Instrument tables equipped with local unidirectional airflow units reduce bacterial contamination during orthopedic implant surgery in an operating room with a displacement ventilation system

Schömig F., Perka C., Pumberger M., Ascherl R.

In spine surgery, surgical site infection (SSI) is one of the main perioperative complications and is associated with a higher patient morbidity and longer patient hospitalization. Most factors associated with SSI are connected with asepsis during the surgical procedure and thus with contamination of implants and instruments used which can be caused by pre- and intraoperative factors. In this systematic review we evaluate the current literature on these causes and discuss possible solutions to avoid implant and instrument contamination. A systematic literature search of PubMed addressing implant, instrument and tray contamination in orthopaedic and spinal surgery from 2001 to 2019 was conducted following the PRISMA guidelines. All studies regarding implant and instrument contamination in orthopaedic surgery published in English language were included. Thirty-five studies were eligible for inclusion and were divided into pre- and intraoperative causes for implant and instrument contamination. Multiple studies showed that reprocessing of medical devices for surgery may be insufficient and lead to surgical site contamination. Regarding intraoperative causes, contamination of gloves and gowns as well as contamination via air are the most striking factors contributing to microbial contamination. Our systematic literature review shows that multiple factors can lead to instrument or implant contamination. Intraoperative causes of contamination can be avoided by implementing behavior such as changing gloves right before handling an implant and reducing the instruments’ intraoperative exposure to air. In avoidance of preoperative contamination, there still is a lack of convincing evidence for the use of single-use implants in orthopaedic surgery.

Svensson K., Rolfson O., Mohaddes M., Malchau H., Erichsen Andersson A.

Aims To investigate the experience and emotional impact of prosthetic joint infection (PJI) on orthopaedic surgeons and identify holistic strategies to improve the management of PJI and protect surgeons’ wellbeing. Methods In total, 18 prosthetic joint surgeons in Sweden were recruited using a purposive sampling strategy. Content analysis was performed on transcripts of individual in-person interviews conducted between December 2017 and February 2018. Results PJI had a negative emotional impact on Swedish surgeons. Many felt guilt, stress, and a sense of failure, and several aspects of PJI management were associated with psychosocial challenges. Peer support was reported as the most important coping strategy as was collaborating with infectious disease specialists. Conclusion Our study affirms that there is a negative emotional impact of PJI on surgeons which can be minimized by improved peer support and working in multidisciplinary teams. Based on the surgeons’ experiences we have identified desired improvements that may facilitate the management of PJI. These may also be applicable within other surgical specialties dealing with postoperative infections, but need to be evaluated for their efficacy. Cite this article: Bone Joint J 2020;102-B(6):736–743.

Uzun E., Misir A., Ozcamdalli M., Kizkapan E.E., Cirakli A., Calgin M.K.

Time-dependent surgical instrument contamination and the effect of covering during arthroplasty have not been investigated. This study aimed to evaluate time-dependent contamination of surgical instruments and the effect of covering on contamination as well as to perform bacterial typing of contaminated samples. The hypothesis was that covering the surgical instruments would decrease contamination rates. Sixty patients who underwent total knee arthroplasty were randomized and divided into two groups: surgical instruments covered with a sterile towel or surgical instruments left uncovered. K-wires were used to extract microbiological samples. The K-wires were placed in a liquid culture medium at 0, 15, 30, 60, 90, and 120 min. After 24-h incubation period, samples from liquid cultures were cultured on blood agar using swabs. Samples with growth after 48 h were considered contaminated. Microscopic, staining, and biochemical properties were used for bacterial typing. Bacterial growth started after 30 and 60 min in the uncovered and covered groups, respectively. An increase in the number of K-wires contaminated with time was detected. At least 10,000 CFU/mL bacterial load was observed in the culture samples. Contamination was more significant in the uncovered group. A statistically significant difference in contamination was found between the uncovered and covered groups at 30-, 60-, 90-, and 120 min (p = 0.035, p = 0.012, p = 0.024, and p = 0.037, respectively). The most common bacteria on the contaminated instruments were coagulase-negative Staphylococci (60.4%), Staphylococcus aureus (22.9%), and Streptococcus agalactia (16.7%), respectively. The risk of contamination increases with time. However, it may decrease if surgical instruments are covered. In the clinical practice, empiric antibiotic regimens based on the type of identified microorganisms in this study may be developed for postoperative periprosthetic joint infection prophylaxis. Prognostic, Level II.

McGee M.

