Preoperative doxycycline does not decolonize Propionibacterium acnes from the skin of the shoulder: a randomized controlled trial

Cutibacterium adaptation to life on humans provides a novel biomarker of C. acnes infections

The domestication of cattle provided Propionibacteriaceae the opportunity to adapt to human skin. These bacteria constitute a distinct genus ( Cutibacterium ), and a single species within that genus ( C. acnes ) dominates 25% of human skin. C. acnes protects humans from pathogen colonization, but it can also infect indwelling medical devices inserted through human skin. Proteins that help Cutibacteria live on our skin may also act as virulence factors during an opportunistic infection, like a shoulder periprosthetic joint infection (PJI). To better understand the evolution of this commensal and opportunistic pathogen, we sought to extensively characterize one of these proteins, RoxP. This secreted protein is only found in the Cutibacterium genus, helps C. acnes grow in oxic environments, and is required for C. acnes to colonize human skin. Structure-based sequence analysis of twenty-one RoxP orthologs (71-100% identity to C. acnes strain KPA171202 RoxP_1) revealed a high-degree of molecular surface conservation and helped identify a potential heme-binding interface. Biophysical evaluation of a subset of seven RoxP orthologs (71-100% identity) demonstrated that heme-binding is conserved. Computational modeling of these orthologs suggests that RoxP heme-binding is mediated by an invariant molecular surface composed of a surface-exposed tryptophan (W66), adjacent cationic pocket, and nearby potential heme axial ligands. Further, these orthologs were found to undergo heme-dependent oligomerization. To further probe the role of this protein in C. acnes biology, we developed four monoclonal anti-RoxP antibodies, assessed the binding of those antibodies to a subset of ten RoxP orthologs (71-100% identity), developed an anti-RoxP sandwich ELISA (sELISA) with sub-nanogram sensitivity, and adapted that sELISA to quantitate RoxP in human biofluids that can be infected by C. acnes (serum, synovial fluid, cerebrospinal fluid). This study expands our understanding of how an environmental bacterium evolved to live on humans, and the assays developed in this work can now be used to identify this organism when it gains access to sterile sites to cause opportunistic infections.

Author Summary

The longer humans live, the more they require internal "replacement parts," like prosthetic joints. Increased placement of these and other medical devices has increased their complications, which frequently are infections caused by microbes that live on humans. One of these microbes is Cutibacterium acnes , which dominates 25% of human skin. It appears that when humans domesticated cattle, a C. acnes ancestor adapted from living in cows to living on people. One of these adaptations was RoxP, a protein only found in Cutibacterium and carried by all C. acnes . Here, we describe our extensive characterization of RoxP. We found that distantly related RoxP conserve high stability at the low pH found on human skin. They also conserve the ability to bind heme, a source of iron used by microbes when they infect humans. As a part of this work, we developed tests that measure RoxP to identify C. acnes growth. In a clinic or hospital, these tests could allow a doctor to rapidly identify C. acnes infections, which would improve patient outcomes and lower healthcare costs. This work has helped us better understand how C. acnes adapted to live on humans and to identify C. acnes infections of medical devices.

Does hydrogen peroxide help mitigate the incidence of Cutibacterium acnes in cervical spine surgeries?

Background

Surgical site infection (SSI) is a common yet serious complication of cervical spine surgery. While initially thought to be clinically insignificant, Cutibacterium acnes (C. acnes) is an important cause of infection. The purpose of this study was to investigate the ability of a hydrogen peroxide (H2O2) application during standard presurgical skin preparation to reduce the burden of C. acnes in patients undergoing cervical spine surgery.

Methods

This was a retrospective review of prospectively collected data. Subjects were randomly assigned to either standard surgical preparation plus H2O2 (experimental) or without H2O2 (control). Prescrub, postscrub, and dermal cultures were obtained to assess the C. acnes burden after cultures on an aerobic and anaerobic growth medium were held for 21 days. Multivariate analysis was conducted to determine factors associated with presence of C. acnes. Outcome measures included the results of intraoperative cultures and the development of a SSI within 90 days postoperatively.

Results

Patients (n=86) undergoing elective 2- or 3-level fusion via anterior approach were included. Prior to application of the antiseptic solution, 65% (28/43) of the experimental cohort and 77% (33/43) of the control cohort had positive C. acnes cultures (p=.34). Following application of antiseptic solution, there were no differences in positive C. acnes culture rates between the experimental and control cohorts in the epidermal (30% vs. 28%, p=1.00) or dermal (40% vs. 42%, p=1.00) cultures. No differences in the rates of C. acnes eradication from preantiseptic to postantiseptic application occurred for epidermal (p=1.00) or dermal (p=1.00) skin layers. None of the factors were associated with positive C. acnes epidermal cultures on multivariable logistic regression analysis (p>.05).

Conclusions

While there is potential for H2O2 to reduce the positive culture rate of C. acnes in cervical spine patients, no difference was seen when compared to standard surgical skin preparation.

