Propionibacterium can be isolated from deep cultures obtained at primary arthroplasty despite intravenous antimicrobial prophylaxis

Unexpected positive cultures of humeral head detected with dithiothreitol in primary shoulder arthroplasty

BACKGROUND

Unexpected positive cultures (UPCs) are frequently observed in primary shoulder arthroplasty, and its clinical significance has not yet been well defined. This study aimed to evaluate the UPCs in humeral head in primary shoulder replacement and to understand if UPCs increase in patients with risk factors for contamination (previous surgery or infiltrations).

METHODS

Patients undergoing total shoulder replacement were enrolled in this prospective observational study. To reduce the risk of humeral head contamination, all known procedures to reduce Cutibacterium acnes burden of the skin were implemented. Patients were divided into 2 groups, namely, patients who had undergone previous rotator cuff repair or infiltration and patients with no risk factors for contamination. All the humeral heads harvested were treated with dl-dithiothreitol, in a specific device (MicroDTTect), to increase the sensitivity of the cultures for bacterial identification. The cultures were analyzed for aerobic and anaerobic bacteria for up to 14 days.

RESULTS

The UPCs' positivity rate of the 80 patients in the study was 19% (15 patients). The positivity rates for UPCs in the group with and without risk factors were 30% (12 patients) and 7.5% (3 patients), respectively. The rate of positive culture was higher in men (87%) than in women (13%). The observed positivity was due to C acnes and Peptoniphilus asaccharolyticus, both slow-growing anaerobes.

CONCLUSIONS

Patients with previous surgery or infiltrations had a 4-fold higher rate of positivity for UPCs compared with patients without previous risk factors. The higher percentage of positivity in patients with risk factors could be related to changes in the joint microenvironment after shoulder procedures. We do not know whether the presence of UPCs could be associated with the development of periprosthetic infections at longer follow-up.

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.

Preventing Infections in Reverse Shoulder Arthroplasty

PURPOSE OF REVIEW

Reverse shoulder arthroplasty (rTSA) is a commonly performed procedure to treat degenerative conditions of the shoulder. With its growing utilization, techniques to reliably diagnose and treat prosthetic joint infection (PJI) have become increasingly important. In this review we outline the current research and prevention methods of prosthetic joint infection in rTSA. This includes preoperative considerations, intraoperative, and postoperative treatment algorithms.

RECENT FINDINGS

There is currently no established standardized protocol for preoperative infection prevention or post operative management. However, recent studies have identified risk factors for infection, as well as successful prevention techniques that can be implemented to minimize infection risk. Although there is no standardized protocol currently utilized to diagnose and treat shoulder PJI, we outline a potential set of preventative measures and postoperative management strategies that clinicians can use to properly diagnose and treat patients with this difficult condition.

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).

Are Cutibacterium acnes delivered from skin to deep tissues in primary reverse shoulder arthroplasty? A prospective study

INTRODUCTION

The objective of this study is to determine whether the deep tissues are inoculated during surgery with the Cutibacterium acnes still present in the skin after the surgical preparation in reverse shoulder arthroplasties.

MATERIALS AND METHODS

Prospective study including patients undergoing surgery with reverse shoulder arthroplasty. All the patients received preoperative antibiotic prophylaxis with cefazolin (2 g IV) and the skin was prepared with 2% chlorhexidine gluconate and 70% isopropyl alcohol. From all the patients, 9 cultures were obtained after the antibiotic was administrated and the skin surgically prepared. The cultures were sent to isolate C. acnes. DNA was extracted from the C. acnes isolated colonies. Isolate nucleotide distances were calculated using the Genome-based distance matrix calculator from the Enveomics collection toolbox.

RESULTS

The study included 90 patients. C. acnes was isolated in 24 patients (26.6%) with a total of 61 positive cultures. There were 12 phylotype II, 27 IB and 22 IA. In 9 patients, C. acnes was present in both skin and deep tissues, and they constituted the sample to be studied by means of genomic analysis. In 7 out of the 9 patients, deep tissue samples clustered closer to at least one of its corresponding skin isolates when compared to the other independent bacterial ones.

CONCLUSIONS

The C. acnes present in the skin at the beginning of the surgery are the same as those found in the deep tissues at the end of the surgery. This result strengthens the possibility that the C. acnes is delivered from the skin to the deep tissues.

