Volume 131, Issue 6, Pages 1718-1725 (June 2007) Panton-Valentine Leukocidin-Positive Methicillin-Resistant Staphylococcus aureus Lung Infection in Patients With Cystic Fibrosis  Elizur Arnon , MD, Orscheln Rachel C. , MD, Ferkol Thomas W. , MD, Atkinson Jeffrey J. , MD, Dunne W. Michael , PhD, Buller Richard S. , PhD, Armstrong Jon R. , MS, Mardis Elaine R. , PhD, Storch Gregory A. , MD, Cannon Carolyn L. , MD, PhD  CHEST  Volume 131, Issue 6, Pages 1718-1725 (June 2007) DOI: 10.1378/chest.06-2756 Copyright © 2007 The American College of Chest Physicians Terms and Conditions

Figure 1 Radiographic evidence of lung abscess secondary to PVL+ MRSA in two adolescent CF patients. Top left, A, and bottom left, D: Chest radiographs obtained before hospital admission in case 1 and case 2, respectively. Top center, B, and bottom center, E. Chest radiographs obtained during hospitalization that showed interval development of cavitary lesions in the left upper lobe in case 1 and in the left lower lobe in case 2. Top right, C, and bottom right, F. CT of the chest of case 1 and case 2 shortly after hospital admission that demonstrated thick-walled, contrast-enhancing cavitary lesions in the left upper lobe and left lower lobe, respectively. CHEST 2007 131, 1718-1725DOI: (10.1378/chest.06-2756) Copyright © 2007 The American College of Chest Physicians Terms and Conditions

Figure 2 Increasing incidence of PVL+ MRSA in CF patients followed up at St. Louis Children's Hospital during a 4-year period. CA = CA-MRSA; HA = HA-MRSA. CHEST 2007 131, 1718-1725DOI: (10.1378/chest.06-2756) Copyright © 2007 The American College of Chest Physicians Terms and Conditions

Figure 3 Characteristics of MRSA isolates from CF patients classified according to presence of absence of clindamycin susceptibility (S) [white boxes, sensitivity not determined; light gray, sensitive; dark gray, resistant (R)], PVL gene, SCC-mec type, and sequence type as determined by MLST. ND = not determined; clinda (S) = clindamycin susceptable; clinda (R) = clindamycin resistant; ST5 = sequence type 5; ST8 = sequence type 8. *Clinda = clindamycin. **constitutive resistance. CHEST 2007 131, 1718-1725DOI: (10.1378/chest.06-2756) Copyright © 2007 The American College of Chest Physicians Terms and Conditions

Figure 4 Characteristics of CF MRSA isolates analyzed by repetitive-sequence PCR, based on the presence of the PVL gene, SCC-mec type, and clindamycin susceptibility. Clindamycin resistance is further defined as inducible (I) or constituitive (C). The scale in the left margin shows percentage relatedness. CHEST 2007 131, 1718-1725DOI: (10.1378/chest.06-2756) Copyright © 2007 The American College of Chest Physicians Terms and Conditions