Propionibacterium in Shoulder Arthroplasty: What We Think We Know Today

One- or two-stage exchange for periprosthetic shoulder infection: Systematic review and meta-analysis

INTRODUCTION

One-stage exchange is the gold-standard for management of periprosthetic shoulder infection. The present review compares efficacy between 1- and 2-stage exchange in this indication.

MATERIAL AND METHODS

We performed a systematic literature review and meta-analysis following the "Preferred Reporting Items for Systematic Reviews and Meta-Analyses" (PRISMA) criteria. The literature search used the Medline, Embase and Central data-bases. The studies included assessed 1- and 2-stage exchange in periprosthetic shoulder infection. The main outcome was reinfection rate, and the secondary outcome postoperative complications rate.

RESULTS

Twenty-one studies, for 501 patients, were included: 5 assessing 1-stage exchange, 11 2-stage, and 5 both. Mean follow-up was 4.3 years (range, 2-6.1 years). Mean reinfection rates ranged between 0 and 50% in 1-stage exchange and between 0 and 36.8% in 2-stage exchange. The combined rate was 7% (95% CI, 3.8-12.5%) in 1-stage and 21.3% (95% CI, 16-27.9%) in 2-stage exchange. Mean complications rates ranged between 0 and 50% in 1-stage exchange and between 5.7% and 73%% in 2-stage exchange. The combined rate was 17% (95% CI, 11.9-23.9%) in 1-stage and 32.8% (95% CI, 25.8-40.6%) in 2-stage exchange.

DISCUSSION

To our knowledge, the present meta-analysis is the first to assess results in 1- and 2-stage exchange for chronic periprosthetic shoulder infection.

CONCLUSION

One-stage exchange seemed to provide better results, with less reinfection and fewer complications than 2-stage exchange.

LEVEL OF EVIDENCE

I, meta-analysis.

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.

Incidence of Propionibacterium acnes in arthroscopic rotator cuff repair

BACKGROUND

Recently, Propionibacterium acnes was reported to be involved in postsurgical outcomes. We investigated the detection rate of P. acnes and clinical features of P. acnes infection following arthroscopic rotator cuff repair.

METHODS

Samples were collected from skin swabs before preparation, swabs of the synovium, sutures, and swabs from the arthroscope tip. We evaluated age, sex, presence of diabetes mellitus, preoperative contracture, operation time, blood test, Japanese Orthopaedic Association (JOA) scores, cuff integrity, deep infection, and positive inoculation rate.

RESULTS

We studied 90 patients (59 men and 31 women). Mean age was 60.6 years. Cultures of P. acnes showed a 65.5% positive superficial colonization rate (78.0%, male; 41.9%, female). Among the synovium swabs, P. acnes was detected in 13.6% and 0% of patients positive and negative for skin colonization with P. acnes, respectively. Positive culture was not correlated with age, sex, presence of diabetes mellitus, preoperative contracture, blood test, JOA score, cuff integrity, deep infection, operation time, and blood test date.

CONCLUSIONS

P. acnes was detected at a higher rate in the skin of male patients. Patients with P. acnes detected on the skin showed higher rates of detection in the synovium. These findings suggest that the route of infection is via contamination.

LEVEL OF EVIDENCE

Diagnostic level III; Case-control study.

Editorial Commentary: In Search of the Optimal Diagnostic Tool for Periprosthetic Joint Infections of the Shoulder

A number of perioperative diagnostic tests are currently available to evaluate for the presence of periprosthetic joint infection (PJI) in painful shoulder arthroplasties. However, data on the utility of these tests are more limited in the shoulder, with worse diagnostic performance compared with the evaluation of hip and knee PJI because of the low virulence of the commonly cultured shoulder organisms, such as Cutibacterium acnes. Diagnostic arthroscopy with culturing of arthroscopic tissue samples may allow for a more definitive diagnosis and treatment planning in patients with shoulder PJI prior to revision shoulder arthroplasty, but data on the efficacy of this procedure have been limited.