Effect of making skin incision with electrocautery on positive Cutibacterium acnes culture rates in shoulder arthroplasty: a prospective randomized clinical trial

BACKGROUND

Cutibacterium acnes remains the most commonly detected organism in shoulder arthroplasty. C acnes infection is thought to occur during shoulder arthroplasty through contamination of the surgical field with C acnes from the incised dermis. The purpose of this study was to examine whether using electrocautery for making skin incisions would decrease C acnes culture rates at the incised dermis compared to using scalpels during shoulder arthroplasty.

METHODS

Patients undergoing primary shoulder arthroplasty were randomized into 2 groups, electrocautery vs. scalpel incision group. All patients received a standard preoperative antiseptic preparation including chlorhexidine gluconate showers, intravenous antibiotic administration, and topical application of hydrogen peroxide, povidone iodine, isopropyl alcohol, and DuraPrep. Cultures were obtained from the incised dermal edge immediately after skin incision and later from surgeon's gloves and forceps immediately prior to humeral component implantation. The primary outcome was positive C acnes culture rates compared between the groups.

RESULTS

A total of 64 patients (32 in each group) were enrolled. There were 24 males in each group. Regarding dermis cultures, 10 patients (31%) in the scalpel group were positive with 8 of them positive for C acnes, whereas no patients in the electrocautery group were positive (P < .001). Regarding glove cultures, the electrocautery group had 8 patients positive C acnes, while the scalpel group had 8 (P = .777). Regarding forceps cultures, the electrocautery group had 4 patients positive for C acnes, and the scalpel group had 6 (P = .491). All positive cultures were exclusively from male patients. There were no wound complications or infection in the electrocautery group while the scalpel group had 1 acute postoperative infection.

CONCLUSIONS

Making skin incisions using electrocautery resulted in 0 C acnes culture at the incised dermis, suggesting its potential effect against C acnes. However, despite this initial antibacterial effect, C acnes still appeared on surgeon's gloves and forceps during surgery of male patients. All positive cultures were from male patients, suggesting that the source of C acnes was specifically related to the male body. While the study hypothesis was supported by the results, the present study also raises new questions and calls for further research.

Functional outcomes and complications of patients contaminated with Cutibacterium acnes during primary reverse shoulder arthroplasty: study at two- and five-years of follow-up

PURPOSE

The objective of the study was to compare the functional outcomes and the complication rate of the patients with C. acnes contamination at the end of the primary reverse shoulder arthroplasty (RSA) surgery to those patients without C. acnes contamination.

METHOD

A total of 162 patients were included. In all cases, skin and deep tissue cultures were obtained. A molecular typing characterization of the C. acnes strains was performed. Functional outcomes were assessed with the Constant score at the two and five year follow-up and all complications were also recorded.

RESULTS

A total of 1380 cultures were obtained from the 162 primary RSA surgeries. Of those, 96 turned out to be positive for C. acnes. There were 25 patients with positive cultures for C. acnes. The overall postoperative Constant score was not significantly different between those patients having C. acnes-positive cultures and those with negative cultures at the two and five year follow-up (59.2 vs. 59.6 at two years, p 0.870, and 59.5 vs. 62.4 at five years, p 0.360). Patients with positive cultures presented a higher complication rate (p 0.001) with two infections, one revision surgery, and one dislocation.

CONCLUSION

Patients ending up with C. acnes-positive cultures after primary shoulder arthroplasty surgery do not have worse clinical outcomes when compared to patients having negative cultures, but a greater number of complications were found in those patients with C. acnes-positive cultures.

Intraoperative Intra-articular Antibiotic Injection Reduces Infection in Shoulder Arthroplasty

Deep infection is a debilitating complication after shoulder arthroplasty. The authors hypothesized that an intra-articular, intraoperative injection of antibiotics would result in a lower infection rate compared with intravenous antibiotics alone. Before 2007, 164 patients (group A) did not receive intra-articular antibiotics. From 2007 to 2018, 1324 patients (group B) received intra-articular antibiotics. Patients received intra-articular gentamicin at the end of surgery with the addition of 1 g of cefazolin in January 2014. Records were retrospectively reviewed for comorbidities, type of surgery, and infection. The cohort that received intra-articular antibiotics was compared with the cohort that did not to determine the effect of prophylactic intra-articular antibiotic administration in preventing infection. There was 1 deep infection in the antibiotic group compared with 5 in the non-antibiotic group (P<.001). Superficial infections developed in 2 cases of patients treated with antibiotics; there were no superficial infections in patients treated without antibiotics (P=.62). One previous study evaluated intra-articular injection of antibiotics for shoulder arthroplasty and found significantly lower rates of infection with the injection of intra-articular gentamicin. In this retrospective follow-up study, the injection of intra-articular gentamicin or gentamicin and cefazolin effectively decreased rates of postoperative infection. At mean follow-up of 399 days, intra-articular antibiotics at the time of surgery resulted in significantly fewer deep infections. Given the minimal risk of adverse events and minimal cost, this is a valid method of reducing infections in total shoulder arthroplasty. [Orthopedics. 2023;46(5):310-314.].

