Propionibacterium acnes in shoulder surgery: is loss of hair protective for infection?

Concordance of three different methods to obtain samples for culture in reverse total shoulder arthroplasty: a prospective study

PURPOSE

The objective of this study was to analyze the concordance of the results obtained when culturing samples that are obtained with three different methods.

METHODS

Prospective study that includes primary Reverse shoulder arthroplasties. From all the patients, 9 cultures were obtained. There were 3 cultures obtained from skin at the beginning of surgery, 3 from the tissue around the insertion of the long biceps on the glenoid side, and 3 from the tissue around the greater tuberosity on the humeral side. At each location, one culture was obtained from a swab, another one was obtained from the instruments on the table, and another one was obtained from a newly-opened set of instruments.

RESULTS

There were 87 patients included, leaving 783 culture samples for the analysis. Of those 783 samples, 69 turned to be positive: 57 were positive for C. acnes, 5 for S. epidermidis, 4 for other coagulase-negative staphylococcus, and 3 were positive for other indolent microorganisms. Comparing the results obtained with the three different methods, the kappa coefficient for all positive cultures was 0.1894 for cultures taken from skin, 0.4891 for cultures from the glenoid and 0.5456 for cultures from the greater tuberosity. Therefore, the kappa coefficient obtained for the three different locations ranged from poor to moderate.

CONCLUSION

The analysis of the concordance of the samples obtained with swab, tissue cultures taken with the instruments of the table and tissue cultures taken with new sets of instruments lead to different culture results in shoulder arthroplasty.

A Literature Review of Cutibacterium Acnes: From Skin Commensal to Pathogen in Shoulder Surgery

Cutibacterium acnes, previously known as Propionibacterium acnes, is a gram-positive rod in the pilosebaceous glands and commonly implicated in acne vulgaris. Its role in prosthetic joint infections, particularly in shoulder surgeries, has recently gained attention due to its prevalence around the shoulder girdle. This review collates evidence on the pathogenic role of C. acnes in shoulder surgeries, discussing preventive measures, risk factors, clinical presentation, investigation, and treatment strategies. C. acnes infections are complex, often presenting with non-specific symptoms and delayed diagnoses. Risk factors include male sex, presence of hair, shoulder steroid injections, and previous shoulder surgeries. Investigations such as inflammatory markers, synovial fluid analysis, diagnostic arthroscopy, tissue cultures, and advanced molecular techniques like next-generation sequencing and multiplex polymerase chain reaction are explored for their effectiveness in detecting C. acnes. Treatment strategies range from prolonged antibiotics and antibiotic spacers to single-stage and two-stage revision surgeries. Studies indicate that single-stage revision may provide better outcomes compared to two-stage revision. Effective management of C. acnes infections requires careful assessment, relevant investigations, and tailored treatment approaches. This review emphasizes the need for further research to address intraoperative contamination and to develop more efficient diagnostic and treatment methods.

Chronological changes in the rate of surgical field contamination in the shoulder joint

BACKGROUND

In shoulder surgery, low-virulence bacteria such as Cutibacterium acnes and coagulase-negative staphylococci can cause postoperative infection. However, the degree of sterility during surgery after disinfection is not known, and the efficacy of double skin preparation for such bacteria is unclear. This study aimed to evaluate chronological changes in the surgical field contamination rate in the shoulder joint and to compare single and double skin preparation.

METHODS

In total, 126 shoulders in 121 patients undergoing shoulder surgery (64 men, 62 women; mean age 64 years) were enrolled. Patients were divided into two groups: single skin preparation, where the site was painted with 10% povidone iodine, and double skin preparation, where the site was treated with 1% chlorhexidine gluconate/83% isopropyl alcohol and painted 10% povidone iodine. Swab samples from the axillary and proximal areas in the surgical field were collected chronologically before starting surgery and at 30, 60, and 120 min after starting surgery (MAS). The contamination rate of each sample was compared and detected species were evaluated.

