Propionibacterium acnes infection after shoulder surgery

Anti-CAMP1 IgG promotes macrophage phagocytosis of Cutibacterium acnes type II

Among 5 types of the Christie-Atkins-Munch-Petersen factor (CAMP) of Cutibacterium acnes, CAMP1 is highly expressed in phylotype II as well as IB, and thought to be a virulence factor of opportunistic but fatal blood, soft tissue, and implant-related infections. The target of a human single-chain variable antibody fragment (scFv), recently isolated from a phage display library, has been identified as CAMP1 of phylotype II, using immunoprecipitation followed by mass spectrometry, phage display peptide biopanning, 3D-modelling, and ELISA. The IgG1 format of the antibody could enhance phagocytosis of C. acnes DMST 14916 by THP-1 human monocytes. Our results suggest that the antibody-dependent phagocytosis process is mediated by the caveolae membrane system and involves the induction of IL-1β. This is the first report on the study of a human antibody against CAMP1 of C. acnes phylotype II, of which a potential use as therapeutic antibody against virulence C. acnes infection is postulated.

The effect of different antibiotic combinations in calcium sulfate cement on the growth of Cutibacterium acnes and Staphylococcus periprosthetic shoulder infection isolates

BACKGROUND

Periprosthetic joint infections (PJI) of the shoulder are a devastating complication of shoulder arthroplasty and are commonly caused by Staphylococcus and Cutibacterium acnes. Absorbable calcium sulfate (CS) beads are sometimes used for delivering antibiotics in PJI. This study evaluates the in vitro effect of different combinations of gentamicin, vancomycin, and ertapenem in beads made from CS cement on the growth of C acnes and coagulase-negative Staphylococcus (CNS) strains.

METHODS

Three strains of C acnes and 5 strains of CNS from clinically proven shoulder PJI were cultured and plated with CS beads containing combinations of vancomycin, gentamicin, and ertapenem. Plates with C acnes were incubated anaerobically while plates with Staphylococcus were incubated aerobically at 37 °C. Zones of inhibition were measured at intervals of 3 and 7 days using a modified Kirby Bauer technique, and beads were moved to plates containing freshly streaked bacteria every seventh day. This process was run in triplicate over the course of 56 days. Statistical analysis was conducted using SPSS v. 28 with repeated measures analysis of variance (ANOVA) and pairwise comparisons with Tukey correction.

RESULTS

In experiments with C acnes, beads containing ertapenem + vancomycin and vancomycin alone formed the largest zones of inhibition over time (P < .001). In experiments with Staphylococcus, beads containing vancomycin alone formed the largest zones of inhibition over time for all 5 strains (P < .001). Zones of inhibition were 1.4x larger for C acnes than for Staphylococcus with beads containing vancomycin alone. For both C acnes and Staphylococcus, beads containing ertapenem had the strongest initial effect, preventing all bacterial growth in C acnes and almost all growth for Staphylococcus during the first week but dropping substantially by the second week. Beads containing gentamicin alone consistently created smaller zones of inhibition than beads containing vancomycin alone, with vancomycin producing zones 5.3x larger than gentamicin in C acnes and 1.3x larger in Staphylococcus (P < .001).

DISCUSSION

These data suggest that for both C acnes and Staphylococcal species, CS beads impregnated with vancomycin were most effective at producing a robust antibiotic effect. Additionally, ertapenem may be a viable supplement in order to create a more potent initial antibiotic effect but is not as effective as vancomycin when used alone. Gentamicin alone was not effective in maintaining consistent and long-term antibiotic effects. These results indicate that amongst the antibiotics currently commercially available to be used with CS, vancomycin is consistently superior to gentamicin in the setting of C. acnes and CNS.

Topical Preparations for Reducing Cutibacterium acnes Infections in Shoulder Surgery: A Systematic Review and Network Meta-analysis of Randomized Controlled Trials

BACKGROUND

Cutibacterium acnes (C acnes) is a commensal skin bacterium, primarily found in sebaceous glands and hair follicles, with a high prevalence in the shoulder region. It is the most common pathogenic organism in prosthetic joint infections after shoulder arthroplasty. Because of its low virulence, its diagnosis remains difficult.

PURPOSE

To evaluate the relative effects of topical preparations in reducing C acnes in shoulder surgery.

STUDY DESIGN

Meta-analysis; Level of evidence, 1.

METHODS

We searched the MEDLINE, Embase, PsychINFO, and Cochrane Library databases in March 2022. Randomized controlled trials (RCTs) comparing any form of topical preparation in arthroscopic or open shoulder surgery were included. The primary outcome was a reduction in the number of positive C acnes cultures. Secondary outcomes were adverse events related to the application of topical preparations. We performed a network meta-analysis to facilitate simultaneous comparisons between multiple preparations across studies. We calculated differences between preparations using odds ratios and their 95% CIs. The risk of bias was assessed using the Cochrane risk-of-bias tool.

RESULTS

The search yielded 17 RCTs (1350 patients), of which 9 were suitable for the network meta-analysis (775 patients). Overall, 2 RCTs were deemed as having a low risk of bias, and 15 raised "some concerns" of bias. Preparations included benzoyl peroxide (BPO), BPO combined with clindamycin, chlorhexidine gluconate, hydrogen peroxide, povidone-iodine, and water with soap. Only BPO resulted in significantly lower odds of a positive C acnes culture compared with placebo or soap and water (odds ratio, 0.12 [95% CI, 0.04-0.36]). There was no statistically significant difference with all other topical preparations. The only adverse events were skin irritation from BPO and chlorhexidine gluconate in a small number of reported cases.

CONCLUSION

BPO was the most effective topical agent in reducing the prevalence of C acnes in shoulder surgery. These results were limited by a combination of indirect and direct data. Future studies should focus on establishing the optimal frequency and duration of preoperative BPO to further reduce the burden of C acnes.

REGISTRATION

CRD42022310312 (PROSPERO).

The incidence of subclinical infection in patients undergoing revision shoulder stabilization surgery: a retrospective chart review

BACKGROUND

Shoulder instability continues to be a common problem that is difficult to treat. Part of this difficulty can be attributed to the numerous postoperative complications that can impact the clinical course. Our study aims to primarily identify the incidence of subclinical infection in patients undergoing revision shoulder stabilization surgery and secondarily identify any risk factors for developing a subclinical infection.

MATERIALS AND METHODS

From January 2012 to December 2022, 94 charts of patients who underwent revision surgery by the senior author after a previous arthroscopic or open stabilization surgery for shoulder instability were reviewed. All patients of any age who underwent either bony or soft tissue revision surgery, regardless of the number of previous surgeries or corticosteroid injections, were included. Patients were excluded if they had a previous infection in the shoulder, if there was no record of the procedures performed in the previous surgery, or if cultures were not available for review. For each patient, demographic information (age, sex, race, smoking status, previous corticosteroid injections, malnutrition, renal failure, liver failure, diabetes mellitus, immunocompromised status, and intravenous drug use), surgical information (procedures performed, type of surgery, and date of surgery), and culture results were recorded.

RESULTS

Overall, 107 patients were included in our study. Twenty-nine patients (27.1%) had positive cultures (60 cultures in total). Twenty-six patients had positive Cutibacterium acnes (C. acnes) cultures. On average, C. acnes cultures took 10.65 days to turn positive, whereas 24 of 27 patients had cultures that were positive within 14 days of the culture being obtained. There was no difference in infection incidence rates between soft tissue and bony stabilization procedures (P = .86) or arthroscopic and open procedures (P = .59). Males were more than 5 times more likely than females to be culture positive in our cohort (93.1% vs. 73.1%, relative risk [RR] = 1.27, P = .03). Finally, 10 control cultures were taken from the operating room air environment (8 distinct surgeries had 1 control culture taken, whereas 1 surgery had 2), 2 of which were positive for C. acnes (both taken from the same patient operation). This patient had their shoulder cultures positive for C. acnes as well.