When the distributional assumptions for a t-test are not met, the default position of many analysts is to resort to a rank-based test, such as the Wilcoxon-Mann-Whitney Test to compare the difference in means between two samples. The Wilcoxon-Mann-Whitney Test presents no danger of tied observations when the observations in the data are continuous. However, in practice, observations are discretized due various logical reasons, or the data are ordinal in nature. When ranks are tied, most textbooks recommend using mid-ranks to replace the tied ranks, a practice that affects the distribution of the Wilcoxon-Mann-Whitney Test under the null hypothesis. Other methods for breaking ties have also been proposed. In this study, we examine four tie-breaking methods—average-scores, mid-ranks, jittering, and omission—for their effects on Type I and Type II error of the Wilcoxon-Mann-Whitney Test and the two-sample t-test for various combinations of sample sizes, underlying population distributions, and percentages of tied observations. We use the results to determine the maximum percentage of ties for which the power and size are seriously affected, and for which method of tie-breaking results in the best Type I and Type II error properties. Not surprisingly, the underlying population distribution of the data has less of an effect on the Wilcoxon-Mann-Whitney Test than on the t-test. Surprisingly, we find that the jittering and omission methods tend to hold Type I error at the nominal level, even for small sample sizes, with no substantial sacrifice in terms of Type II error. Furthermore, the t-test and the Wilcoxon-Mann-Whitney Test are equally effected by ties in terms of Type I and Type II error; therefore, we recommend omitting tied observations when they occur for both the two-sample t-test and the Wilcoxon-Mann-Whitney due to the bias in Type I error that is created when tied observations are left in the data, in the case of the t-test, or adjusted using mid-ranks or average-scores, in the case of the Wilcoxon-Mann-Whitney.

von Vogelsang A.-., Förander P., Arvidsson M., Löwenhielm P.

Surgical site infections (SSIs) after neurosurgery are potentially life-threatening and entail great costs. SSIs may occur from airborne bacteria in the operating room, and ultraclean air is desired during infection-prone cleaning procedures. Door openings and the number of persons present in the operating room affect the air quality. Mobile laminar airflow (MLAF) units, with horizontal laminar airflow, have previously been shown to reduce airborne bacterial contamination.To assess the effect of MLAF units on airborne bacterial contamination during neurosurgical procedures.In a quasi-experimental design, bacteria-carrying particles (colony-forming units: cfu) during neurosurgical procedures were measured with active air-sampling in operating rooms with conventional turbulent ventilation, and with additional MLAF units. The MLAF units were shifted between operating rooms monthly. Colony-forming unit count and bacterial species detection were conducted after incubation. Data was collected for a period of 18 months.A total of 233 samples were collected during 45 neurosurgical procedures. The use of MLAF units significantly reduced the numbers of cfu in the surgical site area (P < 0.001) and above the instrument table (P < 0.001). Logistic regression showed that the only significant predictor affecting cfu count was the use of MLAF units (odds ratio: 41.6; 95% confidence interval: 11.3-152.8; P < 0.001). The most frequently detected bacteria were coagulase-negative staphylococci.MLAF successfully reduces cfu during neurosurgery to ultraclean air levels. MLAF units are valuable when the main operating room ventilation system is unable to produce ultraclean air in infection-prone clean neurosurgery.

Moore A.J., Blom A.W., Whitehouse M.R., Gooberman-Hill R.

Objectives Around 1% of patients who have a hip replacement have deep prosthetic joint infection (PJI) afterwards. PJI is often treated with antibiotics plus a single revision operation (1-stage revision), or antibiotics plus a 2-stage revision process involving more than 1 operation. This study aimed to characterise the impact and experience of PJI and treatment on patients, including comparison of 1-stage with 2-stage revision treatment.Design Qualitative semistructured interviews with patients who had undergone surgical revision treatment for PJI. Patients were interviewed between 2 weeks and 12 months postdischarge. Data were audio-recorded, transcribed, anonymised and analysed using a thematic approach, with 20% of transcripts double-coded.Setting Patients from 5 National Health Service (NHS) orthopaedic departments treating PJI in England and Wales were interviewed in their homes (n=18) or at hospital (n=1).Participants 19 patients participated (12 men, 7 women, age range 56–88 years, mean age 73.2 years).Results Participants reported receiving between 1 and 15 revision operations after their primary joint replacement. Analysis indicated that participants made sense of their experience through reference to 3 key phases: the period of symptom onset, the treatment period and protracted recovery after treatment. By conceptualising their experience in this way, and through themes that emerged in these periods, they conveyed the ordeal that PJI represented. Finally, in light of the challenges of PJI, they described the need for support in all of these phases. 2-stage revision had greater impact on participants’ mobility, and further burdens associated with additional complications.Conclusions Deep PJI impacted on all aspects of patients’ lives. 2-stage revision had greater impact than 1-stage revision on participants’ well-being because the time in between revision procedures meant long periods of immobility and related psychological distress. Participants expressed a need for more psychological and rehabilitative support during treatment and long-term recovery.

