Propionibacterium persists in the skin despite standard surgical preparation

Impact of postoperative skin disinfection with chlorhexidine on bacterial colonisation following shoulder arthroplasty surgery: a controlled randomised study

Background

Surgical site infections are a significant threat to patient safety. Shoulder arthroplasty carries an increased risk due to foreign implants. Skin preparation in general is a key preoperative preventive intervention, and the use of chlorhexidine can have a prolonged effect on bacterial colonisation. There is a lack of evidence regarding whether postoperative disinfection has an impact on bacterial colonisation during the first 48 hours after surgery. Our hypothesis was that applying postoperative antiseptic with 5 mg/ml chlorhexidine in 70% ethanol would lead to reduced bacterial colonisation with Staphylococcus aureus, coagulase-negative staphylococcus and Cutibacterium acnes around the surgical wound within the initial 48 hours after elective shoulder surgery, compared with the use of sodium chloride.

Methods

A single-blinded, controlled study was conducted at a county hospital in Sweden. Swabs from the skin were collected four times: at baseline, preoperatively, after the intervention and after 48 hours.

Results

Our hypothesis was not confirmed. Although not statistically significant, the chlorhexidine group had a higher prevalence of bacterial colonisation of clinically relevant bacteria.

Conclusions

Our study could not confirm that postoperative disinfection with chlorhexidine reduces bacterial colonisation compared with sodium chloride. The results highlight the complexity of SSIs and the importance of evidence-based preventive skin preparation to ensure patient safety. Further research is needed, considering the study's limitations, to explore and evaluate the effectiveness of different skin cleansing solutions and preventive strategies in diverse surgical contexts.

Silver carboxylate-TiO2/polydimethyl siloxane is a safe and effective antimicrobial with significant wound care potential

Introduction

With the rise in antibiotic resistance, new methodologies are needed to combat musculoskeletal infections. Silver is an antimicrobial that can be synthesized in different forms, but its pharmacokinetics are difficult to control. This study details the antibacterial efficacy and cellular cytotoxicity of a formulation consisting of silver carboxylate (AgCar) released through a titanium dioxide/polydimethylsiloxane matrix with a predictable release profile on Pseudomonas aeruginosa, Acinetobacterium baumannii, and human-derived primary osteoblasts.

Methods

Through an Institutional Animal Care and Use Committee and IRB-approved protocol, AgCar was applied to live Yucatan porcine skin and histologically analyzed for skin penetration. Graphite Furnace Atomic Absorption Spectroscopy (GFAAS) was used to measure elution of AgCar. Dose-response curves were generated through optical density to assess potency. Finally, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used to quantify the cellular cytotoxicity of the novel formulation. The results were subject to statistical analysis using analysis of variance and post hoc Tukey tests.

Results

The silver carboxylate coating demonstrated deep penetration into the epithelium at the level of the deep pilosebaceous glands in animal models. GFAAS testing demonstrated the extended elution profile of silver carboxylate over 96 hours, while 100% silver with no titanium dioxide-polydimethylsiloxane matrix fully eluted within 48 hours. 10x silver carboxylate demonstrated superior antimicrobial activity to antibiotics and other silver formulations and showed minimal cytotoxicity compared with other silver formulations.

Discussion/Clinical Relevance

Current antimicrobial therapies in wound care and surgical antisepsis, such as chlorhexidine gluconate, have pitfalls including poor skin penetration and short duration of efficacy. The broad antimicrobial activity, extended elution, and deep skin penetration of this AgCar formulation show great promise for surgical site infection and wound care treatment. Novel technology to fight the growing threat of microbial resistance should be at the forefront of orthopaedic surgical site infection prevention and treatment.

Does hydrogen peroxide application to the dermis following surgical incision affect Cutibacterium acnes cultures in total shoulder arthroplasty in male patients? A randomized controlled trial

BACKGROUND

Periprosthetic joint infections occur in 1%-4% of primary total shoulder arthroplasties (TSAs). Cutibacterium acnes is the most commonly implicated organism and has been shown to persist in the dermis despite use of preoperative antibiotics and standard skin preparations. Studies have shown decreased rates of cultures positive for C acnes with use of preoperative benzoyl peroxide or hydrogen peroxide (H2O2), but even with this positive deep cultures remain common. We sought to determine whether an additional application of H2O2 directly to the dermis following skin incision would further decrease deep culture positivity rates.

METHODS

We performed a randomized controlled trial comparing tissue culture results in primary TSA in patients who received a standard skin preparation with H2O2, ethanol, and ChloraPrep (CareFusion, Leawood, KS, USA) vs. an additional application of H2O2 to the dermis immediately after skin incision. Given the sexual dimorphism seen in the shoulder microbiome regarding C acnes colonization rates, only male patients were included. Bivariable and multivariable analyses were performed to compare rates of positive cultures based on demographic and surgical factors.

RESULTS

Dermal cultures were found to be positive for C acnes at similar rates between the experimental and control cohorts for the initial (22% vs. 28%, P = .600) and final (61% vs. 50%, P > .999) dermal swabs. On bivariable analysis, the rate of positive deep cultures for C acnes was lower in the experimental group, but this difference was not statistically significant (28% vs. 44%, P = .130). However, patients who underwent anatomic TSA were found to have a significantly greater rate of deep cultures positive for C acnes (57% vs. 28%, P = .048); when controlling for this on multivariable analysis, the experimental cohort was found to be associated with significantly lower odds of having positive deep cultures (odds ratio, 0.37 [95% confidence interval, 0.16-0.90], P = .023). There were no wound complications in either cohort.

CONCLUSIONS

An additional H2O2 application directly to the dermis following skin incision resulted in a small but statistically significant decrease in the odds of having deep cultures positive for C acnes without any obvious adverse effects on wound healing. Given its cost-effectiveness, use of a post-incisional dermal decontamination protocol may be considered as an adjuvant to preoperative use of benzoyl peroxide or H2O2 to decrease C acnes contamination.

Best products for skin antisepsis

BACKGROUND

Skin antiseptics are used for several purposes before surgical procedures, for bathing high-risk patients as a means of reducing central line-associated infections and other health care associated infections.

METHODS

A PubMed search was performed to update the evidence on skin antiseptic products and practices.

RESULTS

Current guidelines for prevention of surgical site infections (SSIs) recommend preoperative baths or showers with a plain or antimicrobial soap prior to surgery, but do not make recommendations on the timing of baths, the total number of baths needed, or about the use of chlorhexidine gluconate (CGH)-impregnated cloths. Randomized controlled trials have demonstrated that pre-operative surgical hand antisepsis using an antimicrobial soap or alcohol-based hand rub yields similar SSI rates. Other studies have reported that using an alcohol-based hand rub caused less skin irritation, was easier to use, and required shorter scrub times than using antimicrobial soap. Current SSI prevention guidelines recommend using an alcohol-containing antiseptic for surgical site infection. Commonly used products contain isopropanol combined with either CHG or with povidone-iodine. Surgical site preparation protocols for shoulder surgery in men may need to include coverage for anaerobes. Several studies suggest the need to monitor and improve surgical site preparation techniques. Daily bathing of intensive care unit (ICU) patients with a CHG-containing soap reduces the incidence of central line-associated bloodstream infections (CLABSIs). Evidence for a similar effect in non-ICU patients is mixed. Despite widespread CHG bathing of ICU patients, numerous barriers to its effective implementation exist. Measuring CHG levels on the skin is useful for identifying gaps in coverage and suboptimal skin concentrations. Using alcohol-based products with at least 2% CHG for skin preparation prior to central line insertion reduces CLABSIs.

CONCLUSIONS

Progress has been made on skin antisepsis products and protocols, but improvements in technique are still needed.

Bacterial microbiome and host inflammatory gene expression in foreskin tissue

The penile epithelial microbiome remains underexplored. We sequenced human RNA and a segment of the bacterial 16S rRNA gene from the foreskin tissue of 144 adolescents from South Africa and Uganda collected during penile circumcision after receipt of 1-2 doses of placebo, emtricitabine + tenofovir disoproxil fumarate, or emtricitabine + tenofovir alafenamide to investigate the microbiome of foreskin tissue and its potential changes with antiretroviral use. We identified a large number of anaerobic species, including Corynebacterium acnes, which was detected more frequently in participants from South Africa than Uganda. Bacterial populations did not differ by treatment received, and no differentially abundant taxa were identified between placebo versus active drug recipients. The relative abundance of specific bacterial taxa was negatively correlated with expression of genes downstream of the innate immune response to bacteria and regulation of inflammation. Our results show no difference in the tissue microbiome of the foreskin with short-course antiretroviral use but that bacterial taxa were largely inversely correlated with inflammatory gene expression, consistent with commensal colonization.

Bacterial reservoir in deeper skin is a potential source for surgical site and biomaterial-associated infections

BACKGROUND

The origin of surgical site and biomaterial-associated infection is still elusive. Micro-organisms contaminating the wound may come from the air in the operating theatre, the surgical team or the skin of the patient. The skin of patients is disinfected prior to surgery, but bacteria deeper in the skin (e.g. in sweat glands or sebaceous glands) may not be reached.

METHODS

A preliminary cohort study was performed to study the origin of surgical site and biomaterial-associated infection between May 2020 and February 2021. In order to investigate whether cutaneous microbiota colonize the wound when released from the skin upon cutting, aerobic and anaerobic bacteria were isolated, quantified and identified from the skin of 99 patients undergoing trauma surgery, before and after skin disinfection, from knife blades and from the wound directly after the first cut.

