title: Increasing resistance of the Liverpool Epidemic Strain (LES) of Pseudomonas aeruginosa (Psa) to antibiotics in cystic fibrosis (CF)--a cause for concern?
abstract: BACKGROUND
  Transmissible Pseudomonas aeruginosa (Psa) strains such as the Liverpool Epidemic Strain (LES) are now widespread throughout UK CF clinics: their susceptibility to antibiotics is therefore important. To study this, we compared antibiogram patterns of Psa strains in our CF clinic over 5 years, looking at differences in resistance patterns between strains and changes to these over time.
  
  
  METHODS
  The antibiograms of sputum samples between 2004 and 2008 from patients attending our centre were included. We compared Psa isolate antibiotic resistance (to six anti-pseudomonal antibiotics) patterns for patients infected with LES with those infected with other Psa strains, both in the total population in 2004 (125 patients) and 2008 (166 patients) and also longitudinally from annual review samples 2004 to 2008 in matched and unmatched patient groups.
  
  
  RESULTS
  LES exhibited significantly more resistant isolates in 2004 (p<0.0001). There was an increase in antibiotic resistance in both LES and other Psa strains over time (p<0.001). Cox proportional hazards analysis of both unmatched (n=125) and matched (n=56) patients in 2004 revealed that LES infected patients were more likely to develop antibiotic resistant isolates over time (hazard ratio 8.1, p<0.001). Fewer LES isolates were classed as fully sensitive in both matched and unmatched groups at the end of study period (p<0.001).
  
  
  CONCLUSIONS
  This study shows a worrying trend in antibiotic resistance in the Psa isolates amongst patients chronically infected with LES. This highlights the need to prevent cross infection through segregation and also the need to develop new strategies to treat these organisms.
authors.affiliation: Liverpool Heart and Chest Hospital, Thomas Drive, Liverpool L14 3PE, United Kingdom.
authors.forename: Abdul
authors.initials: A
authors.lastname: Ashish
authors.forename: Matthew
authors.initials: M
authors.lastname: Shaw
authors.forename: C
authors.initials: C
authors.lastname: Winstanley
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Ledson
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Walshaw
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003550:Cystic Fibrosis / Q000150:complications / Q000453:epidemiology* / Q000382:microbiology; D024881:Drug Resistance, Bacterial; D058872:Epidemics; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D011552:Pseudomonas Infections / Q000150:complications / Q000453:epidemiology* / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000302:isolation & purification; D012189:Retrospective Studies; D013183:Sputum / Q000382:microbiology; D013997:Time Factors; D006113:United Kingdom / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents