Fluoroquinolone-resistant Pseudomonas aeruginosa: assessment of risk factors and clinical impact.
OBJECTIVE
Pseudomonas aeruginosa infections have been associated with considerable morbidity and mortality. Fluoroquinolones (FQ) are the only oral therapy available for P. aeruginosa infections, but resistance is increasingly prevalent.


METHODS
We examined annual trends in FQ-resistant P. aeruginosa (FQRPA) from 1991 to 2000. Subsequently, inpatients with a clinical culture positive for P. aeruginosa between January 1, 1999 and December 31, 2000 were included in a case control study to identify risk factors for FQ resistance and a cohort study to examine the impact of FQ resistance on outcomes in P. aeruginosa.


RESULTS
Annual prevalence of FQRPA increased from 15% in 1991 to 41% in 2000 (P <0.001 trend). Between 1999 and 2000, 332 P. aeruginosa isolates were FQ resistant and 540 were FQ susceptible. Prior FQ use was the only independent risk factor for FQRPA (adjusted OR = 3.43; 95% confidence interval [CI] 2.37, 4.96). Subjects with FQRPA had greater median hospital charges (62,325 dollars vs 48,734 dollars) (P =.007) and higher mortality (47.5% vs 35.5%) (P =.004). However, in a multivariate model, only imipenem resistance of the isolate was significantly associated with mortality. FQ resistance was not an independent risk factor.


CONCLUSIONS
FQRPA has increased significantly and is associated with prior FQ use. Limiting FQ use may curb the emergence of resistance among P. aeruginosa. FQRPA is associated with increased hospital charges, but other resistance patterns may have a more significant impact on mortality.
Gasink
Leanne B
LB
Division of Infectious Diseases, University of Pennsylvania School of Medicine, Philadelphia, Penn 19104-6021, USA. leanne.gasink@uphs.upenn.edu
Fishman
Neil O
NO
Weiner
Mark G
MG
Nachamkin
Irving
I
Bilker
Warren B
WB
Lautenbach
Ebbing
E
D000046:Academic Medical Centers / Q000706:statistics & numerical data; D016022:Case-Control Studies; D015331:Cohort Studies; D003428:Cross Infection / Q000188:drug therapy* / Q000191:economics / Q000453:epidemiology / Q000382:microbiology; D024881:Drug Resistance, Bacterial; D024841:Fluoroquinolones / Q000494:pharmacology*; D006801:Humans; D015999:Multivariate Analysis; D016017:Odds Ratio; D015242:Ofloxacin / Q000494:pharmacology; D010414:Pennsylvania / Q000453:epidemiology; D015995:Prevalence; D011552:Pseudomonas Infections / Q000188:drug therapy* / Q000191:economics / Q000453:epidemiology / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000302:isolation & purification; D012189:Retrospective Studies; D012307:Risk Factors
D024841:Fluoroquinolones; D015242:Ofloxacin