Outcomes and Treatment of Chronic Methicillin-Resistant Staphylococcus aureus Differs by Staphylococcal Cassette Chromosome mec (SCCmec) Type in Children With Cystic Fibrosis.
BACKGROUND
Methicillin-resistant Staphylococcus aureus (MRSA) infects ∼25% of patients with cystic fibrosis (CF) in the United States. We hypothesized that health-related outcomes differed between healthcare-associated (staphylococcal cassette chromosome mec [SCCmec] II) vs community-associated (SCCmec IV) MRSA strains in patients chronically infected with CF.


METHODS
At 7 CF centers, MRSA isolates were prospectively obtained from patients ≤18 years old with 2 or more positive MRSA cultures within 1 year. Isolates were classified by SCCmec type and Panton-Valentine-leukocidin (PVL) status at a core laboratory, and sites remained blinded to SCCmec type and PVL results. Prospective clinical data including antibiotic use, respiratory symptoms, and pulmonary exacerbations were obtained.


RESULTS
Among the 295 cohort participants with typeable MRSA isolates, 69.5% had SCCmec II PVL(-), 13.2% had SCCmec IV PVL(-), and 17.3% had SCCmec IV PVL(+) strains. During follow-up of 287 patients with prospective data after enrollment, the risk for pulmonary exacerbations was significantly higher among participants with SCCmec II than SCCmec IV strains (risk ratio [RR] = 1.13; P = .03) and higher in those with SCCmec IV PVL(-) than SCCmec IV PVL(+) strains (RR = 1.62; P < .0001). Neither decline in lung function nor changes in nutritional outcomes differed by SCCmec type or PVL status during the study period.


CONCLUSIONS
Participants harboring chronic SCCmec II MRSA received more antibiotics and may have more lung disease than those with SCCmec IV; PVL(+) isolates were not associated with more advanced disease.
Division of Pediatric Pulmonology, Department of Pediatrics , University of Washington School of Medicine , Seattle ; Cystic Fibrosis Foundation Therapeutics Development Network Coordinating Center , Seattle Children's Research Institute , Washington.
Sonya L
SL
Heltshe
Department of Pediatrics, Columbia University Medical Center , New York ; Department of Infection Prevention & Control , New York-Presbyterian Hospital.
Lisa
L
Saiman
Department of Medicine and ; Department of Microbiology and Immunology, University of North Carolina at Chapel Hill.
Elena B
EB
Popowitch
Department of Medicine and ; Department of Microbiology and Immunology, University of North Carolina at Chapel Hill.
Melissa B
MB
Miller
Cystic Fibrosis Foundation Therapeutics Development Network Coordinating Center , Seattle Children's Research Institute , Washington.
Margaret
M
Kloster
Cystic Fibrosis Foundation Therapeutics Development Network Coordinating Center , Seattle Children's Research Institute , Washington.
Valeria
V
Thompson
Department of Pediatrics ; Department of Genetics, Washington University, St. Louis, Missouri.
Thomas W
TW
Ferkol
Department of Pediatrics , University of Alabama at Birmingham.
Wynton C
WC
Hoover
Emory University School of Medicine , Atlanta, Georgia.
Michael S
MS
Schechter
Division of Pediatric Pulmonology, Department of Pediatrics , University of North Carolina at Chapel Hill.
Marianne S
MS
Muhlebach
D000293:Adolescent; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000009:adverse effects; D001427:Bacterial Toxins; D002648:Child; D002675:Child, Preschool; D002908:Chronic Disease; D003550:Cystic Fibrosis / Q000150:complications* / Q000188:drug therapy; D005098:Exotoxins; D005260:Female; D006801:Humans; D007956:Leukocidins; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000187:drug effects / Q000302:isolation & purification; D012141:Respiratory Tract Infections / Q000188:drug therapy / Q000209:etiology; D013203:Staphylococcal Infections / Q000150:complications* / Q000188:drug therapy*; D016896:Treatment Outcome; D014481:United States
D000900:Anti-Bacterial Agents; D001427:Bacterial Toxins; D005098:Exotoxins; D007956:Leukocidins; C078284:Panton-Valentine leukocidin
PVL; Panton-Valentine leukocidin; SCCmec type; cystic fibrosis; methicillin-resistant Staphylococcus aureus; pulmonary exacerbation