Late Spinal Implant Infection caused by Cutibacterium acnes

Cutibacterium spp. have been frequently associated with foreign-body material infections. The vast majority of these infections occur via the exogenous route. Rarely, haematogenous infections occur, possibly seeding from pilosebaceous glands. A late spinal implant-associated infection is presented in this case report, and the possible sources of haematogenous seeding are discussed.

Is Implant Coating With Tyrosol- and Antibiotic-loaded Hydrogel Effective in Reducing Cutibacterium (Propionibacterium) acnes Biofilm Formation? A Preliminary In Vitro Study

BACKGROUND

Studies have suggested that Cutibacterium acnes (formerly known as Propionibacterium) is the most frequently isolated pathogen after shoulder arthroplasty. To address the burden of periprosthetic joint infections associated with this pathogen, new prevention methods are needed. Tyrosol has a promising record of effectiveness in the field of biofilm-associated infections; however, to our knowledge, it has not been tested against C. acnes thus far.

QUESTIONS/PURPOSES

In this in vitro study, we asked: (1) Is tyrosol effective in inhibiting and eradicating C. acnes planktonic growth? (2) Is there synergy between tyrosol and rifampicin? (3) Is supplementation of hydrogel with tyrosol at the minimum inhibitory and subinhibitory concentrations efficacious in reducing free-floating C. acnes growth? (4) Is implant hydrogel coating (either alone or combined with tyrosol, rifampicin, or vancomycin) beneficial in reducing C. acnes biofilm formation? (5) Is the administration of soluble tyrosol an effective measure against C. acnes biofilm formation?

METHODS

We assessed C. acnes planktonic growth and eradication by inspecting visually the results of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays. We also evaluated macroscopically the presence of synergy among tyrosol and rifampicin by means of the MIC checkerboard testing. Thereafter, we addressed colorimetrically the efficacy of tyrosol-loaded Defensive Antibacterial Coating (DAC®) hydrogel against the C. acnes free-floating form by means of the XTT cell proliferation reduction assay. Then, we explored photometrically the effect of hydrogel and soluble tyrosol at reducing C. acnes biofilm formation on titanium alloy disks that simulated orthopaedic implants by using the minimum biofilm inhibition concentration assay. In particular, 16 disks were sequentially allocated to each of the following testing conditions: (1) hydrogel alone; (2) tyrosol-loaded hydrogel; (3) rifampicin-supplemented hydrogel; (4) vancomycin-loaded hydrogel; and (5) soluble tyrosol. Subsequently, implants were sonicated and cell viability was evaluated in terms of the XTT assay.

RESULTS

Tyrosol was effective in inhibiting C. acnes planktonic (free-floating) growth demonstrating MIC values of 63 mM (9 mg/mL) and MBC values of 250 mM (35 mg/mL). Concerning synergy assessment, the checkerboard testing revealed additivity among tyrosol and rifampicin with a fractional inhibitory concentration index of 0.56. In addition, a hydrogel coating with tyrosol at the MIC showed no difference in the inhibition of free-floating C. Acnes form over control (median absorbance [MA] for tyrosol-supplemented hydrogel versus control groups were 0.21 [interquartile range {IQR}, 0.19-0.24] versus 0.26 [IQR, 0.23-0.31], p = 0.066). Furthermore, loaded hydrogel with tyrosol at 597 mg/mL (1 M) was no more effective than control in reducing C. acnes biofilm formation (MAs for tyrosol versus control were 0.12 [IQR, 0.11-0.13] versus 0.14 [IQR, 0.12-0.16], respectively; p = 0.076). This was also the case when we considered hydrogel in conjunction with vancomycin and rifampicin (MAs for vancomycin at 2% and 5% and rifampicin at 1% versus biofilm control were 0.139 [IQR, 0.133-0.143] and 0.141 [IQR, 0.133-0.143] and 0.135 [IQR, 0.128-0.146] versus 0.142 [IQR, 0.136-0.144], correspondingly). In contrast, soluble tyrosol at 597 mg/mL (1 M) inhibited biofilm formation compared to control (MAs for tyrosol and control groups were 0.11 [IQR, 0.09-0.13] versus 0.13 [IQR, 0.12-0.14], p = 0.007).

