Bacterial Transmission in Anesthesia Work Areas Explains Surgical Site Infections

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A recent study offers potential solutions to the frequent occurrence of surgical site infections, despite the sterile environment of surgical fields.

Surgical fields are fully prepped to be sterile. The instruments are sterile. Gowns and gloves are sterile. Yet large multicenter clinical trials studying many categories of inpatient surgery have shown the rate of postoperative surgical infection incidences to be 6% to 7%.1-3 Those incidences are the endpoints of randomized clinical trials in anesthesia with results published from 2021 to 2022.1-3 Where are the pathogenic bacteria coming from? Not from the surgeons: When surgical gloves were cultured, although there was a 10% prevalence of contamination at the case end, the concordance with patients developing surgical site infections was 0%.4 In a recent article, Loftus and colleagues showed that the anesthesia work area is ground zero for a high percentage of contemporary surgical site infections.4

Surgical site infections can occur through hematogenous seeding, direct contamination, contiguous spread, or aerosolization. Anesthesia reservoirs contribute to transmission pathways causing infection, including patient skin sites, anesthesia provider’s hands, anesthesia machine and cart, and intravenous stopcock and central line.5 One example showed how Staphylococcus aureus transmission in the anesthesia work area contributed to infection. It moved from the anesthesia resident’s hands at the start of the first case of the day, to the nose of the first patient, to the hands of the anesthesiologist at the end of the first case, to the nose of the second patient of the day in the room.6 Instances of S aureus isolated from anesthesia work area reservoirs are often hypertransmissible subtypes with biofilm formation, desiccation tolerance, and multidrug resistance.6,7

Surgical site infections can occur through hematogenous seeding, direct contamination, contiguous spread, or aerosolization. Anesthesia reservoirs contribute to transmission pathways causing infection, including patient skin sites, anesthesia provider’s hands, anesthesia machine and cart, and intravenous stopcock and central line.5

Fortunately, there is a way to reduce these transmissions. Results of an earlier randomized trial showed the efficacy of preventing S aureus transmission in the anesthesia work area and achieving resulting reductions in surgical site infections.8,9 The subsequent effectiveness study showed that basic perioperative preventive measures in operating rooms of a large hospital reduced transmission and infections.9 Importantly, the investigators stated that transmission (movement) through the anesthesia work area was directly related to surgical site infections.9

However, all pathogens are not equivalent. The hypothesis most recently tested was that when S aureus is resistant to the prophylactic antibiotic administered to the patient, then the risk of surgical site infection is especially high. To test the hypothesis, Loftus et al5 used the bacterial isolates from a prospective observational study that had measured the prevalence of S aureus transmission in the anesthesia work area and from the subsequent efficacy study showing that the use of multiple basic preventive measures (eg, improved hand hygiene) resulted in less transmission and fewer surgical site infections.8-11 The patients studied were adults undergoing major inpatient surgery at 3 hospitals in different US states.8,10,11 The S aureus isolates had been archived in a biorepository.4 The isolates were removed and tested for susceptibility to the prophylactic antibiotic that the patient had received.4

The sample was pairs of surgical cases, the first and second patients of the day in an operating room. There were 512 pairs of consecutive cases studied. Surgical site infections were examined for both patients.4,11 For the 406 pairs of cases without any transmitted S aureus detected, 2% (n=8) involved a patient developing surgical site infection.4 For the 84 pairs of cases with transmitted S aureus, but the involved isolates were all sensitive to the patient’s prophylactic antibiotic, there were 11% (9/84) with a patient developing surgical site infection.4 Finally, among the 22 pairs of cases with S aureus transmitted and resistant to the prophylactic antibiotic, 18% (n=4) had a surgical site infection.4 This ordered association was statistically significant (P<.0001) without and with adjustment for covariates associated with transmission.4

We recommend the paper in Journal of Hospital Infection for readers interested in the scientific importance of the results.5 Briefly, this study showed that contamination of the anesthesia work area contributes to general pathogen transmission and antibiotic-resistant pathogens.5 That will be an area of future investigation because transmission of resistance is associated with increased mortality worldwide.12,13 What we must consider, though, is the opening question. Where are the pathogenic bacteria coming from?


When no S aureus transmission was detected in the anesthesia work area, the incidence of surgical site infection was 2%.5 That prevalence is what we would expect intuitively to represent residual risk because of the surgery itself; sterility is a central policy of surgeons and operating room nurses. In other words, contamination of the anesthesia work can explain why surgical site infection rates are so much greater than would be expected.

The anesthesia team can help prevent pathogen transmission by including the following 7 features for efficacy and effectivness8,9,11,13.