RESULTS

Ninety-nine percent of the patients were culture-positive before disinfection with chlorhexidine. Of these, 40% were still culture-positive after disinfection. Of these, 54% had a positive culture of the wound after cutting the skin. Twenty percent of the patients with a negative culture after disinfection had a positive wound culture after cutting the skin. Staphylococcus epidermidis and Cutibacterium acnes were the most commonly cultured bacterial species. In 9% of cases, more than 100 bacterial colonies were cultured from the wound; this may cause biomaterial-associated infection.

CONCLUSION

Bacteria residing in the skin and not eradicated by disinfection may enter the surgical wound upon cutting, resulting in contamination which may cause biomaterial-associated infection.

Is there value in the routine practice of discarding the incision scalpel from the surgical field to prevent deep wound contamination with Cutibacterium acnes? An update

BACKGROUND

Cutibacterium acnes is the most common microbe implicated in periprosthetic infection in shoulder arthroplasty. We present an update of a previous pilot study in which we demonstrated the persistence of C acnes on the skin and contamination of the scalpel used for the initial skin incision despite a robust presurgical skin preparation protocol.

METHODS

We collected a consecutive case series of patients undergoing primary or revision anatomic or reverse total shoulder arthroplasty performed by a single fellowship-trained surgeon at a tertiary referral hospital from November 2019 to December 2022. The scalpel blade used for the initial skin incision in each patient was swabbed, with cultures being held for 21 days according to a C acnes-specific protocol. Demographic data, medical comorbidities, surgical information, culture results, and infections were documented.

RESULTS

We identified 100 patients (51 men and 49 women) who met the inclusion criteria (mean age, 66.91 years; age range, 44-93 years). Cultures returned positive findings for C acnes in 12 patients (12%), 11 of whom were men (odds ratio, 13.2; 95% confidence interval, 1.73-194.87). No association was found between positive culture findings and age, body mass index, medical comorbidities, or procedure type. No postoperative infections occurred in this patient cohort, and the patients will continue to be monitored for the development of infection.

CONCLUSION

Despite stringent presurgical preparation and scrub protocols, a significant portion of patients undergoing shoulder arthroplasty have C acnes in culturable quantities on their skin at the time of incision. C acnes contamination is much more common in male patients. These findings should be taken into consideration regarding preventive measures such as discarding the initial scalpel and avoiding unnecessary dermal contact during the procedure.

Dynamics of Cutibacterium repopulation onto the skin surface of the shoulder after chlorhexidine application

PURPOSE

The objective of this study was to characterize the temporal dynamics of Cutibacterium repopulation of the skin surface after application of chlorhexidine to the shoulder.

METHODS

Ten shoulders in five male subjects were used. A skin swab was taken prior to (0 minutes) and then at three, 30, 60, 120, and 240 minutes after skin preparation with 2% chlorhexidine gluconate and 70% isopropyl alcohol. Semi-quantitative bacterial load was measured for each timepoint.

RESULTS

From zero minutes (pre-treatment) to three minutes, chlorhexidine-isopropyl alcohol reduced the skin bacterial load in eight out of ten shoulders. Of these eight shoulders, four (50%) had growth by 30 minutes, seven (88%) had growth by 60 minutes, and all eight (100%) had growth by 240 minutes. Compared to the three minutes after chlorhexidine application, bacterial load had significantly increased by 60 minutes but were still significantly lower than the pre-prep bacterial load (0 minutes).

CONCLUSION

Following standard surgical skin preparation with chlorhexidine-isopropyl alcohol, the surface of the shoulder is repopulated with Cutibacterium within one hour, presumably from reservoirs in sebaceous glands not penetrated by topical antiseptic agents. Since these dermal glands are transected by skin incision for shoulder arthroplasty, this study suggests that they may be sources of wound contamination during surgery in spite of skin preparation with chlorhexidine.

Unexpected intraoperative positive culture (UIPC) in presumed aseptic revision spine surgery: a systematic review and meta-analysis

BACKGROUND CONTEXT

Unexpected intraoperative positive culture (UIPC) has recently become increasingly common in revision spine surgery, being implicated as an etiological factor in revision spine surgery indications such as implant failure or pseudoarthrosis.

PURPOSE

Utilizing the available literature, this study aimed to investigate the prevalence of UIPC, and its clinical importance in patients following presumed aseptic revision spine surgery.

STUDY DESIGN

Meta-analysis and systematic review.

METHODS

Multiple databases and reference articles were searched until May 2022. The primary outcome was the pooled rate of UIPC, and the secondary outcomes were the microbiological profile of UIPC, the risk factors of UIPC, and the clinical fate of UIPC.

RESULTS

Twelve studies were eligible for meta-analysis, with a total of 1,108 patients. The pooled rate of UIPC was 24.3% (95% CI=15.8%-35.5%) in adult patients, and 43.2% (95% CI=32.9%-54.2%) in pediatric patients. The UIPC rate was higher when both conventional wound culture and sonication were used together compared to sonication alone or conventional wound culture alone. The rates were 28.9%, 23.6%, and 15.5 %, respectively. In adult and pediatric patients, the most commonly cultured organism was Cutibacterium acnes (42.5% vs 57.7%), followed by coagulase-negative Staphylococcus (39.9% vs 30.5%). Male patients had a higher rate of UIPC (OR= 2.6, 95% CI=1.84-3.72, p<.001), as did patients with a longer fusion construct (MD=0.76, 95% CI=0.27-1.25, p<.001).

CONCLUSIONS

The pooled rate of UIPC in aseptic spine revision surgery was 24.3% and 43.2% in adult and pediatric patients respectively. The most common organisms were C. acnes and coagulase-negative Staphylococcus. The impact of UIPC on patients` clinical outcomes is not fully understood. We are not able to recommend routine culture in revision spine surgery, however, adding sonication may aid in the diagnosis of UIPC. There is not enough evidence to recommend specific treatment strategies at this time, and further studies are warranted.

A Microcurrent Dressing Reduces Cutibacterium Acnes Colonization in Patients Undergoing Shoulder Arthroplasty or Arthroscopy: A Prospective Case Series

Background: Cutibacterium acnes infections in the shoulder remain a significant concern in the setting of shoulder arthroplasty. Purpose: We sought to evaluate the efficacy of a microcurrent dressing in reducing C. acnes skin colonization and thereby reducing the risk of periprosthetic joint infection of the shoulder. Methods: This study was designed as a prospective case series. From October 2017 to February 2019, patients undergoing elective shoulder arthroplasty or arthroscopic shoulder surgery at a major academic medical center were offered enrollment; they signed an informed consent to participate. Patients under the age of 18, scheduled for revision shoulder arthroplasty, or with sensitivity or allergy to silver, zinc, or latex were excluded. Subjects underwent skin culture swab of the shoulder in the mid-point of the planned deltopectoral incision. The JumpStart (Arthrex; Naples, FL) microcurrent dressing was then placed over the area of the planned incision, and a full-thickness skin biopsy was harvested from the incision at the initiation of the surgical procedure. All specimens were cultured for C. acnes by the hospital's clinical microbiology laboratory with standard anaerobic technique. Results: Thirty-one subjects were enrolled in the study. Those who demonstrated no growth at baseline for the control specimen were excluded from further analysis (N = 11), given the absence of preoperative C. acnes colonization. Culture results from the 20 remaining subjects revealed significantly diminished C. acnes skin growth at the time of surgery compared to baseline. Sixty percent (12 of 20) of the subjects with positive skin swabs at baseline demonstrated no growth in the skin biopsy specimens at the time of surgery. There were no adverse events associated with the application of the microcurrent dressing. Conclusion: This prospective case series found that preoperative application of a microcurrent dressing resulted in significantly diminished C. acnes skin burden at the time of surgery in patients undergoing elective shoulder arthroplasty or arthroscopic shoulder surgery. Further study is warranted to investigate whether this preoperative intervention may contribute to a reduction in perioperative infections, including prosthetic joint infection.

A high prevalence of Cutibacterium acnes infections in scoliosis revision surgery, a diagnostic and therapeutic dilemma

PURPOSE

To investigate if serum inflammatory markers or nuclear imaging can accurately diagnose a chronic spinal instrumentation infection (SII) prior to surgery.

METHODS

All patients who underwent revision of spinal instrumentation after a scoliosis correction between 2017 and 2019, were retrospectively evaluated. The diagnostic accuracy of serum C-reactive protein (CRP) and Erythrocyte Sedimentation Rate (ESR), ¹⁸F-fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG-PET/CT) and Technetium-99m-methylene diphosphonate (99mTc-MDP) 3-phase bone scintigraphy (TPBS) to diagnose infection were studied. Patients with an acute infection or inadequate culture sampling were excluded. SII was diagnosed if ≥ 2 of the same microorganism(s) were isolated from intra-operative tissue cultures.

RESULTS

30 patients were included. The indication for revision surgery was pseudoarthrosis in the majority of patients (n = 15). 22 patients (73%) were diagnosed with SII. In all infected cases, Cutibacterium acnes was isolated, including 5 cases with a polymicrobial infection. The majority of patients had low inflammatory parameters preoperatively. For CRP > 10.0 mg/L, the sensitivity was 9.1% and specificity 100%; for ESR > 30 mm/h, the sensitivity was 9.1% and specificity 100%. The diagnostic accuracy for nuclear imaging was 64% for the FDG-PET/CT and 67% for the TPBS to diagnose infection.

CONCLUSIONS

The prevalence of SII in patients undergoing revision spinal surgery is high, with Cutibacterium acnes as the main pathogen. No diagnostic tests could be identified that could accurately diagnose or exclude SII prior to surgery. Future studies should aim to find more sensitive diagnostic modalities to detect low-grade inflammation.

Evaluation of the effectiveness of skin preparation methods for the reduction of Cutibacterium acnes (formerly Propionibacterium acnes) in shoulder surgery: a systematic review

Background

Cutibacterium acnes (C. acnes) is the most common pathogen responsible for post-operative shoulder infections. The purpose of this study was to evaluate the effectiveness of skin preparation methods against C. acnes in shoulder surgery.

