Growing evidence suggests that microbes can influence the efficacy of cancer therapies. By studying colon cancer models, we found that bacteria can metabolize the chemotherapeutic drug gemcitabine (2′,2′-difluorodeoxycytidine) into its inactive form, 2′,2′-difluorodeoxyuridine. Metabolism was dependent on the expression of a long isoform of the bacterial enzyme cytidine deaminase (CDDL), seen primarily in Gammaproteobacteria. In a colon cancer mouse model, gemcitabine resistance was induced by intra-tumor Gammaproteobacteria, dependent on bacterial CDDL expression, and abrogated by co-treatment with the antibiotic ciprofloxacin. Gemcitabine is commonly used to treat pancreatic ductal adenocarcinoma (PDAC), and we hypothesized that intra-tumor bacteria might contribute to drug resistance of these tumors. Consistent with this possibility, we found that of the 113 human PDACs that were tested, 86 (76%) were positive for bacteria, mainly Gammaproteobacteria.

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Background-Detailed information on the cost burden of atrial fibrillation (AF) is limited. To provide an up-to-date estimate of the national cost of AF, we conducted a retrospective, observational cohort study using administrative claims from the MarketScan Commercial and Medicare Supplemental research data bases, 2004 to 2006. Methods and Results-Patients aged Ն20 years with Ն1 inpatient or Ն2 outpatient AF diagnoses in 2005 (first diagnosisϭindex) and Ն12 months' enrollment before and after index were selected. AF patients were propensity score-matched (1:1) with non-AF control subjects. Medical costs (2008 US$), including AF costs, other cardiovascular, and noncardiovascular costs, were examined over 1 year after index. National incremental costs of AF were based on age-/sex-specific AF prevalence projections for 2010. In total, 89 066 AF patients were matched to non-AF control subjects. Over 1 year, 37.5% of AF versus 17.5% of control subjects were hospitalized and 2.1% versus 0.1% died during hospitalization. For AF versus control subjects, mean annual inpatient costs per patient were $7841 versus $2622