Franklin Dexter, MD, PhD, FASA, is a professor of anesthesia at the University of Iowa

Carver College of Medicine in Iowa City. He receives no funds personally other than his salary and allowable expense reimbursements from the University of Iowa, has tenure with no incentive program, and has no financial holdings in any company related to his work, other than indirectly through mutual funds for retirement.

Franklin Dexter, MD, PhD, FASA

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%.

Those incidences are the endpoints of randomized clinical trials in anesthesia with results published from 2021 to 2022.

 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%.

 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.

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.

 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.

 isolated from anesthesia work area reservoirs are often hypertransmissible subtypes with biofilm formation, desiccation tolerance, and multidrug resistance.

Fortunately, there is a way to reduce these transmissions. Results of an earlier randomized trial showed the efficacy of preventing 

 transmission in the anesthesia work area and achieving resulting reductions in surgical site infections.

 The subsequent effectiveness study showed that basic perioperative preventive measures in operating rooms of a large hospital reduced transmission and infections.

 Importantly, the investigators stated that transmission (movement) through the anesthesia work area was directly related to surgical site infections.

However, all pathogens are not equivalent. The hypothesis most recently tested was that when 

 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 al

 used the bacterial isolates from a prospective observational study that had measured the prevalence of 

 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.

The patients studied were adults undergoing major inpatient surgery at 3 hospitals in different US states.

 isolates had been archived in a biorepository.

 The isolates were removed and tested for susceptibility to the prophylactic antibiotic that the patient had received.

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.

For the 406 pairs of cases without any transmitted 

 detected, 2% (n=8) involved a patient developing surgical site infection.

For the 84 pairs of cases with transmitted 

, 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.

 Finally, among the 22 pairs of cases with 

 transmitted and resistant to the prophylactic antibiotic, 18% (n=4) had a surgical site infection.

This ordered association was statistically significant (

<.0001) without and with adjustment for covariates associated with transmission.

 for readers interested in the scientific importance of the results.

 Briefly, this study showed that contamination of the anesthesia work area contributes to general pathogen transmission and antibiotic-resistant pathogens.

 That will be an area of future investigation because transmission of resistance is associated with increased mortality worldwide.

 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%.

 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 effectivness

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

 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 

 successfully reduce intraoperative (anesthesia work area) pathogen transmission.

1. Corcoran TB, Myles PS, Forbes AB, et al. Dexamethasone and surgical-site infection. 

. 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. 

. 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. 

. 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. 

. 2023;S1878-8750(23):00550-00558 doi:10.1016/j.wneu.2023.04.065

5. Loftus RW, Dexter F, Brown JR. Transmission of 

 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. 

 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 

 transmission to monitor effectiveness and provide feedback on intraoperative infection control. 

. 2020;21:100137. doi:10.1016/j.pcorm.2020.100137

7. Loftus RW, Dexter F, Robinson ADM. High-risk 

 transmission in the operating room: a call for widespread improvements in perioperative hand hygiene and patient decolonization practices. 

. 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 

 hypertransmissibility, resistance and infection development in the operating room. 

. 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 

 transmission and surgical site infections, a randomised clinical trial. 

. 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. 

. 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. 

. 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. 

. 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. 

. 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. 

. 2020;131(1):37-142. doi:10.1213/ANE.0000000000004829

Articles

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

Bacterial Transmission in Anesthesia Work Areas Explains Surgical Site Infections 

Surgical-site infections invariably involve surgeons, operating room (OR) nurses, sterilization of equipment, and so forth. Anesthesiologists, nurse anesthetists, and other anesthesia practitioners also contribute substantially to the transmission of pathogens.

For context, incidences of surgical-site infections differ based on inclusion criteria and lengths of patient follow‑up.

 For example, measured incidences have been 7.7% for inpatient surgery based on 60-day follow-ups,

 5.5% for inpatient surgery based on 30-day follow-ups,

 and 3.7% for inpatient and outpatient hospital surgery using billing codes for diagnosis.

 A randomized trial showed that perioperative transmission of ESKAPE pathogens (

 species) can be reduced, which reduces surgical-site infections.