2023 Neer Award for Basic Science: Genetics of Cutibacterium acnes in revision shoulder arthroplasty: a large-scale bacterial whole-genome sequencing study

BACKGROUND

Cutibacterium acnes is the bacterium most commonly responsible for shoulder periprosthetic joint infection (PJI) and is often cultured from samples obtained at the time of revision for failed shoulder arthroplasty. We sought to determine whether these bacteria originate from the patient or from exogenous sources. We also sought to identify which C. acnes genetic traits were associated with the development of shoulder PJI.

METHODS

We performed bacterial whole-genome sequencing of C. acnes from a single-institution repository of cultures obtained before or during primary and revision shoulder arthroplasty and correlated the molecular epidemiology and genetic content of strains with clinical features of infection.

RESULTS

A total of 341 isolates collected over a 4-year period from 88 patients were sequenced. C. acnes cultured from surgical specimens demonstrated significant similarity to the strains colonizing the skin of the same patient (P < .001). Infrequently, there was evidence of strains shared across unrelated patients, suggesting that exogenous sources of C. acnes culture-positivity were uncommon. Phylotypes IB and II were modestly associated with clinical features of PJI, but all phylotypes appeared inherently capable of causing disease. Chronic shoulder PJI was associated with the absence of common C. acnes genes involved in bacterial quorum-sensing (luxS, tqsA).

CONCLUSION

C. acnes strains cultured from deep intraoperative sources during revision shoulder arthroplasty demonstrate strong genetic similarity to the strains colonizing a patient's skin. Some phylotypes of C. acnes commonly colonizing human skin are modestly more virulent than others, but all phylotypes have a capacity for PJI. C. acnes cultured from cases of PJI commonly demonstrated genetic hallmarks associated with adaptation from acute to chronic phases of infection. This is the strongest evidence to date supporting the role of the patient's own, cutaneous C. acnes strains in the pathogenesis of shoulder arthroplasty infection. Our findings support the importance of further research focused on perioperative decolonization and management of endogenous bacteria that are likely to be introduced into the arthroplasty wound at the time of skin incision.

Doxycycline Prophylaxis for Skin and Soft Tissue Infections in Naval Special Warfare Trainees, United States1

In 2015, several severe cases of skin and soft tissue infection (SSTI) among US Naval Special Warfare trainees prompted the introduction of doxycycline prophylaxis during the highest-risk portion of training, Hell Week. We performed a retrospective analysis of the effect of this intervention on SSTI incidence and resulting hospital admissions during 2013-2020. In total, 3,371 trainees underwent Hell Week training during the study period; 284 SSTIs were diagnosed overall, 29 of which led to hospitalization. After doxycycline prophylaxis was introduced, admission rates for SSTI decreased from 1.37 to 0.64 admissions/100 trainees (p = 0.036). Overall SSTI rates remained stable at 7.42 to 8.86 SSTIs/100 trainees (p = 0.185). Hospitalization rates per diagnosed SSTI decreased from 18.4% to 7.2% (p = 0.009). Average length of hospitalization decreased from 9.01 days to 4.33 days (p = 0.034). Doxycycline prophylaxis was associated with decreased frequency and severity of hospitalization for SSTIs among this population.

Preoperative prophylactic antibiotics administration does not influence culture yield in revision shoulder arthroplasty

BACKGROUND

The importance of administrating prophylactic antibiotics prior to a surgical procedure is well established. Given the difficulty in diagnosing shoulder periprosthetic infections, which are more indolent in nature, some advocate holding prophylactic antibiotics prior to obtaining cultures as there is a concern antibiotics may lead to a false negative culture result. The purpose of this study is to determine whether administration of antibiotics prior to obtaining cultures in revision shoulder arthroplasty influences culture yield.

METHODS

This was a retrospective analysis of revision shoulder arthroplasty cases performed at a single institution between 2015 and 2021. During the study period, each surgeon had a standardized protocol that dictated whether antibiotics were given or held prior to each revision surgery. Each case was categorized into either a Preculture antibiotic group, if antibiotics were administered prior to incision, or a Postculture antibiotic group if antibiotics were administered after incision and obtaining cultures. The International Consensus Meeting (ICM) scoring criteria provided by the Musculoskeletal Infection Society was used to categorize the probability of periprosthetic joint infection for each case. Culture positivity was calculated as the ratio of positive cultures and total number of cultures obtained.

RESULTS

One hundred twenty-four patients met inclusion criteria. There were 48 patients in the Preculture group and 76 patients in the Postculture group. No significant difference in patient demographics or ICM criteria (P = .09) was observed between the 2 groups. With regard to culture positivity, there was no difference between the Preculture antibiotic group and the Postculture antibiotic group (16% vs. 15%, P = .82, confidence interval = 8%-25% vs. 10%-20%, respectively).

CONCLUSION

In the setting of revision shoulder arthroplasty, timing of antibiotic administration did not significantly influence culture yield. This study supports the use of prophylactic antibiotics prior to obtaining cultures in revision shoulder arthroplasty.

