Williamsia muralis Pulmonary Infection

To the Editor: Bacteria of the genus Williamsia are mycolic acid–containing actinomycetes of the suborder Corynebacterineae (1). This suborder also includes the genera Gordonia, Mycobacterium, Nocardia, Corynebacterium, Rhodococcus, Dietzia, Skermania, Tsukamurella, and Turicella (2,3). Within the genus Williamsia, only 2 species have been reported: Williamsia muralis, isolated from a daycare center (4), and W. maris, isolated from the Sea of Japan (5). One important aspect shared by both species is their apparent lack of pathogenicity, since they have been isolated only from environmental samples. An 80-year-old woman, whose medical history included allergy to penicillin and high blood pressure, was admitted to the cardiothoracic intensive care unit at Juan Canalejo Hospital Complex in La Coruña, Spain, because of a loss of consciousness following an aortic valve replacement. Physical examination showed a systolic murmur and an echocardiogram showed aortic stenosis. Transaortic peak pressure was 100 mm Hg, and the aortic valvular area was 0.3 cm2. A biologic valve prosthesis (Mitroflow 21, Sorin Group Canada, Ltd., Burnaby, British Columbia, Canada) was inserted under the cardiopulmonary bypass. Forty-eight hours later, the patient had paroxysmal atrial fibrillation and a temperature of 39°C, with severe hemodynamic and respiratory impairment. She was intubated and intravenous drugs were administered. Blood and urine cultures were requested. Central venous pressure lines were changed, and cultures were obtained. Empiric treatment with levofloxacin, amikacin, and teicoplanin was started for the patient. One of 2 blood cultures was positive for Staphylococcus epidermidis, as were cultures from femoral and jugular venous lines. Although considered a contaminant, we observed that S. epidermidis was susceptible to empiric antimicrobial drugs. One week later, a chest radiograph showed bilateral alveolar infiltrates suggestive of pulmonary edema (Figure). To rule out infection, bronchoscopy and protected specimen brush were conducted. An unidentified gram-positive bacillus was cultured from the brush sample. Urine cultures were positive for Candida kefyr, but the patient showed no evidence of candidemia. An echocardiogram showed no evidence of infective endocarditis. Since the patient’s condition did not improve, levofloxacin was replaced with imipenem, and treatment with fluconazole was initiated. However, the patient developed septic shock, adult respiratory distress syndrome, and oliguric acute renal failure, and died of multiple organ failure. On direct examination, a Gram stain of the protected specimen brush sample showed numerous gram-positive bacilli. After incubation for 48 h in either an aerobic or capnophilic atmosphere, >1,000 CFU/mL were observed on Columbia agar plates containing 5% sheep blood (BD Stacker Plates, BBL, Franklin Lakes, LETTERS