CONCLUSIONS

Although the implant coating with hydrogel (either pure or supplemented with antimicrobial agents) did not diminish C. acnes biofilm development in vitro, soluble tyrosol at 597 mg/mL (1 M) exceeded the meaningful biofilm inhibition threshold of 80%.

CLINICAL RELEVANCE

The results of the current preclinical investigation did not support the use of a fast, bioresorbable hydrogel as a coating method against C. acnes biofilms. Instead, direct local administration of soluble tyrosol at high concentrations should be further tested in future animal studies.

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.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

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.

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

The Second International Consensus Meeting on Orthopedic Infections was held in Philadelphia, Pennsylvania, in July 2018. A multidisciplinary team of international experts from all 9 subspecialties of orthopedic surgery and allied fields of infectious disease, microbiology, and epidemiology was assembled to form the International Consensus Group. The following consensus proceedings from the International Consensus Meeting involve 30 questions pertaining to the management of periprosthetic shoulder infection.

Cutibacterium (formerly Propionibacterium) acnes clavicular infection

Cutibacterium (formerly Propionibacterium) acnes^{13, 16} is a slow growing, gram-positive bacteria that is naturally found in higher concentrations as skin flora on the chest and back, as well as in other areas with greater numbers of hair follicles.^{25, 37} Most of the reported cases of C. acnes shoulder girdle infection follow arthroplasty surgery,^{18, 20, 26, 27, 32, 35} which then often requires debridement, administration of intravenous antibiotics, and surgical revision of the implanted device.^{12, 15, 21, 28-30} In a recent study, 56% of 193 shoulder revisions had a positive culture, 70% of which grew C. acnes.³⁰ Despite the relatively common presumed association of C. acnes humeral osteomyelitis with prosthetic infection, infection of the scapula or clavicle secondary to C. acnes is rare.^{4, 23, 36} Osteomyelitis of the clavicle involving any organism is also an uncommon event that can arise spontaneously via presumed hematogenous spread, or secondary to open fractures or internal fixation.^{6, 33} The most commonly found organism in clavicular osteomyelitis is Staphylococcus aureus.⁹ We here report two cases of clavicular infection secondary to C. acnes that were not associated with implants.

Outcomes of revision arthroplasty for shoulder periprosthetic joint infection: a three-stage revision protocol

BACKGROUND

This study evaluated outcomes after treatment of shoulder periprosthetic joint infection (PJI) with a 3-stage revision protocol consisting of (1) débridement, explantation, and cement spacer placement, followed by parenteral antibiotics; (2) open biopsy and débridement; and (3) reimplantation if cultures were negative. We hypothesized this protocol would eradicate persistent infection while producing excellent functional and subjective outcomes, and there would be no difference in these parameters for patients with shoulder PJI compared with patients with revision for aseptic indications.

METHODS

We retrospectively analyzed a prospectively collected revision shoulder arthroplasty cohort to identify shoulder PJI patients treated with a 3-stage protocol. Demographics, culture data, range of motion, and patient-reported outcomes were collected. Outcomes for patients with shoulder PJI and revision to RTSA were compared with patients revised to RTSA for noninfectious indications. Significance was defined as P < .05.

RESULTS

There were 28 cases of shoulder PJI in 27 patients (age, 66.4 ± 11.2 years,); of these, 21 shoulders were revised to RTSA, and 7 shoulders were revised to hemiarthroplasty. There was no recurrent infection at a mean 32-month follow-up. One year after surgery, mean forward flexion was 110° ± 41° and abduction was 106° ± 42°. Mean final American Shoulder and Elbow Surgeons subjective score was 66.5 ± 23.3. The 21 shoulders with PJI revised to RTSA had no differences for functional and subjective outcomes compared with revised patients without shoulder PJI.