The Use of Oral Antibiotics After Total Joint Arthroplasty: A Critical Analysis Review

» There is conflicting and insufficient evidence that extended oral antibiotic (EOA) therapy prevents infection in high-risk patients undergoing primary total joint arthroplasty (TJA), limiting recommendation for or against the practice.» In the case of aseptic revision TJA, the evidence is also conflicting and limited by underlying confounders, preventing recommendation for use of EOA.» There is fair evidence that use of EOA after debridement antibiotic therapy and implant retention of the prosthesis prolongs infection-free survival, but randomized controlled trials are needed. On the other hand, there is strong evidence that patients undergoing 2-stage revision should receive a period of suppressive oral antibiotics after the second stage.» The optimal duration of EOA in primary TJA, aseptic revision, and debridement antibiotic therapy and implant retention of the prosthesis is unknown. However, there is strong evidence that 3 months of EOA suppression may be appropriate after reimplantation as part of 2-stage exchange arthroplasty.» Complications secondary to EOA are reported to be between 0% and 13.7%, yet are inconsistently reported and poorly defined. The risks associated with antibiotic use, including development of antimicrobial resistance, must be weighed against a possible decrease in infection rate.

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

»

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.

»

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.

»

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.

»

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.

Culturing explants for Cutibacterium at revision shoulder arthroplasty: an analysis of explant and tissue samples at corresponding anatomic sites

BACKGROUND

Culturing of deep tissues obtained at revision arthroplasty for Cutibacterium is a key component of diagnosing a periprosthetic infection. The value of culturing explanted components has not been well described. This study sought to answer the following questions: (1) How does the culture positivity of explant cultures compare with that of deep tissue cultures? (2) How often are explant cultures positive when tissue cultures are not, and vice versa? (3) How does the bacterial density in explant cultures compare with that in tissue cultures?

METHODS

A total of 106 anatomic arthroplasties revised over a 7-year period were included. Explant (humeral head, humeral stem, and glenoid) and tissue (collar membrane, humeral canal tissue, and periglenoid tissue) specimens were sent for semiquantitative Cutibacterium culture. We compared culture positivity and bacterial density when cultures of an explant and tissue adjacent to the implant were both available.

RESULTS

Explants had positive cultures at a higher rate than adjacent tissue specimens for most anatomic sites. Of the shoulders that had Cutibacterium growth, a higher proportion of explants were culture positive when tissue samples were negative (23%-43%) than vice versa (0%-21%). The Cutibacterium density was higher in explants than in tissues. Considering only the results of tissue samples, 16% of the shoulders met our threshold for infection treatment (≥2 positive cultures); however, with the inclusion of the results for explant cultures, additional 14% of cases-a total of 30%-met the criteria for infection treatment.

CONCLUSIONS

In this group of patients, culturing explants in addition to tissue cultures increased the sensitivity for detecting Cutibacterium in revision shoulder arthroplasty.

What do positive and negative Cutibacterium culture results in periprosthetic shoulder infection mean? A multi-institutional control study

BACKGROUND

Deep tissue culture specimens obtained at the time of revision shoulder arthroplasty are commonly positive for Cutibacterium. Clinical interpretation of positive cultures can be difficult. This was a multi-institutional study evaluating the accuracy of cultures for Cutibacterium using positive control (PC) and negative control (NC) samples. The relationship between time to culture positivity and strength of culture positivity was also studied.

METHODS

Eleven different institutions were each sent 12 blinded samples (10 PC and 2 NC samples). The 10 PC samples included 2 sets of 5 different dilutions of a Cutibacterium isolate from a failed total shoulder arthroplasty with a probable periprosthetic infection. At each institution, the samples were handled as if they were received from the operating room. Specimen growth, time to culture positivity, and strength of culture positivity (based on semiquantitative assessment) were reported.

RESULTS

A total of 110 PC samples and 22 NC samples were tested. One hundred percent of specimens at the 4 highest dilutions were positive for Cutibacterium. At the lowest dilution, 91% of samples showed positive findings. Cutibacterium grew in 14% of NC samples. Cutibacterium grew in PC samples at an average of 4.0 ± 1.3 days, and all of these samples showed growth within 7 days. The time to positivity was significantly shorter (P < .001) and the strength of positivity was significantly higher (P < .001) in true-positive cultures compared with false-positive cultures.

CONCLUSIONS

This multi-institutional study suggests that different institutions may report highly consistent rates of culture positivity for revision shoulder arthroplasty samples with higher bacterial loads. In contrast, with lower bacterial loads, the results are somewhat less consistent. Clinicians should consider using a shorter time to positivity and a higher strength of positivity as adjuncts in determining whether a tissue culture sample is a true positive.

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.

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.

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.

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.

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 acnes: a threat to shoulder surgery or an orthopedic red herring?

Cutibacterium acnes is a lipophilic, anaerobic, gram-positive bacillus that mainly colonizes the pilosebaceous glands of human skin. It has been implicated as the leading cause of prosthetic joint infection (PJI) after shoulder arthroplasty. However, PJI caused by C acnes rarely manifests as overt clinical, laboratory, or imaging features. In fact, more than 40% of shoulders undergoing revision arthroplasty are likely to be culture positive. However, rates of infection following a positive culture can be as low as 5%. The purpose of this review was to put forth alternative explanations for this discordance between positive cultures and infection. We describe C acnes roles as a commensal, bystander, and/or contaminant organism; the role of cultures in diagnosis and other methods that may be more accurate; its existence in a shoulder microbiome; and the variable virulence of C acnes. C acnes is an important cause of shoulder PJI in some patients. However, there is a large body of literature that suggests other functions that need to be considered. Further research is needed to define the role of C acnes that is logically explained by all of the literature and not only some.