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

The Choice of Antibiotic Prophylaxis Influences the Infection Reoperation Rate in Primary Shoulder Arthroplasty: Analysis From the Swedish Shoulder Arthroplasty Register

BACKGROUND

Periprosthetic joint infection is a serious complication and a major reason for revision surgery after primary shoulder arthroplasty. The prophylactic antibiotics for primary shoulder arthroplasty that have predominantly been used in Sweden are cloxacillin and clindamycin. To address Cutibacteriumacnes , benzylpenicillin has recently increasingly been added to cloxacillin, but it is unclear which antibiotic prophylaxis regimen is the most effective to prevent periprosthetic joint infection.

QUESTIONS/PURPOSES

After controlling for baseline differences among patients such as age, gender, previous surgery, cement fixation, and arthroplasty type, was the risk of reoperation for infection higher in patients who received cloxacillin than in those who received clindamycin or the combination of benzylpenicillin and cloxacillin?

METHODS

Data from the Swedish Shoulder Arthroplasty Register were used for this study. The inclusion criterion was registered antibiotic prophylaxis in primary arthroplasty. Between January 1, 1999, and December 31, 2019, 22,470 primary shoulder arthroplasties, including total shoulder, hemiarthroplasty, and reverse shoulder arthroplasties, were entered into the Swedish Shoulder Arthroplasty Register. Reporting of antibiotic prophylaxis to the register was introduced on January 1, 2013. Since then, the completeness of information on the type of antibiotic prophylaxis in the reports has been 85.3%. Consequently, 10,706 arthroplasties were eligible and fulfilled the inclusion criterion of reported antibiotic prophylaxis. A further 129 were excluded because of unusual prophylaxis regimens, leaving 10,577 shoulder arthroplasties for analysis. The Swedish Shoulder Arthroplasty Register gathers information from all 60 hospitals performing shoulder arthroplasty in Sweden, and through a comparison with the National Patient Register, it has been estimated that more than 90% of all primary shoulder arthroplasties and shoulder reoperations are reported to the register. The age of the study population ranged between 16 and 98 years; the mean age at the primary surgery was 70 ± 10 years for the entire cohort, with a mean age of 67 ± 10 years and 72 ± 9 years for men and women, respectively. The mean observation period was 989 ± 669 days. From 2013 to 2019, there was a clear change in prophylaxis; in particular, the use of the combination of benzylpenicillin and cloxacillin increased dramatically and the use of cloxacillin alone decreased. Clindamycin prophylaxis increased moderately. The primary study endpoint was reported reoperation for infection. In the register, this is defined as repeat procedures of any kind, including biopsy, lavage of the joint, or revision, defined as secondary surgery in which a component was exchanged, removed, or added. To compare the reoperation rate in relation to the different antibiotics used, which changed over time, we controlled for age, gender, previous surgery, cement fixation, and arthroplasty type using a Cox proportional hazards model.

RESULTS

When adjusting for age, gender, previous surgery, cement fixation, and arthroplasty type, cloxacillin prophylaxis was associated with an increased relative risk of reoperation for infection compared with the combination of cloxacillin and benzylpenicillin (hazard ratio [HR] 2.40 [95% confidence interval (CI) 1.35 to 4.25]; p = 0.003) and compared with clindamycin alone (HR 1.78 [95% CI 1.11 to 2.85]; p = 0.02). No difference was found between the cloxacillin and benzylpenicillin combination and clindamycin (HR 0.74 [95% CI 0.42 to 1.32]; p = 0.31).

CONCLUSION

Our results indicate that prophylaxis against C. acnes may be warranted in shoulder arthroplasty. Because the absolute number of infections was low and infections could have been underreported to the register, our results should be interpreted with caution. There is no available information about the causative microorganisms. The study lays the groundwork for further investigations of antibiotic prophylaxis regimens in shoulder arthroplasty. Because large randomized controlled trials would be impractical to perform, prospective register-based randomized controlled studies might be a viable method.