 Prospective observational study then showed the strategy can be implemented throughout a multidisciplinary surgical suite.

) are combined with feedback to clinicians about intraoperative bacterial transmission.

 as a marker. For example, investigators at Georgetown were sent boxes with swabs, tubes, etc, and once used, they were returned for culturing and analysis.

 The investigators studied the time it took to perform sampling using the kits.8 Anesthesia assistants essentially opened sterile swabs, swabbed anesthesia-machine valves, patient axilla, stopcock lumens, etc.

There were 13 sites per case, 6 at the start and 7 at the end.

Sampling was done for successive cases in the same OR on the same day (“case pairs”)

. An example of transmission within a case was from the nasopharynx of the patient at the start of the case to the anesthesiologist’s hands sometime by the end of the case.

An example of transmission between cases was from the nurse anesthetist’s hands at the start of the first case to the nasopharynx of the second patient (when sampled after induction), observed on the nurse anesthetist’s hands again at end of second case and also on the anesthesia equipment at the end of the second case.

 From the study, sampling time averaged 3.4 minutes at the start of each case and 4.4 minutes at the end of each case—the total significantly briefer than 10 minutes.8 The cases from which sampling is done generally are 3.3 to 4.8 hours long

; therefore, circulating nurses can obtain the samples. If this is done, instead, by anesthesia technicians or infection preventionists, add the time waiting for patient induction and to be present at the end of surgery.

The primary end point of the randomized trial and observational effectiveness study was 

 transmission. For the randomized trial, 19 surgeons and their patients were randomized to usual care or infection-control bundle with feedback.

 Patients with transmission had 6-fold greater risk of surgical-site infection (

= .007). Treatment reduced the incidence of transmission (incidence risk ratio [IRR], 0.56; 

 For the effectiveness study, 804 patients were observed months before and after the infection-control program, including transmission feedback.

Optimization reduced the incidence of transmission (IRR, 0.39; 

 transmission complements reporting of surgical-site infections. Although the incidence of surgical-site infection varies more than 10-fold among surgical procedures,

 consistently there are no covariates for transmission: not the procedure, not surgical duration, not a dirty wound, not patient characteristics.

 transmission is many-fold higher than resulting surgical-site infections. Both factors make feedback about transmission easier to explain (

 transmission, the first decision to make is which ORs to sample. Some fundamental characteristics of surgical suites are relevant.

 Some ORs have many more cases per week than others, principally because some rooms’ cases take much longer than other rooms’ cases.

 Also, surgical specialties are distributed unequally among ORs (eg, rooms used preferentially for one specialty versus another), and average case urgency differs among rooms, as does the American Society of Anesthesiologists’ physical status score.

 From a study of 57 ORs in a large teaching hospital, the 20% of ORs with the most surgical-site infections accounted for 44% of 

 transmission, whereas the 20% with the least infections accounted for 5% of

 The 10% of specialty and OR combinations with the most surgical-site infections accounted for 76%

 transmission, whereas 47% of operating rooms had zero observed infections.

 That latter result is important for purposes of monitoring 

 transmission within and between case pairs. Use your surgical-site infection data—not for regular feedback, but rather, to choose a few specialty-OR combinations to target for monitoring and intervention.

Pathogens likely are transmitted intraoperatively in all ORs.

 What differs are probabilities of transmission resulting in surgical-site infection.

 Many hospitals report surgical-site infections per month in control charts. With 3 years of data, when plotted by OR, there was no paired association with cases per month.

The reason: Although ORs with more overall minutes per case (ie, longer) had greater incidence of infection (

<.001), those ORs had far fewer cases per day (

In other words, the ORs with very long cases (> 4.8 hours) have the greatest incidence of surgical-site infections, yet on many days, have only one case.

 In contrast, the ORs with cases averaging 3.3 to 4.8 hours in length have cases long enough for greater risk of surgical-site infection and usually 2 or 3 cases per day.

