Propionibacterium acnes in shoulder surgery: true infection, contamination, or commensal of the deep tissue?

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Next-generation Sequencing Results Require Higher Inoculum for Cutibacterium acnes Detection Than Conventional Anaerobic Culture

BACKGROUND

Cutibacterium acnes has been described as the most common causative microorganism in prosthetic shoulder infections. Conventional anaerobic culture or molecular-based technologies are usually used for this purpose, but little to no concordance between these methodologies (k = 0.333 or less) has been observed.

QUESTIONS/PURPOSES

(1) Is the minimum C. acnes load for detection higher for next-generation sequencing (NGS) than for anaerobic conventional culture? (2) What duration of incubation is necessary for anaerobic culture to detect all C. acnes loads?

METHODS

Five C. acnes strains were tested for this study: Four strains were causing infection and were isolated from surgical samples. Meanwhile, the other was a reference strain commonly used as a positive and quality control in microbiology and bioinformatics. To create inoculums with varying degrees of bacterial load, we began with a standard bacterial suspension at 1.5 x 10 8 colony-forming units (CFU)/mL and created six more diluted suspensions (from 1.5 x 10 6 CFU/mL to 1.5 x 10 1 CFU/mL). Briefly, to do so, we transferred 200 µL from the tube with the highest inoculum (for example, 1.5 x 10 6 CFU/mL) to the following dilution tube (1.5 x 10 5 CFU/mL; 1800 µL of diluent + 200 µL of 1.5 x 10 6 CFU/mL). We serially continued the transfers to create all diluted suspensions. Six tubes were prepared per strain. Thirty bacterial suspensions were tested per assay. Then, 100 µL of each diluted suspension was inoculated into brain heart infusion agar with horse blood and taurocholate agar plates. Two plates were used per bacterial suspension in each assay. All plates were incubated at 37°C in an anaerobic chamber and assessed for growth after 3 days of incubation and daily thereafter until positive or Day 14. The remaining volume of each bacterial suspension was sent for NGS analysis to identify bacterial DNA copies. We performed the experimental assays in duplicate. We calculated mean DNA copies and CFUs for each strain, bacterial load, and incubation timepoint assessed. We reported detection by NGS and culture as a qualitative variable based on the identification or absence of DNA copies and CFUs, respectively. In this way, we identified the minimum bacterial load detected by NGS and culture, regardless of incubation time. We performed a qualitative comparison of detection rates between methodologies. Simultaneously, we tracked C. acnes growth on agar plates and determined the minimum incubation time in days required for CFU detection in all strains and loads examined in this study. Growth detection and bacterial CFU counting were performed by three laboratory personnel, with a high intraobserver and interobserver agreement (κ > 0.80). A two-tailed p value below 0.05 was considered statistically significant.

RESULTS

Conventional cultures can detect C. acnes at a load of 1.5 x 10 1 CFU/mL, whereas NGS can detect bacteria when the concentration was higher, at 1.5 x 10 2 CFU/mL. This is represented by a lower positive detection proportion (73% [22 of 30]) for NGS than for cultures (100% [30 of 30]); p = 0.004). By 7 days, anaerobic cultures were able to detect all C. acnes loads, even at the lowest concentrations.

CONCLUSION

When NGS is negative and culture is positive for C. acnes , there is likely a low bacterial load. Holding cultures beyond 7 days is likely unnecessary.

CLINICAL RELEVANCE

This is important for treating physicians to decide whether low bacterial loads necessitate aggressive antibiotic treatment or whether they are more likely contaminants. Cultures that are positive beyond 7 days likely represent contamination or bacterial loads even below the dilution used in this study. Physicians may benefit from studies designed to clarify the clinical importance of the low bacteria loads used in this study at which both methodologies' detection differed. Moreover, researchers might explore whether even lower C. acnes loads have a role in true periprosthetic joint infection.

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.

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.

Shotgun sequencing of sonication fluid for the diagnosis of orthopaedic implant-associated infections with Cutibacterium acnes as suspected causative agent

Orthopaedic implant-associated infections (OIAIs) due to Cutibacterium acnes can be difficult to diagnose. The aim of this pilot study was to determine if metagenomic next-generation sequencing (mNGS) can provide additional information to improve the diagnosis of C. acnes OIAIs. mNGS was performed on sonication fluid (SF) specimens derived from 24 implants. These were divided into three groups, based on culture results: group I, culture-negative (n = 4); group II, culture-positive for C. acnes (n = 10); and group III, culture-positive for other bacteria (n = 10). In group I, sequence reads from C. acnes were detected in only one SF sample, originating from a suspected case of OIAIs, which was SF and tissue culture-negative. In group II, C. acnes sequences were detected in 7/10 samples. In group III, C. acnes sequence reads were found in 5/10 samples, in addition to sequence reads that matched the bacterial species identified by culture. These samples could represent polymicrobial infections that were missed by culture. Taken together, mNGS was able to detect C. acnes DNA in more samples compared to culture and could be used to identify cases of suspected C. acnes OIAIs, in particular regarding possible polymicrobial infections, where the growth of C. acnes might be compromised due to a fast-growing bacterial species. However, since SF specimens are usually low-biomass samples, mNGS is prone to DNA contamination, possibly introduced during DNA extraction or sequencing procedures. Thus, it is advisable to set a sequence read count threshold, taking into account project- and NGS-specific criteria.