CONCLUSION

More than a quarter of patients requiring revision surgery after shoulder stabilization procedures have a subclinical shoulder infection, with males being at a higher risk of developing an infection than females. Surgeons should always consider infection as a reason for the lack of clinical improvement and possibly needing revision surgery after shoulder stabilization. The prompt diagnosis and treatment of these infections could be vital in improving results after these surgeries.

Best products for skin antisepsis

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

A High Rate of Bacteriologic Culture-Positive Findings Is Seen After Revision Rotator Cuff Surgery

Purpose

To determine the incidence of subclinical infections in patients undergoing revision arthroscopic rotator cuff repair and identify any risk factors for developing these infections.

Methods

Patients who underwent revision surgery by the senior author between January 2012 and December 2022 after a previous rotator cuff surgery were identified. All patients undergoing an open or arthroscopic revision of their previous rotator cuff surgery were included. Patients who had noted previous shoulder infections or had incomplete chart documentation were excluded. For each patient, demographic information, surgical information, and culture results were recorded.

Results

A total of 115 patients were identified. Thirty-nine were excluded due to incomplete chart documentation (35) or a history of infection (4); therefore, 22 patients (28.9%) had positive cultures (31 cultures in total). Seventeen patients had only Cutibacterium acnes identified. C acnes cultures turned positive on average 13.52 days after culture collection. There was no difference in infection incidence rates between isolated rotator cuff repair and rotator cuff repair plus additional surgeries (P = .88) or between initial arthroscopic versus open procedures (P = .83). None of the 12 identified risk factors, including age, sex, race, smoking history, previous corticosteroid injections, malnutrition, renal failure, liver failure, diabetes mellitus, immunocompromised status, intravenous drug use, and number of revisions, were correlated with the presence of a subclinical infection. Finally, 6 patients had control cultures taken. One culture (16.6%) was positive for C acnes, while this patient did not have a positive shoulder culture.

Conclusions

Subclinical shoulder infections can be present in more than one-quarter of patients undergoing revision after rotator cuff repair.

Level of Evidence

Level IV, diagnostic case series.

Update on Shoulder Arthroplasties with Emphasis on Imaging

Shoulder pain and dysfunction may significantly impact quality of life. If conservative measures fail, advanced disease is frequently treated with shoulder arthroplasty, which is currently the third most common joint replacement surgery following the hip and knee. The main indications for shoulder arthroplasty include primary osteoarthritis, post-traumatic arthritis, inflammatory arthritis, osteonecrosis, proximal humeral fracture sequelae, severely dislocated proximal humeral fractures, and advanced rotator cuff disease. Several types of anatomic arthroplasties are available, such as humeral head resurfacing and hemiarthroplasties, as well as total anatomic arthroplasties. Reverse total shoulder arthroplasties, which reverse the normal ball-and-socket geometry of the shoulder, are also available. Each of these arthroplasty types has specific indications and unique complications in addition to general hardware-related or surgery-related complications. Imaging-including radiography, ultrasonography, computed tomography, magnetic resonance imaging, and, occasionally, nuclear medicine imaging-has a key role in the initial pre-operative evaluation for shoulder arthroplasty, as well as in post-surgical follow-up. This review paper aims to discuss important pre-operative imaging considerations, including rotator cuff evaluation, glenoid morphology, and glenoid version, as well as to review post-operative imaging of the various types of shoulder arthroplasties, to include normal post-operative appearances as well as imaging findings of complications.

Reverse rhino sign as a radiological sign of low-grade infected reverse shoulder arthroplasty

INTRODUCTION

Low-grade infections following shoulder surgery are difficult to diagnose. Recently, curved-shaped bony spurs, further mentioned "reverse rhino signs" because of its shape, growing inferior on the glenoid were noticed on X-rays of patients with a reverse shoulder arthroplasty (RSA) and a Cutibacterium acnes (C. acnes) infection. This study aimed to determine the sensitivity and specificity of the reverse rhino sign as a radiological marker for detecting low-grade shoulder infections in RSA.

MATERIALS AND METHODS

A diagnostic study was performed including patients who underwent revision surgery of an RSA with perioperative cultures taken. Blinded radiographic evaluation was performed by two orthopedic surgeons for presence of rhino signs, humeral osteophytes, and notching. Efficacy measures of the reverse rhino sign for detecting low-grade infections were determined. Furthermore, results were stratified for notching and gender.

RESULTS

Thirty-two revised RSA patients had a low-grade infection and 36 had no infection. Seventeen (53%) patients with infection had a reverse rhino sign present, compared to 6 (17%) in the non-infection group. Sensitivity, specificity, positive and negative predictive value of the reverse rhino sign were, respectively, 53%, 83%, 74%, and 67%. These measures changed to 68%, 77%, 72%, and 74% for patients without notching and to 47%, 100%, 100%, and 8% for males.

CONCLUSION

In the absence of a reverse rhino sign in RSA patients, a low-grade shoulder infection is unlikely. Hence, the reverse rhino sign can be used to rule in a low-grade shoulder infection, especially in males and in the absence of notching. Low-grade infections should be considered in patients with unexplained persistent shoulder complaints after RSA placement, especially when a rhino sign is present. For these patients, we advise to perform mini-open biopsy for cultures.

LEVEL OF EVIDENCE

Diagnostic level IV.

SPILF update on bacterial arthritis in adults and children

In 2020 the French Society of Rhumatology (SFR) published an update of the 1990 recommendations for management of bacterial arthritis in adults. While we (French ID Society, SPILF) totally endorse this update, we wished to provide further information about specific antibiotic treatments. The present update focuses on antibiotics with good distribution in bone and joint. It is important to monitor their dosage, which should be maximized according to PK/PD parameters. Dosages proposed in this update are high, with the optimized mode of administration for intravenous betalactams (continuous or intermittent infusion). We give tools for the best dosage adaptation to conditions such as obesity or renal insufficiency. In case of enterobacter infection, with an antibiogram result "susceptible for high dosage", we recommend the requesting of specialized advice from an ID physician. More often than not, it is possible to prescribe antibiotics via the oral route as soon as blood cultures are sterile and clinical have symptoms shown improvement. Duration of antibiotic treatment is 6 weeks for Staphylococcus aureus, and 4 weeks for the other bacteria (except for Neisseria: 7 days).

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.

Previous rotator cuff repair increases the risk of revision surgery for periprosthetic joint infection after reverse shoulder arthroplasty

BACKGROUND

Previous studies have indicated an increased risk of periprosthetic joint infection (PJI) in patients treated with reverse shoulder arthroplasty (RSA) compared with patients treated with anatomic total shoulder arthroplasty. The reason for this is unclear but may be related to a high prevalence of previous rotator cuff repair in patients who are treated with RSA. The purpose of this study was to determine previous non-arthroplasty surgery as a risk factor for revision owing to PJI after RSA for cuff tear arthropathy, massive irreparable rotator cuff tears, or osteoarthritis.