 In general, those are the ORs to target to prevent pathogen transmission. Beneficially, when monitoring 

 transmission using the few specialty-OR combinations with the most infections, applying the bundle of infection prevention interventions (

 transmission, the next related question is how many case pairs to sample. From the randomized trial, we have a typical incidence for transmission in the usual care group and a corresponding low incidence achieved with infection prevention bundle and feedback.

 Using those 2 incidences and applying statistical power analysis, the sample size would be 25 case pairs.

 For example, suppose that the targets for infection prevention were the 3 ORs of one specialty.

 Then the cases studied could be the first and second cases of the day in each room for 2 weeks. That would potentially give 30 case pairs, but cases occasionally cancel, all sampling cannot be completed, and so forth. After implementation (

 transmission need not be as large as for the randomized trial and observational study.

 A reasonable choice for feedback is to use culture results from another 75 case pairs.

 This information on sample size helps infection preventionists have context on number of surgical cases for sampling so that they can help the anesthesiologists and nurse anesthetists (and surgeons, OR nurses, and other anesthesia practitioners) know what to change to reduce transmission of the intraoperative bacterial pathogens.

In conclusion, substantial understanding exists about how OR pathogens cause surgical-site infections. It is known that the processes involved include not only contaminated wounds and resistance to otherwise appropriate antibiotics, but also bacterial transmission including the anesthesia environment.

 Feedback to anesthesia practitioners contributes to reduced surgical-site infections because that transmission can be mitigated with basic measures (Table).

 There is considerable understanding of why and how best to use 

 transmission as a marker of transmission for the purpose of feedback.

Taylor JS, Marten CA, Potts KA, et al. What is the real rate of surgical site infection?

. 2016;12(10):e878-e883. doi:10.1200/JOP.2016.011759

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 randomized clinical trial. 

Petrosyan Y, Thavorn K, Maclure M, et al. Long-term health outcomes and health system costs associated with surgical site infections: a retrospective cohort study. 

. 2021;273(5):917-923. doi:10.1097/SLA.0000000000003285

Dexter F, Epstein RH, Loftus RW. Quantifying and interpreting inequality of surgical site infections among operating rooms. 

. 2021;68(6):812-824. doi:10.1007/s12630-021-01931-5

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. 

 2022;77:110632. doi:10.1016/j.jclinane.2021.110632

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. 

. 2020;131(1):37-42.doi:10.1213/ANE.0000000000004829

Dexter F, Elhakim M, Loftus RW, Seering MS, Epstein RH. Strategies for daily operating room management of ambulatory surgery centers following resolution of the acute phase of the COVID-19 pandemic. 

. 2020;64:109854. doi:10.1016/j.jclinane.2020.109854

Datta S, Dexter F, Ledolter J, Wall RT, Loftus RW. Sample times for surveillance of 

Robinson ADM, Dexter F, Renkor V, Reddy S, Loftus RW. Operating room PathTrac analysis of current intraoperative Staphylococcus aureus transmission dynamics. 

. 2019;47(10):1240-1247. doi:10.1016/j.ajic.2019.03.028

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. 

Dexter F, Ledolter J, Epstein RH, Loftus RW. Futility of cluster designs at individual hospitals to study surgical site infections and interventions involving the installation of capital equipment in operating rooms. 

. 2020;44(4):82. doi:10.1007/s10916-020-01555-0

Dexter F, Ledolter J, Epstein RH, Loftus RW. Importance of operating room case scheduling on analyses of observed reductions in surgical site infections from the purchase and installation of capital equipment in operating rooms. 

. 2020;48(5):566-572. doi:10.1016/j.ajic.2019.08.017

Dexter F, Ledolter J, Wall RT, Datta S, Loftus RW. Sample sizes for surveillance of 

 transmission to monitor effectiveness and provide feedback on intraoperative infection control including for COVID-19. 

. 2020;20:100115. doi:10.1016/j.pcorm.2020.100115

To reduce the risk of surgical-site infection, utilize evidence-based interventions and give feedback to clinicians on bacterial transmission using Staphylococcus aureus as a marker. 


Franklin Dexter, MD, PhD, FASA

Articles

Bacterial Transmission in Anesthesia Work Areas Explains Surgical Site Infections

The OR: A Prime Target for Pathogens