CONCLUSIONS

A 3-stage revision protocol for shoulder PJI reliably eradicated infection. Patients with PJI revised to RTSA can have similar outcomes as patients with noninfectious revision to RTSA.

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

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

Imaging of Shoulder Arthroplasties

OBJECTIVE

In this article, we review the preoperative imaging features used for planning shoulder arthroplasty as well as review the various shoulder arthroplasty component types, discussing the expected normal imaging features and specific complications to look for with each.

CONCLUSION

Given the increasing use of shoulder arthroplasty, it is important to understand the imaging features of the various shoulder arthroplasty complications.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Propionibacterium acnes Suture Contamination in Arthroscopic Rotator Cuff Repair: A Prospective Randomized Study

PURPOSE

To examine the contamination rate of the anchor-suture and to determine the efficacy of 2 different surgical skin preparation solutions with or without a plastic adhesive drape from suture contamination in arthroscopic rotator cuff repair.

METHODS

A prospective randomized study was undertaken to evaluate 126 consecutive patients undergoing arthroscopic rotator cuff repair. Each shoulder was prepared with one of 2 randomly selected solutions according to an assigned envelope that indicated the procedure to be used: chlorhexidine-alcohol (1% chlorhexidine gluconate and 70% isopropyl alcohol) or povidone-iodine. Then, each group was further divided according to the usage of a plastic drape. The first cut-tails of the anchor-suture after cuff fixation were submitted to aerobic and anaerobic cultures.

RESULTS

The overall rate of Propionibacterium acnes-positive cultures was 47% (14 of 31 cases) in the povidone-iodine group, 33% (11 of 33 cases) in the povidone-iodine with a drape group, 33% (10 of 30 cases) in the chlorhexidine-alcohol group, and 9.3% (3 of 32 cases) in the chlorhexidine-alcohol with a drape group. The positive culture rate in the chlorhexidine-alcohol with a drape group was lower than that in the povidone-iodine group (relative risk, 0.2; 95% confidence interval: 0.064-0.63; number needed to treat, 2.7; P < .0001). Coagulase-negative staphylococci were isolated in the povidone-iodine with a drape (1 case) and chlorhexidine-alcohol with a drape group (2 cases). No other bacteria were isolated, and no infections occurred in any of the patients treated in this study during the minimum 12-month follow-up period.

CONCLUSIONS

Chlorhexidine-alcohol solution with an adhesive plastic drape was more effective than chlorhexidine-alcohol without a plastic drape and povidone-iodine with/without a plastic drape in eliminating P acnes suture contamination. However, the usage of a plastic drape slightly increased the risk of coagulase-negative Staphylococcus proliferation.

LEVEL OF EVIDENCE

Level I, therapeutic, prospective, randomized trial.

Propionibacterium acnes infections in patients with idiopathic scoliosis: a case-control study and review of the literature

PURPOSE

Surgical site infection (SSI) caused by Propionibacterium acnes is an infrequent but devastating complication after spinal fusion. The purpose of this study was to identify risk factors for SSI with Propionibacterium acnes after spinal fusion for juvenile and adolescent idiopathic scoliosis (JIS and AIS).

METHODS

A case-control study was performed. Each case was matched 2:1 for age, gender and diagnosis. Retrospective chart review was performed to obtain relevant demographic, surgical and clinical data for all cases and controls. Statistical analysis included paired t-test and McNemar test, as well as exact logistic regression and robust regression models.

RESULTS

This study included ten infection cases (eight AIS, two JIS) and 20 controls (16 AIS, four JIS). In total, six infected cases presented within two weeks of the index procedure (acute infection) and four infected cases presented more than one year from the index procedure (delayed infection). The most common presentation for acute infections was wound drainage, while back pain was more common in delayed infections. All infections were successfully treated with surgical irrigation and debridement and postoperative antibiotics. Hardware was removed for patients with delayed infections. The strongest risk factor for infection was increased requirement for blood transfusion, but it did not reach statistical significance.