Erichsen Andersson A., Petzold M., Bergh I., Karlsson J., Eriksson B.I., Nilsson K.

The importance of laminar airflow systems in operating rooms as protection from surgical site infections has been questioned. The aim of our study was to explore the differences in air contamination rates between displacement ventilation and laminar airflow systems during planned and acute orthopedic implant surgery. A second aim was to compare the influence of the number of people present, the reasons for traffic flow, and the door-opening rates between the 2 systems.Active air sampling and observations were made during 63 orthopedic implant operations.The laminar airflow system resulted in a reduction of 89% in colony forming units in comparison with the displacement system (P < .001). The air samples taken in the preparation rooms showed high levels of bacterial growth (≈ 40 CFU/m(3)).Our study shows that laminar airflow-ventilated operating rooms offer high-quality air during surgery, with very low levels of colony forming units close to the surgical wound. The continuous maintenance of laminar air flow and other technical systems are crucial, because minor failures in complex systems like those in operating rooms can result in a detrimental effect on air quality and jeopardize the safety of patients. The technical ventilation solutions are important, but they do not guarantee clean air, because many other factors, such as the organization of the work and staff behavior, influence air cleanliness.

Anderson D.J., Podgorny K., Berríos-Torres S.I., Bratzler D.W., Dellinger E.P., Greene L., Nyquist A., Saiman L., Yokoe D.S., Maragakis L.L., Kaye K.S.

Andersson A.E., Bergh I., Karlsson J., Eriksson B.I., Nilsson K.

Understanding the protective potential of operating room (OR) ventilation under different conditions is crucial to optimizing the surgical environment. This study investigated the air quality, expressed as colony-forming units (CFU)/m(3), during orthopedic trauma surgery in a displacement-ventilated OR; explored how traffic flow and the number of persons present in the OR affects the air contamination rate in the vicinity of surgical wounds; and identified reasons for door openings in the OR.Data collection, consisting of active air sampling and observations, was performed during 30 orthopedic procedures.In 52 of the 91 air samples collected (57%), the CFU/m(3) values exceeded the recommended level of

Høiby N., Ciofu O., Johansen H.K., Song Z., Moser C., Jensen P.Ø., Molin S., Givskov M., Tolker‐Nielsen T., Bjarnsholt T.

Bacteria survive in nature by forming biofilms on surfaces and probably most, if not all, bacteria (and fungi) are capable of forming biofilms. A biofilm is a structured consortium of bacteria embedded in a self‐produced polymer matrix consisting of polysaccharide, protein and extracellular DNA. Bacterial biofilms are resistant to antibiotics, disinfectant chemicals and to phagocytosis and other components of the innate and adaptive inflammatory defense system of the body. It is known, for example, that persistence of staphylococcal infections related to foreign bodies is due to biofilm formation. Likewise, chronic Pseudomonas aeruginosa lung infections in cystic fibrosis patients are caused by biofilm growing mucoid strains. Gradients of nutrients and oxygen exist from the top to the bottom of biofilms and the bacterial cells located in nutrient poor areas have decreased metabolic activity and increased doubling times. These more or less dormant cells are therefore responsible for some of the tolerance to antibiotics. Biofilm growth is associated with an increased level of mutations. Bacteria in biofilms communicate by means of molecules, which activates certain genes responsible for production of virulence factors and, to some extent, biofilm structure. This phenomenon is called quorum sensing and depends upon the concentration of the quorum sensing molecules in a certain niche, which depends on the number of the bacteria. Biofilms can be prevented by antibiotic prophylaxis or early aggressive antibiotic therapy and they can be treated by chronic suppressive antibiotic therapy. Promising strategies may include the use of compounds which can dissolve the biofilm matrix and quorum sensing inhibitors, which increases biofilm susceptibility to antibiotics and phagocytosis.

Nilsson K.-., Lundholm R., Friberg S.