RESULTS

The contamination rate for the axillary area was 48.4%, 85.9%, 95.3%, and 97.1% in the single-preparation group and 32.3%, 72.6%, 87.1%, and 91.2% in the double-preparation group before starting surgery and 30, 60, and 120 MAS, respectively, and that the proximal area was 12.5%, 26.6%, 29.7%, and 35.3% in the single-preparation group and 16.1%, 19.4%, 27.4%, and 38.2% in the double-preparation group, respectively. Significant differences were not seen between the groups by area or time point. Most detected species were Cutibacterium acnes and coagulase-negative staphylococci.

CONCLUSIONS

The incidence of surgical field contamination in shoulder joint was high from immediately after starting surgery. In the axillary area, the contamination rates exceeded 70% from 30 MAS in both groups. Measures against infection should be instituted considering these findings when performing shoulder surgery.

Risk factors for infection in patients undergoing shoulder arthroscopy: a systematic review and meta-analysis

We conducted a meta-analysis to determine the risk of infection following shoulder arthroscopy and to identify risk factors for infection. We systematically searched the PubMed/Medline, Embase and Cochrane Library databases, as well as the reference lists of previous systematic reviews and meta-analyses; manual searches were also performed. A random-effects model was employed to estimate pooled odds ratios (ORs), based on sample size, the P-value of Egger's test and heterogeneity among studies. Of the 29,342 articles screened, 16 retrospective studies comprising 74,759 patients were included. High-quality evidence showed that patients with diabetes (OR, 1.30; 95% confidence interval (CI), 1.20-1.41) or hypertension (OR, 1.26; 95% CI, 1.10-1.44) had a higher risk of infection, while moderate quality evidence showed that patients with obesity (body mass index ≥30 kg/m2) (OR, 1.42; 95% CI, 1.28-1.57), those who were male (OR, 1.65; 95% CI, 1.12-2.44), those who had an American Society of Anesthesiologists (ASA) class ≥3 (OR, 2.02; 95% CI, 1.02-3.99) and those who had a history of smoking (OR, 2.44; 95% CI, 1.39-4.28) had a higher risk of infection. The meta-analysis revealed that there was no association between age, time of surgery, or alcohol consumption and infection. This meta-analysis identified six significant risk factors for infection following shoulder arthroscopy including diabetes, obesity, hypertension, male sex, ASA class, history of smoking. These patient-related risk factors may help identify postoperative patients at higher risk for infection following shoulder arthroscopy.

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.

[Shoulder periprosthetic infections-what to do? : Diagnosis and treatment]

Treatment of an infected shoulder prosthesis differs significantly from other joint infections because of the unique microbiome, dominated by Cutibacterium acnes. The cause of an infection, its time of onset, the bacterial spectrum and comorbidities have to be considered for evaluation and treatment. The diagnostic workup is sometimes complex, and the recognition of a chronic and low-grade infection is often difficult because typical clinical and laboratory markers may be normal. Treatment is surgical; the therapeutic spectrum ranges from arthroscopic irrigation and open debridement with the exchange of components to one- and two-stage revisions using antibiotic-loaded spacers. Early detection and a targeted, appropriate therapy are crucial to avoid extensive soft tissue and bone damage.

C.acnes in the joint, is it all just a false positive?

BACKGROUND

Cutibacterium Acnes (C.acnes) has been linked to several shoulder pathologies. An alternative hypothesis suggests it only occurs in the joint secondary to previous instrumentation. Our hypothesis was patients with previous instrumentation would have C.acnes in their joint if it was in skin.

MATERIALS AND METHODS

Sixty-six patients undergoing arthroscopic shoulder surgery had biopsies taken from the affected joint at the time of surgery, along with control biopsies of subdermal fat. The extended culture results were assessed and correlated to previous intervention.