Cutibacterium positive cultures in total joint arthroplasty: a comparison of the hip, knee, and shoulder

PURPOSE

Cutibacterium spp. (formerly Propionibacterium) is a slow growing, Gram-positive, anaerobic bacteria and is an emerging clinical entity in prosthetic joint infection (PJI). This study compares the presentation, surgical management, and post-operative antibiotic therapy of patients with positive intraoperative cultures during revision total joint arthroplasty (TJA) of the hip, knee, and shoulder.

METHODS

This was a retrospective cohort study of patients from 2014 to 2020 of 57 revision TJAs (27 total hip arthroplasty (THA), 17 total shoulder arthroplasty (TSA), and 13 total knee arthroplasty (TKA)) with intraoperative cultures positive for Cutibacterium at a tertiary academic centre. Patient demographics, pre-operative labs, radiographs, and aspirate results were collected. Intraoperative data was reviewed. Post-operative antibiotic therapy and repeat infections were recorded. Data was compared with univariate analyses.

RESULTS

There was no significant difference in pre-operative lab values between the cohorts. All cohorts had > 58% radiographic lucency. Revision TSA patients had significantly fewer pre-operative aspirates. Six patients undergoing revision THA, three TKA and one TSA had a repeat infection requiring further surgery. Four in the THA cohort and one in the TKA cohort with repeat infections did not receive prolonged antibiotic therapy.

CONCLUSION

Cutibacterium is an infectious agent that can present in an indolent fashion after TJA. It commonly causes progressive radiographic lucency. The workup and post-operative management differs in the hip, knee, and shoulder, which is likely due to existing literature guiding physician practice. In all joints, Cutibacterium is a virulent pathogen that can cause repeat infections requiring surgical treatment.

Detection of Cutibacterium acnes in Tissue Samples from Clean Primary Shoulder Surgeries - Part II

Objective  Research and identification of Cutibacterium acnes ( C. acnes ) and other microorganisms in deep tissue samples collected in clean shoulder surgeries of patients who did not undergo any previous invasive joint procedure and who had no clinical history of infection. Methods  We analyzed the results of cultures of intraoperative deep tissue samples from 84 patients submitted to primary clean shoulder surgery. Tubes containing culture medium were used for storage and transport of anaerobic agents, prolonged incubation time, and mass spectrometer for diagnosis of bacterial agents. Results  Bacteria growth was evidenced in 34 patients (40.4%) of the 84 included in the study. Of these, 23 had growth of C. acnes in at least one sample of deep tissue collected, corresponding to 27.3% of the total patients. The second most common agent was Staphylococcus epidermidis , present in 7.2% of the total individuals included. We showed a higher relationship between sample positivity and males, a lower mean age, absence of diabetes mellitus, ASA I score, and antibiotic prophylaxis in anesthetic induction with cefuroxime. Conclusions  A high percentage of isolates of different bacteria was found in shoulder tissue samples of patients undergoing clean and primary surgeries, who had no history of previous infection. Identification of C. acnes was high (27.6%), and Staphylococcus epidermidis was the second most frequent agent (7.2%).

Prevalence of antimicrobial-resistant Cutibacterium isolates and development of multiplex PCR method for Cutibacterium species identification

INTRODUCTION

Cutibacterium species such as C. acnes, C. avidum, and C. granulosum are known anaerobic skin inhabitants and often cause surgical site infections. These species are genetically similar and are difficult to identify rapidly. In addition, their pathogenicity and antimicrobial resistance remain unknown. In this study, antimicrobial resistance in Cutibacterium isolates was studied and a multiplex PCR method for their identification was developed.

METHODS

A total of 497 C. acnes, 71 C. avidum, and 25 C. granulosum strains which were isolated from the acne pustule and infectious regions, were used.

RESULTS

The antimicrobial resistance rates of C. acnes, C. avidum, and C. granulosum strains isolated from patients with acne vulgaris were higher than those of strains isolated from patients with infectious diseases. In particular, macrolide-clindamycin-resistant strains were isolated most frequently from all species. Among the resistant strains, strains with 23S rRNA mutations were the most common in C. acnes (24.3%, 71/292), whereas C. avidum and C. granulosum strains were most frequently found with erm(X). For the first time, a C. granulosum strain carrying pTZC1, which codes erm(50) and tet(W), was isolated from patients with acne vulgaris. Regarding the rapid identification of causative pathogens from infectious regions, three Cutibacterium species were identified with 100% sensitivity and specificity using multiplex PCR method.

CONCLUSIONS

Our data showed that antimicrobial resistance differed among Cutibacterium species. The multiplex PCR method may contribute to the rapid detection of Cutibacterium species and selection of appropriate antimicrobial agents.