LEVEL OF EVIDENCE

Level Ⅲ, therapeutic study.

Preoperative topical benzoyl peroxide treatment is effective in reducing Cutibacterium acnes in shoulder surgery: a systematic review

BACKGROUND

Cutibacterium acnes (C acnes) colonization can have a significant impact on patients undergoing both arthroscopic and open shoulder surgery with regard to postoperative infection. Its resistance to standard preoperative skin preparations and prophylactic antibiotics has led to a need for a more targeted therapy. Topical benzoyl peroxide (BPO) has been used by dermatologists in the treatment for acnes due to its bactericidal and penetrative effects through the dermal layer. The aim of this systematic review is to review the effectiveness of topical BPO preoperatively in shoulder surgery in reducing C acnes colonization and postoperative infection.

METHODS

A review of the online databases Medline and Embase was conducted on December 15, 2021, according to Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. The review was registered prospectively in the PROSPERO database. Clinical studies reporting superficial and deep sample microbiology and postoperative complications were included. The studies were appraised using the revised Cochrane Risk of Bias 2 (ROB 2) tool for randomized studies and the Methodological Index for Non-Randomized Studies (MINORS) tool.

RESULTS

The search strategy identified 10 studies for inclusion (6 randomized control trials, 2 prospective cohort studies, and 2 case series), including a total of 482 patients. Seven studies were comparable, testing BPO against alternative standard skin preparations. Of the 10 studies, 7 showed a decrease in the load of C acnes on the skin and/or deep tissues, of which 6 demonstrated statistical significance. Men were shown to have a statistically significant increase in the colonization rate of C acnes. Scheer et al (2021) demonstrated 4500 colony-forming units/mL in males and 900 colony-forming units/mL in females. In studies where the number of BPO applications was higher, BPO appeared more effective. Dizay et al demonstrated C acnes elimination in 78.9% with more than 1 application compared with 66.7% if only applied once. Three studies looked at the effectiveness of BPO during the operative timeline with 1 demonstrating its statistically significant effectiveness at reducing colonization 2 hours into the operation (P = .048).

CONCLUSION

BPO is effective as a topical treatment at reducing C acnes colonization before shoulder surgery. However, the relationship between duration of treatment, frequency of application, and gender requires further research.

Minimal number of cultures needed to detect Cutibacterium acnes in primary reverse shoulder arthroplasty: a prospective study

BACKGROUND

The objective of this study was to determine the minimum number of cultures needed to detect Cutibacterium acnes in primary reverse shoulder arthroplasties (RSAs).

METHODS

It is a prospective study including 160 primary RSAs. Exclusion criteria included an active infection, an invasive shoulder treatment in the last 6 months before surgery, an Arthro-SCAN or Arthro-MRI in the last 6 months before surgery, previous shoulder surgeries and revision cases. In 90 cases, 11 cultures were obtained. Another 10 cultures were obtained in the other 70 cases (culture 10 was a sterile sponge to detect false positives). To determine the minimum number of cultures needed to detect C acnes, the prevalence of C acnes contamination of the 160 patients included was determined.

RESULTS

There were 128 females and 32 males, with a mean age of 74 years. There were 1690 cultures obtained from the 160 primary RSA surgeries, and 132 of them turned out to be positive for C acnes. There were 42 patients with positive cultures. Twenty of them were males and 22 females. When considering the skin and the deep tissue cultures altogether, the prevalence of positive cultures for C acnes was of 26.25%. If only deep tissues cultures were considered, the prevalence of positive cultures for C acnes was of 23.13%. When considering the skin and the deep tissue cultures together, the sensitivity to detect the C acnes is 19% if only 1 culture is obtained, 31% if 2 cultures are obtained, 50% if 3 cultures are obtained, 59.5% if 4 cultures are obtained, 66.7% if 5 cultures are obtained, 73.8% if 6 cultures are obtained, 85.7% if 7 cultures are obtained, and 92.9% if 8 cultures are obtained. When considering only the deep tissue cultures, if only 1 culture is obtained, the sensitivity to detect the C acnes is 24.3%, 40.5% if 2 cultures are obtained, 54.1% if 3 cultures are obtained, 73% if 4 cultures are obtained, 89.2% if 5 cultures are obtained, and 97.3% if 6 or 7 cultures are obtained.