Methods

A systematic review was conducted evaluating the effectiveness of skin preparation methods in the reduction of C. acnes in patients undergoing shoulder surgery. Outcomes were assessed based on the effectiveness of the method used; side effects and cost were also analysed.

Results

Of the 19 included studies, 9 evaluated pre-surgical home treatments: 8 assessed benzoyl peroxide (BPO) and 6 concluded it is effective in reducing C. acnes. Nine studies assessed surgical skin preparation and concluded that Chlorhexidine gluconate (CHG) was not effective; in contrast hydrogen peroxide reduced C. acnes. Finally, one study evaluated an aseptic protocol using CHG and concluded that it was not effective.

Conclusions

It was demonstrated that BPO as home treatment is effective in reducing C. acnes load on skin; it rarely causes side effects and is also cost-effective. This study highlights non-effectiveness of CHG. There was some evidence that the addition of hydrogen peroxide could have a positive effect in the reduction of C. acnes skin load; however, more studies are required.

Techniques for Decreasing Bacterial Load for Open Shoulder Surgery

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Benzoyl peroxide (BPO) 5% has been shown to reduce Cutibacterium acnes load on the skin. BPO 5% with miconazole nitrate (MN) 2% may be beneficial, whereas BPO 5% with clindamycin cream 1% to 1.2% does not seem to have additive effects when compared with BPO 5% alone. Chlorhexidine gluconate solutions reduce the total bacterial load on the skin, but do not seem to have a significant effect on C. acnes.

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ChloraPrep seems to be the best surgical skin preparation to decrease overall positive skin cultures. Preincisional hydrogen peroxide 3% application has been shown to be a cost-effective practice to inhibit growth of C. acnes. Vancomycin powder before deltopectoral interval closure has antimicrobial effects against C. acnes and is a cost-effective practice. Finally, Bactisure surgical lavage is protective against the formation of biofilms.

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IV cefazolin has been shown to be more effective for shoulder arthroplasty infection prophylaxis than antibiotic alternatives such as vancomycin. Thus, patients with a questionable history of penicillin allergy should undergo additional testing.

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For shoulder surgery infection prophylaxis, we recommend the use of BPO 5% cream for 5 days preoperatively with chlorhexidine wipes the night before and the morning of surgery. IV cefazolin should be administered perioperatively, and patients with a questionable history of penicillin allergy should be tested. Surgeons should consider preincisional application of hydrogen peroxide 3% for 5 minutes, followed by standard ChloraPrep preparation. Normal saline should be used for preclosure lavage. Finally, application of vancomycin powder deep to the deltopectoral interval closure should be considered.

Melimine-Modified 3D-Printed Polycaprolactone Scaffolds for the Prevention of Biofilm-Related Biomaterial Infections

Biomaterial-associated infections are one of the major causes of implant failure. These infections result from persistent bacteria that have adhered to the biomaterial surface before, during, or after surgery and have formed a biofilm on the implant's surface. It is estimated that 4 to 10% of implant surfaces are contaminated with bacteria; however, the infection rate can be as high as 30% in intensive care units in developed countries and as high as 45% in developing countries. To date, there is no clinical solution to prevent implant infection without relying on the use of high doses of antibiotics supplied systemically and/or removal of the infected device. In this study, melimine, a chimeric cationic peptide that has been tested in Phase I and II human clinical trials, was immobilized onto the surface of 3D-printed medical-grade polycaprolactone (mPCL) scaffolds via covalent binding and adsorption. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) spectra of melimine-treated surfaces confirmed immobilization of the peptide, as well as its homogeneous distribution throughout the scaffold surface. Amino acid analysis showed that melimine covalent and noncovalent immobilization resulted in a peptide density of ∼156 and ∼533 ng/cm², respectively. Furthermore, we demonstrated that the immobilization of melimine on mPCL scaffolds by 1-ethyl-3-[3-(dimethylamino)propyl] carbodiimide hydrochloride (EDC) coupling and noncovalent interactions resulted in a reduction of Staphylococcus aureus colonization by 78.7% and 76.0%, respectively, in comparison with the nonmodified control specimens. Particularly, the modified surfaces maintained their antibacterial properties for 3 days, which resulted in the inhibition of biofilm formation in vitro. This system offers a biomaterial strategy to effectively prevent biofilm-related infections on implant surfaces without relying on the use of prophylactic antibiotic treatment.

Impact of Skin Disinfection on Cutaneous Microbiota, before and after Peripheral Venous Catheter Insertion

Introduction. Patients with invasive medical devices are at high risk for infection. Skin colonization is the initial stage of these infections, leading to the recommendation of practices requiring disinfection using antiseptics. Microbial communities playing a major role in skin health could be impacted by antiseptic procedures. Aim. To characterize and compare the bacterial communities of skin samples from patients before an antisepsis procedure, and after removal of the medical device itself, according to the nature of the antiseptic molecule (povidone iodine or chlorhexidine). Methods. The study focused on alterations in bacterial communities depending on the nature of the antiseptic procedure and type of intravascular device. After amplification of 16S rDNA, libraries (n = 498 samples) were sequenced using MiSeq platform. Results. Using an in-house pipeline (QIIME2 modules), while no alteration in skin microbiota diversity was associated with antiseptic procedure or PVC type, according to culture results (p < 0.05), alterations were at times associated with restricted diversity and higher dissimilarity (p < 0.05). Antiseptic procedures and PVC types were associated with the modification of specific bacterial representations with modulation of the Bacillota/Bacteroidota (Firmicutes/Bacteroidetes) ratio (modulation of C. acnes, Prevotella, Lagierella, and Actinomyces spp.) (p < 0.05). At baseline, the microbiota shows certain bacteria that are significantly associated with future PVC colonization and/or bacteremia (p < 0.05). All of these modulations were associated with altered expression of metabolic pathways (p < 0.05). Discussion. Finally, this work highlights the need to optimize the management of patients requiring intravascular devices, possibly by modulating the skin microbiota.

Short-term Clinical Outcomes of Unexpected Culture-positive Cutibacterium acnes (Formerly Propionibacterium acnes) in Open Orthopaedic Surgery

INTRODUCTION

The clinical significance and treatment recommendations for an unexpected positive Cutibacterium acnes (C acnes) culture remain unclear. The purpose of our study was to evaluate the clinical effect of a C acnes positive culture in patients undergoing open orthopaedic surgery.

METHODS

Patients with a minimum of one positive C acnes intraoperative culture were retrospectively reviewed over a 7-year period. True C acnes infection was defined as culture isolation from ≥1 specimens in the presence of clinical or laboratory indicators of infection.

RESULTS

Forty-eight patients had a positive intraoperative C acnes culture. 4.2% had a C acnes monoinfection, and 12.5% of the patients had a coinfection. The remainder was classified as indeterminate. Significant differences were identified between the indeterminate and true C acnes infection groups, specifically in patients with surgery history at the surgical site (P = 0.04), additional antibiotic therapy before surgery (P < 0 .001), and postoperative clinical signs of infection (P < 0 .001).

DISCUSSION

Suspicion for true C acnes infection should be raised in patients with surgery site history, antibiotic therapy before surgery, and clinical infectious signs. The indeterminate unexpected positive culture patients had a low risk of developing a true clinical infection that required antibiotic therapy.

The efficacy of topical preparations in reducing the incidence of Cutibacterium acnes at the start and conclusion of total shoulder arthroplasty: a randomized controlled trial

BACKGROUND

Preoperative skin preparations for total shoulder arthroplasty (TSA) are not standardized for Cutibacterium acnes eradication. Topical benzyl peroxide (BPO) and benzyl peroxide with clindamycin (BPO-C) have been shown to reduce the bacterial load of C acnes on the skin. Our aim was to investigate whether preoperative application of these topical antimicrobials reduced superficial colonization and deep tissue inoculation of C acnes in patients undergoing TSA.

METHODS

In a prospective, single-blinded randomized controlled trial, 101 patients undergoing primary TSA were randomized to receive either topical pHisoHex (hexachlorophene [1% triclosan; sodium benzoate, 5 mg/mL; and benzyl alcohol, 5 mg/mL]) (n = 35), 5% BPO (n = 33), or 5% BPO with 1% clindamycin (n = 33). Skin swabs obtained prior to topical application and after topical application before surgery, as well as 3 intraoperative swabs (dermis after incision, on joint capsule entry, and dermis at wound closure), were cultured. The primary outcome was positive culture findings and successful decolonization.

RESULTS

All 3 topical preparations were effective in decreasing the rate of C acnes. The application of pHisoHex reduced skin colonization by 50%, BPO reduced skin colonization by 73.7%, and BPO-C reduced skin colonization by 81.5%. The topical preparation of BPO-C was more effective in decreasing the rate of C acnes at the preoperative and intraoperative swab time points compared with pHisoHex and BPO (P = .003). Failure to eradicate C acnes with topical preparations consistently resulted in deep tissue inoculation. There was an increase in the C acnes contamination rate on the skin during closure (33%) compared with skin cultures taken at surgery commencement (22%).

CONCLUSION

Topical application of BPO and BPO-C preoperatively is more effective than pHisoHex in reducing colonization and contamination of the surgical field with C acnes in patients undergoing TSA.

Acne cream reduces the deep Cutibacterium acnes tissue load before elective open shoulder surgery: a randomized controlled pilot trial

BACKGROUND

Cutibacterium acnes is the main pathogen in periprosthetic shoulder infections. In acne vulgaris therapy, benzoyl peroxide-miconazole nitrate cream effectively reduces the superficial C acnes burden of the skin. Its additional potential in the subcutaneous and capsular layers (eg, for prevention of future periprosthetic shoulder infections) is unknown. The aim of this study was to investigate the efficacy of a topical acne vulgaris cream (benzoyl peroxide-miconazole nitrate) to reduce subcutaneous and capsular C acnes in individuals with C acnes skin colonization undergoing open shoulder surgery.