The area in a vertical ultraclean laminar air flow (LAF) theatre is usually too small to accommodate all the equipment needed for major surgery. We investigated the addition of an instrument table supplied with fixed ultraclean LAF and placed alongside the existing main LAF unit, to determine its physical and bacteriological effect on the main unit. In phase 1, with two investigators but without a patient, smoke tests showed no intrusion of air from the table into the main unit and particle counts did not show any adverse effect on the main LAF unit. In phase 2, during patients undergoing two total knee replacements, the LAF table and a table without LAF were placed alongside the main LAF unit. The tables were subjected to the activity of an extra operating room (OR) nurse working from inside the main LAF vigorously simulating handling of instruments. During this activity, the >5μm particle counts were 275/m(3) at the instrument table with LAF and 8550/m(3) at the table without LAF (P

Pinto F.M., de Souza R.Q., da Silva C.B., Jenné Mimica L.M., Graziano K.U.

Because of advances in technology, the number of orthopedic surgeries, mainly hip and knee replacement surgeries, has increased, with a total of 150,000 prosthetic surgeries estimated per year in the United States and 400,000 worldwide.We used an exploratory cross-sectional study, with a quantitative approach to determine the microbial load in instruments used in orthopedic surgeries, quantifying and identifying the microbial growth genus and species, according to the surgical potential of contamination that characterizes the challenge faced by the Material and Sterilization Center at the Institute of Orthopedics and Traumatology of Hospital das Clinicas of the School of Medicine of the University of Sao Paulo, Brazil.The orthopedic surgical instruments were immersed, after their use, in sterilized distilled water, sonicated in an ultrasonic washer, and posteriorly agitated. Subsequently, the wash was filtrated through a 0.45-mum membrane and incubated in aerobic and anaerobic mediums and in medium for fungi and yeasts.In clean surgeries, 47% of the instruments were contaminated; in contaminated surgeries, 70%; and, in infected surgeries, 80%. Regardless of the contamination potential of the surgeries, the highest quantitative incidence of microorganism recovery was located in the 1 to 100 colony-forming unit range, and 13 samples presented a microbial growth potential >300 colony-forming units. Regardless of the contamination potential of the surgeries, there was a convergence in the incidence of negative-coagulase Staphylococcus growth (28%, clean surgeries; 32%, contaminated surgeries; and 29%, infected surgeries) and Staphylococcus aureus (28%, contaminated surgeries; and 43%, infected surgeries).Most of the microorganisms recovered from the analyzed instruments (78%) were vegetative bacteria that presented their death curve at around 80 degrees C, characterizing a low challenge considering the processes of cleaning and sterilization currently employed by the Material and Sterilization Center. Fewer microorganisms were recovered from instruments used in clean surgeries in comparison with those used in contaminated and infected surgeries.

Del Pozo J.L., Patel R.

A 62-year-old woman with osteoarthritis presents with a 7-month history of progressively worsening left hip pain radiating to the groin, 8 months after undergoing total left-hip arthroplasty. The pain has not responded to nonsteroidal antiinflammatory drugs. Physical examination reveals a sinus tract overlying her left hip. Her leukocyte count is 8000 per cubic millimeter, and the C-reactive protein (CRP) level is 15.5 mg per liter. A radiograph shows loosening of the prosthesis at the bone–cement interface. Synovial-fluid aspirate shows 15×103 cells per cubic millimeter (89% neutrophils); cultures of an aspirate from the hip grow Staphylococcus epidermidis. How should her case be managed?

Betsch B., Eggli S., Siebenrock K., Täuber M., Mühlemann K.

Recently recommended treatment modalities for prosthetic joint infection (PJI) were evaluated.A retrospective cohort analysis of 68 patients with PJI of hip or knee who were treated from 1995 through 2004 was conducted at the University Hospital Bern (Bern, Switzerland).A 2-stage exchange was the most frequent (75.0%) surgical strategy, followed by retention and debridement (17.6%), 1-stage exchange (5.9%), and resection arthroplasty or suppressive antimicrobial treatment (1.5%). The chosen strategy was in 88% agreement with the recommendations. Adherence was only 17% for retention and debridement and was 0% for 1-stage exchange. Most PJIs (84%) were treated with an adequate or partially adequate antimicrobial regimen. Recurrence-free survival was observed in 51.5% of PJI episodes after 24 months of follow-up. The risk of treatment failure was significantly higher for PJI treated with a surgical strategy other than that recommended (hazard ratio, 2.34; 95% confidence interval, 1.10-4.70; P = .01) and for PJIs treated with antibiotics not corresponding to recommendations (hazard ratio, 3.45; confidence interval, 1.50-7.60; P = .002). Other risk factors associated with lack of healing were a high infection score at the time of diagnosis (hazard ratio, 1.29; 95% confidence interval, 1.10-1.40; P < .001) and presence of a sinus tract (hazard ratio, 2.35; 95% confidence interval, 1.10-5.0; P = .02).Our study demonstrates the value of current treatment recommendations. Inappropriate choice of conservative surgical strategies (such as debridement and retention) and inadequate antibiotic treatment are associated with failure.