METHODS

Data were retrieved from the Danish Shoulder Arthroplasty Registry and medical records. We included 2217 patients who underwent RSA for cuff tear arthropathy, massive irreparable rotator cuff tears, or osteoarthritis between 2006 and 2019. PJI was defined as ≥3 of 5 tissue samples positive for the same bacteria or as definite or probable PJI evaluated based on criteria from the International Consensus Meeting. The Kaplan-Meier method was used to illustrate the unadjusted 14-year cumulative rates of revision. A Cox regression model was used to report hazard for revision owing to PJI. Results were adjusted for previous non-arthroplasty surgery, sex, diagnosis, and age.

RESULTS

Revision was performed in 88 shoulders (4.0%), of which 40 (1.8%) underwent revision owing to PJI. There were 272 patients (12.3%) who underwent previous rotator cuff repair, of whom 11 (4.0%) underwent revision owing to PJI. The 14-year cumulative rate of revision owing to PJI was 14.1% for patients with previous rotator cuff repair and 2.7% for patients without previous surgery. The adjusted hazard ratio for revision owing to PJI for patients with previous rotator cuff repair was 2.2 (95% confidence interval, 1.04-4.60) compared with patients without previous surgery.

CONCLUSION

There is an increased risk of revision owing to PJI after RSA for patients with previous rotator cuff repair. We recommend that patients with previous rotator cuff repair be regarded as high-risk patients when considering RSA.

Seasonal variations of the airborne microbial assemblages of the Seoul subway, South Korea from 16S and ITS gene profiles with chemical analysis

In this study, we determined the seasonal airborne microbial diversity profiles at SMRT stations by sequencing the 16S rRNA and ITS. Particulate matter samples were collected from air purifiers installed in the platform area of the SMRT subway stations. Three stations that included the most crowded one were selected for the sampling. The sampling was done at each season during 2019. After extracting the total DNA from all seasonal samples, PCR was performed with Illumina overhang adapter primers for the V3-V4 region of the 16S rRNA gene and ITS2 region of the ITS gene. The amplified products were further purified, and sequencing libraries were made. Sequencing was carried with the Illumina Miseq Sequencing system (Illumina, USA) followed by in-depth diversity analyses. The elemental composition of the particulate matter samples collected from the different subway stations were obtained using a WD-XRF spectrometer. The SMRT microbiome showed extensive taxonomic diversity with the most common bacterial genera at the subway stations associated with the skin. Overall, the stations included in this study harbored different phylogenetic communities based on α- and β-diversity comparisons. Microbial assemblages also varied depending upon the season in which the samples were taken and the station. Major elements present at the subway stations were from aerosols generated between wheels and brake cushions and between the catenaries and the pantographs. This study shows that the microbial composition of the SMRT subway stations comes from a diverse combination of environmental and human sources, the season and the lifestyle of commuters.

Ultrasound evaluations and guided procedures of the painful joint arthroplasty

The purpose of this article is to describe the use of ultrasound for the diagnosis and treatment of painful joint arthroplasty. Ultrasound plays a crucial role in the diagnosis of the painful joint arthroplasty, especially given its unique dynamic capabilities, convenience, and high resolution. Ultrasound guidance is also instrumental for procedures in both diagnosing and in select cases, treating the painful joint arthroplasty. Topics to be discussed in this article include trends in arthroplasty placement, benefits of the use of ultrasound overall, and ultrasound evaluation of periprosthetic joint infections. We will also review the sonographic findings with dissociated/displaced components and adverse reaction to metallic debris including metallosis, trunnionosis, and metal-on-metal pseudotumors. Additionally, we will discuss ultrasound evaluation of tendon pathologies with arthroplasties, including dynamic maneuvers to evaluate for tendon impingement/snapping. Finally, we will cover ultrasound-guided joint arthroplasty injection indications and precautions. KEY POINTS: • Ultrasound is preferred over MRI in patients with joint arthroplasty and plays a crucial role in diagnosis, especially given its unique dynamic capabilities, convenience and high resolution. • It is especially beneficial for US-guided aspiration in periprosthetic joint infections; effectively used to evaluate periprosthetic fluid collections, facilitating differentiation between abscesses and aseptic collections, and tracking sinus tracts. • Recently, the diagnosis of periprosthetic joint infections has shifted focus to biomarkers in the periprosthetic fluid, specifically α-defensin, which has a high sensitivity and specificity for diagnosing infection. • Cutibacterium acnes is a major pathogen responsible for shoulder arthroplasty infections, often presenting with normal laboratory values and since slow growing, must be kept for a minimum of 14 days.

Comparison of two different antiseptics regarding intracutaneous microbial load after preoperative skin cleansing in total knee and hip arthroplasties

Periprosthetic infections (PPIs) are a serious concern in total knee and hip arthroplasty, and they have an increasing incidence. To prevent PPI, preoperative skin disinfection, as a key element of antisepsis, represents an important part of infection prevention. However, no specific antiseptic agent is endorsed by the relevant guidelines. The purpose of this retrospective, not randomized study was to investigate the difference in the residual bacteria load between an approved antiseptic with an alcohol-based solution with additional benzalkonium chloride (BAC) and an alcohol-based solution with additional octenidine dihydrochloride (OCT) at two different time periods. In 200 consecutive patients with total knee or hip arthroplasty, skin samples from the surgical sites were collected after skin disinfection with BAC (100 g solution contain: propan-2-ol 63.0 g, benzalkonium chloride 0.025 g) or OCT (100 g solution contain: octenidine dihydrochloride 0.1 g, propan-1-ol, 30.0 g, propan-2-ol 45.0 g) (100 patients per group). Following the separation of cutis and subcutis and its processing, culture was performed on different agar plates in aerobic and anaerobic environments. In the case of bacteria detection, the microbial identification was determined by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), and the number of contaminated samples was compared between the groups. Additionally, multiple regression analysis was performed to examine the effect of the type of disinfectant, BMI, age, sex, rheumatoid arthritis, diabetes mellitus, skin disorders, smoking status, and localization of skin samples on positive bacteria detection. A total of 34 samples were positive for bacteria in the BAC group, while only 17 samples were positive in the OCT group (p = 0.005). Disinfectant type was the only significant parameter in the multiple regression analysis (p = 0.006). A significantly higher contamination rate of the subcutis was shown in the BAC group compared to the OCT group (19 vs. 9, p = 0,003). After the change from BAC to OCT in preoperative skin cleansing in the hip and knee areas, the number of positive cultures decreased by 50%, which might have been caused by a higher microbicidal activity of OCT. Therefore, the use of OCT in preoperative cleansing may reduce the risk of PPI in hip and knee surgery. Randomized controlled trials are required to confirm the effect and to evaluate if it reduces the risk of PPI.

Efficacy of antimicrobial washes before shoulder surgery against Cutibacterium: a systematic review and meta-analysis

Background

Cutibacterium acnes is a commensal intradermal microorganism that is commonly isolated at revision shoulder arthroplasty. Standard practice chlorhexidine gluconate (CHG) skin preparation agents have limited effectiveness at eradicating C. acnes in the dermis. Benzoyl peroxide (BPO) has demonstrated effectiveness against C. acnes. This meta-analysis compares the efficacy of at-home shoulder decolonization before surgery using CHG vs. BPO to reduce shoulder C. acnes burden.

Methods

This was a Preferred Reporting Items for Systematic Reviews and Meta-Analyses systematic review. PubMed and MEDLINE databases were searched for studies evaluating the effects of CHG and BPO in reducing C. acnes at the shoulder. Trial results were extracted and pooled using a random effects model, separating data from randomized controlled trials (RCTs) and non-RCTs. Methodologic quality of studies was assessed using the Cochrane Risk of Bias Assessment Tools.