DISCUSSION

A minimum number of 8 cultures are needed to detect C acnes in skin. Moreover, a minimum of 6 cultures are needed to detect it in deep tissues when performing an RSA.

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.

Soft-Tissue Considerations in Shoulder Surgery in the Patient With Lymphedema

Lymphedema is a chronic, progressive, and often debilitating condition that results in swelling of the affected tissue. Secondary lymphedema is most commonly recognized by unilateral swelling of the ipsilateral extremity after the treatment of cancer. It is estimated that nearly 1.45 million women suffer from breast cancer-related lymphedema in the United States. The number of patients suffering from upper extremity lymphedema is expected to increase because multimodal treatment of breast cancer increases the long-term survival after diagnosis. Because this population ages, the likelihood of encountering a patient with concurrent lymphedema and shoulder pathology requiring orthopaedic intervention is likely to rise. A patient with an already edematous arm and/or impaired drainage of that arm is likely to have different and more complex intraoperative and postoperative courses than patients with normal lymphatic drainage. Although a lymphedematous arm should not preclude surgical intervention, there are considerations when approaching shoulder surgery in the setting of upper extremity lymphedema that may help mitigate complications and aid the patient in their orthopaedic recovery.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

LEVEL OF EVIDENCE

Level II.

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

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

Diagnosis of orthopaedic-implant-associated infections caused by slow-growing Gram-positive anaerobic bacteria - a clinical perspective

Slow-growing Gram-positive anaerobic bacteria (SGAB) such as Cutibacterium acnes are increasingly recognized as causative agents of implant-associated infections (IAIs) in orthopaedic surgeries. SGAB IAIs are difficult to diagnose because of their non-specific clinical and laboratory findings as well as the fastidious growth conditions required by these bacteria. A high degree of clinical suspicion and awareness of the various available diagnostic methods is therefore important. This review gives an overview of the current knowledge regarding SGAB IAI, providing details about clinical features and available diagnostic methodologies. In recent years, new methods for the diagnosis of IAI were developed, but there is limited knowledge about their usefulness in SGAB IAI. Further studies are required to determine the ideal diagnostic methodology to identify these infections so that they are not overlooked and mistakenly classified as aseptic failure.

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

BACKGROUND

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

METHODS

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

RESULTS

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

DISCUSSION

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

Dynamics of skin microbiota in shoulder surgery infections

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

Are Cutibacterium acnes present at the end of primary shoulder prosthetic surgeries responsible for infection? Prospective study

The purpose of this study was to investigate if the C. acnes present at the end of a primary shoulder arthroplasty could be responsible for shoulder arthroplasty infection. Prospective study includes patients undergoing primary shoulder arthroplasty from January 2015 until December 2018. From all the patients included, 5 to 12 tissue samples were obtained and were specifically cultured to detect the presence of C. acnes. DNA was extracted from the C acnes isolated colonies and Whole Genome Sequencing (WGS) analysis was done. A cohort of 156 patients was finally included. In twenty-seven patients, the C. acnes was present at the end of the primary surgery. Two of these patients developed a C. acnes periprosthetic shoulder infection at 6 and 4 months after the primary surgery. WGS of C. acnes isolated colonies showed that all the revision-surgery isolates clustered near to the corresponding primary-surgery isolates compared to the other independent bacterial colonies. (99.89% of similarity). C. acnes present at the end of the primary surgery can be the cause of early or delayed periprosthetic joint infections in shoulder arthroplasty.

Validation of new shoulder periprosthetic joint infection criteria

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

BACKGROUND

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

METHOD

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

RESULTS

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

CONCLUSION

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

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

STUDY DESIGN

Retrospective review of hospital charts.

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

Level IV.

The incidence and incubation period of false-positive culture results in shoulder surgery

BACKGROUND

Postoperative shoulder infection is a significant complication requiring timely identification and treatment. Indolent infections such as those involving Cutibacterium acnes (formerly Propionibacterium acnes) provide a diagnostic dilemma as they present differently, without the acute symptoms associated with most postoperative bone and joint infections. Furthermore, Cacnes is thought to be a common contaminant isolated from intraoperative cultures. With no consensus algorithm, long-held cultures play a major role in guiding management decisions in potential postoperative shoulder infection. Our study sought to determine the incidence of positive culture results in both open and arthroscopic procedures in noninfected patients, as well as to clarify whether an increase in the incubation time frame leads to an increased rate of culture growth.

