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Phialophora richardsiae bursitis treated medically

      To the Editor:
      Although Staphylococcus aureus is responsible for most cases of septic bursitis, fungi are rarely isolated (
      • Zimmerman B.
      • Mikolich D.J.
      • Ho G.
      Septic bursitis.
      ). Phialophora richardsiae, a dematiaceous fungi, was first reported as a cause of human infection in 1968 (
      • Schwartz I.S.
      • Emmons C.W.
      Subcutaneous cystic granuloma caused by a fungus of wood pulp (Phialophora richardsiae).
      ). There has been one case of septic bursitis caused by P. richardsiae(
      • Torstrick R.F.
      • Harrison K.
      • Heckman J.D.
      • Johnson J.D.
      Chronic bursitis caused by Phialophora richardisaea case report.
      ). The dearth of information on antifungal susceptibility for P. richardsiae, and the favorable response to excision, have made surgery the treatment of choice (
      • Pitrak D.L.
      • Koneman E.W.
      • Estupinan R.C.
      • Jackson J.
      Phialophora richardsiae infection in humans.
      ). We report a case of septic bursitis with contiguous cellulitis caused by P. richardsiae that was treated successfully with systemic antifungal agents and irrigation of the bursa.
      A healthy 77-year-old man presented with chronic swelling below the right knee. On examination, the infrapatellar bursa was markedly enlarged without warmth or erythema. Microscopic examination of fluid aspirated from the bursa revealed abundant neutrophils. Gram’s stain and bacterial culture were negative. A presumptive diagnosis of “Carpenter’s knee” was made. Methylprednisolone was instilled into the bursa to reduce inflammation.
      The infrapatellar bursa subsequently diminished in size; however, 2 months later the patient presented with redness, pain, and swelling of the bursa. The infrapatellar bursa was enlarged with overlying erythema and warmth. There was contiguous extension to the lateral calf with edema and skin pustules. A bursal aspirate yielded 15 mL of purulent material. Microscopy revealed abundant neutrophils; however, septate hyphae were noted on Gram’s stain and subsequently confirmed by Fungifluor stain (Figure 1). The patient was hospitalized for treatment of a locally invasive fungal infection.
      Figure thumbnail GR1
      Figure 1Fungifluor stain of infrapatellar bursa fluid (original magnification ×40).
      The bursal aspirate, an aspirate of a superficial pustule, and a punch biopsy specimen grew P. richardsiae (Figure 2). Microscopic examination of the skin specimen showed dermal neutrophilic infiltrate and perivascular lymphohistiocytic infiltration. Fungal blood cultures were negative.
      Figure thumbnail GR2
      Figure 2Lactophenol cotton blue stain of organisms obtained from culture specimen (original magnification ×40).
      Treatment with intravenous amphotericin B was instituted. Erythema and edema decreased rapidly. The bursa was irrigated with normal saline through a draining tract. Neither incision and drainage nor debridement was undertaken given the clinical improvement. Following 2 weeks of amphotericin, oral itraconazole was administered for 3 months, which led to resolution of the infection. Minimum inhibitory concentrations (performed in the laboratory of Dr. Michael Rinaldi, Department of Veterans Affairs Mycology Reference Laboratory, South Texas Veteran’s Health Care System) were as follows: amphotericin B, 0.25 μg/mL at 24 hours and 0.5 μg/mL at 48 hours; itraconazole, 0.25 μg/mL at 24 hours and 0.5 μg/mL at 48 hours; voriconazole, 0.25 μg/mL at 24 hours and 0.5 μg/mL at 48 hours; and posaconazole, 0.06 μg/mL at 24 hours and 0.13 μg/mL at 48 hours.
      Phialophora richardsiae rarely causes infection in humans. Subcutaneous granuloma, the most common clinical presentation, is characterized by a solitary, painless, well-encapsulated, subcutaneous lesion on the extremities without overlying skin abnormalities or regional adenopathy (
      • Pitrak D.L.
      • Koneman E.W.
      • Estupinan R.C.
      • Jackson J.
      Phialophora richardsiae infection in humans.
      ). Histologic examination typically demonstrates granulomas with central necrosis.
      The extension of the infection from the bursal space into adjacent soft tissues, confirmed by culture of both a skin biopsy specimen and an aspirate from a superficial pustule, make our patient atypical. Although it is plausible that this soil organism was introduced into the bursa during the patient’s daily activities, it is notable that he had recently received a corticosteroid injection. There has been one report of P. richardsiae infection following corticosteroid injection (
      • Reyes F.A.
      • Buchman M.T.
      Phialophora richardsiae infection mimicking a soft tissue mass of a finger.
      ). In our patient, it is unknown whether the fungus was in the bursa before the injection, was inoculated into the bursa after the injection, or was introduced into the bursa by the injection. Contamination of the steroid preparation, as proposed previously (
      • Reyes F.A.
      • Buchman M.T.
      Phialophora richardsiae infection mimicking a soft tissue mass of a finger.
      ), seems less likely. Regardless, the effects of the local steroid almost certainly contributed to the contiguous spread of infection.
      The most salient feature of this case is that surgical excision was not required. Most previous cases of subcutaneous granulomas achieved cure through surgical excision alone. Antifungal therapy has been used in one case of subcutaneous granuloma as an adjunct to surgical excision (
      • Ikai K.
      • Tomono H.
      • Watanabe S.
      Phaeohyphomycosis caused by Phialophora richardsiae.
      ). That patient died of unrelated causes. Two reports of invasive infection (endocarditis and osteomyelitis) involved treatment with systemic antifungal agents but yielded indeterminate results (
      • Uberti-Foppa C.
      • Fumagalli L.
      • Gianotti N.
      • et al.
      First case of osteomyelitis due to Phialophora richardsiae in a patient with HIV infection.
      ,
      • Juma A.
      Phialophora richardsiae endocarditis of aortic and mitral valves in a diabetic man with a porcine mitral valve.
      ). Although we considered surgical intervention in this patient, we determined that empiric antifungal therapy with close clinical monitoring was a reasonable approach given his intact immune system. He showed rapid clinical improvement and has not had recurrence of infection 1 year later. In select immunocompetent patients with P. richardsiae infection, systemic antifungal therapy and percutaneous drainage may obviate the need for surgery.

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