Early adherence and biofilm formation of Cutibacterium acnes (formerly Propionibacterium acnes) on spinal implant materials

BACKGROUND

Cutibacterium acnes (C. acnes) is associated with infection following shoulder and spine surgery due to follicular pore concentrations in these anatomic regions. It has been established that it can form biofilms on surgical implant materials, which may contribute to its role in perioperative infection, but its behavior of early colonization on those materials is not yet well understood.

PURPOSE

The purpose of this study was to evaluate the time to adherence and subsequent biofilm formation of C. acnes in the first 24 hours on implant materials commonly used in spinal surgery.

STUDY DESIGN

We compared the colonization and behavior of C. acnes over time when applied to five commonly used spine implant materials - polyether ether ketone (PEEK), cobalt chromium (CC), stainless steel (SS), titanium, and titanium alloy.

METHODS

C. acnes was applied onto the samples of PEEK, CC, SS, titanium, and titanium alloy, and allowed to adhere for periods of 4, 8, 12, 16, and 20 hours. Nonadherent bacteria were then washed from the samples. These samples were then allowed to continue incubating for a total 24 hours. Scanning electron microscopy and confocal laser scanning microscopy were used to visualize all samples for the presence and quantification of C. acnes adherence at each time period. Subsequent transition to biofilm formation on these samples was assessed via scanning electron microscopy at each time period.

RESULTS

The PEEK specimens exhibited the highest amount of surface biological burden in the first 24 hours compared with the other materials, which displayed little or no adherence. Rapid biofilm formation first observed at 8 hours of allowed adhesion on PEEK, whereas no significant biofilm formation was seen on the other materials during the observed time period.

CONCLUSIONS

Although C. acnes is known to have a slow proliferation rate, the results of this investigation demonstrate that it can rapidly adhere to and form a biofilm on PEEK. These data suggest that the use of PEEK implants placed during spinal surgery may facilitate early intraoperative colonization, and subsequent infection, compared with metallic implants.

CLINICAL SIGNIFICANCE

The findings of this study suggest that PEEK may prove to be problematic as a choice of implant material in cases were C. acnes infection is a possibility.

Cutibacterium acnes is less commonly identified by next-generation sequencing than culture in primary shoulder surgery

INTRODUCTION

High rates of positive Cutibacterium acnes cultures from primary shoulder surgery make positive cultures in the revision surgery setting difficult to interpret. Our goal was to determine concordance between culture and next-generation sequencing techniques for identification of C. acnes from primary shoulder surgery.

METHODS

Patients undergoing shoulder arthroscopy for rotator cuff tear or primary anatomic shoulder arthroplasty for osteoarthritis were prospectively enrolled. Specimens were sent for culture (aerobic and anaerobic) and next-generation sequencing. For next-generation sequencing, the entire microbial DNA was sequenced in order to identify pathogens within the sample.

RESULTS

Our cohort consisted of 90 patients (45 patients in the osteoarthritis group and 45 patients in the rotator cuff tear group). At least one sample was positive for C. acnes in 18 (20%) cases by culture and in 14 (15.6%) cases by next-generation sequencing (p = 0.559). Four (22.2%) of the 18 cases with positive C. acnes cultures also had C. acnes identified by next-generation sequencing (kappa = 0.238). There was no difference in C. acnes identification rates between osteoarthritis and rotator cuff tear groups.

CONCLUSIONS

There was limited concordance between culture and next-generation sequencing for C. acnes identification. Further studies are needed to determine the potential for next-generation sequencing as a diagnostic tool.

The presence of Cutibacterium acnes on the skin of the shoulder after the use of benzoyl peroxide: a placebo-controlled, double-blinded, randomized trial

HYPOTHESIS AND BACKGROUND

We hypothesized that benzoyl peroxide (BPO) would reduce the presence of Cutibacterium acnes on the skin of the shoulder by 50% compared with placebo. Infections after shoulder surgery are most commonly caused by C acnes. Current prophylactic methods do not effectively reduce the bacterial load of this bacterium. However, it seems that BPO may reduce C acnes on the skin of the shoulder. Therefore, this study aimed to investigate the effect of BPO on the presence of C acnes on the shoulder skin.

METHODS

A double-blinded, randomized, placebo-controlled trial was performed including healthy participants aged between 40 and 80 years. Thirty participants with C acnes on the shoulder skin according to baseline skin swabs were randomized into the BPO or placebo group. After gel application 5 times, skin swabs were taken to determine the presence of C acnes.

RESULTS

Forty-two participants were screened for the presence of C acnes to include 30 participants with the bacterium. Participants with C acnes at baseline were 7.4 years younger than participants without C acnes (P = .015). One participant in the placebo group dropped out before application because of fear of adverse events. After application, C acnes remained present in 3 of 15 participants (20.0%) in the BPO group and in 10 of 14 participants (71.4%) in the placebo group, resulting in a 51.4% reduction in the presence of C acnes.

CONCLUSION

Applying BPO 5 times on the shoulder skin effectively reduces C acnes. Consequently, BPO may reduce the risk of postoperative infections.

