Lack of effect of fluoroquinolone resistance on mortality in subjects with Pseudomonas aeruginosa bacteraemia

Objectives: Despite the well-documented increase in fluoroquinolone resistance to Pseudomonas aeruginosa, the effect on pathogenicity is unknown. This paper will explore the clinical effect. Methods: A retrospective, observational, cohort study of 215 hospital inpatients was performed. Subjects with fluoroquinolone-resistant P. aeruginosa (FQRPA) bacteraemia were compared to subjects with fluoroquinolone-sensitive P. aeruginosa (FQSPA) bacteraemia from January 2000 to December 2003. Mortality prior to discharge, time to discharge, and time to negative culture were assessed. Additionally, baseline morbidity/mortality risk factors including Charlson morbidity score (CMS) were assessed. Results: Mortality prior to discharge (32 vs. 29%, P=0.73), mean days to discharge (17.5 vs. 14.6, P=0.24), and mean days to negative culture (3.6 vs. 3.2, P=0.1) did not differ between FQRPA and FQSPA, respectively. Active antibiotic treatment within 24 h of drawn blood culture (FQRPA 63% vs. FQSPA 93%, P<0.0001) and median CMS (FQRPA 3 vs. FQSPA 5, P=0.004) differed significantly between the groups. Conclusions: Subjects with FQRPA received active antibiotics less often within 24 h of obtained culture. A large difference in mortality does not likely exist based on fluoroquinolone susceptibility. A study with greater enrollment must be conducted to determine if fluoroquinolone resistance imparts a smaller yet clinically significant impact on clinical outcomes.