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

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

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

BACKGROUND

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Septic Olecranon Bursitis With Osteomyelitis Attributed to Cutibacterium acnes: Case Report and Literature Overview of the Dilemma of Potential Contaminants and False-Positives

We report an unusual case of acute septic olecranon bursitis, with probable olecranon osteomyelitis, where the only organism isolated in culture was initially considered a contaminant, Cutibacterium acnes. However, we ultimately considered it the likely causal organism when treatment for most of the other more likely organisms failed. This typically indolent organism is prevalent in pilosebaceous glands, which are scarce in the posterior elbow region. This case illustrates the often challenging empirical management of a musculoskeletal infection when the only organism isolated might be a contaminant, but successful eradication requires continued treatment as if it is the causal organism. The patient is a Caucasian 53-year-old male who presented to our clinic with a second episode of septic bursitis at the same location. Four years prior, he had septic olecranon bursitis from methicillin-sensitive Staphylococcus aureus that was treated uneventfully with one surgical debridement and a one-week course of antibiotics. In the current episode reported here, he sustained a minor abrasion. Cultures were obtained five separate times because of no growth and difficulty eradicating the infection. One culture grew C. acnes on day 21 of incubation; this long duration has been reported. The first several weeks of antibiotic treatment failed to eradicate the infection, which we ultimately attributed to inadequate treatment of C. acnes osteomyelitis. Although C. acnes has a well-known propensity for false-positive cultures as typically reported in post-operative shoulder infections, treatment for our patient's olecranon bursitis/osteomyelitis was successful only after several surgical debridements and a prolonged course of intravenous and oral antibiotics that targeted it as the presumptive causal organism. However, it was possible that C. acnes was a contaminant/superinfection, and another organism was the culprit, such as a Streptococcus or Mycobacterium species that was eradicated by the treatment regime targeted for C. acnes.

Periprosthetic joint infections of the shoulder: A 10-year retrospective analysis outlining the heterogeneity among these patients

Background

Diagnosis and treatment of shoulder periprosthetic joint infection is a difficult problem. The purpose of this study was to utilize the 2018 International Consensus Meeting definition of shoulder periprosthetic joint infection to categorize revision shoulder arthroplasty cases and determine variations in clinical presentation by presumed infection classification.

Methods

Retrospective review of patients undergoing revision shoulder arthroplasty at a single institution. Likelihood of periprosthetic joint infection was determined based on International Consensus Meeting scoring. All patients classified as definitive or probable periprosthetic joint infection were classified as periprosthetic joint infection. All patients classified as possible or unlikely periprosthetic joint infection were classified as aseptic. The periprosthetic joint infection cohort was subsequently divided into culture-negative, non-virulent microorganism, and virulent microorganism cohorts based on culture results.

Results

Four hundred and sixty cases of revision shoulder arthroplasty were reviewed. Eighty (17.4%) patients were diagnosed as definite or probable periprosthetic joint infection, of which 29 (36.3%), 39 (48.8%), and 12 (15.0%) were classified as virulent, non-virulent, or culture-negative periprosthetic joint infection, respectively. There were significant differences among periprosthetic joint infection subgroups with regard to preoperative C-reactive protein (p = 0.020), erythrocyte sedimentation rate (p = 0.051), sinus tract presence (p = 0.008), and intraoperative purulence (p < 0.001). The total International Consensus Meeting criteria scores were also significantly different between the periprosthetic joint infection cohorts (p < 0.001).

Discussion

While the diagnosis of shoulder periprosthetic joint infection has improved with the advent of International Consensus Meeting criteria, there remain distinct differences between periprosthetic joint infection classifications that warrant further investigation to determine the accurate diagnosis and optimal treatment.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Techniques for Decreasing Bacterial Load for Open Shoulder Surgery

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

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

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

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

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.

An evidence-based approach to managing unexpected positive cultures in shoulder arthroplasty

BACKGROUND

Unexpected positive cultures (UPCs) are very commonly found during shoulder arthroplasty when surgeons send intraoperative cultures to rule out periprosthetic joint infection (PJI) without clinical or radiographic signs of infection. Cutibacterium acnes is thought to be the most common bacteria cultured in this setting; however, the implications of an unexpected positive result are neither well defined nor agreed upon within the literature. The current review evaluates the incidence of UPCs and C acnes in reverse total arthroplasty; the clinical significance, if any, of these cultures; and various prognostic factors that may affect UPC incidence or recovery following PJI.

METHODS

A systematic review was performed with PRISMA guidelines using PubMed, CINAHL, and Scopus databases. Inclusion criteria included studies published from January 1, 2000, to May 20, 2021, that specifically reported on UPCs, native or revision shoulder surgery, and any study that directly addressed one of our 6 proposed clinical questions. Two independent investigators initially screened 267 articles for further evaluation. Data on study design, UPC rate/speciation, UPC risk factors, and UPC outcomes were analyzed and described.