RESULTS

35% tested positive for C.acnes in their joint. 78% were male. 53% had absence of C.acnes in both skin and joint and 29% had presence in both (p = 0.0001). 15% with previous surgery had C.acnes. 53% with previous injection had C.acnes. 25% of patients with virgin joints had C.acnes. There was no statistical difference in the presence of C.acnes in the joint between those with previous instrumentation and without.

CONCLUSION

The significant factors for joint C.acnes were male sex and the presence of the bacteria in the fat. Previous instrumentation was not correlated with C.acnes in the joint. This raises the question of whether the process of biopsy itself may lead to inoculation of the joint.

Revision surgery after failed surgical treatment of midshaft clavicle fractures is often associated with positive detection of bacteria

BACKGROUND

Midshaft clavicle fractures are common, and the proportion of patients treated surgically has increased in recent years. With this increase in surgical treatments, the complication rate, for instance of infection, non-union, or implant failure, has also risen. This study evaluates the frequency of pathogen detection during revision surgeries occurring after a prior failed osteosynthesis of midshaft clavicle fractures.

METHODS

All patients treated in our hospital with a prior failed surgical therapy of a clavicle midshaft fracture between January 2013 and March 2022 were screened. Epidemiological data, intraoperative tissue samples, sonication, and the type of revision surgery were assessed. A postoperative follow-up at a minimum of 6 month was defined and osseous consolidation was verified.

RESULTS

Twenty-one patients (twelve male and eight female) were included with a mean age of 40.4 ± 14.1 years. Eleven of the patients showed pathogen detection (Group I), and seven remained without (Group II). A significant difference in age existed between Groups I and II (36.1 ± 12.8 and 51.6 ± 11.5, p  ≤ 0.05). The three most common pathogens were Cutibacterium acnes (n = 7), Staphylococcus epidermidis (n = 4), and Staphylococcus sacchorlyticus (n = 3), respectively. Thirteen patients presented for a follow-up. In nine patients (69%), bone healing was detectable. Four patients received a second revision surgery.

CONCLUSION

Revision surgery frequently shows pathogen detection without signs of infection. Cutibacterium acnes is the most common pathogen. Despite pathogen detection, bone healing can be achieved with revision surgery, although the rate of repeat revision surgeries is high.

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.

A Janus-Faced Bacterium: Host-Beneficial and -Detrimental Roles of Cutibacterium acnes

The bacterial species Cutibacterium acnes (formerly known as Propionibacterium acnes) is tightly associated with humans. It is the dominant bacterium in sebaceous regions of the human skin, where it preferentially colonizes the pilosebaceous unit. Multiple strains of C. acnes that belong to phylogenetically distinct types can co-exist. In this review we summarize and discuss the current knowledge of C. acnes regarding bacterial properties and traits that allow host colonization and play major roles in host-bacterium interactions and also regarding the host responses that C. acnes can trigger. These responses can have beneficial or detrimental consequences for the host. In the first part of the review, we highlight and critically review disease associations of C. acnes, in particular acne vulgaris, implant-associated infections and native infections. Here, we also analyse the current evidence for a direct or indirect role of a C. acnes-related dysbiosis in disease development or progression, i.e., reduced C. acnes strain diversity and/or the predominance of a certain phylotype. In the second part of the review, we highlight historical and recent findings demonstrating beneficial aspects of colonization by C. acnes such as colonization resistance, immune system interactions, and oxidant protection, and discuss the molecular mechanisms behind these effects. This new insight led to efforts in skin microbiota manipulation, such as the use of C. acnes strains as probiotic options to treat skin disorders.

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.

Cutibacterium acnes is an intracellular and intra-articular commensal of the human shoulder joint

BACKGROUND

Cutibacterium acnes (C acnes) is a mysterious member of the shoulder microbiome and is associated with chronic postoperative complications and low-grade infections. Nevertheless, it is unclear whether it represents a contaminant or whether it accounts for true infections. Because it can persist intracellularly in macrophages at several body sites, it might in fact be an intra-articular commensal of the shoulder joint.