METHODS

A prospective randomized pilot trial was performed, allocating 60 adult patients (1:1) to either a 7-day preoperative application of a commercial acne cream (benzoyl peroxide-miconazole nitrate) on the preoperative skin (intervention group) or no cream (control group) from November 1, 2018, to May 31, 2020. The superficial skin of the shoulder was sampled at enrollment and before incision, and deep subcutaneous and capsular shoulder samples were taken during surgery.

RESULTS

Sixty patients (mean age, 59 years; 55% female patients) undergoing primary open shoulder surgery (17 Latarjet procedures and 43 arthroplasties) were included in the study. At baseline, both randomized groups showed the presence of C acnes on the skin at a rate of 60% (18 of 30 patients in intervention group and 19 of 30 patients in control group, P = .79). In patients with C acnes skin colonization, the intervention resulted in a significant reduction in the overall number of intraoperative samples with positive findings compared with the control group (8 of 18 patients vs. 16 of 19 patients, P = .01), especially in capsular samples (0 of 18 patients vs. 4 of 19 patients, P = .04).

CONCLUSION

The topical 7-day preoperative skin application of acne cream (benzoyl peroxide-miconazole nitrate) significantly reduced the intraoperative C acnes load in 56% of the patients in the intervention group compared with 16% of the control patients.

Amplicon-Based Next-Generation Sequencing as a Diagnostic Tool for the Detection of Phylotypes of Cutibacterium acnes in Orthopedic Implant-Associated Infections

The diagnosis of orthopedic implant-associated infections (OIAIs) caused by the slow-growing anaerobic bacterium Cutibacterium acnes is challenging. The mild clinical presentations of this low-virulent bacterium along with its ubiquitous presence on human skin and human-dominated environments often make it difficult to differentiate true infection from contamination. Previous studies have applied C. acnes phylotyping as a potential avenue to distinguish contamination from infection; several studies reported a prevalence of phylotypes IB [corresponding to type H in the single-locus sequence typing (SLST) scheme] and II (SLST type K) in OIAIs, while a few others found phylotype IA₁ (more specifically SLST type A) to be abundant. However, phylotype determination has mainly been done in a culture-dependent manner on randomly selected C. acnes isolates. Here, we used a culture-independent amplicon-based next-generation sequencing (aNGS) approach to determine the presence and relative abundances of C. acnes phylotypes in clinical OIAI specimens. As amplicon, the SLST target was used, a genomic fragment that is present in all C. acnes strains known to date. The aNGS approach was applied to 30 sonication fluid (SF) samples obtained from implants removed during revision surgeries, including 17 C. acnes culture-positive and 13 culture-negative SF specimens. In 53% of the culture-positive samples, SLST types were identified: relative abundances were highest for K-type C. acnes, followed by H- and D-type C. acnes. Other types, including A- and C-type C. acnes that are more prevalent on human skin, had low relative abundances. The aNGS results were compared with, and confirmed by a culture-dependent approach, which included the isolation, whole genome sequencing (WGS) and phylotyping of 36 strains of C. acnes obtained from these SF samples. Besides serving as a powerful adjunct to identify C. acnes phylotypes, the aNGS approach could also distinguish mono- from heterotypic infections, i.e., infections caused by more than one phylotype of C. acnes: in eight out of nine culture-positive SF samples multiple C. acnes types were detected. We propose that the aNGS approach, along with the patient’s clinical information, tissue and SF cultures and WGS, could help differentiate C. acnes contamination from true infection.

The Efficacy of Peroxide Solutions in Decreasing Cutibacterium acnes Burden Around the Shoulder

BACKGROUND

Cutibacterium acnes is a common pathogen associated with surgical site infection after shoulder surgery; current standard of care products are largely ineffective at reducing C acnes bacterial burden before surgery. The purpose of this systematic meta-analysis was to assess the efficacy of peroxide-containing solutions (PCS) in decreasing the C acnes burden on the shoulder.

METHODS

This was a systematic review of all level I and II studies investigating the effect of peroxidase-containing products for skin preparation. We extracted data regarding demographics, treatment details and timing, study methodology, and culture positivity. Forest plots were used to determine the pooled efficacy of peroxide solutions versus control.

RESULTS

Seven studies with 412 patients were eligible for inclusion. Notable heterogeneity was observed in the manner and timing of peroxide application. Two studies applied PCS at the time of surgery; four studies applied PCS in the 24- to 72-hour period leading up to culture acquisition. Compared with the placebo, peroxide significantly diminished C acnes culture positivity (Hazard Ratio 0.174, P = 0.009). When considering using peroxide-containing products in the period leading up to surgery or at the time of surgery, in addition to standard preparation, the addition of peroxide significantly diminished C acnes culture positivity (HR 0.467, P = 0.004). Owing to study heterogeneity, we could not make notable comparisons based on the timing or duration of benzoyl peroxides application.

CONCLUSIONS

Despite heterogeneity in study design, pooled results of high-quality data suggest that the addition of PCS can markedly reduce C acnes bioburden. This review was not able to identify the ideal regimen for the utilization of PCS for reduction of C acnes burden.

LEVEL OF EVIDENCE

Level II.

Important interventions in the operating room to prevent bacterial contamination and surgical site infections

BACKGROUND

The aim of this study was to explore interventions that Swedish operating room (OR) nurses considered important for the prevention of bacterial contamination and surgical site infections (SSIs).

METHODS

A web-based cross-sectional survey with an open-ended question was answered by OR nurses and analyzed using summative content analysis and descriptive statistics.

RESULTS

The OR nurses (n = 890) worked within 11 surgical specialties and most of them worked at university hospitals (37%) or county hospitals (53%). The nurses described twelve important interventions to prevent bacterial contamination and SSI: skin disinfection (25.9%), the OR environment (18.2%), aseptic technique (16.4%), OR clothes (13.4%), draping (9.8%), preparation (6.1%), dressing (3.6%), basic hygiene (3.4%), normothermia (2.1%), communication (0.7%), knowledge (0.3%), and work strategies (0.2%).

DISCUSSION

Skin disinfection was considered the most important intervention in order to prevent bacterial contamination and SSI. The responses indicated that many OR nurses believed the patients' skin to be sterile after the skin disinfection process. This is not a certainty, but skin disinfection does significantly decrease the amount of bacterial growth.

CONCLUSIONS

This study shows that many OR nurses' interventions are in line with recommendations. Although, knowledge regarding the effect of skin disinfection needs further research, and continued education.

The pencil eraser swab technique to quantify Cutibacterium acnes on shoulder skin

Introduction: Cutibacterium acnes is the most common cause of postoperative infections in orthopaedic shoulder surgery and is hard to eradicate with current measures. Newer strategies focus on reducing bacterial load on the skin before surgery. Several previous studies have used a large number of both described and undescribed sampling techniques. The purpose of this study was to compare three previously described swab techniques to obtain bacterial cultures: Levine's (L) technique, the Z technique and the pencil eraser swab (PES) technique. Methods: Three consecutive skin swabs were collected from the right shoulder, on 15 healthy male volunteers, using Levine's technique, Z technique and PES technique from each participant. To determine the number of living bacteria, serial dilutions were made, and after culturing for 5 d, viable count (VC) was expressed as CFU/mL (with CFU representing colony-forming unit). Results: The PES technique yielded significantly higher VC than the two others. PES: median 3700 CFU/mL, L: 200 CFU/mL and Z: 220 CFU/mL ( p = 0.003 ). There was no significant difference between the methods regarding the number of positive cultures. PES: 14/15, L: 11/15 and Z: 12/15. Conclusions: There is a need to harmonise sampling techniques of C. acnes in order to compare the efficacy of different measures to reduce the bacterial load on the skin before and during surgery. Of the three tested methods, the PES technique is simple and produces the highest bacterial counts.

Association Between Serum Testosterone Levels and Cutibacterium Skin Load in Patients Undergoing Elective Shoulder Arthroplasty: A Cohort Study

Cutibacterium periprosthetic joint infections are important complications of shoulder arthroplasty. Although it is known that these infections are more common among men and that they are more common in patients with high levels of Cutibacterium on the skin, the possible relationship between serum testosterone levels and skin Cutibacterium levels has not been investigated.

Cutibacterium acnes phylogenetic type IC and II isolated from patients with non-acne diseases exhibit high-level biofilm formation

Cutibacterium (formerly Propionibacterium) acnes is an important for not only exacerbating factor of acne vulgaris but also pathogen of surgical site infections (SSIs) in orthopedics and plastic surgery. Although biofilm-forming (BF) C. acnes are associated with intractable SSI, characteristics of these strains were still unknown. Here, we explored detailed molecular epidemiological features of BF C. acnes isolated as causative pathogen of infectious diseases. Phylogenetic types of 205 C. acnes strains isolated between 2013 and 2018 from 18 clinical departments of a university hospital in Japan were determined by single-locus sequence type (SLST). Clade H (traditional type IC) and K (type II) which are less relevant with healthy skin and acne vulgaris, were detected in 26.8% (55/205) and 16.1% (33/205) of the strains, respectively. The incidence of them was significantly higher than that of acne patients (H and K, each 2.9%, P < 0.05). In addition, SLST distribution of C. acnes strains differed by each department and isolation site. When biofilm formation was quantified, 51 strains (24.9%) were defined as high-BF strains. Notably, most high-BF strains were classified into the strains of clade H (56.4%, 31/55) and clade K (54.4%, 18/33), and these strains were frequently found in the strains isolated from patients of medical emergency center and plastic surgery. Similarly, high-BF strains were frequently found among the isolates from blood (35.7%) and catheters (30.0%), with a high proportion belonging to clades H and K. Compared to C. acnes strains isolated from acne patients, antimicrobial-resistant strains were less identified in non-acne patients. Our findings showed that pathogenicity of C. acnes strains differs by their phylogenetic types. Furthermore, we showed clade H and K have the ability of high biofilm formation and suggest that these strains have potential to become a risk factor for SSI.