Strategies to decolonize the shoulder of Cutibacterium acnes: a review of the literature

Cutibacterium acnes is the most prevalent cause of joint infection after shoulder surgery. Current methods for decolonizing this bacterium from the shoulder region have proved ineffective owing to its unique niche within dermal sebaceous glands and hair follicles. When we are making decisions to decolonize the skin of C acnes, the risks associated with decolonization must be balanced by the potential benefits of reduced deep tissue inoculation. The purpose of this review was to describe currently available methods of decolonization and their efficacy.

While home chlorhexidine washes prior to shoulder surgery lower skin loads of most bacteria, they are not effective against Cutibacterium (Propionibacterium)

PURPOSE

Chlorhexidine showers prior to shoulder arthroplasty are commonly recommended by surgeons to lower the risk of periprosthetic infection; however, the effectiveness of these washes in eliminating bacteria from the skin of the shoulder has not been thoroughly evaluated. The objective of this study was to determine the degree to which pre-operative chlorhexidine washes effectively eliminate bacteria from the epidermal skin surface and from the dermis freshly incised during shoulder arthroplasty.

METHODS

Around 66 patients undergoing primary shoulder arthroplasty were instructed to shower with chlorhexidine before surgery. Each patient had three skin swabs: (1) the epidermis at a pre-operative clinic appointment, (2) the epidermis at surgery after home chlorhexidine showers but prior to skin preparation, and (3) the dermis after incision of the prepared skin. The bacterial loads of Cutibacterium and other bacterial types from each swab were compared to determine whether the showers were effective in altering the bacterial loads.

RESULTS

Chlorhexidine washes were effective in reducing the skin load of other bacterial species (p < 0.005), but they did not decrease the skin load of Cutibacterium (p = 0.585).

CONCLUSIONS

Pre-operative skin showers with chlorhexidine were not effective in reducing the load of Cutibacterium on the skin of patients having shoulder arthroplasty. Since Cutibacterium is responsible for the highest percentage of shoulder periprosthetic infections, research is needed to identify more effective means of removing these bacteria from the surgical field.

Incidence and predictors of positive intraoperative cultures in primary shoulder arthroplasty following prior ipsilateral shoulder surgery

Background

To our knowledge, the rate of positive intraoperative cultures in patients undergoing primary shoulder arthroplasty with prior ipsilateral nonarthroplasty shoulder surgery is unknown. The aim of this study was to determine the incidence and predictors of positive cultures in these patients.

Methods

We performed a retrospective review of patients with prior ipsilateral shoulder surgery with intraoperative cultures taken at the time of primary shoulder arthroplasty. We evaluated culture results, demographics, and number of prior surgeries. Regression analysis was used to determine patient-related risk factors that predict positive cultures.

Results

A total of 682 patients underwent primary shoulder arthroplasty, 83 had at least 1 prior ipsilateral shoulder surgery: 65.1% male, mean age 64.2 ± 10.9 years. For the cohort of 83 patients, an average of 3.2 ± 1.2 tissue samples were obtained for each patient, with a mean of 0.84 ± 1.14 tissue cultures being positive (range 0-5). Thirty-seven of the 83 patients (44.5%) had at least 1 positive culture, with Cutibacterium acnes the most frequent organism (31/37; 83.4%). An average of 1.9 ± 0.96 tissue cultures resulted positive (range 1-5) for the 37 patients who had positive cultures, 40.5% (15/37) had only 1 positive tissue culture (12/15 C acnes, 2/15 Staphylococcus epidermidis, and 1/15 vancomycin-resistant enterococcus). Male sex and history of prior shoulder infection were predictive of culture positivity (odds ratios: 2.5 and 20.9, respectively). Age, race, medical comorbidities, number of prior shoulder surgeries, and time from index shoulder surgery were not predictive of culture positivity.

Conclusion

About 45% of patients with no clinical signs of infection and a history of prior ipsilateral shoulder surgery undergoing primary shoulder arthroplasty grew positive intraoperative cultures. The significance of these findings remains unclear with regard to risk of periprosthetic infection and how these patients should be managed.

Addition of 3% hydrogen peroxide to standard skin preparation reduces Cutibacterium acnes-positive culture rate in shoulder surgery: a prospective randomized controlled trial

BACKGROUND

Hydrogen peroxide is an inexpensive and effective antimicrobial agent that can be implemented in surgical skin preparations. The purpose of this study was to evaluate the decolonization effect of Cutibacterium acnes when adding hydrogen peroxide to a standard sterile preparation for shoulder surgery.

METHODS

This was a single-institution, prospective, randomized controlled trial of male patients undergoing shoulder arthroscopy (April 2018 and May 2019). Patients were randomized to a standard skin preparation vs. an additional sterile preparation with 3% hydrogen peroxide. After draping, a 3-mm punch biopsy was obtained from the posterior arthroscopic portal site of all patients. Anaerobic and aerobic culture substrates were used and held for 13 days.