Results

Ten studies (589 patients) were included. RCTs showed that both BPO and CHG led to significant reductions in culture positivity compared with negative controls (risk ratio [RR] with 95% confidence interval [CI] = 0.20 [0.13, 0.30], P < .0001 and 0.46 [0.37, 0.57], P < .0001, respectively). Non-RCT data demonstrated similar results comparing BPO and CHG to the control (RR with 95% CI = 0.34 [0.21, 0.57], P < .0001 and 0.31 [0.20, 0.49], P < .0001, respectively). Comparing BPO and CHG, RCT data showed a significant reduction in culture positivity with BPO (RR with 95% CI = 0.46 [0.27, 0.77], P < .009). Of RCTs, 5 were low and one was of moderate risk of bias. Of non-RCTs, 3 had low risk of bias, whereas one had moderate risk of bias.

Conclusion

This review demonstrated that preoperative CHG and BPO can reduce C. acnes at the shoulder. However, BPO exhibits greater efficacy than CHG, potentially because of the compound's ability to penetrate the dermis. BPO is a simple and economical agent that may reduce joint exposure to C. acnes in shoulder surgery.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Fast and Sensitive Multiplex Real-Time Quantitative PCR to Detect Cutibacterium Periprosthetic Joint Infections

Diagnosis of Cutibacterium periprosthetic joint infections (PJIs) is challenging due to a long cultivation time of up to 14 days. Faster culture-independent diagnosis would improve patient care with early and accurate treatment. Specific primers and probes were designed for Cutibacterium acnes, Cutibacterium avidum, and Cutibacterium granulosum and evaluated in a multiplex TaqMan real-time quantitative PCR (qPCR) format on 57 skin swabs and 20 culture-negative cerebrospinal fluid samples. The multiplex qPCR was tested in a PJI cohort of 41 sonication fluid samples from removed implants infected with different pathogens. All five culture-positive Cutibacterium PJIs were detected with the corresponding Cutibacterium-specific probe (100% positive percent agreement). The multiplex qPCR additionally detected C. avidum in two PJI sonication fluid samples that were diagnosed as Staphylococcus species infections according to culture (95% negative percent agreement). The new multiplex qPCR can provide a Cutibacterium PJI diagnosis within 1 day, allowing early and accurate antibiotic treatment. A prospective diagnostic trial in PJI with a high number of Cutibacterium species infections (shoulder PJI) is needed for further evaluation.

Occult clavicle osteomyelitis caused by Cutibacterium acnes (C. acnes) after coracoclavicular ligament reconstruction: A case report and review of the literature

INTRODUCTION

Clavicle osteomyelitis is a rare, but serious complication following operative repair of acromioclavicular (AC) joint separations. Cutibacterium Acnes (C. acnes) is rarely a causative pathogen in clavicle osteomyelitis and diagnosis can be challenging due to the indolent nature of this organism.

CASE PRESENTATION

A 45-50 year old female with a chronic AC joint separation underwent an open coracoclavicular reconstruction using semitendinosus allograft and FiberTape (Arthrex, Naples, FL). At the six month follow up, the patient complained of mild persistent pain. Imaging demonstrated widening of the medial suture tunnel with distal clavicle osteolysis, which was concerning for osteomyelitis. This was successfully treated with implant removal revision surgery and additional intravenous antibiotics. Cultures of the graft material were positive for C. acnes. The patient continued to have osteolysis of the distal left clavicle for a period of time despite resolution of osteomyelitis.

DISCUSSION

C. acnes osteomyelitis of the clavicle is difficult to diagnose because of its vague associated symptoms when implicated in infections. There are no known obvious predisposing factors for C. acnes clavicle osteomyelitis. Literature suggests management should include aggressive irrigation and debridement, removal of any hardware, and extended intravenous antibiotic administration.

CONCLUSION

C. acnes clavicular osteomyelitis is uncommon, thus established treatment guidelines have not yet been formed. Revision surgery to remove graft material, irrigate, and debride in addition to antibiotic treatment was successful for our patient. Additional pathologic manifestations of C. acnes infections could include continued clavicular erosion post-clearance of infection, although further investigation is necessary.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

LEVEL OF EVIDENCE

Level II.

Efficacy of combinational therapy using blue light and benzoyl peroxide in reducing Cutibacterium acnes bioburden at the deltopectoral interval: a randomized controlled trial

BACKGROUND

The purpose of this study was to compare the efficacy of blue light therapy (BLT) and 5% topical benzoyl peroxide (BPO) gel in combination with standard chlorhexidine (CHX) preparation in eradicating Cutibacterium acnes at the deltopectoral interval measured by positive, quantitative culture findings.

METHODS

Adult male volunteers were randomized to 1 of 3 treatment groups: BPO, BLT, and BPO followed by BLT. Contralateral shoulders served as matched controls. Volunteers randomized to BPO applied the gel for a total of 5 treatments. In the BLT group, a single 23-minute treatment was administered at an estimated irradiance of 40 mW/cm² (radiant exposure, 55.2 J/cm²). In the BPO-BLT group, volunteers received both treatments as described earlier. After treatment with either BPO, BLT, or both, a single swab culture was taken from the treatment shoulder. Next, control and treatment shoulders were prepared with CHX, and cultures were taken from each shoulder. Cultures were sent for anaerobic quantitative growth analysis with both polymerase chain reaction and Sanger sequencing confirmation of presumptive C acnes colonies.

RESULTS

This study enrolled 60 male volunteers, 20 per group, with no loss to follow-up. After treatment but prior to CHX administration, all culture samples in the BPO group and BLT group grew C acnes. Prior to CHX, 16 samples (80%) in the BPO-BLT group grew C acnes. On quantitative analysis, the BPO group and BPO-BLT group had significantly less growth of C acnes compared with the BLT group after treatment but prior to CHX (P < .05 for each). Following CHX administration, the BPO and BPO-BLT groups had significantly fewer positive culture findings (odds ratios of 0.03 and 0.29, respectively) and less quantity of growth compared with their control arms (P < .05). This was not seen in the BLT group. For quantitative between-group analysis, no significant synergistic effects were seen with BPO-BLT compared with BPO alone (P = .688). There was no difference in side effects between groups.

CONCLUSION

The combination of topical BPO and CHX was effective at eliminating C acnes in most cases. BLT alone did not demonstrate effective antimicrobial properties against C acnes at the radiant exposure administered in this study. Combining BPO and BLT did not lead to significant synergistic antimicrobial effects. Both BPO and BLT are safe with few, transient side effects reported. More work is needed to determine whether BLT at higher radiant exposures or serial treatment results in bactericidal effects against C acnes in vivo.

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.

One Versus 2-Stage Revision for Shoulder Arthroplasty Infections: A Systematic Review and Analysis of Treatment Selection Bias

BACKGROUND

There is controversy regarding the optimal treatment for infection following shoulder arthroplasty. The purpose of this systematic review is to analyze the bias in treatment selection, infection clearance rates, and functional outcomes after 1 versus 2-stage revision surgery for periprosthetic shoulder infections.

METHODS

A systematic search strategy following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was conducted in 4 phases. Articles were identified using MEDLINE (PubMed), Embase (Elsevier), and Cochrane Library databases with Boolean search terms related to infection after shoulder arthroplasty. Included articles were analyzed for quality, and data were extracted for use. Preoperative treatment selection bias was analyzed and postoperative infection clearance rates and functional outcome scores were compared between 1 and 2-stage revision surgery for periprosthetic shoulder infection.