RESULTS

A total of 22 studies met the inclusion criteria for this study. There was a pooled rate of 27.5% (653/2373) deep UPC specimen positivity, and C acnes represented 76.4% (499/653) of these positive specimens. Inanimate specimen positivity was reported at a pooled rate of 20.1% (29/144) across 3 studies. Male patients were more likely to have a UPC; however, the significance of prior surgery, surgical approach, and type of surgery conflicted across multiple articles. Patient-reported outcomes and reoperation rates did not differ between positive-UPC and negative-UPC patients. The utilization of antibiotics and treatment regimen varied across studies; however, the reinfection rates following surgery did not statistically differ based on the inclusion of antibiotics.

CONCLUSION

UPCs are a frequent finding during shoulder surgery and C acnes represents the highest percentage of cultured bacteria. Various preoperative risk factors, surgical techniques, and postoperative treatment regimens did not significantly affect the incidence of UPCs as well as the clinical outcomes for UPC vs. non-UPC patients. A standardized protocol for treatment and follow-up would decrease physician uncertainty when faced with a UPC from shoulder surgery. Given the results of this review, shoulder surgeons can consider not drastically altering the postoperative clinical course in the setting of UPC with no other evidence of PJI.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

DISCUSSION

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

Cutibacterium Positive Cultures in Total Hip Arthroplasty: Contaminant or Pathogen?

BACKGROUND

Cutibacterium spp. is an emerging pathogen in total hip arthroplasty (THA) that is not well evaluated in the literature. This study reported on the presentation and management of THA complicated by positive intraoperative Cutibacterium cultures.

METHODS

This is a retrospective review of 27 revision THAs with positive monomicrobial intraoperative Cutibacterium cultures from 2014 to 2020 at one academic center. These patients were divided into two cohorts based on meeting Musculoskeletal Infection Society (MSIS) criteria for prosthetic joint infections (PJI). Patient demographics, preoperative labs, and hip aspirate results were collected. Procedure performed, postoperative antibiotic regimens, and repeat infections were recorded. Data were compared with univariate analysis.

RESULTS

Nine of the 27 patients preoperatively met MSIS criteria for PJI. Patients with positive MSIS criteria had significantly higher median synovial cell count (P = .048) and neutrophil percentage in a preoperative aspirate (P = .050). Eight patients with positive MSIS criteria received six weeks of postoperative antibiotics compared to two patients with negative criteria. Two patients with positive MSIS criteria had a postoperative infection that required further surgical intervention. Four patients with negative criteria who required further surgical intervention did not receive postoperative antibiotics after initial revision.

CONCLUSION

While often categorized as a contaminant, Cutibacterium is an increasingly recognized pathogen in THA. Cutibacterium can often present with normal serology, which may result in misdiagnosis as aseptic THA failure. Without the administration of postoperative antibiotics after positive cultures, there is a risk for persistent infection requiring further surgical intervention.

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.

Pain at the Cochlear Implant Site Requiring Device Removal in Pediatric Patients

OBJECTIVES

Idiopathic pain at the cochlear implant (CI) site outside of the immediate postoperative period is an uncommon occurrence but may necessitate device explantation. Our objective was to describe the clinical course for pediatric patients with CI site pain who ultimately required device explantation.

STUDY DESIGN

Retrospective chart review.

METHODS

We performed a retrospective database review of CIs performed at a tertiary referral center for pediatric cochlear implantation. We specifically evaluated pediatric patients who presented with pain at or near the CI device site and ultimately required explantation.

RESULTS

Fifteen patients (16 CIs) had pain at or near the CI site requiring device explantation. Cultures taken during site exploration or device explantation identified bacteria in 86% and 81% of procedures, respectively. Propionibacterium acnes and Staphylococcus non-aureus were the most commonly identified organisms.

CONCLUSIONS

The majority of patients with idiopathic pain in this cohort ultimately requiring CI explantation had chronic bacterial colonization.

LEVEL OF EVIDENCE

Level 4 (Case series) Laryngoscope, 2022.

Bone marrow mesenchymal stem cells offer an immune-privileged niche to Cutibacterium acnes in case of implant-associated osteomyelitis

Considered as some of the most devastating complications, Cutibacterium acnes (C. acnes)-related osteomyelitis are among the hardest infections to diagnose and treat. Mesenchymal stem cells (MSCs) secrete number of immunomodulatory and antimicrobial soluble factors, making them an attractive treatment for bacterial infection. In this study, we examined MSCs/C. acnes interaction and analyzed the subsequent MSCs and bacteria's behaviors. Human bone marrow-derived MSCs were infected by C. acnes clinical strain harvested from non-infected bone site. Following 3 h of interaction, around 4% of bacteria were found in the intracellular compartment. Infected MSCs increased the secretion of prostaglandin E2 and indolamine 2,3 dioxygenase immunomodulatory mediators. Viable intracellular bacteria analyzed by infrared spectroscopy and atomic force microscopy revealed deep modifications in the wall features. In comparison with unchallenged bacteria, the viable intracellular bacteria showed (i) an increase in biofilm formation on orthopaedical-based materials, (ii) an increase in the invasiveness of osteoblasts and (iii) persistence in macrophage, suggesting the acquisition of virulence factors. Overall, these results showed a direct impact of C. acnes on bone marrow-derived MSCs, suggesting that blocking the C. acnes/MSCs interactions may represent an important new approach to manage chronic osteomyelitis infections. STATEMENT OF SIGNIFICANCE: The interaction of bone commensal C. acnes with bone marrow mesenchymal stem cells induces modifications in C. acnes wall characteristics. These bacteria increased (i) the biofilm formation on orthopaedical-based materials, (ii) the invasiveness of bone forming cells and (iii) the resistance to macrophage clearance through the modification of the wall nano-features and/or the increase in catalase production.