RESULTS

Seventy male patients were randomized into the hydrogen peroxide group and 70 male patients were in the traditional group. Twelve (17.1%) patients in the hydrogen peroxide group and 24 (34.2%) patients in the traditional group had positive cultures for C acnes (P = .033). Cultures were positive at a mean of 4.5 days (range 3-7) in the hydrogen peroxide group and 4.1 days (range 3-8) in the traditional group (P = .48). There were no cases of skin reaction to the surgical preparation in either group.

DISCUSSION

The results of this study suggest that the addition of hydrogen peroxide to preoperative surgical site preparation can reduce the C acnes culture rate. Hydrogen peroxide is inexpensive and can be added to the typical skin preparation used prior to shoulder surgery without substantial risk of skin reactions.

Cutibacterium acnes Isolates from Deep Tissue Specimens Retrieved during Revision Shoulder Arthroplasty: Similar Colony Morphology Does Not Indicate Clonality

Cutibacterium acnes is the most common bacterium associated with periprosthetic shoulder infections. Sequencing of C. acnes has been proposed as a potential rapid diagnostic tool and a method of determining subtypes associated with pathogenicity and antibiotic resistance patterns. When multiple deep samples from the same surgery are culture positive for the same species and the isolates show the same culture phenotype, it is typically assumed that these isolates are clonal. However, it is well-known that C. acnes is not clonal on the skin of most individuals. We hypothesized that the C. acnes bacteria recovered at the time of revision shoulder arthroplasty would often represent more than one subtype, and we tested this hypothesis in this work. For patients undergoing revision shoulder arthroplasty, multiple samples from the surgical field were taken. For those patients with multiple samples that were culture positive for C. acnes, isolates from each sample were subjected to full genome sequencing. Of 11 patients, 5 (45%) had different subtypes of C. acnes within the deep tissues even though the colony morphology was similar. One patient had four subtypes in the deep tissues, while four patients had two different subtypes. Up to four different subtypes of C. acnes were observed in the deep tissues of a single patient. Clonality of C. acnes isolates from deep specimens from a potential periprosthetic shoulder infection cannot be assumed. Sequence-based characterization of virulence and antibiotic resistance may require testing of multiple deep specimens.

Cutibacterium acnes Infection in Orthopedics: Microbiology, Clinical Findings, Diagnostic Strategies, and Management

Cutibacterium (formerly called Propionibacterium) acnes is a human skin flora often implicated in orthopedic infections. The unique characteristics of this microorganism make the diagnosis of infection difficult. The diagnosis often is made based on clinical evidence, radiographic signs, and laboratory and/or surgical findings combined. Treatment often involves both pharmacologic and surgical methods. In addition, formation of biofilms and increased resistance to drugs exhibited by the microorganism can require combined antimicrobial therapy. Prophylactic measures are particularly important, but no single method has been shown to fully eliminate the risk of C acnes infections. Previous reports have focused on C acnes infections involving surgical implants or after certain orthopedic procedures, particularly in the shoulder and spine. This article reviews current clinical, diagnostic, and treatment principles for C acnes in orthopedics in general. [Orthopedics. 2020; 43(1):52-61.].

Use of electrocautery does not diminish the transmission rate of Cutibacterium acnes compared to a scalpel blade

Many methods are used during shoulder surgery to prevent wound contamination with Cutibacterium acnes, but there are no accepted standards for prevention. Some surgeons use an electrosurgical instrument instead of a scalpel blade during open shoulder surgery in an effort to prevent deep tissue contamination with C. acnes. We sought to compare the transference rate of C. acnes between a scalpel blade at room temperature and an electrosurgical blade heated to 41°C (temperature of electrosurgical blade after standard deltopectoral approach). In our model, using a scalpel blade versus a heated electrosurgical blade resulted in no difference in pathogen transference.

A review of microscopy-based evidence for the association of Propionibacterium acnes biofilms in degenerative disc disease and other diseased human tissue

PURPOSE

Recent research shows an increasing recognition that organisms not traditionally considered infectious in nature contribute to disease processes. Propionibacterium acnes (P. acnes) is a gram-positive, aerotolerant anaerobe prevalent in the sebaceous gland-rich areas of the human skin. A ubiquitous slow-growing organism with the capacity to form biofilm, P. acnes, recognized for its role in acne vulgaris and medical device-related infections, is now also linked to a number of other human diseases. While bacterial culture and molecular techniques are used to investigate the involvement of P. acnes in such diseases, definitive demonstration of P. acnes infection requires a technique (or techniques) sensitive to the presence of biofilms and insensitive to the presence of potential contamination. Fortunately, there are imaging techniques meeting these criteria, in particular, fluorescence in situ hybridization and immunofluorescence coupled with confocal laser scanning microscopy, as well as immunohistochemistry.

METHODS

Our literature review considers a range of microscopy-based studies that provides definitive evidence of P. acnes colonization within tissue from a number of human diseases (acne vulgaris, degenerative disc and prostate disease and atherosclerosis), some of which are currently not considered to have an infectious etiology.

RESULTS/CONCLUSION

We conclude that P. acnes is an opportunistic pathogen with a likely underestimated role in the development of various human diseases associated with significant morbidity and, in some cases, mortality. As such, these findings offer the potential for new studies aimed at understanding the pathological mechanisms driving the observed disease associations, as well as novel diagnostic strategies and treatment strategies, particularly for degenerative disc disease. These slides can be retrieved under Electronic Supplementary Material.