METHODS

In 23 consecutive, otherwise healthy patients (17 male, 6 female; 58 years) who had no previous injections, multiple specimens were taken from the intra-articular tissue during first-time arthroscopic and open shoulder surgery. The samples were investigated by cultivation, genetic phylotyping, and immunohistochemistry using C acnes-specific antibodies and confocal laser scanning microscopy.

RESULTS

In 10 patients (43.5%), cultures were C acnes-positive. Phylotype IA1 dominated the subcutaneous samples (71%), whereas type II dominated the deep tissue samples (57%). Sixteen of 23 patients (69.6%) were C acnes-positive by immunohistochemistry; in total, 25 of 40 samples were positive (62.5%). Overall, 56.3% of glenohumeral immunohistochemical samples, 62.5% of subacromial samples, and 75% of acromioclavicular (AC) joint samples were positive. In 62.5% of the tested patients, C acnes was detected immunohistochemically to reside intracellularly within stromal cells and macrophages.

DISCUSSION

These data indicate that C acnes is a commensal of the human shoulder joint, where it persists within macrophages and stromal cells. Compared with culture-based methods, immunohistochemical staining can increase C acnes detection. Phylotype II seems to be most prevalent in the deep shoulder tissue. The high detection rate of C acnes in osteoarthritic AC joints might link its intra-articular presence to the initiation of osteoarthritis.

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.

Mid- to Long-Term Outcomes After Deep Infections After Arthroscopic Rotator Cuff Repair

Purpose

To review clinical and subjective outcomes in patients with deep infections after arthroscopic rotator cuff repair.

Methods

All patients in whom deep infections developed after arthroscopic rotator cuff repair at a single center between 2002 and 2016 were retrospectively reviewed. Demographic data, clinical and microbiological findings, and treatment were analyzed. Clinical and subjective outcomes included the Constant score, visual analog scale score for pain, American Shoulder and Elbow Surgeons score, and Simple Shoulder Test score.

Results

Thirty patients could be identified and included in the study. The most commonly isolated pathogens were Staphylococcus epidermidis (36.7%) and Cutibacterium acnes (30.0%). In 26 of 30 patients (86.7%), the infection was treated initially with an open surgical approach, whereas 4 patients (13.3%) underwent arthroscopic revision. A transosseous rotator cuff repair could be performed in 20.0% of patients. A single reoperation was sufficient in 80% of patients, whereas 13.3% required 2 revisions and 6.7% required 3. At the final follow-up of 8.3 years (range, 4-14 years), 26 patients (1 woman and 25 men) were available for outcome evaluation. Significant improvement from the initial surgical procedure to final follow-up was detected in the Constant score (25.7 vs 65.7, P < .001), visual analog scale score for pain (7.0 vs 1.7, P < .001), American Shoulder and Elbow Surgeons score (38.0 vs 76.7, P < .001), and Simple Shoulder Test score (4.0 vs 8.3, P < .001).

Conclusions

Patients with deep infections after arthroscopic rotator cuff repair showed moderate mid- to long-term outcomes.

Level of Evidence

Level IV, therapeutic case series.

Cutibacterium Acnes (Formerly Propionibacterium Acnes) Contamination of the Surgical Field During Shoulder Arthroscopy

PURPOSE

To evaluate the prevalence of Cutibacterium acnes in the shoulder region and to analyze changes in C acnes contamination during shoulder arthroscopy, as well as to investigate the influence of sex and type of arthroscopic surgery on those parameters.

METHODS

Forty-eight consecutive patients undergoing reconstructive or non-reconstructive shoulder arthroscopy, after hair removal with a medical clipper, routine antibiotic prophylaxis, and skin preparation with an alcohol-based skin disinfectant, were prospectively enrolled in this study. The shoulder was divided into 4 regions of interest (anterior, medial, posterior, and axilla). Skin swabs were taken from each region at 3 time points (preoperatively before and after skin preparation, and at the conclusion of surgery), cultured for 21 days, and analyzed for the prevalence of C acnes.

