Successful Medical Therapy for Deeply Invasive Facial Infection Due toPythium insidiosumin a Child

Abstract

Pythiosis occurs in animals and humans who encounter aquatic habitats that harbor Pythium insidiosum. Drug therapy for deeply invasive infections with this organism has been ineffective in humans and animals; patients have been cured only by radical surgical debridement. A 2-year-old boy developed periorbital cellulitis unresponsive to antibiotic and antifungal therapy. The cellulitis extended to the nasopharynx, compromising the airway and necessitating a gastrostomy for feeding. P. insidiosum was isolated from surgical biopsy specimens of the affected tissue. On the basis of in vitro susceptibility studies of the isolate, the patient was treated with a combination of terbinafine and itraconazole. The infection resolved over a period of a few months. The patient remained well 1.5 years after completing a 1-year course of therapy. Cure of deep P. insidiosum infection is feasible with drug therapy.

Unusual Fungal and Pseudofungal Infections of Humans

“…The ocular form of pythiosis is manifest as keratitis that can be severe and result in corneal perforation. The cutaneous and subcutaneous form most often presents as a periorbital cellulitis or mass with progressive local invasion of soft tissue (85,94). The arterial form is the most serious and is largely limited to farmers in Thailand who also suffer from thalassemia (56,75,82,92,100).…”

“…Immunodiagnosis using an immunodiffusion or a fluorescent-antibody assay to detect antibodies to P. insidiosum has been useful (75,85). Likewise, the presence of the organism in tissue may be confirmed by staining with specific fluorescentantibody conjugates (57).…”

“…In contrast, treatment of cutaneous and subcutaneous infection with surgical debridement and antifungal therapy is generally successful (75). One notable case in the United States of deep facial infection in a child demonstrated that pharmacological cure with itraconazole plus terbinafine is feasible (85).…”

Development of a Species-Specific Probe forPythium insidiosumand the Diagnosis of Pythiosis

“…This can be especially problematic in the case of pythiosis because this disease is often confused with those caused by members of the zygomycetes, and this would likely result in the prescription of antifungal agents. Although Shenep et al (48) demonstrated successful synergistic treatment with a combination of itraconazole and terbinafine, therapeutic measures are not expected to have a curative effect since P. insidiosum is not a member of the true fungi and does not respond to common antifungal agents.…”

Human Pythiosis

“…Treatment options reported to be successful include supersaturated potassium iodide for the chronic cutaneous form ( 2 ), a combination of terbinafine and itraconazole in a single case of an acute, severe ocular, subcutaneous infection ( 6 ), and therapeutic vaccination for severe infections involving major arteries ( 7 , 8 ) in conjunction with surgery. The first case suggested that, with chronic pythiosis involving the aorta, effective management is difficult.…”