Unchanged antibiotic susceptibility in Escherichia coli and Pseudomonas aeruginosa after long-term in vitro exposure to antineoplastic drugs.

Background: Certain antineoplastic drugs inhibit bacterial growth. Whether these drugs also cause genetic changes in bacteria that lead to increased antibiotic resistance is not yet documented. Given the massive and repeated antibiotic treatment most cancer patients undergo, this question is important. We have examined the possible effects of in vitro long-term antineoplastic exposure on antibiotic resistance. Methods: Using the disc diffusion method, two bacterial strains (Escherichia coli, ATCC 25922, and Pseudomonas aeruginosa, ATCC 27583) were exposed to methotrexate, fluorouracil, vincristine, doxorubicin and cytarabine during 50 overnight cycles. The bacterial strains were susceptibility-tested to several antibiotics before and after repeated exposure to antineoplastics. Results: No changes in antibiotic susceptibility were seen in the two bacterial strains after long-term exposure to any of the antineoplastic drugs tested. Conclusion: Long-term in vitro antineoplastic exposure did not change the antibiotic susceptibility in the E. coli or P. aeruginosa strains. Copyright (C) 2012 S. Karger AG, Basel