METHODS

One hundred patients were prospectively enrolled into either the open or arthroscopic procedure group. Patients with abnormal inflammatory laboratory findings, a history of shoulder surgery, or corticosteroid injection within 6 months of surgery were excluded from the study. Three cultures were obtained for each patient: superficial tissue culture, tissue culture, and "sterile" control swab. Cultures were held for 28 days and checked at regular intervals. All patients were followed up clinically for 6 months to ensure no signs of postoperative infection occurred.

RESULTS

Ultimately, 95 patients were included in the final analysis. The false-positive rate was 17.0% in those who underwent open shoulder surgery and 10.4% in those who underwent arthroscopic shoulder surgery. The incidence of positive Cacnes culture results was 6.4% in the open group, whereas Cacnes was not isolated in the arthroscopic group. All positive bacterial culture results were reported within 7 days of collection. One culture result was positive for mold at 26 days.

CONCLUSION

A relatively high false-positive culture rate occurred in both open and arthroscopic shoulder surgery. Cacnes was the most commonly identified bacterium in cultures in the open surgery group. Knowledge of one's institutional false-positive culture rate could be important in avoiding potentially inappropriate treatment. Additionally, we found that holding cultures longer than 14 days did not lead to an increased rate of false-positive culture results.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Reduction in the infection rate of cranioplasty with a tailored antibiotic prophylaxis: a nonrandomized study

BACKGROUND

Cranioplasty carries a high risk of surgical site infections (SSIs) for a scheduled procedure, particularly with antibiotic-resistant bacteria.

METHODS

The goal of this retrospective study was to measure the effect of tailored antibiotic prophylaxis on SSIs resulting from cranioplasties. The authors collected a prospective database of cranioplasties from 2009 to 2018. Risk factors for SSI were registered, as well as infection occurring during the first year postoperatively. A new protocol was initiated in 2016 consisting of antibiotic prophylaxis tailored to the colonizing flora of the skin of the scalp and decolonization of patients who were nasal carriers of methicillin-resistant S. aureus (MRSA); infection rates were compared.

RESULTS

One hundred nine cranioplasties were identified, 64 in the old protocol and 45 in the new protocol. Of the 109 cranioplasties, 16 (14.7%) suffered an infection, 14 (21.9%) in the old protocol group and 2 (4.4%) in the new protocol group (OR for the new protocol 0.166, 95% CI 0.036-0.772). Multiple surgeries (OR 3.44), Barthel ≤ 70 (OR 3.53), and previous infection (OR 3.9) were risk factors for SSI. Of the bacteria identified in the skin of the scalp, 22.2% were resistant to routine prophylaxis (cefazoline). Only one patient was identified as a nasal carrier of MRSA and was decolonized.

CONCLUSIONS

A high percentage of bacteria resistant to routine prophylaxis (cefazoline) was identified in the skin of these patients' scalps. The use of tailored antibiotic prophylaxis reduced significantly the infection rate in this particular set of patients.

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.

Cutaneous microbiology of patients having primary shoulder arthroplasty

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Antibiotic prophylaxis in primary and revision shoulder replacement: a systematic review

Background

One of the most common bacteria responsible for most Periprosthetic joint infection (PJI) is Propionibacterium acnes. Even though the rate of infections in patients undergoing total shoulder arthroplasty is increasing, effective diagnostic tests and the precautions taken during the surgery are not yet adequate. This systematic review aims to evaluate the effectiveness of antimicrobial prophylaxis in PJI in shoulder replacement and to provide health workers with the best approach to the use of antimicrobial agents based on currently available clinical evidence.

Methods

a systematic review of the literature was carried out in accordance with the PRISMA Statement. Studies concerning the effectiveness of antimicrobial prophylaxis in the prevention of PJI in patients undergoing shoulder replacement were included.

Results

Seven studies were included in the final analysis because they were considered valid. A total of 3272 patients underwent a surgical procedure, most of which were males. The male population has a greater presence of hair, therefore a greater risk of P. acnes. in surface cultures. Patients were assessed at an average follow-up period of 20 months ranging from 9 weeks to 53 months.

Conclusion

The optimal perioperative antimicrobial regimen is controversial. The clinical guidelines recommend the use of only one antibiotic as prophylaxis but considering the increase in the rates of antibiotic-resistant infections, the question arises whether antibiotic prophylaxis should be extended for adequate coverage. Shoulder arthroplasty performed on the male population must be carefully checked after surgery for the possible presence of P. Acnes.

