title: Unchanged antibiotic susceptibility in Escherichia coli and Pseudomonas aeruginosa after long-term in vitro exposure to antineoplastic drugs.
abstract: 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.
  
  
  CONCLUSIONS
  Long-term in vitro antineoplastic exposure did not change the antibiotic susceptibility in the E. coli or P. aeruginosa strains.
authors.affiliation: Institute of Clinical Medicine, University of Oslo, Oslo, Norway. Kristin.Marie.Kvakkestad@so-hf.no
authors.forename: Kristin M
authors.initials: KM
authors.lastname: Kvakkestad
authors.forename: Karianne W
authors.initials: KW
authors.lastname: Gammelsrud
authors.forename: Petter
authors.initials: P
authors.lastname: Brandtzaeg
authors.forename: E Arne
authors.initials: EA
authors.lastname: Høiby
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D052978:Disk Diffusion Antimicrobial Tests; D004352:Drug Resistance, Microbial / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects*; D011550:Pseudomonas aeruginosa / Q000187:drug effects*
chemical_list: D000900:Anti-Bacterial Agents; D000970:Antineoplastic Agents