The management of the shoulder skin microbiome (Cutibacterium acnes) in the context of shoulder surgery: a review of the current literature

BACKGROUND

This review aims to establish current knowledge of the shoulder skin microbiome and how to manage the bacteria that reside within it.

METHODS

A review was undertaken of the current literature through OvidSP. All abstracts were reviewed by three independent researchers.

RESULTS

Thirty-five studies met the inclusion criteria. With forward referencing an additional 14 were included. None commented on organisms specific to the shoulder microbiome other than Cutibacterium acnes. Therefore, this review is focussed on the current knowledge of C. acnes.

DISCUSSION

C. acnes is a skin commensal within the pilo-sebaceous glands reported to be the primary pathogen in up to 86% of shoulder joint infections. Pre-operative culture of unprepared skin can be indicative of underlying joint infection in shoulder arthroplasty revision. Intra-articular biopsies may have a high false positive due to skin contamination. Correlating the number of positive samples and certain associated signs can give a greater than 90% probability of a true infection. Standard surgical skin preparation, peri-surgical intravenous antibiotics and oral pre-operative antibiotics do not reduce bacterial load within the skin. However, topical benzoyl peroxide and clindamycin have both demonstrated significantly reduced bacteria load. Phylogenetically there are six main types. Patients may have more than one phenotype present during infection.

Dynamics of skin microbiota in shoulder surgery infections

Post-surgical infections arise due to various contributing factors. Most important is the presence of potential pathogenic microorganisms in the skin complemented by the patient´s health status. Cutibacterium acnes is commonly present in the pilosebaceous glands and hair follicle funnels in human skin. After surgical intervention, these highly prevalent, slow-growing bacteria can be found in the deeper tissues and in proximity of implants. C. acnes is frequently implicated in post-surgical infections, often resulting in the need for revision surgery. This review summarizes the current understanding of microbial dynamics in shoulder surgical infections. In particular, we shed light on the contribution of C. acnes to post-surgical shoulder infections as well as their colonization and immune-modulatory potential. Despite being persistently found in post-surgical tissues, C. acnes is often underestimated as a causative organism due to its slow growth and the inefficient detection methods. We discuss the role of the skin environment constituted by microbial composition and host cellular status in influencing C. acnes recolonization potential. Future mapping of the individual skin microbiome in shoulder surgery patients using advanced molecular methods would be a useful approach for determining the risk of post-operative infections.

Meta-analysis of the efficacy of preoperative skin preparation with alcoholic chlorhexidine compared to povidone iodine in orthopedic surgery

Preoperative skin preparation is an effective method to prevent surgical site infections (SSI). Alcoholic chlorhexidine (CHG) and povidone iodine (PV-I) are the most widely used antiseptic agents. This meta-analysis aims to determine their efficacy in reducing natural bacterial skin flora in clean orthopedic surgery. A systematic search was conducted through current literature up to June 2021 to identify clinical randomized trials that compared the efficacy of alcoholic chlorhexidine and povidone iodine in reducing bacterial skin colonization after preoperative skin preparation. A meta-analysis was conducted. Of 235 screened articles, 8 randomized controlled trials were included. The results of the meta-analysis demonstrate a significantly lower positive culture rate in the chlorhexidine group than in the povidone iodine group (RR = 0.53, 95% Cl: 0.32-0.88). The present data show the superiority of chlorhexidine in reducing the normal bacterial flora compared to povidone iodine in clean orthopedic surgery.

Periprosthetic Infections of the Shoulder Joint: Characteristics and 5-Year Outcome of a Single-Center Series of 19 Cases

Periprosthetic shoulder infection (PSI) remains a devastating complication after total shoulder arthroplasty (TSA). Furthermore, there is a paucity in the literature regarding its diagnostic and therapeutic management, especially the absence of therapy concepts devised exclusively for PSI. The aim of the presenting study is to examine the characteristics and outcome of patients with PSI who were treated according to well-established algorithms developed originally for periprosthetic joint infection (PJI) of the hip and knee and determine if these algorithms can be applied to PSI. This single-center case series included all patients with a PSI presenting between 2010 and 2020. Recorded parameters included age, sex, affected side, BMI, ASA score, Charlson comorbidity index, preoperative anticoagulation, indication for TSA (fracture, osteoarthritis or cuff-arthropathy), and type of infection (acute or chronic PSI). The outcome was divided into treatment failure or infect resolution. Staphylococcus epidermidis and aureus were the commonest infecting pathogens. Acute PSI was mainly treated with debridement, irrigation, and retention of the prosthesis (DAIR) and chronic cases with two/multiple-stage exchange. The treatment failure rate was 10.5%. C-reactive protein was preoperatively elevated in 68.4% of cases. The mean number of operative revisions was 3.6 ± 2.6, and the mean total duration of antibiotic treatment was 72.4 ± 41.4 days. The most administered antibiotic was a combination of clindamycin and fluoroquinolone. In summary, the data of the current study suggest that therapeutical algorithms and recommendations developed for the treatment of PJI of the hip and knee are also applicable to PSI.

Benzoyl Peroxide is Cost-Effective for Preventing Infection by Cutibacterium Acnes in Arthroscopic Rotator Cuff Repair

Purpose

To evaluate the cost-effectiveness of benzoyl peroxide (BPO) in decreasing postoperative infections through a mathematical model in the setting of arthroscopic rotator cuff repair (RCR).

Methods

A break-even equation compared the costs associated with perioperative BPO use and postoperative infection following an arthroscopic RCR. The postoperative infection rate used for calculations was 0.28%, a value established in current literature. The break-even analysis produced a new infection rate, which defined how much BPO is needed to reduce the known infection rate in order for its prophylactic use to be cost-effective. The institution’s business office assessed the minimum itemized costs associated with the standard-of-care treatment of postoperative RCR infection. Sensitivity analysis was conducted to demonstrate how variability in the costs of BPO, in infection rates and in the cost of infection treatment affected the absolute risk reduction (ARR) and number needed to treat (NNT).

Results

Financial review yielded a minimum institutional cost of treating a postoperative infection following arthroscopic RCR of $24,991.31. Using the break-even formula to calculate the ARR at which the overhead costs of BPO and the treatment of infection were equal, BPO was economically viable if it decreased infection rate by 0.000734% (NNT = 1,361.92). This value was low because of the order of magnitude of difference between the costs of infection prevention when compared to the costs of treating postoperative infections.

Conclusions

This break-even analysis model suggests that the use of preoperative BPO in the setting of arthroscopic RCR is cost-effective for prevention of infection with Cutibacterium acnes, given the high cost of treating the infection versus the low cost of the solution.

Clinical Relevance

The economic feasibility of preoperative use of BPO in the setting of arthroscopic RCR could alter the standard of care.

Review of Pre-Operative Skin Preparation Options Based on Surgical Site in Orthopedic Surgery

Background: Surgical site infections (SSIs) are a primary contributor to surgical morbidity and mortality, causing a substantial financial burden on the healthcare system. Specifically, Cutibacterium acnes contributes greatly to infections in the shoulder and spine regions. Prevention of infection is crucial to improve patient outcomes and reduce costs. This article reviews current surgical skin preparation solutions, the unique distribution of organisms at common orthopedic surgical sites, and recommends solutions based on surgical location. Methods: A search of electronic databases (PubMed, MEDLINE, and Embase) was conducted for relevant literature until December 2020. Sources were compiled based on title and abstract, then full texts were read for possible inclusion. This review summarizes the most recent publications in the field of SSIs and preparation solutions. Results: The mechanism and efficacy of alcohol-, iodine-, and chlorhexidine-based preparations were reviewed, along with experimental preparations. This article identifies common colonization patterns for the shoulder, elbow, hip, knee, spine, foot, and ankle, and discusses recommendations for preparations based on current evidence. Recommendations: For shoulder and elbow operations, we recommend ChloraPrep™ (CareFusion, BD, El Paso, TX), DuraPrep™ (3M Health Care, St. Paul, MN), or Betadine^® applied with 4 × 4 gauze sponge, three-day pre-operative benzyl peroxide, and application of 3% hydrogen peroxide before skin preparation. For the hip and knee, we recommend application of 2% chlorhexidine gluconate (CHG) cloth the night before and morning of surgery and either DuraPrep or iodine-alcohol skin prep prior to surgery. For spine surgeries, we recommended ChloraPrep. For foot and ankle, our recommendations are: ChloraPrep or DuraPrep, submersion of foot in 70% ethanol/10% isopropyl alcohol for five minutes prior to procedure, application with a bristled brush, and a second vigorous scrub with 4 × 4 soaked gauze. Conclusions: The current surgical skin preparations have both benefits and drawbacks. We recommend that orthopedic surgeons choose a skin preparation based on surgical site and prevalence of unique skin flora there.

Efficacy comparison of chlorhexidine and iodine preparation in reduction of surgical site infection: A systemic review and meta-analysis

BACKGROUND

Chlorhexidine and povidone-iodine are the most common disinfectants used in preoperative skin preparation. However, there is no consistent conclusion regarding the prevention of surgical site infection (SSI) and bacterial culture data.

OBJECTIVE

To assess the efficacy of chlorhexidine and povidone-iodine in the prevention of postoperative SSI and relevant bacterial data.

