title: Incidence and risk factors for multiple antibiotic-resistant Pseudomonas aeruginosa in cystic fibrosis.
abstract: BACKGROUND
  Infection with multiple antibiotic-resistant Pseudomonas aeruginosa (MARPA) in individuals with cystic fibrosis (CF) has caused much concern among caregivers, yet little is known about the risks associated with acquiring resistance. The main objective of the study was to estimate the incidence and identify risk factors for the acquisition of MARPA among individuals with CF.
  
  
  METHODS
  Five-year cohort study of individuals followed in the Cystic Fibrosis Foundation Registry from 1998 through 2002.
  
  
  RESULTS
  Demographics, anthropometrics, spirometry, respiratory culture results, comorbidities, antibiotic usage, and hospitalizations were collected. Of the 4,293 patients with P aeruginosa infection during the study period, MARPA developed in 341. The overall incidence of MARPA was 1.8%/yr. Independent risk factors for MARPA included CF-related diabetes mellitus (hazard ratio [HR], 1.64; 95% confidence interval [CI], 1.11 to 2.43), long-term inhaled tobramycin usage (HR, 2.08; 95% CI, 1.56 to 2.77), and care at a CF center with a baseline MARPA prevalence in the top quartile (HR, 2.00; 95% CI, 1.31 to 3.04). Frequent courses of IV antibiotics and repeated hospitalizations were also found to independently increase the risk for MARPA.
  
  
  CONCLUSIONS
  Infection with MARPA is common among patients with CF. Diabetes, long-term inhaled tobramycin usage, and frequent acute pulmonary exacerbations requiring hospitalization or IV antibiotics increase the risk for MARPA. Receiving CF care at a center with a high prevalence of resistant Pseudomonas also increases the risk for MARPA in patients with CF. Further study is needed to investigate the mechanisms of acquiring resistant strains and the clinical impact of MARPA on CF outcomes.
authors.affiliation: The Johns Hopkins University School of Medicine, 1830 E. Monument St/Fifth Floor, Baltimore, MD 21205, USA. cmerlo@jhmi.edu
authors.forename: Christian A
authors.initials: CA
authors.lastname: Merlo
authors.forename: Michael P
authors.initials: MP
authors.lastname: Boyle
authors.forename: Marie
authors.initials: M
authors.lastname: Diener-West
authors.forename: Bruce C
authors.initials: BC
authors.lastname: Marshall
authors.forename: Christopher H
authors.initials: CH
authors.lastname: Goss
authors.forename: Noah
authors.initials: N
authors.lastname: Lechtzin
mesh_terms: D000280:Administration, Inhalation; D000293:Adolescent; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000009:adverse effects*; D002648:Child; D016001:Confidence Intervals; D003550:Cystic Fibrosis / Q000150:complications*; D024901:Drug Resistance, Multiple, Bacterial; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D011552:Pseudomonas Infections / Q000150:complications / Q000188:drug therapy / Q000453:epidemiology; D011550:Pseudomonas aeruginosa; D012189:Retrospective Studies; D012307:Risk Factors; D014031:Tobramycin / Q000008:administration & dosage / Q000009:adverse effects; D014481:United States / Q000453:epidemiology
chemical_list: D000900:Anti-Bacterial Agents; D014031:Tobramycin