RESULTS

Overall, 163 1-stage shoulder procedures and 289 2-stage shoulder procedures were included in the analysis. Cutibacterium acnes was the organism most frequently grown on culture (37%) followed by coagulase-negative Staphylococcus (19%). The overall infection clearance rate was 95.6% for 1-stage and 85.2% for 2-stage procedures. In a comparison of the change in outcome scores from preoperatively to postoperatively between 1-stage and 2-stage revision, the Constant-Murley Score (CMS) improved 21.0 points (1-stage) versus 22.8 points (2-stage), the American Shoulder and Elbow Surgeons (ASES) score improved 26.2 points versus 33.6 points, and the Simple Shoulder Test (SST) score improved 3.5 points versus 6.4 points, respectively. Overall, 23 of 26 studies cited a reason for selection of a 1 versus 2-stage procedure, which was due to standard treatment protocol in 10 studies, based on the timing of the infection (acute versus subacute versus chronic) in 5, due to a combination of factors (age, comorbidities, intraoperative appearance, adequacy of debridement, bone loss) in 6, and due to preoperative identification of a specific organism in 2.

CONCLUSIONS

One-stage revisions resulted in higher infection clearance rates; however, 2-stage revisions resulted in greater functional improvement as measured with ASES and SST scores from the preoperative assessment to the final postoperative follow-up. The decision between 1 and 2-stage revisions is due to a combination of factors including pathogen type, timing of infection, findings on the preoperative clinical examination, the patient's own decision, the surgeon's preference, and the intraoperative soft-tissue/osseous appearance, which may have biased the overall results. There is no consensus in the literature on the decision between 1 and 2-stage treatment for periprosthetic shoulder infection, which is based on a combination of factors. However, both treatment strategies are effective in treating periprosthetic shoulder infection.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Acute Propionibacterium acnes Infection After Carpal Tunnel Release

Propionibacterium acnes (P. acnes) is a gram-positive, anaerobic, commensal organism found on nonglabrous skin, including the face, scalp, chest, and axilla. Recently, P. acnes is one of the more frequently recognized organisms causing postoperative infections in implant surgery of the shoulder, second to only Staphylococcus aureus (S. aureus), yet it is a rare postoperative complication of the wrist and hand. Multiple factors, including slow growth, multiorganism involvement, and selective growth media, complicate attributing a primary infection to P. acnes. We present a case of primary, acute P. acnes infection after carpal tunnel decompression, demonstrating the need for considering P. acnes for persistent postoperative hand and wrist infections.

Development of a 3D Bioartificial Shoulder Joint Implant Mimetic of Periprosthetic Joint Infection

Post-surgical infections of the shoulder joint involving Cutibacterium acnes are difficult to diagnose and manage. Despite the devastating clinical complications and costly healthcare burden of joint infections, the scarcity of joint infection models was identified as an unmet need by the 2019 International Consensus on Orthopedic Infections. In this study, we have developed a novel 3D shoulder joint implant mimetic (S-JIM) that includes a surgical metal surface and supports a co-culture of C. acnes and patient-derived shoulder capsule fibroblasts. Our findings indicate the S-JIM can generate a near anaerobic interior environment that allows for C. acnes proliferation and elicit fibroblast cell lysis responses that are consistent with clinical reports of tissue necrosis. Using the S-JIM, we provided proof-of-concept for the use of mass spectrometry in real-time detection of C. acnes joint infections during surgery. The S-JIM is the first in vitro cell culture-based biomimetic of periprosthetic joint infection that provides a preclinical method for the rapid and reliable testing of novel anti-PJI interventions.

Complications Associated With Intravenous Antibiotic Treatment for Cutibacterium acnes Periprosthetic Shoulder Infection

Whether positive Cutibacterium acnes cultures during revision shoulder arthroplasty represent true periprosthetic joint infection (PJI), deep tissue inoculant, or laboratory contaminant is a point of substantial controversy. The purpose of this study was to review complications of intravenous antibiotics used for treatment of presumed C acnes shoulder PJI. A study population of 26 patients treated for C acnes PJI with a minimum follow-up of 2 years after operative treatment was established. Complication occurrence and severity were obtained through chart review and phone survey. Sixteen (61.5%) patients experienced a therapeutic complication. Twelve (46.2%) patients experienced a total of 47 antibiotic-associated adverse effects and 10 (38.5%) patients experienced 11 total peripherally inserted central catheter line-associated complications. Female sex carried an increased risk for severe complications (relative risk, 3.3; 95% CI, 1.2-9.5; P=.024). Treatment duration of greater than 6 weeks was a significant predictor for the total number of complications experienced [F(1,23)=5.361; P=.030; adjusted R²=0.189]. Age older than 65 years, treatment duration greater than 6 weeks, and female sex were significant predictors for the number of severe complications [F(3,21)=3.249; P=.042; adjusted R²=0.219]. Treating C acnes infection with intravenous antibiotics carries a substantial risk of adverse events, highlighting the importance of accurate diagnosis of shoulder PJI. Further investigations into the efficacy and safety profile of oral antibiotics for shoulder PJI are necessary. [Orthopedics. 2021;44(3):e422-e426.].

Clinical and microbiological features of anaerobic implant-related infection in 80 patients after orthopedic surgery

OBJECTIVES

Implant-related infection is a common complication after orthopedic surgery, but there is limited research focused on anaerobic infections. We retrospectively analyzed data from 80 patients with anaerobic implant-related infections in order to investigate the clinical features, bacterial distribution and antimicrobial resistant characteristics of this disease.

METHODS

80 patients who underwent implant-related infections with anaerobes were included. Pathogens were isolated and identified by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry with verification of 16s rRNA sequencing. Antimicrobial susceptibility testing (AST) was performed using Epsilometric test (E-test).

RESULTS

Among the 80 patients, 61.2% (49/80) were infected with anaerobes alone, while 38.8% (31/80) were co-infected with anaerobes and other bacteria. Early infection cases involving anaerobe-alone infections were significantly higher compared to the co-infection group (P < 0.001), also exhibiting lower levels of neutrophils (P = 0.033) and ESR (P = 0.046). Anaerobe-alone infections in the prosthetic joint infection group represented a higher proportion compared with other implant-related infections (P = 0.031). Among all species of anaerobes identified, the top 3 were Cutibacterium acnes, Finegoldia magna and Peptostreptococcus anaerobius. Low MIC values to vancomycin was recorded in C. acnes strains and for amoxicillin/clavulanic acid and piperacillin/tazobactam in most F. magna strains. One of the C. acnes and F. magna strains appeared multi-drug resistant except to vancomycin.

CONCLUSIONS

Anaerobe-alone infections have later first onset times and lower infection biomarker levels compared to co-infected patients. The first choice against C. acnes is vancomycin, while amoxicillin/clavulanic acid and piperacillin/tazobactam are recommended for F. magna.

Cutibacterium acnes as an Opportunistic Pathogen: An Update of Its Virulence-Associated Factors

Cutibacterium acnes is a member of the skin microbiota found predominantly in regions rich in sebaceous glands. It is involved in maintaining healthy skin and has long been considered a commensal bacterium. Its involvement in various infections has led to its emergence as an opportunist pathogen. Interactions between C. acnes and the human host, including the human skin microbiota, promote the selection of C. acnes strains capable of producing several virulence factors that increase inflammatory capability. This pathogenic property may be related to many infectious mechanisms, such as an ability to form biofilms and the expression of putative virulence factors capable of triggering host immune responses or enabling C. acnes to adapt to its environment. During the past decade, many studies have identified and characterized several putative virulence factors potentially involved in the pathogenicity of this bacterium. These virulence factors are involved in bacterial attachment to target cells, polysaccharide-based biofilm synthesis, molecular structures mediating inflammation, and the enzymatic degradation of host tissues. C. acnes, like other skin-associated bacteria, can colonize various ecological niches other than skin. It produces several proteins or glycoproteins that could be considered to be active virulence factors, enabling the bacterium to adapt to the lipophilic environment of the pilosebaceous unit of the skin, but also to the various organs it colonizes. In this review, we summarize current knowledge concerning characterized C. acnes virulence factors and their possible implication in the pathogenicity of C. acnes.