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.

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.

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.

Next-generation sequencing for diagnosis of infection: is more sensitive really better?

BACKGROUND

The utility of next-generation sequencing (NGS) in differentiating between active infection and contaminant or baseline flora remains unclear. The purpose of this study is to compare NGS with culture-based methods in primary shoulder arthroplasty.

METHODS

A prospective series of primary shoulder arthroplasty patients with no history of infection or antibiotic use within 60 days of surgery was enrolled. All patients received standard perioperative antibiotics. After skin incision, a 10 × 3-mm sample of the medial skin edge was excised. A 2 × 2-cm synovial tissue biopsy was taken from the rotator interval after subscapularis takedown. Each sample set was halved and sent for NGS and standard cultures.

RESULTS

Samples from 25 patients were analyzed. Standard aerobic/anaerobic cultures were positive in 10 skin samples (40%, 95% confidence interval [CI] 20%-60%) and 3 deep tissue samples (12%, 90% CI 1%-23%]). NGS detected ≥1 bacterial species in 17 of the skin samples (68%, 95% CI 49%-87%) and 7 deep tissue samples (28%, 95% CI 9%-47%). There was a significant difference (P < .03) in the mean number of bacterial species detected with NGS between the positive standard culture (1.6 species) and the negative standard culture groups (5.7 species).

CONCLUSION

NGS identified bacteria at higher rates in skin and deep tissue samples than standard culture did in native, uninfected patients undergoing primary procedures. Further research is needed to determine which NGS results are clinically relevant and which are false positives before NGS can be reliably used in orthopedic cases.

Cutibacterium acnes persists despite topical clindamycin and benzoyl peroxide

BACKGROUND

Cutibacterium (formerly Propionibacterium) acnes persists in the dermis despite standard skin antiseptic agents, prompting some surgeons to use topical antimicrobials such as benzoyl peroxide and clindamycin prior to shoulder arthroplasty surgery. However, the efficacy of these topical agents has not been established.

METHODS

The upper backs of 12 volunteers were randomized into 4 treatment quadrants: topical benzoyl peroxide, topical clindamycin, combination topical benzoyl peroxide and clindamycin, and a negative control. The corresponding topical agents were applied to each site twice daily for 3 days. A 3-mm dermal punch biopsy specimen was obtained from each site and cultured for 14 days to assess for C acnes growth. Positive cultures were assessed for the hemolytic phenotype. The McNemar test was used to compare the proportion of positive cultures in each group.

RESULTS

C acnes grew in 4 of 12 control sites (33.3%), 1 of 12 benzoyl peroxide sites (8.3%), 2 of 12 clindamycin sites (16.7%), and 2 of 12 combination benzoyl peroxide-clindamycin sites (16.7%). The C acnes hemolytic phenotype was present in 2 of 12 control specimens (16.7%) compared with 0 (0.0%) in the benzoyl peroxide group, 2 of 12 (16.7%) in the clindamycin group, and 2 of 12 (16.7%) in the combination benzoyl peroxide-clindamycin group. There were no statistically significant differences between treatment arms.

CONCLUSION

The topical application of benzoyl peroxide and clindamycin did not eradicate C acnes in all subjects. The clinical implications of these findings are yet to be determined.

Hydrogen peroxide skin preparation reduces Cutibacterium acnes in shoulder arthroplasty: a prospective, blinded, controlled trial

BACKGROUND

The purpose of this study was to determine whether preoperative skin preparation with hydrogen peroxide reduces intraoperative culture positivity for Cutibacterium acnes in shoulder arthroplasty.

METHODS

This was a prospective, controlled, parallel/noncrossover, nonrandomized, single-blinded trial registered at clinicaltrials.gov. We included a consecutive series of patients scheduled to undergo primary anatomic or reverse total shoulder arthroplasty. The first group of patients underwent a standard skin preparation and the second group underwent the same preparation with the addition of hydrogen peroxide. We then took skin, dermis, glenohumeral joint, and air (negative control) aerobic and anaerobic culture swabs. We blinded the laboratory analyzing the samples. An a priori power analysis determined that 56 patients would be needed to see a 50% reduction in culture positivity rates. We also conducted a post hoc gender-stratified analysis.