Proceedings from the 2018 International Consensus Meeting on Orthopedic Infections: prevention of periprosthetic shoulder infection

The Second International Consensus Meeting on Orthopedic Infections was held in Philadelphia, Pennsylvania, in July 2018. Over 800 international experts from all 9 subspecialties of orthopedic surgery and allied fields of infectious disease, microbiology, and epidemiology were assembled to form a consensus workgroup. The following proceedings on the prevention of periprosthetic shoulder infection come from 16 questions evaluated by delegates from the shoulder section.

Cutibacterium acnes in primary reverse shoulder arthroplasty: from skin to deep layers

BACKGROUND

The aim of this study was to determine the presence of Cutibacterium acnes (formerly Propionibacterium acnes) on the skin and in deep tissue in a real clinical scenario of primary reverse shoulder arthroplasty.

METHODS

This prospective study included 90 primary reverse shoulder arthroplasties, and 12 cultures were obtained from each patient. Each sample was homogenized and used to inoculate PolyVitex (bioMérieux, Marcy-l'Etoile, France) agar and Schaedler (bioMérieux) agar plates. The same procedure was also followed with a thioglycolate broth. Culture was considered positive for C acnes when 2 or more colonies were observed. Total DNA from C acnes isolates was extracted using the InstaGene Matrix (Bio-Rad Laboratories, Hercules, CA, USA) method. The phylotype was determined, and single-locus sequence typing was done on all isolates.

RESULTS

We obtained 1080 tissue cultures from the 90 patients included, and 62 of those tissue cultures (5.7%) were positive for C acnes. There were 22 C acnes-positive tissue cultures before prosthesis implantation and 40 after implantation. C acnes was isolated in 17 patients (18.8%). We sent 38 positive samples for blinded phylotyping, single-locus sequence typing, and multi-locus sequence typing type determination. Many of the clusters isolated belonged to phylotype IB and clonal complex (CC) 36 or phylotype II and CC53.

DISCUSSION

In the real scenario of patients undergoing primary reverse shoulder arthroplasty using antibiotic prophylaxis and standard preoperative skin preparation with chlorhexidine, C acnes was isolated in the deep layers of 18.8% of the patients. The C acnes K1 and K2 subtypes (belonging to phylotype II and CC53), reported to be commonly involved in prosthetic joint infection, were usually isolated.

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.

Comparative study of cultures and next-generation sequencing in the diagnosis of shoulder prosthetic joint infections

BACKGROUND

Serum and synovial markers used to diagnose lower extremity prosthetic joint infection (PJI) have performed poorly for shoulder PJI. As a result, diagnosis is commonly reliant on the accuracy of positive or negative cultures. Next-generation sequencing (NGS) can sequence an entire bacterial genome. This study was conducted to determine the correlation between NGS and routine cultures in revision shoulder arthroplasty.

METHODS

All patients undergoing revision shoulder arthroplasty were prospectively enrolled. In a standardized manner, tissue samples were transferred immediately into sterile specimen containers and transported for culture and NGS (MicroGen Dx, Lubbock, TX, USA). Infection definitions using culture and NGS were analyzed for concordance.

RESULTS

There were 44 total revision arthroplasty cases included. There were no cases of polymicrobial culture results. Cutibacterium (formerly Propionibacterium) acnes was the most common bacterial species cultured (8 of 13 [61.5%]) and identified by NGS (12 of 17 [70.1%]) in cases of definite and probable infection. The concordance (κ) between the 2 diagnostic criteria for defining infection that included culture or NGS was 0.333 (fair). There were significantly more cases of probable contaminants when cultures (10 of 44 [22.7%]) were used in the definition of infection compared with NGS (0 of 44 [0%]; P = .001).

DISCUSSION

Culture data from revision shoulder arthroplasty cases commonly yields monomicrobial results; whereas, NGS data suggests that bacterial loads in revision arthroplasty are most commonly polymicrobial. In addition, a definition of infection that uses cultures is more prone to "probable contaminants" than NGS. Significant uncertainty remains about our current methods of diagnosing shoulder PJI.

Preoperative skin cultures are predictive of Propionibacterium load in deep cultures obtained at revision shoulder arthroplasty

BACKGROUND

Propionibacterium-specific cultures are commonly positive in revised shoulders without obvious signs of infection. To help identify patients at risk for these "stealth" presentations of positive Propionibacterium cultures, we assessed the value of a preoperative skin culture in predicting the results of deep cultures obtained at the time of revision shoulder arthroplasty in patients without clinical evidence of infection.

METHODS

The study enrolled 60 patients undergoing revision for a prior shoulder arthroplasty without clinical evidence of infection. A preoperative culture of the skin surface was taken before skin preparation. At surgery, multiple (mean 5.9 ± standard deviation 1.6) deep tissue and explant cultures were harvested from the shoulder. Each culture was semiquantitatively reported as the specimen Propionibacterium value (SpPV). All SpPVs from the deep specimens from each patient were summed as the total shoulder Propionibacterium score (ShPS). The averaged ShPS was the total ShPS divided by the number of deep specimens harvested.

