Photo Quiz: Skin Lesions from a Returning Traveler.

Abstract

A26-year-old woman presented to her general practitioner with a 3-week history of nonhealing lesions over the right shin. She had returned from a holiday in Thailand 3 weeks prior and remembered numerous insect bites but could not specifically recall any bites over her shin. During her stay in Thailand, she had been working with elephants. At one stage, she had sustained a laceration to the right shin from a bamboo stick lifted by an elephant. Shortly after the injury, three lesions appeared approximately a centimeter away from the laceration. She had no contact with any other animals and has been systemically well. On examination, there were three vesicular eruptions with dried scabs on her right shin. One scab was carefully lifted, and underlying skin was swabbed and sent for microscopy and culture. Empirical topical mupirocin cream was given for presumptive Staphylococcus aureus folliculitis, without much effect. No systemic antibiotic was given, pending culture results. A Gram stain performed on the lesion showed no polymorphs or bacteria. After 24 h of culture at 35°C under a 5% CO2 atmospheric condition, rough grayish brown colonies of 0.5 to 1.0 mm with deep pitting were observed on horse blood agar (Fig. 1A). The colonies were slightly beta-hemolytic and difficult to scrape off the agar. The Gram stain showed long, solidly stained thick curved Gram-positive bacilli with transverse septa (Fig. 1B). Numerous 90° lateral branches with different thicknesses were observed, along with occasional coccoid forms. Acid-fast and modified acid-fast stains were negative. A wet mount was performed on the colonies on day 3, which showed multiple motile structures (Fig. 1C). Attempts to identify this organism with matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry provided no reliable results.

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