RESULTS

The rate of C acnes-positive skin cultures was significantly increased at the end of surgery compared with preoperatively before (44.3% vs 27.6%, P < .001) and after (44.3% vs 31.3%, P = .001) skin preparation. No reduction in C acnes was observed with preoperative skin preparation (27.6% vs 31.3%, P = .401). At the end of shoulder arthroscopy, 64.6% of patients showed at least 1 culture positive for C acnes. The C acnes prevalence was significantly higher in male patients (48.3%) than female patients (20.1%, P < .001), at all time points (P < .016), and in all regions of interest (P < .001) except the axilla. No differences in the prevalence of C acnes were found between non-reconstructive and reconstructive procedures.

CONCLUSIONS

Skin contamination with C acnes around the shoulder increased significantly from before and after skin preparation to the conclusion of surgery in patients undergoing shoulder arthroscopy despite perioperative preventive measures.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Bactericidal efficacy of hydrogen peroxide on Cutibacterium acnes

Objectives

The purpose of this study was to examine the bactericidal efficacy of hydrogen peroxide (H₂O₂) on Cutibacterium acnes (C. acnes). We hypothesize that H₂O₂ reduces the bacterial burden of C. acnes.

Methods

The effect of H₂O₂ was assessed by testing bactericidal effect, time course analysis, growth inhibition, and minimum bactericidal concentration. To assess the bactericidal effect, bacteria were treated for 30 minutes with 0%, 1%, 3%, 4%, 6%, 8%, or 10% H₂O₂ in saline or water and compared with 3% topical H₂O₂ solution. For time course analysis, bacteria were treated with water or saline (controls), 3% H₂O₂ in water, 3% H₂O₂ in saline, or 3% topical solution for 5, 10, 15, 20, and 30 minutes. Results were analyzed with a two-way analysis of variance (ANOVA) (p < 0.05).

Results

Minimum inhibitory concentration of H₂O₂ after 30 minutes is 1% for H₂O₂ prepared in saline and water. The 3% topical solution was as effective when compared with the 1% H₂O₂ prepared in saline or water. The controls of both saline and water showed no reduction of bacteria. After five minutes of exposure, all mixtures of H₂O₂ reduced the percentage of live bacteria, with the topical solution being most effective (p < 0.0001). Maximum growth inhibition was achieved with topical 3% H₂O₂.

Conclusion

The inexpensive and commercially available topical solution of 3% H₂O₂ demonstrated superior bactericidal effect as observed in the minimum bactericidal inhibitory concentration, time course, and colony-forming unit (CFU) inhibition assays. These results support the use of topical 3% H₂O₂ for five minutes before surgical skin preparation prior to shoulder surgery to achieve eradication of C. acnes for the skin.Cite this article: P. Hernandez, B. Sager, A. Fa, T. Liang, C. Lozano, M. Khazzam. Bactericidal efficacy of hydrogen peroxide on Cutibacterium acnes. Bone Joint Res 2019;8:3-10. DOI: 10.1302/2046-3758.81.BJR-2018-0145.R1.