RESULTS

A multivariate analysis demonstrated that the preoperative skin SpPV was predictive of the Propionibacterium load in the revised shoulders as indicated by the total ShPS (P = .004) and averaged ShPS (P = .003).

CONCLUSIONS

In this series of patients, a preoperative culture of the unprepared skin was strongly predictive of the Propionibacterium load in revised shoulder arthroplasties without clinical evidence of infection. This result suggests that the results of skin cultures taken before revision surgery may help inform operative management with respect to the need for prosthesis exchange and extended postoperative antibiotic treatment.

Preoperative Skin-Surface Cultures Can Help to Predict the Presence of Propionibacterium in Shoulder Arthroplasty Wounds

Background:

Propionibacterium species are commonly cultured from specimens harvested at the time of revision shoulder arthroplasty. These bacteria reside in normal sebaceous glands, out of reach of surgical skin preparation. The arthroplasty incision transects these structures, which allows Propionibacterium to inoculate the wound and to potentially lead to the formation of a biofilm on the inserted implant. To help identify patients who are at increased risk for wound inoculation, we investigated whether preoperative cultures of the specimens from the unprepared skin surface were predictive of the results of intraoperative cultures of dermal wound-edge specimens obtained immediately after incision of the surgically prepared skin.

Methods:

Sixty-six patients (mean age, 66.1 ± 9.4 years [range, 37 to 82 years]; 73% male) undergoing primary shoulder arthroplasty had preoperative cultures of the unprepared skin surface and intraoperative cultures of the freshly incised dermis using special culture swabs. For the first 50 patients, a control swab was opened to air during the same time that the dermal specimen was obtained. The results for female and male patients were characterized as the Specimen Propionibacterium Value (SpPV). We then determined the degree to which the results of cultures of the skin surface specimens were predictive of the results of culture of the dermal specimens.

Results:

The skin-surface SpPV was ≥1 in 3 (17%) of the 18 female patients and 34 (71%) of the 48 male patients (p < 0.001). The dermal SpPV was ≥1 in 0 (0%) of the 18 female patients and 19 (40%) of the 48 male patients (p < 0.001). None of the control samples had an SpPV of ≥1. The predictive characteristics of a skin-surface SpPV of ≥1 for a dermal SpPV of ≥1 were as follows: sensitivity, 1.00 (95% confidence interval [CI], 0.82 to 1.00); specificity, 0.62 (95% CI, 0.46 to 0.75); positive predictive value, 0.51 (95% CI, 0.34 to 0.68); and negative predictive value, 1.00 (95% CI, 0.88 to 1.00).

Conclusions:

A preoperative culture of the unprepared skin surface can help to predict whether the freshly incised dermal edge is likely to be positive for Propionibacterium. This test may help to identify patients who may merit more aggressive topical and systemic antibiotic prophylaxis.

Clinical Relevance:

This study shows that surgeons have the opportunity to use preoperative skin cultures to determine the likelihood that the shoulder arthroplasty wound will be culture-positive for Propionibacterium.

Examination of concomitant glenohumeral pathologies in patients treated arthroscopically for calcific tendinitis of the shoulder and implications for routine diagnostic joint exploration

BACKGROUND

Glenohumeral exploration is routinely performed during arthroscopic removal of rotator cuff calcifications in patients with calcific tendinitis of the shoulder (CTS). However, evidence on the prevalence of intraarticular co-pathologies is lacking and the benefit of glenohumeral exploration remains elusive. The aim of the present study was to assess and quantify intraoperative pathologies during arthroscopic removal of rotator cuff calcifications in order to determine whether standardized diagnostic glenohumeral exploration appears justified in CTS patients.

METHODS

One hundred forty five patients undergoing arthroscopic removal of calcific depots (CD) that failed conservative treatment were included in a retrospective cohort study. Radiographic parameters including number/localization of calcifications and acromial types, intraoperative arthroscopic findings such as configuration of glenohumeral ligaments, articular cartilage injuries, and characteristics of calcifications and sonographic parameters (characteristics/localization of calcification) were recorded.

RESULTS

One hundred forty five patients were analyzed. All CDs were removed by elimination with a blunt hook probe via "squeeze-and-stir-technique" assessed postoperatively via conventional X-rays. Neither subacromial decompression nor refixation of the rotator cuff were performed in any patient. Prevalence of glenohumeral co-pathologies, such as partial tears of the proximal biceps tendon (2.1%), superior labral tears from anterior to posterior (SLAP) lesions (1.4%), and/or partial rotator cuff tears (0.7%) was low. Most frequently, glenohumeral articular cartilage was either entirely intact (ICRS grade 0 (humeral head/glenoid): 46%/48%) or showed very mild degenerative changes (ICRS grade 1: 30%/26%). Two patients (1.3%) required intraarticular surgical treatment due to a SLAP lesion type III (n = 1) and an intraarticular rupture of CD (n = 1).

CONCLUSIONS

Routine diagnostic glenohumeral exploration does not appear beneficial in arthroscopic treatment of CTS due to the low prevalence of intraarticular pathologies which most frequently do not require surgical treatment. Exploration of the glenohumeral joint in arthroscopic removal of CD should only be performed in case of founded suspicion of relevant concomitant intraarticular pathologies.