Detecção de Cutibacterium acnes em amostras de tecidos de cirurgias limpas primárias do ombro – Parte I

Objective  The present study aimed to identify bacterial agents in shoulder surgery specimens from patients with no history of previous shoulder infection or surgery.

Methods  Tendon, bursa, and bone specimens were collected during surgery, stored in sterile dry bottles, and sent to a hospital-associated laboratory for culture growth analysis in media for aerobic and anaerobic agents. Findings from 141 samples from 47 shoulders were analyzed.

Results  The cultures were negative in 46 cases (97.8%) and in 140 samples (99.2%). The culture was positive in a single patient, with growth of Staphylococcus hominis from one of three specimens collected.

Conclusions  The rates of bacterial growth were not consistent with the international literature, indicating the low effectiveness of laboratory methods used in Brazil.

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.

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.

Effectiveness of topical adjuvants in reducing biofilm formation on orthopedic implants: an in vitro analysis

BACKGROUND AND HYPOTHESIS

The treatment of periprosthetic joint infection is complicated by the presence of residual biofilm, which resists eradication owing to bacterial adherence to orthopedic implants. The purpose of this study was to compare Bactisure (Zimmer Biomet, Warsaw, IN, USA), povidone-iodine (Betadine), and chlorhexidine gluconate solution (Irrisept; Irrimax, Gainesville, FL, USA) in reducing biofilm formation of Staphylococcus aureus, Staphylococcus epidermidis, and Cutibacterium acnes inoculated on cobalt-chrome, titanium, and stainless steel disks, representing metals commonly used for shoulder arthroplasty. The hypothesis was that there would be no significant difference in biofilm reduction among the 3 topical adjuvants.

METHODS

Strains of S aureus (ATCC 35556), S epidermidis (ATCC 35984), and C acnes (LMG 16711) were grown on cobalt-chrome, titanium, and stainless steel disks. For each strain, the disks were divided into 4 groups: (1) control, (2) povidone-iodine (Betadine), (3) chlorhexidine gluconate (Irrisept), and (4) Bactisure. Bacteria were grown on 5% sheep blood agar plates. Biofilm eradication was quantified using adenosine triphosphate bioluminescence and compared with controls 48 and 72 hours after implementation of the topical adjuvant.

RESULTS

At 72 hours after implementation of the topical adjuvant, a statistically significant reduction in colony-forming units was observed for all topical adjuvants across all tested metals, as compared with their respective control. With respect to the topical adjuvants themselves, Bactisure more consistently demonstrated the most significant reduction in colony-forming units across all bacteria when the tested medium was adjusted for, with the exception of S aureus, which showed similar results to Betadine at 72 hours.

CONCLUSION

By use of commonly encountered topical adjuvants on S aureus-, S epidermidis-, and C acnes-inoculated disks of various implant metals, a significant reduction in biofilm production was observed. Bactisure, a recent Food and Drug Administration-approved topical adjuvant, demonstrated the overall greatest efficacy of the agents studied.

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.].

Complications of reverse shoulder arthroplasty: a concise review

Reverse shoulder arthroplasty is an ideal treatment for glenohumeral dysfunction due to cuff tear arthropathy. As the number of patients treated with reverse shoulder arthroplasty is increasing, the incidence of complications after this procedure also is increasing. The rate of complications in reverse shoulder arthroplasty was reported to be 15%-24%. Recently, the following complications have been reported in order of frequency: periprosthetic infection, dislocation, periprosthetic fracture, neurologic injury, scapular notching, acromion or scapular spine fracture, and aseptic loosening of prosthesis. However, the overall complication rate has varied across studies because of different prosthesis used, improvement of implant and surgical skills, and different definitions of complications. Some authors included complications that affect the clinical outcomes of the surgery, while others reported minor complications that do not affect the clinical outcomes such as minor reversible neurologic deficit or minimal scapular notching. This review article summarizes the processes related to diagnosis and treatment of complications after reverse shoulder arthroplasty with the aim of helping clinicians reduce complications and perform appropriate procedures if/when complications occur.