Single versus Double Skin Preparation for Infection Prevention in Proximal Humeral Fracture Surgery

Preoperative skin preparation plays a major role in preventing postoperative infections. This study aims to compare a single skin preparation (povidone iodine) with a double skin preparation (chlorhexidine gluconate followed by povidone iodine). Forty patients affected by proximal humeral fracture were included in the study. The day of surgery the two skin preparation strategies were performed in the same shoulder, divided into two areas, at the level of the deltopectoral approach. Skin swabs were collected from each area and subjected to microbiological analysis. Both skin preparations significantly reduced the positive culture rate. Coagulase-negative staphylococci (CoNS) dropped from 92.5% to 40% and to 7.5% after the single and double skin preparation (p<0.001), respectively. The positivity rate was reduced from 50% to 17.5% (p=0.002) and from 27.5% to 0% (p= 0.001) for Propionibacterium acnes and Staphylococcus aureus, respectively, with no difference between the two preparations. The double skin preparation had a more significant effect on bacterial load against CoNS compared to the single skin preparation (p<0.001 versus p= 0.015). In conclusion, both the approaches reduced S. aureus and P. acnes skin load, whereas the double skin preparation is more effective than the single one against CoNS. In light of our findings, preoperative strategies able to reduce bacterial load could potentially increase the final efficacy of perioperative traditional skin preparations.

Lack of level I evidence on how to prevent infection after elective shoulder surgery

PURPOSE

Infection is a concern after all orthopedic procedures, including shoulder surgery. This systematic review of literature aimed to determine risk factors for infection as well as the availability and effectiveness of measures utilized to prevent infection after elective shoulder surgery.

METHODS

An electronic database search was performed using MEDLINE (1950-October 2017), EMBASE (1980-October 2017), CINAHL (1982-October 2017), and the Cochrane database to identify studies reporting a risk factor or preventive measure for infection after shoulder surgery.

RESULTS

Fifty-one studies were eligible for inclusion. Risk factors identified for infection were male sex, the presence of hair, receiving an intra-articular cortisone injection within the 3 months prior to surgery, smoking, obesity, and several comorbidities. The only preventive measure with level I evidence was for the use of chlorhexidine wipes for cleansing the skin in the days prior to surgery and for the use of ChloraPrep or DuraPrep over povodine and iodine to prep the skin at the time of surgery. Level II-IV evidence was found for other infection prevention methods such as intravenous antibiotic prophylaxis.

CONCLUSION

There are many risk factors associated with developing an infection after elective shoulder surgery. Many preventive measures have been described which may decrease the risk of infection; however, most lack a high level evidence to support them. The findings of this systematic review are clinically relevant as it has been shown that infection after shoulder surgery results in poor patient-reported outcomes and pose a significant financial burden. As surgeons the goal should be to prevent infections to avoid the morbidity for patients and the increased cost for society.

LEVEL OF EVIDENCE

IV systematic review of literature.

Prevalence of Propionibacterium acnes in the glenohumeral compared with the subacromial space in primary shoulder arthroscopies

HYPOTHESIS

We hypothesized that the prevalence of Propionibacterium acnes in patients undergoing primary shoulder arthroscopy is equal in the glenohumeral space compared with the subacromial space.

METHODS

Patients aged 18 years or older with shoulder arthroscopies were included. The exclusion criteria were prior shoulder operations, complete rotator cuff tears, systemic inflammatory diseases, tumors, shoulder injections within 6 months of surgery, and antibiotic therapy within 14 days preoperatively. After standardized skin disinfection with Kodan Tinktur Forte Gefärbt, a skin swab was taken at the posterior portal. Arthroscopy was performed without cannulas, prospectively randomized to start either in the glenohumeral space or in the subacromial space, with direct harvesting of a soft-tissue biopsy specimen. Sample cultivation was conducted according to standardized criteria for bone and joint aspirate samples and incubated for 14 days. Matrix-assisted laser desorption-ionization time-of-flight spectrometry was used for specimen identification in positive culture results.

RESULTS

The study prospectively included 115 consecutive patients with normal C-reactive protein levels prior to surgery (54.8% men; mean age, 47.2 ± 14.6 years). P acnes was detected on the skin after disinfection in 36.5% of patients, in the glenohumeral space in 18.9%, and in the subacromial space in 3.5% (P = .016).

