We report two cases of invasive infections caused by Panton-Valentine leukocidin-positive, communityassociated, methicillin-resistant Staphylococcus aureus (CA-MRSA) after kidney transplantation. This report emphasizes the clinical importance of considering CA-MRSA as a causative agent in the differential diagnosis of infections of the skin and soft tissues in organ transplant recipients.
CASE REPORTS Case 1.A 32-year-old African American male with hypertension and type I diabetes mellitus who had undergone livingdonor kidney transplantation 28 months earlier was admitted with severe left-flank pain, subjective fevers, and a 20-lb weight loss over 1 month. Intermittent left-sided low-back pain had been present for 6 months. Fifteen, 11, and 7 months earlier, the patient had recurring furunculosis and cellulitis involving the buttocks. Cultures performed during the two most recent episodes revealed methicillin-resistant Staphylococcus aureus (MRSA) with the following susceptibility profile: resistance to oxacillin (MICs, Ͼ4 g/ml) and erythromycin (Ͼ8 g/ml) but susceptibility to vancomycin (Յ1 g/ml), trimethoprim-sulfamethoxazole (TMP-SMX) (Յ0.5/9.5 g/ml), tetracycline (Յ1 g/ml), gentamicin (Յ0.5 g/ml), rifampin (Յ0.5 g/ml), clindamycin (Յ0.25 g/ml), and linezolid (2 g/ml). These infections were treated by his primary care physician with incision, drainage, and oral anti-infectives, including cephalexin, amoxicillin-clavulanate, and TMP-SMX. He underwent an attempt at decolonization with mupirocin applications to the anterior nares. He reported having had sex with men, and the human immunodeficiency virus antibody was nonreactive. The posttransplant course was otherwise uncomplicated, with good allograft function on a stable immunosuppression regimen that included tacrolimus, mycophenolate mofetil, and prednisone.On examination, his vital signs were as follows: oral temperature, 36.9°C; pulse, 74/min; blood pressure, 100/68 mm Hg; and respirations, 19/min. Left-flank tenderness and a limping gait were present. The laboratory evaluation determined a white blood cell count of 20,200 cells/l with 86% neutrophils, an erythrocyte sedimentation rate of 107 mm/hour, a C-reactive protein level of 21.5 mg/dl, and a serum creatinine level of 1.8 mg/dl. Computed tomography imaging of his pelvis demonstrated a 6.6-cm by 8.5-cm left iliopsoas abscess, and magnetic resonance spine imaging revealed osteomyelitis of the L5 vertebral body and left transverse process (Fig. 1A). The abscess was drained by interventional radiology, and monomicrobial MRSA was isolated from the abscess culture; anaerobic cultures were negative. Blood cultures were also negative. He completed 6 weeks of parenteral vancomycin therapy, followed by 2 weeks of linezolid therapy. Due to the patient's desire to return to work without an intravenous catheter, vancomycin was changed to linezolid to complete the intended 8-week course of therapy. TMP-SMX was administered for an additional 8 weeks of suppressive therapy. Follow-up testing demonstrated an erythroc...
