Effectiveness of reducing bacterial air contamination when covering sterile goods in the operating room setting: a systematic review and meta-analysis.

BACKGROUND: Postoperative surgical site infection is a serious problem. Coverage of sterile goods may be important to protect the goods from bacterial air contamination while awaiting surgery. AIM: To evaluate the effectiveness of this practice in a systematic review covering five databases using search terms related to bacterial contamination in the operating room and on surgical instruments. METHODS: MEDLINE, Cochrane, CINAHL, Embase, and Web of Science databases were searched from inception to February 13th, 2023, for randomized and non-randomized controlled studies of covering interventions conducted in the operating room setting. The outcome was bacterial air contamination measured as colony-forming units, and a meta-analysis was performed in separate time periods of coverage. This systematic review and meta-analysis is reported according to the PRISMA statement, and the protocol was prospectively registered in PROSPERO (CRD42022323113). The time points ranged from 30 min to 24 h. FINDINGS: The results showed that covering sterile goods significantly prevented bacterial air contamination as compared to uncovered goods. The meta-analysis was in favour of covering sterile goods for protection from bacterial air contamination, and showed an effect size Z of 4.76 (P<0.00001; confidence interval: -1.94 to -0.81). The heterogeneity analysis showed a heterogeneity of 83%. CONCLUSION: No negative effects regarding bacterial contamination were found, and so we conclude that protection with a sterile cover decreases bacterial air contamination of sterile goods while waiting for surgery to start.

The presence of skin bacteria in the sternal wound and contamination of implantation materials during cardiac surgery.

BACKGROUND: Sternal wound infections (SWIs) and aortic graft infections (AGIs) are serious complications after cardiac surgery. Staphylococcus aureus and coagulase-negative staphylococci are the most common causes of SWIs, whereas AGIs are less studied. AGIs may occur from contamination during surgery or postoperative haematogenous spread. Skin commensals, such as Cutibacterium acnes, are present in the surgical wound; however, their ability to cause infection is debated. AIM: To investigate the presence of skin bacteria in the sternal wound and to evaluate their potential to contaminate surgical materials. METHODS: Fifty patients undergoing coronary artery bypass graft surgery and/or valve replacement surgery at Örebro University Hospital from 2020 to 2021 were included. Cultures were collected from skin and subcutaneous tissue at two timepoints during surgery, and from pieces of vascular graft and felt that were pressed against subcutaneous tissue. The most common bacterial isolates were tested for antibiotic susceptibility with disc diffusion and gradient tests. FINDINGS: Cultures from skin had bacterial growth in 48% of patients at surgery start and in 78% after 2 h, and cultures from subcutaneous tissue were positive in 72% and 76% of patients, respectively. The most common isolates were C. acnes and S. epidermidis. Cultures from surgical materials were positive in 80-88%. No difference in susceptibility was found for S. epidermidis isolates at surgery start compared with after 2 h. CONCLUSION: The results suggest that skin bacteria are present in the wound and may contaminate surgical graft material during cardiac surgery.

Time-dependent bacterial air contamination of sterile fields in a controlled operating room environment: an experimental intervention study.

BACKGROUND: Surgical site infections are a global patient safety concern. Due to lack of evidence on contamination, pre-set surgical goods are sometimes disposed of or re-sterilized, thus increasing costs, resource use, and environmental effects. AIM: To investigate time-dependent bacterial air contamination of covered and uncovered sterile goods in the operating room. METHODS: Blood agar plates (N = 1584) were used to detect bacterial air contamination of sterile fields on 48 occasions. Each time, three aerobe and three anaerobe plates were used as baseline to model the preparation time, and 60 (30 aerobe, 30 anaerobe) were used to model the time pending before operation; half of these were covered with sterile drapes and half remained uncovered. Plates were collected after 4, 8, 12, 16, and 24 h. FINDINGS: Mean time before contamination was 2.8 h (95% confidence interval: 2.1-3.4) in the uncovered group and 3.8 h (3.2-4.4) in the covered group (P = 0.005). The uncovered group had 98 colony-forming units (cfu) versus 20 in the covered group (P = 0.0001). Sixteen different micro-organisms were isolated, the most common being Cutibacterium acnes followed by Micrococcus luteus. Of 32 Staphylococcus cfu, 14 were antibiotic resistant, including one multidrug-resistant Staphylococcus epidermidis. CONCLUSION: Protecting sterile fields from bacterial air contamination with sterile covers enhances the durability of sterile goods up to 24 h. Prolonged durability of sterile goods might benefit patient safety, since surgical sterile material could be prepared in advance for acute surgery, thereby enhancing quality of care and reducing both climate impact and costs.