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BackgroundThe hospital environment has been suggested as playing an important role in the transmission of hospital-associated (HA) pathogens. However, studies investigating the contamination of the hospital environment with methicillin-resistant Staphylococcus aureus (MRSA) or Clostridium difficile have generally focused on point prevalence studies of only a single pathogen. Research evaluating the roles of these two pathogens, concurrently, in the general hospital environment has not been conducted. The objectives of this study were to determine the prevalence and identify risk factors associated with MRSA and C. difficile contamination in the general environment of three community hospitals, prospectively.MethodsSampling of environmental surfaces distributed over the medicine and surgical wards at each hospital was conducted once a week for four consecutive weeks. Sterile electrostatic cloths were used for environmental sampling and information regarding the surface sampled was recorded. For MRSA, air sampling was also conducted. Enrichment culture was performed and spa typing was performed for all MRSA isolates. For C. difficile, isolates were characterized by ribotyping and investigated for the presence of toxin genes by PCR. Using logistic regression, the following risk factors were examined for MRSA or C. difficile contamination: type of surface sampled, surface material, surface location, and the presence/absence of the other HA pathogen under investigation.ResultsOverall, 11.8% (n=612) and 2.4% (n=552) of surfaces were positive for MRSA and C. difficile, respectively. Based on molecular typing, five different MRSA strains and eight different C. difficile ribotypes, including ribotypes 027 (15.4%) and 078 (7.7%), were identified in the hospital environment. Results from the logistic regression model indicate that compared to computer keyboards, the following surfaces had increased odds of being contaminated with MRSA: chair backs, hand rails, isolation carts, and sofas.ConclusionsMRSA and C. difficile were identified from a variety of surfaces in the general hospital environment.Several surfaces had an increased risk of being contaminated with MRSA but further studies regarding contact rates, type of surface material, and the populations using these surfaces are warranted.

Halogenated pyrimidines (HP) represent a unique class of non-hypoxic cell radiosensitizers currently under clinical re-investigation. In order for halogenated pyrimidines to sensitize cells to radiation, they must be incorporated into cellular DNA. In the case of human tumors, which have in general rather long cell cycle times, this may require many days of continuous drug infusion to achieve adequate replacement of the DNA base thymidine with HP. In vitro studies support the relationship between the extent of radiosensitization and the percentage of thymidine replacement. Recent clinical studies evaluating the role of iododeoxyuridine (IdUrd) as a radiation sensitizer in large unresectable sarcomas have been extremely encouraging. To support and expand upon these positive clinical findings more information and research is needed regarding: (1) the mechanism of HP-induced radiosensitization; (2) the percentage of HP thymidine replacement in human tumors achievable and how it relates to treatment outcome; (3) the means of increasing HP incorporation in tumor and minimizing incorporation in normal tissues; (4) a better understanding of optimal timing between HP administration and radiation treatment; and (5) methods to evaluate which tumors are appropriate candidates for HP therapy. While presently limited to use in conventional high dose-rate X-ray therapy, laboratory studies suggest that HP might also be effective in low dose-rate brachytherapy and for selected high LET clinical beams. HPs probably will not be 'general' non-hypoxic cell radiosensitizers for all tumor types, but with appropriate tumor-type/anatomical site selection and refinement in their administration, HPs may prove beneficial in cancer treatment.

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