# The effect of five versus two personnel on bacterial air contamination during preparation of sterile surgical goods in the operating room: a randomised controlled trial

## TL;DR

Fewer people in the operating room during sterile surgical preparation reduces bacterial contamination, potentially lowering infection risks.

## Contribution

This study is the first randomized controlled trial showing that fewer personnel in the OR significantly reduces bacterial air contamination during sterile surgical preparation.

## Key findings

- Using two personnel instead of five reduced bacterial colony forming units (CFU) from a median of 5 to 2.
- Cutibacterium acnes and Staphylococcus epidermidis were the most frequently isolated bacteria, with some drug-resistant strains identified.

## Abstract

Surgical site infection (SSI) and antimicrobial resistance are a worldwide problem affecting patient safety. It is lacking randomised controlled trials (RCT) regarding how the number of personnel in the operating room (OR) affects the air quality. We aimed to investigate the effect the number of personnel in the OR have on bacterial air contamination during the preparation of sterile surgical goods, to identify the species and antibiotic susceptibility of the bacteria isolated, and to describe the number of SSIs together with causative microorganisms.

This RCT used an intervention group in which two individuals prepared the surgical goods and a control group in which five individuals prepared the goods. Bacteria were isolated on aerobic and anaerobic plates, and bacterial growth was measured as colony forming units (CFU). All isolates were typed, and types known to cause SSI were tested for susceptibility to eight antibiotics. Data were analysed with the Mann-Whitney U test, the chi-square test, or Fisher’s exact test.

Results were based on 69 open-heart surgeries and 414 plates. When sterile surgical goods were prepared with two personnel, the median CFU was 2 with an IQR of 2, compared with five personnel, the median CFU was 5, with an IQR of 5 (p < 0.001). The 272 CFU represented 45 different bacterial species, with 38 species isolated in the control group and 21 in the intervention group. The most frequently isolated bacteria were Cutibacterium acnes (82/272, 30%), and Staphylococcus epidermidis (36/272, 13%). Of the 36 S. epidermidis isolates, 11 (31%) were drug-resistant, including three multidrug-resistant. One patient in the control group was infected by Staphyloccocus aureus and Staphylococcus lugdunensis, neither of which was isolated during the preparation of sterile goods. One patient in the intervention group developed an SSI caused by C. acnes, Corynebacterium kroppenstedtii, and S. epidermidis. C. acnes and S. epidermidis were isolated during the preparation.

Minimising the number of personnel in the OR during preparation of sterile surgical goods is important to reduce the bacterial load.

Prospectively 15 May 2022 at FoU Sweden (275659) and retrospectively 22 October 2022 at ClinicalTrials.Gov (NCT05597072).