DESIGN

Systematic Review and Meta-Analysis SETTINGS: N/A PARTICIPANTS: N/A METHOD: Literature relevant to "skin antisepsis" and "surgical site infections" was retrieved from PUBMED, Web of Science, EMBASE, CINHAL and CNKI. The incidence of SSI was the primary outcome, while the secondary outcome was bacterial data from the infected incision. All data were analyzed with Revman 5.3 and Stata Statistical Software.

RESULTS

A total of 36 studies were identified in this study, which included 16,872 participants. This study revealed that chlorhexidine is superior to povidone-iodine in the prevention of postoperative SSI (risk ratio [RR], 0.73; 95% confidence interval [CI], 0.61-0.87; p = 0.019, I² = 39%). Further meta-regression analysis revealed that the effect of chlorhexidine was directly associated with the type of incision, but failed to differentiate between the subgroups divided according to the type of incision. With respect to bacteria colonization, the most common bacteria for chlorhexidine arm were propionibacterium's, while the most common bacteria for the iodine arm were staphylococci species.

CONCLUSION

In comparison to povidone-iodine, chlorhexidine showed better results in preventing postoperative SSI.

Is D-dimer a Reliable Serum Marker for Shoulder Periprosthetic Joint Infection?

BACKGROUND

The diagnosis of periprosthetic shoulder infection continues to be difficult to make with confidence. Serum D-dimer has proven to be effective as a screening tool for periprosthetic joint infection in other major joints; however, it has yet to be evaluated for use in periprosthetic shoulder infection.

QUESTIONS/PURPOSES

(1) Is D-dimer elevated in patients with probable or definite periprosthetic shoulder infections? (2) What is the diagnostic accuracy of D-dimer for periprosthetic shoulder infections? (3) What are the diagnostic accuracies of serum tests (erythrocyte sedimentation rate [ESR], C-reactive protein [CRP], and D-dimer), singly and in combination?

METHODS

Between March 2016 and March 2020, 94 patients undergoing revision total shoulder arthroplasty (anatomic or reverse) at a single institution had preoperative serum testing with CRP, ESR, and D-dimer. These 94 patients were a subset of 189 revision shoulder arthroplasties performed at this institution during the study period who met inclusion criteria and consented to participate. Included patients had a mean ± SD age of 69 ± 8 years, and 56% (53 of 94) were men. Patient records were reviewed to classify patients as definitely having infection, probably having infection, possibly having infection, or unlikely to have an infection, according to the International Consensus Meeting (ICM) definition of periprosthetic shoulder infection. Statistical analyses, including a receiver operating characteristic curve analysis, were performed to quantify the diagnostic value of D-dimer for periprosthetic shoulder infection. Based on the ICM definition, 4% (4 of 94), 15% (14 of 94), 14% (13 of 94), and 67% (63 of 94) of patients had definite, probable, possible, or unlikely periprosthetic shoulder infections.

RESULTS

D-dimer was elevated in patients with definite or probable infections (median [range] 661 ng/mL [150 to 8205]) compared with those with possible infections or those who were unlikely to have an infection (263 ng/mL [150 to 3060]; median difference 143 ng/mL [95% CI 40 to 503]; p = 0.01). In the receiver operating characteristic curve analysis, D-dimer had an area under the curve of 0.71 (0.50-0.92), demonstrating weak diagnostic value. A D-dimer level of 598 ng/mL provided a sensitivity and specificity of 61% (95% CI 36% to 82%) and 74% (95% CI 62% to 83%), respectively, for diagnosing a definite or probable infection according to the ICM definitions. The specificity of detecting periprosthetic joint infection (88% [95% CI 79% to 94%]) was high when three positive serum markers (ESR, CRP, and D-dimer) were required, at the expense of sensitivity (28% [95% CI 10% to 53%]).

CONCLUSION

In periprosthetic shoulder infection, D-dimer is elevated. However, similar to other serum tests, it has limited diagnostic utility in identifying patients with periprosthetic shoulder infection. Further work is needed to understand the process by which D-dimer is associated with active infection.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Validation of new shoulder periprosthetic joint infection criteria

BACKGROUND

A periprosthetic joint infection (PJI) in the shoulder can be difficult to diagnose. Many variables have been used to determine a PJI. Recently, the 2018 International Consensus Meeting (ICM) on orthopedic infections gave new criteria to help identify PJI in the shoulder. With the new criteria (major and minor), the PJI definition can be categorized into definite, probable, possible, and unlikely. This study was conducted to assess the new criteria for a series of consecutive first stage revision shoulder arthroplasty cases.

METHODS

All patients undergoing a first stage revision shoulder arthroplasty using a prosthesis made of antibiotic-loaded acrylic cement (PROSTALAC) spacer from 2016 through 2019 were evaluated retrospectively. All cases were performed by a single surgeon. Each case was reviewed using the 2018 shoulder ICM diagnostic criteria. Secondary factors evaluated were type of organism identified, accuracy of minor criteria, and frozen vs. permanent section accuracy.

RESULTS

A total of 87 first-stage revision arthroplasty cases were reviewed. Based on the 2018 ICM criteria, there were 20 definite (30.0%), 19 probable (21.8%), 6 possible (6.9%), and 42 unlikely (48.3%) infections. Cutibacterium acnes was the most common infectious organism overall (77.3% of culture positive cases) and was present in 39.1% of cases overall. Ten patients (25.6%) grew multiple organisms. Thirty-one patients (35.6%) had a loose humeral stem, with 23 of those patients (74.2%) having a definite or probable infection (odds ratio [OR] 7.2, 95% confidence interval [CI] 2.67-19.37, P = .0001). Eleven patients (91.7%) with an elevated intraoperative synovial neutrophil cell count had a definite or probable infection. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) was elevated in patients with a definite or probable infection (OR 9.4, 95% CI 2.47-35.62, P = .0010, and OR 7.7, 95% CI 2.29-25.56, P = .0009), respectively. Discordant results between frozen and permanent sections were found in 4 patients (4.6%).

CONCLUSION

The 2018 ICM shoulder infection criteria gave a new scoring system to diagnose PJI. C acnes was the most common infectious organism identified. Patients who had a loose humeral stem, elevated ESR, or elevated CRP were more likely to have either a definite or probable PJI. Frozen sections were able to accurately identify definite infections. Unexpected wound drainage and positive preoperative cultures were low-yield criteria in this series. More research into determining periprosthetic shoulder infection is needed to help identify which patients are more likely to have an infection.

Benzoyl peroxide treatment decreases Cutibacterium acnes in shoulder surgery, from skin incision until wound closure

INTRODUCTION

Most surgical site infections after shoulder surgery are caused by Cutibacterium acnes. Topically applied benzoyl peroxide (BPO) has for years been used to decrease the skin load of C acnes in treatment of acne vulgaris. The purpose of this study was to examine this effect on bacterial colonization in patients subjected to elective shoulder surgery at different stages of the procedure.

METHODS

A total of 100 patients scheduled for primary elective open shoulder surgery were randomized to prepare either with BPO or according to local guidelines-with soap (control group). Four skin swabs were taken in a standardized manner at different times, before and after surgical skin preparation, 1 in dermis, and finally after the skin was sutured. Before skin incision, 5 punch biopsies (3 mm in diameter and maximum 4 mm deep) were retrieved spaced 2 cm apart in the planned skin incision. On culturing, quantification of C acnes was made by serial dilutions.

RESULTS

Men had a 5-fold higher amount of C acnes on untreated skin. Treatment with BPO considerably lowered this count (P = .0001) both before and after skin disinfection compared to the control group. This positive effect of BPO persisted until skin closure, the point at which some recolonization of C acnes had occurred, but to a higher degree in the control group (P = .040).

CONCLUSION

Preoperative BPO treatment of the shoulder may be an effective method to decrease bacterial skin load of C acnes from skin incision until wound closure.

What is the clinical impact of positive cultures at the time of primary total shoulder arthroplasty?

BACKGROUND

Cultures taken at the time of primary shoulder arthroplasty are commonly positive for Cutibacterium acnes. Despite our limited understanding of the clinical implication of deep tissue inoculation from dermal colonization, significant efforts have been made to decolonize the shoulder prior to surgery. The purpose of this study is to determine differences in clinical outcomes based on culture positivity at the time of primary shoulder arthroplasty.

METHODS

A series of 134 patients who underwent primary anatomic or reverse total shoulder arthroplasty and had intraoperative cultures obtained via a standard protocol were included. In each case, 5 tissue samples were collected and processed in a single laboratory for culture on aerobic and anaerobic media for 13 days. Minimum 2-year functional outcomes scores (American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form [ASES] and Single Assessment Numeric Evaluation [SANE]) and reoperation data were analyzed.

RESULTS

Forty-two (31.3%) patients had positive cultures (30 C acnes and 21 with at least 2 positive cultures) at the time of surgery. There was no statistically significant difference in postoperative functional outcome scores (ASES: 82.5 vs. 81.9; P = .89, SANE: 79.5 vs. 82.1; P = .54) between culture-positive and culture-negative cohorts. There were no cases of infection. Two patients (4.8%; 2/42) with positive cultures required reoperation compared with 4 patients (5.6%; 4/71) without positive cultures.

CONCLUSION

The apparent colonization by nonvirulent organisms in patients undergoing primary shoulder arthroplasty does not appear to have a clinically significant effect on functional outcomes or need for repeat surgery in the short term.