CONCLUSION

The prevalence of P acnes is significantly higher in the glenohumeral space compared with the subacromial space in primary shoulder arthroscopies. The results do not confirm the contamination theory but also cannot clarify whether P acnes is a commensal or enters the joint hematologically or even lymphatically or via an unknown pathway. Despite standardized surgical skin disinfection, P acnes can be detected in skin swab samples in more than one-third of patients.

Risk Factors for Infection After Shoulder Arthroscopy in a Large Medicare Population

BACKGROUND

Shoulder arthroscopy is well established as a highly effective and safe procedure for the treatment for several shoulder disorders and is associated with an exceedingly low risk of infectious complications. Few data exist regarding risk factors for infection after shoulder arthroscopy, as previous studies were not adequately powered to evaluate for infection.

PURPOSE

To determine patient-related risk factors for infection after shoulder arthroscopy by using a large insurance database.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

The PearlDiver patient records database was used to query the 100% Medicare Standard Analytic Files from 2005 to 2014 for patients undergoing shoulder arthroscopy. Patients undergoing shoulder arthroscopy for a diagnosis of infection or with a history of prior infection were excluded. Postoperative infection within 90 days postoperatively was then assessed with International Classification of Diseases, Ninth Revision codes for a diagnosis of postoperative infection or septic shoulder arthritis or a procedure for these indications. A multivariate binomial logistic regression analysis was then utilized to evaluate the use of an intraoperative steroid injection, as well as numerous patient-related risk factors for postoperative infection. Adjusted odds ratios (ORs) and 95% CIs were calculated for each risk factor, with P < .05 considered statistically significant.

RESULTS

A total of 530,754 patients met all inclusion and exclusion criteria. There were 1409 infections within 90 days postoperatively (0.26%). Revision shoulder arthroscopy was the most significant risk factor for infection (OR, 3.25; 95% CI, 2.7-4.0; P < .0001). Intraoperative steroid injection was also an independent risk factor for postoperative infection (OR, 1.46; 95% CI, 1.2-1.9; P = .002). There were also numerous independent patient-related risk factors for infection, the most significant of which were chronic anemia (OR, 1.58; 95% CI, 1.4-1.8; P < .0001), malnutrition (OR, 1.42; 95% CI, 1.2-1.7; P = .001), male sex (OR, 2.71; 95% CI, 2.4-3.1; P < .0001), morbid obesity (OR, 1.41; 95% CI, 1.2-1.6; P < .0001), and depression (OR, 1.36; 95% CI, 1.2-1.5; P < .0001).

CONCLUSION

Intraoperative steroid injection was a significant independent risk factor for postoperative infection after shoulder arthroscopy. There were also numerous significant patient-related risk factors for postoperative infection, including revision surgery, obesity, male sex, chronic anemia, malnutrition, depression, and alcohol use, among others.

Cutibacterium (formerly Propionibacterium) acnes infections associated with implantable devices

INTRODUCTION

Cutibacterium acnes (C. acnes), a Gram-positive biofilm-forming rod implicated in acne vulgaris, is increasingly recognized for its role in implant-associated infections. The diagnosis of C. acnes implant-associated infections remains challenging. The optimal treatment is a combination of both surgical intervention and antibiotic therapy. Areas covered: In this review, we discuss the different types of implant-associated infections caused by C. acnes. We also highlight the clinical manifestations pertaining to the various sites of infection, and identify several risk factors previously reported in the literature. We then cover the diagnostic laboratory markers, such as IL-6 and AD-1, optimizing C. acnes recovery in culture, and the specific molecular techniques. Finally, we examine the various effective antibiotic regimens and identify some preventive methods against C. acnes infections. Expert commentary: Biomarkers such as IL-6 and AD-1 should be further investigated for the diagnosis of C. acnes implant-associated infections. The use of 16S rRNA gene sequencing and other molecular techniques should be further explored in this setting. Longer incubation periods should be requested whenever C. acnes infection is suspected. If the clinical suspicion is high, sonication of the excised implant should be encouraged. Research should focus on developing effective anti-biofilm agents. Finally, preventive methods such as hair removal prior to surgery should be further explored.

