Can a Single Strand of Hair Contaminate a Surgical Instrument Set? A Controlled Experimental Study

Abstract

Birch, J., Schnell, A. K., & Clayton, N. S. (2020). Dimensions of Animal Consciousness. Trends in cognitive sciences, 24(10), 789–801. https://doi.org/10.1016/j.tics.2020.07.007

Background: Surgical site infections account for a substantial proportion of hospital-acquired infections, and the proper sterilization of surgical instruments is crucial for their prevention. Hair strands detected in sterile surgical sets are generally considered sufficient grounds for rejection, leading to delays in surgical procedures. The present study evaluates the impact of hair strands on the efficacy of sterilization and the potential for contamination. Patients and Methods: This controlled experimental study was conducted in the sterilization unit of a public hospital in Istanbul between January 15 and February 15, 2023. It was hypothesized that no microbial growth would occur in hair strands or on surgical instruments after sterilization, regardless of the contamination status or sterilization method. The surgical sets obtained for the study were divided into three groups: experiment group 1, to which uncontaminated hair strands were applied (n = 6); experiment group 2, to which hair strands contaminated with one of five bacterial pathogens were applied (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, and Enterococcus faecalis; n = 30); and the control group, to which no hair strands were applied (n = 6). The soft tissue surgical instruments in each group were standardized by weight (3-3.5 kg) and sterilized using one of three methods: pressurized steam, ethylene oxide, or hydrogen peroxide. After sterilization, microbiological samples were collected by culturing swabs from the hair strands and surgical instruments under appropriate conditions in tryptic soy broth and various agar media. Results: No microbial growth was observed in any group after sterilization, regardless of the presence or contamination of hair strands or the sterilization method used. The biological indicators also identified no growth after sterilization. Conclusion: The present highlights the effectiveness of proper sterilization techniques, even in the presence of hair strands, and suggests that hair should not be treated as a potential source of contamination in all surgical settings. It should be noted, however, that the present study was conducted under controlled clinical microbiology laboratory conditions and so does not consider the complexity and variability of clinical environments. Surgical units should thus be encouraged to replicate these data or carry out similar studies and revise their practices based on their own results.