title: Bacterial Contamination of CT Equipment: Use of ATP Detection and Culture Results to Target Quality Improvement.
abstract: This study aimed to evaluate the use of an adenosine triphosphate (ATP) monitoring system to minimize surface contamination on inpatient computed tomography (CT) scanners.
  
  
  
  The bore, table, and wrap of two quaternary care inpatient CT scanners (load/scanner: ~ 30-40 CT examinations/day) were assayed with bacterial cultures and an ATP detection system during six prospective iterative plan-do-check-act improvement cycles from January 6, 2016 to October 12, 2016. Per-cycle sampling was for eight consecutive weekdays. ATP detection was expressed as relative light units (RLUs) through a luciferase reaction, with >350 RLU considered contaminated per manufacturer recommendations. Culture swabs were placed into 6.5% NaCl broth, a Staphylococcus enrichment broth, and incubated aerobically at 37°C for 48 hours. Positive broths were plated to chromogenic Staphylococcus media. Culture rates (Fisher exact test) and RLU values (Mann-Whitney U test) were compared.
  
  
  
  In Cycle 1, both culture results and median RLU values indicated the wrap was the most contaminated item (positive culture rate: 63% [10/16], median RLU interquartile range: 173 [IQR: 56-640]); however, RLU values were not predictive of per-sample culture results (P = .36). Following iterative improvements, RLU values at Cycle 6 were significantly lower than at peak (P = .02-.04) and within manufacturer's recommendations: all samples: 45 (IQR: 16-87), bore: 26 (IQR: 0-51), table: 68 (IQR: 21-89), wrap: 47 (IQR: 38-121).
  
  
  
  The Velcro wrap is the most contaminated item on a CT scanner, and special processes may be needed to ensure adequate cleansing. ATP detection is a crude surrogate for bacterial culture results but benefits from speed, reduced cost, and greater statistical power.
authors.affiliation: Department of Radiology, University of Michigan Health System, 1500 E. Medical Center Dr. B2-A209P, Ann Arbor, MI 48108.
authors.forename: John
authors.initials: J
authors.lastname: Childress
authors.affiliation: Department of Radiology, University of Michigan Health System, 1500 E. Medical Center Dr. B2-A209P, Ann Arbor, MI 48108.
authors.forename: Debborah
authors.initials: D
authors.lastname: Burch
authors.affiliation: Department of Radiology, University of Michigan Health System, 1500 E. Medical Center Dr. B2-A209P, Ann Arbor, MI 48108.
authors.forename: Cheryl
authors.initials: C
authors.lastname: Kucharski
authors.affiliation: Department of Microbiology, University of Michigan Health System, Ann Arbor, MI.
authors.forename: Carol
authors.initials: C
authors.lastname: Young
authors.affiliation: Department of Radiology, University of Michigan Health System, 1500 E. Medical Center Dr. B2-A209P, Ann Arbor, MI 48108; Michigan Radiology Quality Collaborative, Ann Arbor, MI.
authors.forename: Ella A
authors.initials: EA
authors.lastname: Kazerooni
authors.affiliation: Department of Radiology, University of Michigan Health System, 1500 E. Medical Center Dr. B2-A209P, Ann Arbor, MI 48108; Michigan Radiology Quality Collaborative, Ann Arbor, MI; Department of Urology, University of Michigan Health System, Ann Arbor, MI. Electronic address: matdaven@med.umich.edu.
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Davenport
mesh_terms: D000255:Adenosine Triphosphate / Q000032:analysis*; D001419:Bacteria / Q000737:chemistry / Q000302:isolation & purification*; D001431:Bacteriological Techniques; D003470:Culture Media; D004866:Equipment Contamination / Q000517:prevention & control; D006801:Humans; D011446:Prospective Studies; D058996:Quality Improvement; D015898:Tomography Scanners, X-Ray Computed / Q000382:microbiology*
chemical_list: D003470:Culture Media; D000255:Adenosine Triphosphate
keywords: Quality improvement; bacterial contamination; hospital-acquired infection; radiology equipment; surface contamination