Cutibacterium acnes infections in revision surgery for persistent shoulder complaints: a retrospective cohort study

INTRODUCTION

Low-grade Cutibacterium acnes (C. acnes) infections after shoulder surgery usually result in unexplained complaints. The absence of clinical signs of infection makes the incidence unclear and underreported. This study aimed to determine the incidence of C. acnes infections in patients with artificial material and unexplained persistent shoulder complaints. We hypothesized that the incidence of C. acnes infections would be higher in patients with artificial material. Risk factors and associations between culture time and contaminations/infections were also assessed.

MATERIALS AND METHODS

This retrospective cohort study included patients with and without artificial material undergoing revision shoulder surgery for persistent complaints after primary surgery and the suspicion of a low-grade infection. Three-six cultures were taken in all patients. C. acnes infection incidence was determined and logistic regression analysis was performed to identify risk factors. The association between time to culture growth and infections/contaminations was evaluated using Kaplan-Meier analysis and log-rank test.

RESULTS

26/61 (42.6%) patients with and 14/33 (42.2%) without material had a C. acnes infection. Age (OR 0.959; 95% CI 0.914-1.000) and BMI (OR 0.884; 95% CI 0.787-0.977) were risk factors. Time to C. acnes culture positivity was not different between infections and contaminations.

CONCLUSION

The incidence of C. acnes infections was 42.6% in patients with artificial material and 42.2% in patients without artificial material. Younger age and lower BMI are risk factors. Low-grade C. acnes infections should be considered in patients with unexplained persistent complaints following shoulder surgery.

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.

RSA, TSA and PyC hemi-prostheses: comparing indications and clinical outcomes using a second-generation modular short-stem shoulder prosthesis

INTRODUCTION

The goal of this study was to provide an insight into the clinical results after modular short-stem shoulder arthroplasty for various indications.

MATERIALS AND METHODS

A consecutive cohort study of 76 patients followed up for 23-55 (mean 31.4) months. 23 anatomical (TSA), 32 reverse (RSA) and 21 hemi-prostheses with a pyrocarbon head (PyC), using a modular short stem with proximal porous coating were implanted. Range of motion, pain and Constant score (CS) were recorded. Comparisons of pre- vs postoperative outcomes, between prosthesis types and indications, were made.

RESULTS

All prosthesis types brought about a significant improvement (p < 0.05) in all measured outcomes. TSA had a significantly higher increase in the CS than PyC and RSA (p = 0.002 and 0.003, respectively). TSA produced superior gains in all ROM compared with RSA (p < 0.02). RSA brought about significantly smaller improvements in internal rotation than TSA and PyC (p = 0.0001 and 0.008, respectively). TSA had greater pain relief than PyC (p = 0.02). TSA with Walch A glenoids seemed to improve more than type B in the CS. PyC patients with Walch B glenoids improved more than Walch A (p = 0.03). When implanted due to Osteoarthritis (OA), PyC had a comparable final outcome to TSA (p = 0.95), although the preoperatively worse TSA patients had a greater improvement in the CS (p = 0.026). The outcome of RSA did not differ between indications, but Walch A glenoids tended to improve more.

CONCLUSIONS

Using a second-generation short-stem shoulder prostheses, TSA achieves the best clinical improvements overall, especially for OA with a Walch A glenoid. Despite refixation of the subscapularis tendon in all cases, RSA has inferior internal rotation than TSA and PyC, suggesting a mechanical limitation. OA, a Walch B glenoid and arthritis caused by instability seem to be ideal indications when considering PyC.

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

BACKGROUND

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

METHODS

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

RESULTS

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

DISCUSSION

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

The management of infected shoulder arthroplasty by two-stage revision

BACKGROUND

There remains no gold standard management for deep shoulder periprosthetic joint infection (PJI). This case series aims to present our experience of two-stage revision arthroplasty, including eradication of infection and reoperation rates.

METHODS

We retrospectively reviewed patients undergoing revision arthroplasty for shoulder PJI between 2006 and 2015. Cases were confirmed using Musculoskeletal Infection Society (MSIS) and American Academy of Orthopaedic Surgeons (AAOS) guidelines. TSA removal, debridement and irrigation preceded antibiotic-loaded cement spacer insertion and a minimum of six weeks intravenous antibiotics. Reimplantation was performed as a second stage following a negative aspirate.

RESULTS

Twenty-eight patients underwent a first stage procedure (mean age 69 years; 16 male, 12 female). Propionibacterium acnes, Methicillin-sensitive Staphylococcus aureus, Coagulase-negative Staphylococcus and Staphylococcus epidermidis were the commonest microorganisms cultured. Five cases had mixed growths and six cases provided no growth. Three patients did not proceed to a second stage. Twenty-five patients underwent reimplantation (mean interval 6.7 months), with 80% remaining infection-free (mean follow-up 38.3 months).

DISCUSSION

Managing complex and late presentation shoulder PJI with two-stage revision is associated with high rates of infection eradication (80%). In the absence of a management consensus, our experience supports two-stage revision arthroplasty for eradicating infection in this complex patient group.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Cutibacterium colonization of the anterior and lateral thigh

AIMS

Of growing concern in arthroplasty is the emergence of atypical infections, particularly Cutibacterium (formerly Propionibacterium) sp. infections. Currently, the dermal colonization rate of Cutibacterium about the hip is unknown. Therefore, the aim of this study was to investigate colonization rates of Cutibacterium sp. at locations approximating anterior and posterolateral approaches to the hip joint.

