title: Levels of microbial contamination on surgical instruments.
abstract: OBJECTIVE
  To ascertain the microbial load and type of organisms on used surgical instruments following standard cleaning, which consisted of the use of a washer sterilizer followed by sonic cleaning.
  
  
  METHODS
  In this prospective experimental study, used surgical instruments were immersed in Peptamin Tween broth, the broth agitated, and then filtered through a 0.45 microm filter. Quantitative cultures were performed, and all microbes were identified by using standard techniques.
  
  
  METHODS
  This study was conducted at a 660-bed university hospital.
  
  
  RESULTS
  The microbial load remaining on used surgical instruments after cleaning was as follows: 36 (72%) instruments 0 to 10 colony-forming units (CFU), 7 (14%) instruments 11 to 100 CFU, and 7 (14%) instruments > 100 CFU. Organisms contaminating the instruments included coagulase-negative staphylococcus (56%) followed by Bacillus (22%) and diphtheroids (14%). No other microbes were isolated from more than 4% of the instruments.
  
  
  CONCLUSIONS
  Most used nonlumen surgical instruments contain less than 100 CFU of relatively nonpathogenic microorganisms after cleaning. This suggests that new low-temperature sterilization technologies are likely to be highly effective in preventing cross-transmission of infection via nonlumen medical instruments.
authors.affiliation: Division of Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, USA.
authors.forename: W A
authors.initials: WA
authors.lastname: Rutala
authors.forename: M F
authors.initials: MF
authors.lastname: Gergen
authors.forename: J F
authors.initials: JF
authors.lastname: Jones
authors.forename: D J
authors.initials: DJ
authors.lastname: Weber
mesh_terms: D001419:Bacteria / Q000302:isolation & purification*; D015169:Colony Count, Microbial; D004866:Equipment Contamination / Q000517:prevention & control / Q000706:statistics & numerical data*; D005069:Evaluation Studies as Topic; D006746:Hospital Bed Capacity, 500 and over; D006785:Hospitals, University; D006801:Humans; D009657:North Carolina; D009873:Operating Rooms / Q000592:standards; D011446:Prospective Studies; D013242:Sterilization / Q000592:standards*; D013525:Surgical Instruments / Q000382:microbiology*