Cutibacterium acnes in shoulder surgery: a scoping review of strategies for prevention, diagnosis, and treatment

BACKGROUND

Cutibacterium acnes is a commensal, gram-positive, facultatively anaerobic bacillus that resides in the dermis. Historically thought to be a contaminant when identified on cultured specimens, recent advances in diagnostic technology have now implicated it as the most common organism responsible for postoperative shoulder infections. Despite a recognition of the role of this organism and a significant research interest in recent years, there is clear lack of consensus guideline on strategies to prevent, diagnose, and treat postoperative shoulder infection.

METHOD

The electronic databases PubMed, MEDLINE, CINAHL, Scopus, and Web of Science were searched in March 2020. All experimental and nonexperimental studies that investigate C acnes in shoulder surgery were included. Inclusion was limited to articles published after 2000 and written in English; reviews, gray literature, or abstracts were excluded. A total of 70 studies were included in this review. This scoping review was performed in accordance with the Extended Preferred Reporting Items of Systematic Reviews and Meta-Analyses Statement for Scoping Reviews (PRISMA-ScR).

RESULTS

Standard surgical prophylactic regimens such as intravenous antibiotics and topical chlorhexidine are ineffective at removing C acnes from the deep layer of the dermis, and there is a shift toward using topical benzoyl peroxide with significantly improved efficacy. An improved understanding of the bacteria has demonstrated that a prolonged culture time of up to 14 days is needed, especially in cases of established infection. Advances in diagnostics such as sonication and molecular-based testing are promising. Although usually thought to be susceptible to a broad range of antibiotics, resistance is emerging to clindamycin. An improved understanding of its ability to form a biofilm highlights the difficulty in treating an established infection.

CONCLUSION

The role of C acnes causing postoperative infection following shoulder surgery is being increasingly recognized. Strategies for prevention, diagnosis, and treatment have been outlined from both an antimicrobial and surgical perspective. A number of these strategies are emerging and require further research to demonstrate efficacy before implementation into clinical guidelines.

Is Propionibacterium acnes becoming the most common bacteria in delayed infections following adolescent idiopathic scoliosis surgery?

STUDY DESIGN

Retrospective review of hospital charts.

OBJECTIVE

(1) To determine the microbiological profile of patients with surgical site infections following posterior spinal fusion surgery (PSF) for Adolescent Idiopathic scoliosis (AIS). (2) To study the treatment outcome of patients with surgical site infections (SSI) following surgery for AIS. (3) To identify the key differences in presentation and management of acute and delayed SSI following AIS surgery. There has been increasing evidence of the role of P. acnes in deep surgical site infections. Literature related to this is abundant in relation to shoulder arthroplasty; however, it is sparse in relation to spine surgery.

METHODS

We conducted a retrospective review of all patients treated for AIS during a 5-year period (2010-2014) at our institution, with a minimum of 2-year follow-up after the index surgery. Patients with a postoperative infection following their index surgery were included. Charts of AIS patients with post-op infections were reviewed for details of the index surgery, time to presentation of the infection, presenting signs/symptoms, microbiology details, details of surgical and antibiotic treatment, and outcomes.

RESULTS

Nine (2.8%) post-op infections were identified out of 315 cases for AIS during this period. Seven (2.2%) involved P. acnes. Two (0.6%) involved MSSA. The average time for cultures to show growth was 6.1 days (range 5-8 days) in P. acnes group and 2-3 days in MSSA group. Patients with P. acnes infections were treated with implant removal, debridement and antibiotics. All patients achieved solid fusion except two patients from the P. acnes group had pseudoarthrosis and had to undergo revision fusion.

CONCLUSION

Propionibacterium acnes was the single most common bacteria isolated from delayed surgical site infection following PSF in AIS patients. Optimal treatment consists of debridement, implant removal and antibiotics. These patients have high incidence of pseudoarthrosis.

LEVEL OF EVIDENCE

Level IV.

Is there value in the routine practice of discarding the incision scalpel from the surgical field to prevent deep wound contamination with Cutibacterium acnes?

BACKGROUND

Cutibacterium acnes is found in skin flora of the shoulder and is the most common microbe identified in periprosthetic shoulder infections. The purpose of this study is to determine if there is C acnes present on the incision scalpel in patients undergoing shoulder arthroplasty despite extensive skin preparation techniques to prevent wound contamination.

METHODS

The authors collected a consecutive case series of patients meeting inclusion criteria. Patients were included if they underwent either primary or revision shoulder arthroplasty at the tertiary care hospital with the senior author during the study period. Culture swab samples, testing for presence of C acnes, were collected from 17 consecutive patients who underwent shoulder arthroplasty with a single fellowship-trained surgeon between November 2019 and March 2020. Culture reports were recorded as "positive" or "negative" after 21 days. Institutional review board approval of the study protocol was obtained. The null hypothesis was that there would be no cases with knife blades "culture positive" for C acnes.

RESULTS

17 patients were identified and fit inclusion criteria. There were 12 men (mean age 64.3 years, range 48-79 years) and 5 women (mean age 69.8 years, range 59-79 years). Two patients (11.8%) were found to have C acnes growth on the skin knife. Both patients were male and older than 70 years undergoing primary reverse shoulder arthroplasty with no history of previous shoulder infections.

CONCLUSION

The presence of C acnes on the skin blade in 2 patients validates concerns that there is C acnes present in dermal tissue despite extensive attention to eradication of these microbes. There was a high rate of C acnes contamination on scalpel blades used for initial skin incisions and the authors conclude that there is value in discarding these blades from the surgical field.

Hydrogen Peroxide Does Not Significantly Reduce Cutibacterium acnes Suture Contamination in Arthroscopic Rotator Cuff Repair

PURPOSE

To evaluate the efficacy of application of the 3% hydrogen peroxide (HP)-soaked gauze as an addition to the standard preoperative sterile skin preparation for Cutibacterium acnes suture contamination in arthroscopic rotator cuff repairs.

METHODS

A prospective randomized study was undertaken to evaluate 151 consecutive patients undergoing arthroscopic rotator cuff repair. Each shoulder was prepared with 1 of the 2 randomly selected protocols: chlorhexidine alcohol (1% chlorhexidine gluconate in 70% isopropyl alcohol)(control group) and chlorhexidine alcohol with 3% HP (HP-treated group). In the HP-treated group, the 3% HP-soaked gauze was applied over the shoulder for 5 minutes before the application of the chlorhexidine-alcohol. The first cut-tails of the anchor suture after cuff fixation were submitted to aerobic and anaerobic cultures. Patients were clinically evaluated for infection 10 days, 28 days, 3 months, 6 months, and 12 months after surgery.

RESULTS

The rate of C acnes-positive cultures was 13.0% (10 of 77 cases) in the control group and 6.8% (5 of 74 cases) in the HP-treated group. The HP-treated group showed a trend of lower C acnes-positive culture rate, which did not reach statistical significance (relative risk, 0.52; 95% confidence interval, 0.19 and 1.45; number needed to treat, 16.1; P = .20). One case of coagulase-negative Staphylococcus (Staphylococcus intermedius) was isolated in the HP-treated group (1 of 74 cases, 1.3%). No other bacteria were isolated. No infections occurred in any of the patients treated in this study during the minimum 3-month follow-up period. One patient in the HP-treated group complained of skin irritation.

CONCLUSIONS

The use of a 3% HP-soaked gauze as an addition to the standard preoperative sterile skin preparation for arthroscopic rotator cuff repairs showed only a marginal effect (statistically insignificant) in reducing the C acnes suture contamination rate in the arthroscopic rotator cuff repair patients.

LEVEL OF EVIDENCE

I, prospective, randomized trial.

Cutibacterium avidum resists surgical skin antisepsis in the groin-a potential risk factor for periprosthetic joint infection: a quality control study

BACKGROUND

The skin commensal Cutibacterium avidum has been recognized as an emerging pathogen for periprosthetic joint infections (PJI). One currently assumes that the early occurring PJIs are a consequence of skin commensals contaminating the peri-implant tissue during surgery. We addressed whether standard skin antisepsis with povidone-iodine/alcohol before total hip arthroplasty (THA) is effective to eliminate colonizing bacteria with focus on C. avidum.

METHODS

In a single-center, prospective study, we screened all patients for skin colonizing C. avidum in the groin before THA. Only in the patients positive for C. avidum, we preoperatively repeated skin swabs after the first and third skin antisepsis and antibiotic prophylaxis. We also obtained dermis biopsies for microbiology and fluorescence in situ hybridization (FISH).

RESULTS

Fifty-one out of 60 patients (85%) were colonized on the skin with various bacteria, in particular with C. avidum in 12 out of 60. Skin antisepsis eliminated C. avidum in eight of ten (20%) colonized patients undergoing THA. Deeper skin (dermis) biopsies were all culture negative, but FISH detected single positive ribosome-rich C. avidum in one case near sweat glands.

CONCLUSION

Standard skin antisepsis was not effective to completely eliminate colonizing C. avidum on the skin in the groin of patients undergoing THA. Colonizing with C. avidum might pose an increased risk for PJI when considering a THA. Novel more effective antisepsis strategies are needed. Trial registration No clinical trial.

Comparison of the antimicrobial efficacy of povidone-iodine-alcohol versus chlorhexidine-alcohol for surgical skin preparation on the aerobic and anaerobic skin flora of the shoulder region

Background

Cutibacterium acnes is part of the anaerobic skin microbiome and resides in deeper skin layers. The organism is an agent of surgical site infections (SSI) in shoulder surgery. We hypothesized that prolonged skin preparation with an agent that penetrates deeply into the skin would be beneficial. Thus, we compared two classes of antiseptics, each combined with alcohol, each applied with two different contact times.

Methods

Using a cross-over arrangement, shoulders of 16 healthy volunteers were treated for 2.5 min (standard) or 30 min (prolonged) with alcohol-based chlorhexidine (CHG-ALC) or alcohol-based povidone-iodine (PVP-I-ALC). Skin sites were sampled before, immediately after, and 3 h after treatment, using a standardized cup-scrub technique.