CONCLUSION

SSI with Propionibacterium acnes is an important complication after spinal fusion for idiopathic scoliosis. These infections can be successfully treated, but larger studies are needed to further identify risk factors and establish standardized guidelines for the treatment and prevention of this complication.

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

Background:

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

Methods:

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

Results:

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

Conclusions:

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

Clinical Relevance:

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

Propionibacterium acnes and Staphylococcus epidermidis olecranon bursitis/osteomyelitis: a case involving surgical and antibiotic treatment

This report describes a 63-year-old generally healthy male with septic olecranon bursitis caused by Propionibacterium acnes The patient sustained a small laceration after striking the posterior aspect of his left elbow on a metal railing when he was at a public swimming pool. We concluded that P. acnes was not initially detected because cultures were only kept for 5 days. Consequently, initial antibiotic treatment failed. P. acnes and Staphylococcus epidermidis grew in a subsequent tissue culture. The infection did not respond to intravenous vancomycin although soft-tissue debridements were done. This likely reflected the presence of olecranon osteomyelitis (seen on MRI scans) in addition to inadequate treatment with this antibiotic in the setting of a polymicrobial infection. Eventually, the infection was eradicated with multiple soft-tissue debridements in addition to the continuation of vancomycin with daily intravenous piperacillin/tazobactam that was added for the final 4 weeks of antibiotic treatment.

Do Elevated Inflammatory Markers Associate With Infection in Revision Shoulder Arthroplasty?

Background

Serologic erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) measurements, which have been successfully utilized in the lower extremity, are thought to lack adequate sensitivity in the diagnosis of infection after shoulder arthroplasty. The purpose of this study is to determine the diagnostic performance of preoperative white blood cell (WBC) count, ESR, and CRP in the diagnosis of infection in the setting of revision shoulder arthroplasty with the gold standard of infection being defined as a later diagnosis of infection.

Patients and methods

A national insurance database between the years of 2007 and 2015 (PearlDiver, Warsaw, IN) was queried for those patients who underwent revision shoulder arthroplasty using a combination of procedural (common procedural terminology codes 23472 and 23474) and diagnostic codes (International Classification of Diseases [ICD]-9 code 81.97 and equivalent ICD-10 codes). This database contains demographics, laboratory data, and complication data to allow identification of patients with an infection within 1 year postoperatively.

Results

The database contained 1392 patients who met criteria. Among these, the best diagnostic performance was with a combined test which was positive if CRP, ESR, or WBC was positive with a sensitivity of 7% to 42%, a specificity of 92%, a positive predictive value of 8% to 45%, a negative predictive value of 91%, and an accuracy of 84% to 85%. On multivariate analyses, predictors included an abnormal ESR (odds ratio 2.4, P = .05) and male gender (3.8, <.001).

Conclusions

Those patients with an abnormal preoperative ESR have significantly increased odds of a subsequent infection following revision shoulder arthroplasty. ESR, CRP, and WBC in combination are specific but insensitive. Level of Evidence: Diagnostic, Level III

Routine cultures for seemingly aseptic revision shoulder arthroplasty: are they necessary?

Propionibacterium acnes has recently gained attention as the leading cause of periprosthetic joint infections (PJIs) after shoulder arthroplasty. Unlike PJIs in the lower extremity, PJIs after shoulder arthroplasty usually have an indolent course and are notoriously difficult to diagnose. Most of the time, the diagnosis is made after positive intraoperative cultures are taken at the time of revision surgery. Adding even more complexity to the diagnosis is the high rate of P acnes-positive cultures taken at the time of primary shoulder surgery. In many cases the preoperative workup yields no suspicion for infection; however, intraoperative cultures are taken to completely eliminate the potential of an ongoing indolent infection. Concerns over how to interpret positive P acnes culture results and the high rate of culture positivity in primary shoulder arthroplasty, as well as the potentially high rate of contamination, have led surgeons to wonder about the utility of obtaining intraoperative cultures at the time of revision shoulder arthroplasty. We present evidence for and against the practice of obtaining routine intraoperative cultures at the time of seemingly aseptic revision shoulder arthroplasty.