METHODS

For this non-randomized non-blinded study, 101 adult patients scheduled for hip or knee surgery were recruited. For each, four 3 mm dermal punch biopsies were collected after administration of anaesthesia, but prior to antibiotics. Prebiopsy skin preparation consisted of a standardized preoperative 2% chlorhexidine skin cleansing protocol and an additional 70% isopropyl alcohol mechanical skin scrub immediately prior to biopsy collection. Two skin samples 10 cm apart were collected from a location approximating a standard direct anterior skin incision, and two samples 10 cm apart were collected from a lateral skin incision (suitable for posterior, direct-lateral, or anterolateral approaches). Samples were cultured for two weeks using a protocol optimized for Cutibacterium.

RESULTS

A total of 23 out of 404 cultures (collected from 101 patients) were positive for a microorganism, with a total of 22 patients having a positive culture (22%). Overall, 15 of the cultures in 14 patients were positive for Cutibacterium sp. (65%), of which Cutibacterium acnes comprised the majority (n = 13; 87%). Other isolated microorganisms include coagulase-negative Staphylococcus (n = 6), Clostridium (n = 1), and Corynebacterium (n = 1). Of all positive cultures, 15 were obtained from the anterior location (65%), of which seven (60%) were from the most proximal biopsy location. However, these findings were not statistically significant (anterior vs lateral, p = 0.076; proximal vs distal, p =0.238).

CONCLUSION

Approximately 14% (14/101) of the patients demonstrated a positive Cutibacterium colonization about the hip, the majority anteriorly. Given the high colonization rate of Cutibacterium, alternative skin preparations for total hip arthroplasty should be considered. Cite this article: Bone Joint J 2020;102-B(7 Supple B):52-56.

The Use and Adverse Effects of Oral and Intravenous Antibiotic Administration for Suspected Infection After Revision Shoulder Arthroplasty

BACKGROUND

When performing revision shoulder arthroplasty, surgeons do not have access to the results of intraoperative culture specimens and will administer empiric antibiotics to cover for the possibility of deep infection until the culture results are finalized. The purpose of this study was to report the factors associated with the initiation, modification, and adverse events of 2 different postoperative antibiotic protocols in a series of revision shoulder arthroplasties.

METHODS

In this study, 175 patients undergoing revision shoulder arthroplasty were treated with either a protocol of intravenous (IV) antibiotics if there was a high index of suspicion for infection or a protocol of oral antibiotics if the index of suspicion was low. Antibiotics were withdrawn if cultures were negative and were modified as indicated if the cultures were positive. Antibiotic course, modification, and adverse effects to antibiotic administration were documented.

RESULTS

On univariate analysis, factors significantly associated with the initiation of IV antibiotics were male sex (p < 0.001), history of infection (p < 0.001), intraoperative humeral loosening (p = 0.003), and membrane formation (p < 0.001). On multivariate analysis, male sex (p = 0.003), history of infection (p = 0.003), and membrane formation (p < 0.001) were found to be independent predictors of the initiation of IV antibiotics. On the basis of preoperative and intraoperative characteristics, surgeons anticipated the culture results in 75% of cases, and modification of antibiotic therapy was required in 25%. The modification from oral to IV antibiotics due to positive culture results was made significantly more often in male patients (p < 0.001). Adverse effects of antibiotic administration occurred in 19% of patients. The rates of complications were significantly lower in the patients treated with oral antibiotics and a shorter course of antibiotics (p < 0.001).

CONCLUSIONS

Complications associated with antibiotic administration after revision shoulder arthroplasty are not infrequent and are more common in patients whose initial protocol is IV antibiotics. Further study is needed to balance the effectiveness and risks of post-revision antibiotic treatment given the frequency of antibiotic-related complications.

LEVEL OF EVIDENCE

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

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

BACKGROUND

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

PURPOSE

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

STUDY DESIGN

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

CLINICAL SIGNIFICANCE

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

Is Cutibacterium acnes early surgical site infection rate related to the duration of antibiotic prophylaxis in adolescent idiopathic scoliosis surgery?

PURPOSE

Cutibacterium acnes (C. acnes) is a gram-positive anaerobic bacillus located in pilosebaceous glands, usually responsible for late postoperative surgical site infections (SSI). A recent study performed in our institution highlighted an unexpected emergence of C. acnes early SSI. One potential explanation was the change of the perioperative antibioprophylaxis (ATB) protocol, which switched from 48 h postoperative cefamandole to intraoperative only cefazoline. The aim of this study was therefore to investigate the influence of the ATB duration on the occurrence of C. acnes early SSI, by comparing the incidence rates during 3 consecutive ATB protocols.