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.

Longitudinal time-lapse in vivo micro-CT reveals differential patterns of peri-implant bone changes after subclinical bacterial infection in a rat model

Subclinical infection associated with orthopedic devices can be challenging to diagnose. The goal of this study was to evaluate longitudinal, microcomputed tomography (microCT) imaging in a rat model of subclinical orthopedic device-related infection caused by Staphylococcus epidermidis and four different Cutibacterium (previously Propionibacterium) acnes strains, and compare outcomes with non-inoculated and historical S. aureus-inoculated controls. Sterile screws or screws colonized with bacteria were placed in the tibia of 38 adult Wistar rats [n = 6 sterile screws; n = 6 S. epidermidis-colonized screws; n = 26 C. acnes-colonized screws (covering all three main subspecies)]. Regular microCT scans were taken over 28 days and processed for quantitative time-lapse imaging with dynamic histomorphometry. At euthanasia, tissues were processed for semiquantitative histopathology or quantitative bacteriology. All rats receiving sterile screws were culture-negative at euthanasia and displayed progressive bony encapsulation of the screw. All rats inoculated with S. epidermidis-colonized screws were culture-positive and displayed minor changes in peri-implant bone, characteristic of subclinical infection. Five of the 17 rats in the C. acnes inoculated group were culture positive at euthanasia and displayed bone changes at the interface of the screw and bone, but not deeper in the peri-implant bone. Dynamic histomorphometry revealed significant differences in osseointegration, bone remodeling and periosteal reactions between groups that were not measurable by visual observation of still microCT images. Our study illustrates the added value of merging 3D microCT data from subsequent timepoints and producing inherently richer 4D data for the detection and characterization of subclinical orthopedic infections, whilst also reducing animal use.

Cutibacterium acnes Infection Induces Type I Interferon Synthesis Through the cGAS-STING Pathway

Cutibacterium (previously Propionibacterium) acnes is an anaerobic, Gram-positive commensal of the human body. The bacterium has been associated with a variety of diseases, including acne vulgaris, prosthetic joint infections, prostate cancer, and sarcoidosis. The accumulation of C. acnes in diseases such as acne and prostate cancer has been shown to correlate with enhanced inflammation. While the C. acnes-induced proinflammatory axis, via NF-κB and MAPK signaling and inflammasome activation, has been investigated over the last few decades, the potential role of C. acnes in triggering the type I interferon (IFN-I) pathway has not been addressed. Our results show that C. acnes induces the IFN-I signaling axis in human macrophages by triggering the cGAS-STING pathway. In addition, IFN-I signaling induced by C. acnes strongly depends on the adapter protein TRIF in a non-canonical manner; these signaling events occurred in the absence of any detectable intracellular replication of the bacterium. Collectively, our results provide important insight into C. acnes-induced intracellular signaling cascades in human macrophages and suggest IFN-I as a factor in the etiology of C. acnes-induced diseases. This knowledge may be valuable for developing novel therapies targeting C. acnes in diseases where the accumulation of the bacterium leads to an inflammatory pathology.

Risk factors for increased shoulder Cutibacterium acnes burden

Background

Cutibacterium acnes is the primary cause of shoulder surgery infections, but the predisposition to larger skin counts and potentially higher risk for postoperative infection remains unclear. This study aimed to quantify risk factors influencing endogenous C. acnes burden and to compare counts among 4 shoulder sites.

Methods

C. acnes counts were quantified via a detergent scrub technique for 173 participants. Bivariate and multivariable stepwise linear regression statistical analyses were used to investigate the association of sex, age, ethnicity, degree of hirsutism, diabetes, smoking status, body mass index, and location with counts. A separate Wilcoxon rank-sum test was performed analyzing counts of East/Southeast Asians vs. all other ethnicities.

Results

Sex, age, degree of hirsutism, diabetes, smoking status, and body mass index were included in the multivariable stepwise linear regression analysis. The multiple regression analysis isolated individuals <40 years with the highest burden (P = .001). Males had a 191% increase in C. acnes counts compared with females (P = .001). Increased hirsutism was further indicated to be a risk factor for the male sex although not in a dose-dependent manner (P = .027). Wilcoxon rank-sum test results found that East/Southeast Asians had the lowest load (P = .019), although not significant in the multivariate model.

Conclusion

Surgical site C. acnes infections occur more frequently in younger males, and males <40 years with shoulder-specific hirsutism have the highest preoperative burden. East/Southeast Asians have lower raw counts of C. acnes compared with other ethnicities that may be related to less hirsutism.

Effect of Blue Light and Photosensitizers on Cutibacterium acnes on Shoulder Periprosthetic Joint Infection Isolates

Introduction:Cutibacterium acnes is gaining recognition as a leading pathogen after orthopaedic shoulder procedures. Photodynamic therapy, a combination of light and a photosensitizer, has demonstrated antimicrobial activity against C. acnes in the treatment of acne vulgaris. We sought to evaluate the effect of photodynamic therapy using blue light and photosensitizers on C. acnes isolates from shoulder prosthetic joint infections.

Methods:C. acnes strains isolated from 19 patients with shoulder PJI were exposed to blue light alone (415 nm) or in combination with photosensitizers (fluorescein, riboflavin and demeclocycline). C. acnes strains were divided into 4 categories: Highly Sensitive (HS), Sensitive (S), Weakly Sensitive (WS), Resistant to blue light.

Results: 13 of 19 C. acnes strains (68%) were S or HS to blue light alone. Of these 19 strains tested, 11 were tested with blue light and fluorescein or blue light plus riboflavin. Fluorescein (1 µg/mL) enhanced the effect of blue light in 6 of 11 strains (55%). Blue light plus riboflavin (10 µg/mL) resulted enhanced killing in 3 of 11 strains (27%), but produced a paradoxical photoprotective effect in 4 of 11 strains (36%), resulting in a net decrease compared to blue light alone. Demeclocycline, however, enhanced the effect of blue light in 16 of 17 strains (94 %).

Conclusions: Blue light with the addition of photosensitizers killed C. acnes from periprosthetic shoulder infections in vitro, with demeclocycline having the most pronounced effect.

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.

Exploring Penicillin G as an Intrawound Antibiotic Powder for Prevention of Postoperative Shoulder Infections: Does It Exhibit In Vitro Chondrotoxicity?

Cutibacterium acnes (C. acnes) is a significant insidious pathogen for postoperative infections in shoulder surgery. Studies have demonstrated that certain topical antibiotic powders used have the potential for chondrotoxicity. Benzylpenicillin, commonly referred to as Penicillin G (Pen G) has the lowest minimum inhibitory concentration (MIC) for C. acnes. There is no research regarding the topical application of Pen G during shoulder surgery, nor has its chondrocyte toxicity been previously investigated. This study sought to characterize the in vitro chondrocyte toxicity of Pen G. Culture-derived bovine chondrocytes were exposed to serial Pen G concentrations and compared with a positive and negative control. A negative control of growth medium and positive control of 1% Triton solution. The chondrocyte viability was assessed via spectrophotometer absorbance. The treatment groups were analyzed using one-way repeated measures analysis of variance and Pearson's correlation analysis. The chondrocyte viability was significantly higher for all Pen G concentrations as compared with the positive control (p < 0.001). All concentrations of Pen G exhibited continued chondrocyte metabolic activity over time. Analysis of variance, independent of time, demonstrated no significant decrease in chondrocyte viability for Pen G concentrations ≤6.25 mg/ml, as compared with the negative control (p > 0.05). Pen G demonstrated a significant negative correlation with its concentration and absorbance (r = 0.371, p < 0.001), however, concentrations ≤6.25 mg/ml did not demonstrate a significant decrease in chondrocyte viability (p = 0.063). Pen G in concentrations appropriate for C. acnes is not significantly chondrotoxic and may be safe for intrawound application. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:726-730, 2020.

