections. Children have a higher incidence of developing pseudomonal folliculitis than adults.9

   Skin and soft tissue infections caused by Pseudomonas include burn wound sepsis, dermatitis, ecthyma gangrenosum, pyoderma, surgical and wound infections, including cellulitis, hot tub folliculitis, necrotizing fasciitis and chronic paronychia.

   Ecthyma gangrenosum is a rare but pathognomonic form of pseudomonal infection. Although ecthyma gangrenosum is often due to Pseudomonas, case reports indicate that the same frequency is associated with non-Pseudomonas ecthyma gangrenosum (i.e., Fusarium, Klebsiella). Ecthyma gangrenosum in patients without neutropenia is very rare as are non-bacteremic ecthyma gangrenosum cases. However, non-septicemic cases occur in patients without immunosuppression or neutropenia, or following antibiotic therapy. Pseudomonal burn wound infections occur with systemic involvement (e.g., bacteremia, fever, hypothermia, disorientation, obtundation, hypotension, oliguria, ileus and leukopenia). Chronic paronychia slowly evolves and initially presents with tenderness and mild swelling about the proximal and lateral nail folds. Pseudomonal toe web infections are distinctive clinical entities that are often misdiagnosed as tinea pedis.

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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