Pasquarella C., Sansebastiano G.E., Ferretti S., Saccani E., Fanti M., Moscato U., Giannetti G., Fornia S., Cortellini P., Vitali P., Signorelli C.

The aim of this study was to evaluate the efficacy of a mobile laminar airflow (LAF) unit in reducing bacterial contamination at the surgical area in an operating theatre supplied with turbulent air ventilation. Bacterial sedimentation was evaluated during 76 clean urological laparotomies; in 34 of these, a mobile LAF unit was added. During each operation, settle plates were placed at four points in the operating theatre (one at the patient area and three at the perimeter), a nitrocellulose membrane was placed on the instrument table and an additional membrane near the wound. During four operations, particle counting was performed to detect particles > or =0.5 microm. Mean bacterial sedimentation on the nitrocellulose membrane on the instrument table was 2730 cfu/m(2)/h under standard ventilation conditions, whereas it decreased significantly to a mean of 305 cfu/m(2)/h when the LAF unit was used, i.e. within the suggested limit for ultraclean operating theatres (P=0.0001). The membrane near the wound showed a bacterial sedimentation of 4031 cfu/m(2)/h without the LAF unit and 1608 cfu/m(2)/h with the unit (P=0.0001). Particle counts also showed a reduction when the LAF unit was used. No significant difference was found at the four points in the operating theatre between samplings performed with, and without, the LAF unit. Use of a mobile LAF unit with turbulent air ventilation can reduce bacterial contamination at the surgical area in high-risk operations (e.g. prosthesis implant).

Fiore T., De Santi N., Pietrella D., Barcaccia M., Palmieri M.I., Lupidi M., Mariotti C., Cagini C.

To evaluate and compare the mycobacterial load using a mobile laminar airflow (LAF) device in an IVI-dedicated outpatient clean room (OCR) without ventilation systems and in a hospital-based operating theatre (HOT). This case–control study was conducted in 2 different settings: OCR and HOT during a series of intravitreal injections (IVIs). The Air Microbial analysis was performed using a Surface Air System instrument at three different moments during the IVI sessions in both settings: at the operative site (OS), four meters from the OS (DOS) and in the disinfection room (DR). At the OS in the OCR, the microbial load was 20.33 ± 16.51 CFU/m3 at T-1; 1.00 ± 1.00 CFU/m3 at T0; 6.67 ± 6.03 CFU/m3 at T1; 10.00 ± 9.54 CFU/m3 at T2 and 4.33 ± 3.06 CFU/m3 at T3. At the OS in the HOT, the CFU were respectively 0.00 ± 0.00 at T0; 0.67 ± 0.58 at T1; 0.00 ± 0.00 at T2 and 0.00 ± 0.00 T3. This standardized sterile technique in an OCR setting, with a mobile LAF, reduces the microbial colonies to levels that are safe and comparable to those recorded in the HOT setting, thus potentially improving the safety of IVIs in an OCR setting.

Fann L., Cheng C., Chien Y., Hsu C., Chien W., Huang Y., Chung R., Huang S., Jiang Y., Yin S., Cheng K., Wu Y., Hsiao S., Hsu S., Huang Y., et. al.

AbstractThe sterilisation of surgical instruments is a major factor in infection control in the operating room (OR). All items used in the OR must be sterile for patient safety. Therefore, the present study evaluated the effect of far-infrared radiation (FIR) on the inhibition of colonies on packaging surface during the long-term storage of sterilised surgical instruments. From September 2021 to July 2022, 68.2% of 85 packages without FIR treatment showed microbial growth after incubation at 35 °C for 30 days and at room temperature for 5 days. A total of 34 bacterial species were identified, with the number of colonies increasing over time. In total, 130 colony-forming units were observed. The main microorganisms detected were Staphylococcus spp. (35%) and Bacillus spp. (21%) , Kocuria marina and Lactobacillus spp. (14%), and mould (5%). No colonies were found in 72 packages treated with FIR in the OR. Even after sterilisation, microbial growth can occur due to movement of the packages by staff, sweeping of floors, lack of high-efficiency particulate air filtration, high humidity, and inadequate hand hygiene. Thus, safe and simple far-infrared devices that allow continuous disinfection for storage spaces, as well as temperature and humidity control, help to reduce microorganisms in the OR.