QUINOLONE USE NAD BACTERIAL RESISTANCE

NEW YORK (Reuters Health) Jan 27 - Antibacterial therapy and prophylaxis in cancer patients is tied to bacterial resistance, and fluoroquinolones appear to be one of the biggest offenders, researchers report in a January 5th on-line publication in Cancer.

"This study reaffirms the challenge of balancing protection from infection for immunocompromised patients -- cancer, bone marrow transplant -- using broad spectrum antibacterials with the development of resistant organisms that are very difficult to treat," coauthor Dr. Bruno P. Granwehr, from the University of Texas M. D. Anderson Cancer Center, Houston, told Reuters Health by email.

Dr. Granwehr and colleagues analyzed isolates from 622 bacteremia episodes, 345 that were breakthrough episodes and 277 that occurred in patients who had not received antimicrobial drugs. Roughly 10% of episodes in each group were polymicrobial.

Breakthrough bacteremia was more likely than non-breakthrough bacteremia to be associated with multi-drug resistant (MDR) Escherichia coli, MDR Pseudomonas aeruginosa, and vancomycin-resistant enterococci.

On multivariate analysis, breakthrough bacteremia was significantly associated with hematologic malignancies (OR, 9.9) and neutropenia (OR, 3.0).

Monotherapy with fluoroquinolones, compared to treatment with any other regimen (including combination therapy with fluoroquinolones), was significantly linked to isolation of methicillin-resistant Staphylococcus aureus (MRSA) and MDR P. aeruginosa. Multivariate analysis showed that fluoroquinolones had the strongest association of any antibiotics with breakthrough bacteremia (odds ratio, 22.0).

Exposure to cephalosporins alone significantly increased the risk of isolating vancomycin-resistant enterococci.

The researchers also note that compared with no treatment at all, any combination regimen increased the risk of isolating MDR P. aeruginosa, MDR E. coli, and vancomycin-resistant enterococci.

Finding a balance between minimizing drug resistance and using antimicrobial prophylaxis appropriately "will require a commitment by institutions and health systems to monitor these relations and their impact on important outcomes," the authors conclude.

Cancer 2010.