Cutibacterium acnes (formerly Proprionibacterium acnes) and Shoulder Surgery

Infection is a rare but serious complication of shoulder arthroplasty. The most prevalent cause of patient infections is Cutibacterium acnes (formerly Proprionibacterium acnes), a commensal skin bacterial species. Its presentation is often non-specific and can occur long after shoulder arthroplasty, leading to delay in diagnosis. This bacterium is difficult to culture, typically taking 14 to 17 days for a positive culture and often does not exhibit abnormal results on a standard laboratory workup for infection (eg, ESR, CRP, and synovial WBC count). Male patients are at particularly high-risk due to having a greater number of sebaceous follicles than females. While it is difficult to diagnose, early diagnosis can lead to decreased morbidity, appropriate treatment, and improved clinical outcomes. Current options for treatment include antibiotics, one stage implant exchange, or two stage implant exchange, although success rates of each are not currently well described. A better understanding of the prevention, diagnosis, and treatment of C. acnes infection could lead to better patient outcomes from shoulder arthroplasty.

Arthroscopy of the symptomatic shoulder arthroplasty

BACKGROUND

Assessment of a painful or stiff shoulder arthroplasty can be challenging. The cause of pain can sometimes be easily identified. However, some patients have normal levels of inflammatory markers, normal plain films, and no clinical signs to indicate a diagnosis. Indolent organisms may not raise blood marker levels or result in obvious radiologic findings such as loosening. We report the utility of performing arthroscopy in these patients for a diagnostic advantage.

METHODS

We retrospectively reviewed the health records of all patients who underwent diagnostic shoulder arthroscopy over a 3-year period. Patients were included if they were aged 18 years or older, had undergone previous arthroplasty surgery, and had symptoms of shoulder pain or stiffness. Patients were excluded if they had any traditional symptoms of infection or had a raised serum white cell count or C-reactive protein level prior to diagnostic arthroscopy.

RESULTS

Fourteen patients met the initial inclusion criteria. The mean interval between index surgery and arthroscopic evaluation was 65.4 months (standard deviation, 58 months; range, 17-192 months). Arthroscopic biopsy specimens returned positive culture results in 3 patients (21%). Rotator cuff tears were noted in 8 patients (57%). Capsular contraction requiring release was noted in 2 patients (10%). In all patients, the diagnostic arthroscopy directed the next stage of management.

CONCLUSIONS

Diagnostic arthroscopy allows a full assessment of implants, the rotator cuff, the native articular surfaces, and scar tissue, as well as biopsy specimens to be obtained for indolent infection, in patients considering revision arthroplasty surgery. This allows a more informative consent process for patients, directs surgical management, and on occasion, allows for therapeutic intervention in a painful or stiff shoulder arthroplasty.

Indolent Propionibacterium acnes infection associated with orthopedic hardware in the ankle: A case report and literature review

Propionibacterium acnes (P. acnes) infections of the foot and ankle are very rare and require a unique approach to prevention, diagnosis, and treatment. Clinicians should consider P. acnes as a cause for all late and indolent orthopedic infections, as appropriate surgical and medical management can result in a good outcome.

Cutibacterium acnes (formerly Propionibacterium acnes) isolated from prosthetic joint infections is less susceptible to oxacillin than to benzylpenicillin

Introduction: The frequency of prosthetic joint infections (PJIs) due to Cutibacterium acnes (formerly Propionibacterium acnes) is increasing, especially shoulder PJIs. The recommended antibiotic prophylaxis for hip and knee arthroplasties is beta-lactam antibiotics, predominantly cephalosporins. However, for example in Sweden, isoxazolyl-penicillin cloxacillin is used. No specific recommendations for shoulder arthroplasties are available. The aim of the present study was to determine the minimum inhibitory concentration (MIC) values for different antibiotics for C. acnes; and, more specifically, to compare the MIC values for benzylpenicillin and oxacillin. Materials and methods: Minimum inhibitory concentration (MIC) values for nine different antibiotic agents were obtained by gradient test (Etest) using strains of C. acnes (n= 57) isolated from PJIs from shoulders (n=31), hips (n=21), and knees (n=5). Results: All isolates had low MIC values for most of the tested antibiotic agents, and showed a wild type MIC distribution. The exception was clindamycin with 9% of the isolates displaying decreased susceptibility. The MIC values obtained for benzylpenicillin were significantly lower than the MIC values for isoxazolyl-penicillin (oxacillin). Conclusion: These in vitro results indicate that benzylpenicillin might be a more effective prophylactic treatment to prevent shoulder PJIs caused by C. acnes. However, further studies on the subject are needed, and the effectiveness of the prophylactic treatment should be evaluated using randomized controlled studies and/or register-based studies.

Polymicrobial anaerobic infection with a deep abscess in the supraspinous fossa following a subacromial corticosteroid injection

In September 2015, a male aged 61 years with poorly controlled diabetes (his only medical problem) had left shoulder surgery that included an arthroscopic acromioplasty with debridement of suture material from a rotator cuff repair done 10 years prior. A subacromial corticosteroid injection was given 7 months later for pain and reduced motion. Three weeks later a fulminate infection was evident. Cultures grew Propionibacterium acnes. Treatment included two arthroscopic debridement surgeries and 8 weeks of intravenous antibiotics (primarily daptomycin). Eight weeks after the cessation of the antibiotics, purulence recurred and tissue cultures then grew Staphylococcus epidermidis. Several additional surgeries were needed to control the infection. We failed to recognise that an abscess that extended from the subacromial space across the entire supraspinous fossa. We report this case to alert clinicians that a seemingly innocuous subacromial corticosteroid injection can lead to an atypical infection and also extend into the supraspinous fossa.

Growth of Cutibacterium acnes is common on osteosynthesis material of the shoulder in patients without signs of infection

Background and purpose - Cutibacterium acnes, formerly known as Propionibacterium acnes, is often isolated from deep tissues of the shoulder. It is recognized as an important causative agent of foreign-material associated infections. However, the incidence and significance of its detection in tissues from patients without clinical evidence for infection is unclear. We assessed the incidence of C. acnes colonization of osteosynthesis material in asymptomatic patients, and evaluated the short-term outcome in relation to the microbiological findings. Patients and methods - We microbiologically analyzed osteosynthesis material of 34 asymptomatic patients after surgery on the clavicle. Material obtained from 19 asymptomatic patients after osteosynthesis of the fibula served as a control group. Patients were clinically followed up for 3-24 months after removal of the osteosynthesis material. Results - Bacteria were recovered from devices in 29 of 34 patients from the clavicle group. 27 of 29 positive samples grew C. acnes. Isolation of C. acnes was more common in male than in female patients. No bacterial growth was observed on foreign material from patients in the fibula group. All patients remained asymptomatic at follow-up. Interpretation - Growth of C. acnes is common on osteosynthesis material of the shoulder, especially in males. Samples were positive irrespective of clinical signs of infection. Therefore, detection of C. acnes in this clinical setting is of questionable clinical significance. The high positivity rate in asymptomatic patients discourages routine sampling of material in cases without clinical evidence for infection.