METHODS

Between January 2007 and September 2017, all patients who underwent posterior fusion for AIS were retrospectively reviewed. Early C. acnes SSI were reported and compared between 3 periods, during which the ATB protocols were modified. January 2007-February 2012: Intraoperative Cefamandole continued 48 h (protocol 1) March 2012-August 2016: Single shot of intraoperative Cefazoline (protocol 2) September 2016-September 2017: Intraoperative Cefazoline continued 48 h (protocol 3).

RESULTS

Fifty-three early SSI (7.2%) were reported among the 732 posterior AIS fusions included. Global incidence of C. acnes infection was 2.9%. The incidence of C. acnes in early SSI increased from 0 to 4.9% between protocol 1 and 2, but was reduced to 1.7% with protocol 3.

CONCLUSIONS

Early C acnes SSI can be explained by the difficulty to eradicate this pathogen with current skin preparation procedures and some Beta-lactam antibiotics tolerance. Longer duration antibioprophylaxis is preferable to prevent from early C. acnes SSI.

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.

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

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

Periprosthetic Infections of the Shoulder: Diagnosis and Management

The use of shoulder arthroplasty is continuing to expand. Periprosthetic joint infection of the shoulder is a devastating complication occurring in approximately 1% of cases. The most common organisms responsible for the infection are Cutibacterium acnes (formerly Propionibacterium acnes) (∼39%) and coagulase-negative Staphylococcus (∼29%). Evaluation of patients includes history and physical examination, serologic testing, imaging, possible joint aspiration, and tissue culture. Diagnosing infections caused by lower virulence organisms (eg, C acnes) poses a challenge to the surgeon because traditional diagnostic tests (erythrocyte sedimentation rate, C-reactive protein, and joint aspiration) have a low sensitivity due to the lack of an inflammatory response. Periprosthetic joint infections of the shoulder due to Staphylococcus aureus and other highly virulent organisms are often easy to diagnose and are usually treated with two-stage revisions. However, for infections with C acnes and coagulase-negative Staphylococcus, single- and two-stage revision surgeries have shown similar ability to clear the infection. Unexpected positive cultures for C acnes during revision surgery are not uncommon; the proper management is still under investigation and remains a challenge.

Capsular needle biopsy as a pre-operative diagnostic test for peri-prosthetic shoulder infection

BACKGROUND

Establishing the diagnosis of peri-prosthetic shoulder infection prior to revision shoulder arthroplasty can be difficult. The objectives of the present study were (i) to describe the technique of fluoroscopic capsular needle biopsy for the diagnosis of peri-prosthetic shoulder infection and (ii) to determine the feasibility and preliminary accuracy of the test in a pilot sample of patients undergoing revision shoulder arthroplasty.

METHODS

Eighteen patients, comprising eight females and nine males with a mean age of 61 years (range 37 years to 81 years) underwent capsular needle biopsy during the work-up of suspected chronic arthroplasty-related glenohumeral infection. Intra-operative tissue samples were taken from a minimum of three regions of the joint capsule during revision surgery. Standard serum indices were obtained.

RESULTS

Of 17 patients with possible infection, five had confirmed culture positive infections based on intra-operative biopsies. Of these five patients, four (80%) had positive cultures from fluoroscopic capsular needle biopsy, with matching cultures. There were no complications. No culture-positive patients had elevated serum indices for infection.

CONCLUSIONS

The technique for fluoroscopic capsular needle biopsy appears to be feasible and the preliminary results for this technique appear to be promising, with a sensitivity of 80% and a specificity of 100%.Level of evidence: Level II: diagnostic test.

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.

Application of dermal chlorhexidine antisepsis is ineffective at reducing Proprionibacterium acnes colonization in shoulder surgery

BACKGROUND

Chlorhexidine as a skin surface antiseptic has been shown to be ineffective with respect to reducing Proprionibacterium acnes colonization within the dermis. The purpose of the present study was to determine whether the application of aqueous chlorhexidine solution to the dermal layer decreased P. acnes colonization during open shoulder surgery.

METHODS

The present study enrolled 50 patients who were undergoing open shoulder surgery. Patients received standard antimicrobial preparation. Three dermal swabs were taken from each patient: swab 1 following skin incision; swab taken 2 minutes to 5 minutes post-application of aqueous chlorhexidine to the dermis; and swab 3 taken 60 minutes post-application.

RESULTS

Mean age was 57.5 years (22 males, 28 females). There were 21 patients (42%) with P. acnes present on any dermal swab. There were significantly more P. acnes positive cultures identified at swab 3 compared to swab 1 (p = 0.043). In nine patients with positive P. acnes at cultures swab 1, eight also isolated P. acnes after at swabs 2 or 3. Males were significantly more likely to have P. acnes on any swab (p < 0.001). Positive P. acnes cultures were significantly more common in patients ≤50 years (p < .001). None of the patients had any clinical signs of infection at a minimum of 1 year following surgery.

CONCLUSIONS

Dermal application of aqueous chlorhexidine during open shoulder surgery fails to eradicate or reduce P. acnes on deep cultures.