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Levels of microbial contamination on surgical instruments
W A Rutala1, M F Gergen, J F Jones
1Division of Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, USA.
American Journal of Infection Control
|May 19, 1998
Summary
Standard cleaning effectively reduces microbial load on surgical instruments to less than 100 colony-forming units (CFU). This indicates that new sterilization methods will likely prevent cross-transmission of infections from nonlumen instruments.
Area of Science:
- Microbiology
- Infection Control
- Surgical Instrument Reprocessing
Background:
- Surgical instruments require thorough cleaning to prevent healthcare-associated infections.
- Standard cleaning protocols involve washer sterilizers and sonic cleaning.
Purpose of the Study:
- To determine the microbial load and types of microorganisms on used surgical instruments after standard cleaning.
- To assess the effectiveness of washer sterilizer and sonic cleaning methods.
Main Methods:
- Prospective experimental study at a university hospital.
- Used surgical instruments were cultured using Peptamin Tween broth and filtered.
- Quantitative cultures and standard microbiological identification techniques were employed.
Main Results:
- 72% of instruments had 0-10 colony-forming units (CFU) post-cleaning.
- 14% had 11-100 CFU, and 14% had over 100 CFU.
- Coagulase-negative staphylococcus (56%) was the most common organism, followed by Bacillus (22%) and diphtheroids (14%).
Conclusions:
- Most nonlumen surgical instruments harbor fewer than 100 CFU of relatively nonpathogenic microbes after cleaning.
- Current cleaning methods are effective in reducing microbial burden.
- New low-temperature sterilization technologies are expected to be highly effective for nonlumen instruments.