Nonunion After Clavicle Osteosynthesis: High Incidence of Propionibacterium acnes

OBJECTIVE

The objective of this study was to review the etiology of clavicle nonunions after osteosynthesis and investigate the outcomes of a treatment with a single-stage revision.

DESIGN

Retrospective case series.

SETTING

Orthopaedic specialty hospital.

PATIENTS

Twenty cases of nonunion after osteosynthesis of the clavicle were identified. The average age was 44 years (±13 years). In 9 cases, there was catastrophic implant failure that prompted the revision surgery. In the 18 cases in which cultures were taken, 15 of the 18 (83%) were treated as infections with a course of antibiotics. In 14 cases, the cultures were positive for Propionibacterium acnes.

RESULTS

Fifteen patients were treated with a prolonged course of antibiotics. Eighteen patients had follow-up, and the average time to radiographic union was 22 weeks. There were no cases of nonunion after revision surgery.

CONCLUSIONS

There is a high rate of positive cultures in cases of nonunion after osteosynthesis of the clavicle. This suggests the etiology of midshaft clavicle nonunions may result from a combination of suboptimal mechanical fixation and latent infection. Our treatment protocol of superior and anterior plating, interfragmentary fixation, bone grafting, and appropriate antimicrobial treatment of latent infections has resulted in 100% union rate.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Infections following arthroscopic rotator cuff repair: incidence, risk factors, and prophylaxis

PURPOSE

The primary aim of the present study was to determine the incidence of infections following arthroscopic rotator cuff repair in a single department over a 10-year period. Secondary goals included the evaluation of potential risk factors for infections and to investigate the efficacy of perioperative antibiotic prophylaxis in the reduction of infectious complications.

METHODS

A retrospective evaluation of 3294 all-arthroscopic rotator cuff repairs performed between 2004 and 2014 at a single institution was conducted to determine the rate of infection in all-arthroscopic rotator cuff repairs. Detailed data including demographics, co-morbidities, initial surgical procedure, time from index surgery to infection, clinical presentation, isolated pathogens, and subsequent treatment were recorded of patients with infections. Univariate logistic regression was performed, and a multivariate model was developed to identify variables that were predictive of infections following arthroscopic rotator cuff repair.

RESULTS

The rate of infection was 8.5/1000 in whom rotator cuff repairs were performed (95 % CI 0.58-1.23 %) during the study period. The most commonly identified pathogen was Staphylococcus epidermidis (n = 11, 39.3 %), followed by Propionibacterium acnes (n = 8, 28.6 %) and Staphylococcus aureus (n = 2, 7.1 %). Patients presented at our institution with signs of infection an average of 28.9 ± 14.7 days after the index surgery. The leading symptom that was present in all patients was diffuse or localized shoulder pain, followed by local signs of infection in 19 (67.9 %), secretion in 14 (50 %), and fever in 9 (32.1 %) patients, respectively. Univariate and multivariate analyses identified the male gender, age over 60, and duration of surgery over 90 min as predictive factors for infection. Administration of perioperative antibiotic prophylaxis was an independent mitigating factor for postoperative infection and reduced the infection rate from 1.54 % (95 % CI 0.98-2.30 %) to 0.28 % (95 % CI 0.10-0.67 %).

CONCLUSIONS

The overall incidence of infection was 8.5/1000 arthroscopic rotator cuff repairs over a 10-year period. Gender, age, and length of surgery were identified as predictive factors for infection. The administration of perioperative antibiotic prophylaxis significantly reduced the overall risk of infection and is therefore recommended in all-arthroscopic rotator cuff repairs. However, current prophylactic treatment strategies were not equally efficient for all types of pathogens.

LEVEL OF EVIDENCE

Retrospective comparative study, Level III.