DNA Sequencing Allows ID of Unusual, Oft-Fatal Pathogen in Patient

A 14-year-old Texas girl was finally cured of an oft-fatal emerging disease when doctors amputed her lower leg, where the infection arose, after various antimicrobials proved ineffective. The culprit was Pythium insidiosum, a fungus-like microbe which rarely causes disease in humans and then primarily in Thailand. The case "clearly highlights the need for clinicians to have the best support possible from the clinical microbiology lab," says Dr. Don Murphey of Cook Children's Medical Center, who served as attending physician during the case. The case report is published in the April 2012 issue of the Journal of Clinical Microbiology. The girl, otherwise healthy, presented to an urgent care facility with a 2-week history of a continuously enlarging erythematous bump on her lower leg, having reported recently swimming in an algae-filled pool. "Over the course of several weeks, what started as a very small lesion grew to involve most of her leg," says first author Dr. Stephen J. Salipante, of the University of Washington, Seattle. "Initial cultures of the wound suggested that this was a bacterial infection, and it was treated as such, but without success. She eventually needed to be hospitalized," says Dr. Salipante. Her treatment team at Cook Children's hospital tried increasingly aggressive medical and surgical management, including different antibiotic regimens, antifungals, and surgical debridements, but the infection simply didn't respond. "Given the microscopic appearance of the organism, our working hypothesis was that this was some kind of unusual, and very aggressive fungus," says Dr. Salipante. However, sequencing a segment of DNA that is useful for categorizing fungi, the ITS1 sequence, "revealed that this was not a fungus at all—rather, the DNA sequence very closely matched… P. insidiosum," says Dr.
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