Results

Aerobic skin flora was reduced more effectively by PVP-I-ALC than by CHG-ALC after 2.5 min application and immediate sampling (reduction factor [RF] 2.55 ± 0.75 vs. 1.94 ± 0.91, p = 0.04), but not after prolonged contact times and 3-h sampling. Coagulase-negative staphylococci were completely eliminated after PVP-I-ALC application, but still recovered from 4 of 32 samples after CHG-ALC application. Anaerobic flora was reduced more effectively by PVP-I-ALC than CHG-ALC after standard (RF 3.96 ± 1.46 vs. 1.74 ± 1.24, p < 0.01) and prolonged (RF 3.14 ± 1.20 vs. 1.38 ± 1.16, p < 0.01) contact times and immediate sampling, but not after 3-h sampling. No adverse events were reported.

Conclusions

PVP-I-ALC showed marginal benefits concerning the aerobic flora, but more substantial benefits over CHG-ALC concerning the anaerobic flora of the shoulder. Standard and prolonged contact times showed superiority for PVP-I-ALC for anaerobic flora at all immediate sampling points, but missed significance at 3-h sampling. The results underscore the need for protection against C. acnes and coagulase-negative staphylococci in orthopaedic surgery. The clinical relevance of these findings, however, should be studied with SSI as an endpoint.

Can sterility of stripped iodophor-impregnated plastic adhesive drape be maintained at the time of incision closure in total hip arthroplasty?

OBJECTIVE

The aim of this study was to analyze the contamination rates of the skin under the iodophor-impregnated plastic adhesive drape (IOD) at the time of incision closure in total hip arthroplasty (THA).

METHODS

A total of 225 patients undergoing primary THA (28 men, 197 women; mean age=65 years; age range=30-85) were included in this study. After asepsis using a solution of 1% chlorhexidine with 83% alcohol by volume, the surgical site was painted with a 10% povidone-iodine solution, and IOD was attached tautly at the start of surgery. Swabs of the surgical site were collected as follows: swab A from the skin before IOD application, swab B from the surface of the IOD at the time of incision closure, and swab C from the skin after peeling back the IOD. The obtained samples were promptly sent for microbiological analysis. The contamination rate was determined for swabs A, B, and C, and the contamination rate of swab C was compared with that of swabs A and B, and the bacterial species were identified.

RESULTS

Positive cultures were seen in 8 cases (3.6%) for swab A, 10 cases (4.4%) for swab B, and 22 cases (9.8%) for swab C. The contamination rate of swab C was significantly higher than that of swabs A (p=0.008) and B (p=0.028). Coagulase-negative Staphylococcus (n=10) and Cutibacterium acnes (n=7) were the most frequently cultured microorganisms from swab C.

CONCLUSION

In THA, the contamination rate of the skin after peeling off the IOD before incision closure was higher than that of the skin immediately after sterilization with povidone-iodine and higher than that on the IOD at the time of incision closure. The detected bacterial species were considered clinically significant pathogens. Preventive measures against infection, such as minimizing stripping of the IOD or re-sterilizing bare skin after IOD stripping, should be instituted in consideration of these findings when performing THA using IOD.

Incidence of Cutibacterium acnes from shoulder arthroplasties in Asians: ethnic differences should be considered

BACKGROUND

Most studies on Cutibacterium acnes in shoulder surgery have been conducted in the Western population, and studies on Asians are rare. We evaluated the incidence and risk factors of C acnes in shoulder arthroplasty in Asians.

METHODS

We retrospectively analyzed 154 patients between January 2017 and May 2019 who underwent shoulder arthroplasty. Swabs were taken after skin preparation from the skin surface of the anterior acromion, axilla, and joint fluid to study the incidence of C acnes. Before skin preparation we also collected swabs from the anterior acromion, axilla, and thigh from 59 of the 154 patients.

RESULTS

Eight of 154 patients after and 6 of 59 patients before skin preparation were positive for C acnes. C acnes were found in 2 patients at the anterior acromion and in 6 at the synovial joint after skin preparation and in 1 patient at the axilla, in 5 at the anterior acromion, and in 3 at the thigh before preparation. History of steroid injection and number of steroid injections were significantly associated with C acnes isolation (P = .039 and P = .006, respectively), whereas age, sex, body mass index, shoulder surgery history, hypertension, diabetes, and cerebrovascular disease were not, as were serum inflammatory markers, including white blood cell count, C-reactive protein level, and erythrocyte sedimentation rate.

CONCLUSION

A total of 5.2% of the patients after skin preparation and 10.2% of patients before skin preparation were found to be positive for C acnes. The incidence of C acnes in patients who underwent shoulder arthroplasties in Asia was low and, thus, ethnic differences should be considered for C acnes. The history and number of steroid injections were associated with isolation of C acnes.

Reduced Bacterial Burden of the Skin Surrounding the Shoulder Joint Following Topical Protocatechuic Acid Application: Results of a Pilot Study

Reducing the rising health-care burden associated with shoulder surgical site infection (SSI) is of paramount importance. The purpose of this study was to investigate the antimicrobial efficacy of protocatechuic acid (PCA) as a topical reagent for surgical skin antisepsis surrounding the shoulder joint.

Is there a risk for bacterial transmission from surgical marker pens?

Markers for preoperative skin marking are used several times and bear a risk of transmitting bacteria. Bacterial contamination was assessed by sonication and culture. Antimicrobial susceptibility testing (AST) was performed for facultative pathogens to assess multi-drug resistance (MDR). An accelerated failure time model was applied to assess the statistical relationship between the bacterial contamination and the filling status of markers. Of 45 markers, 13 had a colony count <10 cfu/mL and 32 had counts from 10 to 12,500 cfu/mL. Three markers were colonized by Staphylococcus aureus. No MDR bacteria were found. We recommend single use of markers to reduce transmission risk.

Photodynamic therapy improves skin antisepsis as a prevention strategy in arthroplasty procedures: A pilot study

BACKGROUND

Current standard skin antisepsis to prevent surgical site infections are ineffective to eradicate all skin-colonizing bacteria. Photodynamic therapy (PDT) has shown bactericidal effects in vitro, but no clinical study with improvements in skin antisepsis has been documented.

METHODS

We investigated the effect of methyl aminolevulinate (MAL)-PDT versus no PDT for skin antisepsis treatment (povidone-iodine/alcohol) in the groin of 10 healthy participants. Skin swabs were taken at baseline, immediately after PDT, and after skin antisepsis treatment to cultivate bacteria. At day 7 and 21, bacterial cultures were repeated before and after antisepsis treatment without PDT. Skin biopsies were performed to examine the grade of inflammation.

RESULTS

Skin-colonizing bacteria were found in all 20 participants at baseline sampling. Immediately after MAL-PDT, skin was sterile in 7 (70%) participants before and in all 10 (100%) participants after skin antisepsis treatment. In contrast, we found skin-colonizing bacteria in 5 (50%) participants of the control group receiving only skin antisepsis. After 7 and 21 days, skin sterility was similar to the baseline. We observed slight perivascular inflammation with lymphocytes and eosinophils without changes in the histomorphology of eccrine or sebaceous glands in skin biopsies. PDT was generally well tolerated except for localized redness.

CONCLUSION

MAL-PDT with skin antisepsis treatment sterilized skin immediately after its use but did not maintain sterility 7-21 days post-treatment. Due to local side effects, further clinical studies with less intensive PDT conditions or other photosensitizers are needed before PDT is integrated into clinical practice.

Cutaneous microbiology of patients having primary shoulder arthroplasty

BACKGROUND

Shoulder periprosthetic infections are predominantly caused by bacteria residing in the skin of healthy individuals. Knowledge of the factors associated with the loads of the different cutaneous bacteria in individuals having shoulder arthroplasty may help identify patients at higher risk of periprosthetic infection and help guide preventive measures. For this reason, we tested the hypothesis that easy-to-obtain preoperative characteristics were significantly associated with the cutaneous microbiology and the loads of specific bacteria in shoulders having joint replacement.

METHODS

This study identified the microbiology of the unprepared epidermal skin surface and of the dermal edge freshly incised at surgery in 332 patients having primary shoulder arthroplasty. The load of bacteria in each sample was characterized as a value based on the laboratory report: 0 for "no growth"; 0.1 for "one colony only" or for "broth only"; and 1, 2, 3, and 4 for 1+, 2+, 3+, and 4+ growth, respectively. The relationships between preoperative patient characteristics and these semiquantitative results of the cutaneous cultures were analyzed.

RESULTS

Cultures of the unprepared epidermal skin surface showed positive results for a wide variety of organisms, including Cutibacterium in 72%, coagulase-negative Staphylococcus in 61%, and a spectrum of other organisms in 32%. By contrast, cultures of the freshly incised dermal edge showed a great preponderance of Cutibacterium (34%) in comparison to low levels of coagulase-negative Staphylococcus (8%) and other organisms (2%). An increased dermal load of Cutibacterium was significantly associated with male sex, younger patient age, American Society of Anesthesiologists class 1, use of testosterone supplements, prior shoulder surgery, and higher Cutibacterium loads on the unprepared skin surface.

CONCLUSIONS

Although the microbiology of the unprepared skin surface is diverse, the same is not true for the freshly incised dermis, where Cutibacterium is the predominant organism. Readily available preoperative patient characteristics are significantly associated with the load of Cutibacterium in the incised dermis. Preoperative cultures of the unprepared skin surface appear to be a new method for predicting the type and load of bacteria found in the freshly incised dermis at the time of surgery. Additional studies are needed to determine whether preoperative cultures of the unprepared epidermal skin surface can provide a method for identifying patients at increased risk of shoulder periprosthetic infections.