Superior Capsular Release After Failed Combined Superior Labral Repair And Biceps Tenodesis For Slap Tear

Introduction:

Optimal treatment of type II superior labrum anterior and posterior (SLAP) tears is controversial. There has been a recent trend towards biceps tenodesis over SLAP repair in older patients. Few surgeons have performed combined biceps tenodesis and SLAP repair with inferior results.

Case Report:

This case describes a 46-year-old patient who had persistent pain and stiffness after combined biceps tenodesis and SLAP repair for a type II SLAP tear. His pain and motion improved after arthroscopic superior capsular release.

Conclusion:

Failed SLAP repair is often multifactorial and a thorough workup is needed. Combined biceps tenodesis and SLAP repair can cause pain, stiffness, and dysfunction which can be successfully treated with arthroscopic superior capsular release.

Orthopedic implant-associated infections caused by Cutibacterium spp. - A remaining diagnostic challenge

Background

The definition criteria and clinical characteristics of implant-associated infection (IAI) caused by Cutibacterium (formerly Propionibacterium) spp. are poorly known. We analyzed microbiologically proven Cutibacterium orthopedic IAI in a prospective cohort.

Methods

Patients with periprosthetic joint infections (PJI) and fixation device–associated infections (FDAI) caused by Cutibacterium spp. were prospectively included. IAI was defined by significant growth of Cutibacterium spp. and presence of at least one non-microbiological criterion for infection. The McNemar’s chi-squared or binomial test was used to compare the performance of diagnostic tests.

Results

Of 121 patients with Cutibacterium IAI, 62 patients (51%) had PJI and 59 (49%) had FDAI. 109 infections (90%) were caused by C. acnes and 12 (10%) by C. avidum. The median time from implantation until diagnosis of infection was 15.7 months (interquartile range, 5–46.5 months). Clinical local signs were present in 30 patients (28%) and radiological implant loosening in 64 patients (63%). Culture sensitivity of sonication fluid was 84%, of peri-implant tissue 84% and of synovial or peri-implant fluid 56% after 14 days of incubation.

Conclusion

Cutibacterium IAI was diagnosed late in the disease course and presented with subtle signs. Prolonged culture incubation and implant sonication improved the poor performance of conventional microbiological tests. Due to lack of reliable diagnostic tests, Cutibacterium remains difficult to detect making the diagnosis challenging.

Presence of Bacteria in Spontaneous Achilles Tendon Ruptures

BACKGROUND

The structural pathology of Achilles tendon (AT) ruptures resembles tendinopathy, but the causes remain unknown. Recently, a number of diseases were found to be attributed to bacterial infections, resulting in low-grade inflammation and progressive matrix disturbance. The authors speculate that spontaneous AT ruptures may also be influenced by the presence of bacteria.

HYPOTHESIS

Bacteria are present in ruptured ATs but not in healthy tendons.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Patients with spontaneous AT ruptures and patients undergoing anterior cruciate ligament (ACL) reconstruction were recruited for this study. During AT surgical repair, excised tendinopathic tissue was collected, and healthy tendon samples were obtained as controls from hamstring tendon grafts used in ACL reconstruction. Half of every sample was reserved for DNA extraction and the other half for histology. Polymerase chain reaction (PCR) was conducted using 16S rRNA gene universal primers, and the PCR products were sequenced for the identification of bacterial species. A histological examination was performed to compare tendinopathic changes in the case and control samples.

RESULTS

Five of 20 AT rupture samples were positive for the presence of bacterial DNA, while none of the 23 hamstring tendon samples were positive. Sterile operating and experimental conditions and tests on samples, controlling for harvesting and processing procedures, ruled out the chance of postoperative bacterial contamination. The species identified predominantly belonged to the Staphylococcus genus. AT rupture samples exhibited histopathological features characteristic of tendinopathy, and most healthy hamstring tendon samples displayed normal tendon features. There were no apparent differences in histopathology between the bacterial DNA-positive and bacterial DNA-negative AT rupture samples.

CONCLUSION

The authors have demonstrated the presence of bacterial DNA in ruptured AT samples. It may suggest the potential involvement of bacteria in spontaneous AT ruptures.

Prevalence of Propionibacterium acnes in Intervertebral Discs of Patients Undergoing Lumbar Microdiscectomy: A Prospective Cross-Sectional Study

Background

The relationship between intervertebral disc degeneration and chronic infection by Propionibacterium acnes is controversial with contradictory evidence available in the literature. Previous studies investigating these relationships were under-powered and fraught with methodical differences; moreover, they have not taken into consideration P. acnes’ ability to form biofilms or attempted to quantitate the bioburden with regard to determining bacterial counts/genome equivalents as criteria to differentiate true infection from contamination. The aim of this prospective cross-sectional study was to determine the prevalence of P. acnes in patients undergoing lumbar disc microdiscectomy.

Methods and Findings

The sample consisted of 290 adult patients undergoing lumbar microdiscectomy for symptomatic lumbar disc herniation. An intraoperative biopsy and pre-operative clinical data were taken in all cases. One biopsy fragment was homogenized and used for quantitative anaerobic culture and a second was frozen and used for real-time PCR-based quantification of P. acnes genomes. P. acnes was identified in 115 cases (40%), coagulase-negative staphylococci in 31 cases (11%) and alpha-hemolytic streptococci in 8 cases (3%). P. acnes counts ranged from 100 to 9000 CFU/ml with a median of 400 CFU/ml. The prevalence of intervertebral discs with abundant P. acnes (≥ 1x10³ CFU/ml) was 11% (39 cases). There was significant correlation between the bacterial counts obtained by culture and the number of P. acnes genomes detected by real-time PCR (r = 0.4363, p<0.0001).

Conclusions

In a large series of patients, the prevalence of discs with abundant P. acnes was 11%. We believe, disc tissue homogenization releases P. acnes from the biofilm so that they can then potentially be cultured, reducing the rate of false-negative cultures. Further, quantification study revealing significant bioburden based on both culture and real-time PCR minimize the likelihood that observed findings are due to contamination and supports the hypothesis P. acnes acts as a pathogen in these cases of degenerative disc disease.

Incidence of Propionibacterium acnes in initially culture-negative thioglycollate broths-a prospective cohort study at a Danish University Hospital

The aim of this study was to prospectively investigate the incidence of Propionibacterium acnes in thioglycollate broths reported as culture-negative at the Department of Clinical Microbiology, Rigshospitalet, to evaluate whether 5 days of incubation was enough to find all relevant cases. Five hundred thioglycollate broths reported as culture-negative after 5 days were consecutively collected and incubated for at least a further 9 days (at least 14 days of incubation in total). Only tissue samples from sterile sites of the body (n = 298), bone tissue (n = 197) and foreign material (n = 5) were included in this study. Samples were divided into two groups: infected group and control group. This made it possible to compare findings between groups, thereby making it possible to estimate the level of true-positive findings and contamination. Samples from 296 participants were included in this study. After exclusion criteria were met, P. acnes was cultured from ten out of 151 patients (6.6%) in the infected group and from one out of 138 participants (0.7%) in the control group. This resulted in more findings of P. acnes in the infected group on day 14 than on day 5 (p 0.002). Furthermore, P. acnes was cultured more often from bone tissue and tissue surrounding foreign materials on day 14 than on day 5 (p 0.04). Clinical microbiology laboratories should consider incubating thioglycollate broths for at least 14 days to find all relevant cases of P. acnes, especially when it comes to bone tissue and tissue surrounding foreign materials.