A threshold of 100 or more colony-forming units on the anesthesia machine predicts bacterial pathogen detection: a retrospective laboratory-based analysis
Authors' conclusion
Anesthesia machine reservoir samples returning < 100 CFU were associated with negligible pathogen detection.
Study context
- Population
- Anesthesia work area reservoirs (providers' hands, patient skin sites, anesthesia machine, intravenous stopcock sets) sampled at case start and end in nine hospitals, 2017–2022
- Participants
- 31,783 reservoir samples
- Exposure
- Anesthesia machine reservoir samples returning ≥ 100 colony-forming units (CFU) vs < 100 CFU
- ≥ 100 CFUn = 2,262
- < 100 CFUn = 2,888reference
- Outcome
- Isolation of ≥ 1 CFU of a bacterial pathogen (S aureus, MRSA, Enterococcus, VRE, gram-negative spp. or coagulase-negative Staphylococcus); hypothesis: < 5% prevalence with < 100 CFU
Methodological detailslaboratory-based, multicentre (nine hospitals)
- Laboratory-based
- Multicentre (nine hospitals)
Main finding
As reported in the abstract
≥ 1 bacterial pathogen in anesthesia machine samples
| Group | Value | 99% lower confidence limit | 99% upper limit |
|---|---|---|---|
| ≥ 100 CFU | 23% | 22% | |
| < 100 CFU | 3% | 4% |
Value
≥ 100 CFU23%
< 100 CFU3%
99% lower confidence limit
≥ 100 CFU22%
< 100 CFU— not stated in the abstract
99% upper limit
≥ 100 CFU— not stated in the abstract
< 100 CFU4%
Observational data: associations, not effects.
Further findings
Pathogen isolation overall
- Reservoir samples with bacterial pathogens (7,601/31,783)
- 24%
- Operating rooms with bacterial pathogens (98/105)
- 93%
- Cases with bacterial pathogens (2,170/2,616)
- 83%
- Ratio of total pathogen isolates to total CFU
- < 0.0003%
Anesthesia machine reservoirs returning ≥ 100 CFU
- Cases (2,262/5,150)
- 44%
Original publication
A threshold of 100 or more colony-forming units on the anesthesia machine predicts bacterial pathogen detection: a retrospective laboratory-based analysis. Can J Anaesth. Published 27 February 2024. doi:10.
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