  • Decolonizing the patient’s nose (eg, using nasal povidone iodine)
  • Decolonizing the patient’s groin and axilla (eg, using chlorhexidine wipes)
  • Conveniently locating hand antiseptic (eg, right next to the patient)
  • Wiping the anesthesia machine with a disinfectant before each case starts and after patient stabilization following induction of anesthesia
  • Being mindful of intravenous catheter care, including disinfecting caps for needleless connectors, disinfecting port protectors, and disinfecting caps for syringe tips
  • Monitoring S aureus transmission to provide feedback regarding improvement targets (eg, poor use of wipes to disinfect the patient’s groin before surgery) to the clinicians (anesthesiologists, nurse anesthetists, surgeons, infection preventionists)
  • Targeting use of ultraviolet-C disinfection to augment terminal surface disinfection cleaning for operating rooms with residual contamination (eg, first cases of the day) contributing to pathogen transmission

Yes, infection preventionists working with the anesthesia teams can successfully reduce intraoperative (anesthesia work area) pathogen transmission.


1. Corcoran TB, Myles PS, Forbes AB, et al. Dexamethasone and surgical-site infection. N Engl J Med. 2021;384(18):1731-1741. doi:10.1056/NEJMoa2028982

2. Meersch M, Weiss R, Küllmar M, et al. Effect of intraoperative handovers of anesthesia care on mortality, readmission, or postoperative complications among adults: the HandiCAP Randomized Clinical Trial. JAMA. 2022;327(24):2403-2412. doi:10.1001/jama.2022.9451

3. Sessler DI, Pei L, Li K, et al; PROTECT Investigators. Aggressive intraoperative warming versus routine thermal management during non-cardiac surgery (PROTECT): a multicentre, parallel group, superiority trial. Lancet. 2022;399(10337):1799-1808. doi:10.1016/S0140-6736(22)00560-8

4. Litofsky NS, Cohen D, Schlesselman C, Vallabhaneni A, Warner T, Herbert JP. No link between inadvertent surgical glove contamination and surgical site infection in patients undergoing elective neurosurgical operations. World Neurosurg. 2023;S1878-8750(23):00550-00558 doi:10.1016/j.wneu.2023.04.065

5. Loftus RW, Dexter F, Brown JR. Transmission of Staphylococcus aureus in the anaesthesia work area has greater risk of association with development of surgical site infection when resistant to the prophylactic antibiotic administered for surgery. J Hosp Infect. 2023;134:121‑128. doi:10.1016/j.jhin.2023.01.007

6. Datta S, Dexter F, Ledolter J, Wall RT, Loftus RW. Sample times for surveillance of S. aureus transmission to monitor effectiveness and provide feedback on intraoperative infection control. Periop Care Oper Room Manag. 2020;21:100137. doi:10.1016/j.pcorm.2020.100137

7. Loftus RW, Dexter F, Robinson ADM. High-risk Staphylococcus aureus transmission in the operating room: a call for widespread improvements in perioperative hand hygiene and patient decolonization practices. Am J Infect Control. 2018;46(10):1134-1141. doi:10.1016/j.ajic.2018.04.211

8. Loftus RW, Dexter F, Robinson ADM, Horswill AR. Desiccation tolerance is associated with Staphylococcus aureus hypertransmissibility, resistance and infection development in the operating room. J Hosp Infect. 2018;100(3):299-308. doi:10.1016/j.jhin.2018.06.020

9. Loftus RW, Dexter F, Goodheart MJ, et al. The effect of improving basic preventive measures in the perioperative arena on Staphylococcus aureus transmission and surgical site infections, a randomised clinical trial. JAMA Netw Open. 2020;3(3):e201934. doi:10.1001/jamanetworkopen.2020.1934

10. Wall RT, Datta S, Dexter F, et al. Effectiveness and feasibility of an evidence-based intraoperative infection control program targeting improved basic measures: a post-implementation prospective case-cohort study. J Clin Anesth. 2022;77:110632. doi:10.1016/j.jclinane.2021.110632

11. Loftus RW, Brown JR, Koff MD, et al. Multiple reservoirs contribute to intraoperative bacterial transmission. Anesth Analg. 2012;114(6):1236‑1248. doi:10.1213/ANE.0b013e31824970a2

12. Dexter F, Brown JR, Wall RT, Loftus RW. The efficacy of multifaceted versus single anesthesia work area infection control measures and the importance of surgical site infection follow-up duration. J Clin Anesth. 2023;85:111043. doi:10.1016/j.jclinane.2022.111043

13. Antimicrobial Resistance Collaborators. Global burden of bacterial antimicrobial resistance in 2019: a systematic analysis. Lancet. 2022;399(10325):629-655. doi:10.1016/S0140‑6736(21)02724‑0

14. Dexter F, Parra MC, Brown JR, Loftus RW. Perioperative COVID-19 defense: an evidence-based approach for optimization of infection control and operating room management. Anesth Analg. 2020;131(1):37-142. doi:10.1213/ANE.0000000000004829