RESULTS

Between January 2017 and October 2018, the authors performed 124 primary shoulder arthroplasties, of which we included 65 and collected samples on 61. There were no demographic differences. There were fewer patients within the peroxide group with triple-positive cultures (skin, dermis, and joint) (0% vs. 19%, P = .024) and positive cultures from the joint (10% vs. 35%, P = .031). In our subgroup analysis, these differences were only significant in males. The vast majority of positive cultures were with C. acnes.

CONCLUSION

Although larger, randomized studies are needed, adding hydrogen peroxide to the preoperative skin preparation may be a low-cost, low-risk method to reduce deep tissue contamination with C. acnes, particularly within males.

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

The Second International Consensus Meeting on Orthopedic Infections was held in Philadelphia, Pennsylvania, in July 2018. More than 800 experts from all 9 subspecialties of orthopedic surgery and allied fields of infectious disease, microbiology, and epidemiology were assembled to form the International Consensus Group. The shoulder workgroup reached consensus on 27 questions related to culture techniques, inflammatory markers, and diagnostic criteria used to evaluate patients for periprosthetic shoulder infection. This document contains the group's recommendations and rationale for each question related to evaluating periprosthetic shoulder infection.

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.

Editorial Commentary: Already "Stealth" Organism Propionibacterium acnes Goes Covert by Changing Its Name to Cutibacterium acnes: Shoulder Bacterial Contamination

Propionibacterium acnes, now Cutibacterium acnes, is found on skin and subcutaneous tissue and is thus hard to eradicate. Infection can result in shoulder pain but be indolent and hard to diagnose; in addition, the organism is difficult to identify requiring long-hold cultures. Despite skin preparation, and second preparation before conversion of arthroscopy to mini-open surgery, we do not yet have a way to effectively eradicate C acnes from deeper dermal layers.

Scoping review: Diagnosis and management of periprosthetic joint infection in shoulder arthroplasty

BACKGROUND

The aim of this scoping review is to assess the current evidence regarding periprosthetic shoulder infection to inform development of evidence and consensus-based guidelines.

METHODS

A search of Medline, Embase and PubMed was performed; two authors screened the results independently for inclusion.

RESULTS

Totally 88 studies were included. Incidence of periprosthetic shoulder infection ranged from 0.7% to 7%. The most common organisms to cause periprosthetic shoulder infection were Propionibacterium acnes, Staphylococcus aureus, Staphylococcus epidermidis and coagulase-negative Staphylococcus. Male gender and younger age are the most reported risk factors. Erythrocyte sedimentation rate, C-reactive protein and serum/synovial biomarkers had limited diagnostic accuracy. Thirty-nine studies reported the outcome of surgical management of periprosthetic shoulder infection. Eradication rates vary from 54% to 100% for debridement procedures; 66-100% for permanent spacers; 50-100% following single-stage revision; 60-100% following two-stage revision; and 66-100% following resection arthroplasty.

CONCLUSION

There is wide heterogeneity in study designs and outcomes of studies are often contradictory and due to issues with methodology and small sample sizes the optimal pathways for diagnosis and management cannot be determined from this review. Future research should be based on larger cohorts and randomised trials where feasible to provide more valid research for guiding future treatment of periprosthetic shoulder infection.

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.

Reduced Time to Positive Cutibacterium acnes Culture Utilizing a Novel Incubation Technique: A Retrospective Cohort Study

Introduction

Cutibacterium acnes (C. acnes) is a common pathogen in postoperative shoulder infections. The purpose of this study was to evaluate the time to positive cultures for C. acnes and compare our experience before and after implementation of a regulated anaerobic chamber system. We hypothesized that this would reduce the time to identify positive cultures.

Methods

This was a retrospective review of 34 patients with cultures obtained from the shoulder that were positive for C. acnes. The time until positive result was evaluated before and after implementation of a regulated anaerobic incubation chamber.

Results

Following implementation of the regulated anaerobic incubation chamber, the time until C. acnes culture growth significantly decreased from 6.5 days (range 3–10 days) to 4.9 days (range 2.75–10 days) (mean difference: 1.6 days, 95% confidence interval: 1.06–2.66 days; P = .002). True infections had a significantly shorter time to positive culture compared to contaminants (5.5 vs 6.8 days, respectively, P = .003). Increased number of positive culture specimens correlated with a shorter time to positivity (Spearman rank = −0.58, P = .007).

Conclusion

Improved anaerobic culture protocols and techniques may lead to greater accuracy and earlier diagnosis and initiation of treatment of postoperative shoulder infections.

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.