Prevention of Propionibacterium acnes biofilm formation in prosthetic infections in vitro

Chronic preoperative steroid use and total shoulder arthroplasty: a propensity score matched analysis of early-onset infectious outcomes

BACKGROUND

While the role of chronic preoperative steroid use in orthopedic outcomes has been studied, particularly in hip, knee, and lumbar surgeries, its impact on total shoulder arthroplasty (TSA) outcomes is not well understood. This study aimed to evaluate the impact of chronic preoperative steroid use on early-onset postoperative infectious outcomes and readmission within 30 days following TSA compared to patients without chronic steroid use.

METHODS

A retrospective analysis was performed using data from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) spanning from 2010-2018. Clinical data including preoperative demographics, operative variables, and 30-day post-TSA outcomes were collected. Groups were balanced using propensity score matching based on gender, age, race, ethnicity, BMI, functional status, ASA, smoking status, alcohol use, year of operation, and comorbidities. A conditional logistic regression model was used to calculate odds ratios for each outcome measure.

RESULTS

A total of 3,445 identified cases were included in this analysis after propensity score matching, with 1,157 exhibiting chronic steroid use. The steroid group demonstrated significantly greater rates of readmission (OR: 1.86; 95% CI: 1.22-2.81; P = 0.004). No significant differences were observed between groups in all other adverse outcomes, including reoperation, specific infectious outcomes, and combined infectious outcomes.

CONCLUSIONS

Preoperative chronic steroid use is an independent predictor of readmission but not infection following TSA. While the surgeon should be aware of the increased risk of readmission associated with chronic steroid use, the role of steroid use as a risk factor for postoperative infections following TSA may be less pronounced, particularly compared to surgeries of other joints. Further investigation of infectious outcomes and readmissions with longer follow-up is needed to clarify the specific role of chronic preoperative steroid use in adverse outcomes following TSA.

In Vivo Intra-Articular Antibiotic Concentrations at 24 Hours After TKA Fall Below the Minimum Inhibitory Concentration for Most Bacteria: A Randomized Study of Commercially Available Bone Cement

BACKGROUND

The use of antibiotic-loaded bone cement (ALBC) to help reduce the risk of infection after primary total knee arthroplasty (TKA) is controversial. There is a paucity of in vivo data on the elution characteristics of ALBC. We aimed to determine whether the antibiotic concentrations of 2 commercially available ALBCs met the minimum inhibitory concentration (MIC) and minimum biofilm eradication concentration (MBEC) for common infecting organisms.

METHODS

Forty-five patients undergoing TKA were randomized to receive 1 of the following: bone cement without antibiotic (the negative control; n = 5), a commercially available formulation containing 1 g of tobramycin (n = 20), or a commercially available formulation containing 0.5 g of gentamicin (n = 20). Intra-articular drains were placed, and fluid was collected at 4 and 24 hours postoperatively. An automated immunoassay measuring antibiotic concentration was performed, and the results were compared against published MIC and MBEC thresholds.

RESULTS

The ALBC treatment groups were predominantly of White (65%) or Black (32.5%) race and were 57.5% female and 42.4% male. The mean age (and standard deviation) was 72.6 ± 7.2 years in the gentamicin group and 67.6 ± 7.4 years in the tobramycin group. The mean antibiotic concentration in the tobramycin group was 55.1 ± 37.7 μg/mL at 4 hours and 19.5 ± 13.0 μg/mL at 24 hours, and the mean concentration in the gentamicin group was 38.4 ± 25.4 μg/mL at 4 hours and 17.7 ± 15.4 μg/mL at 24 hours. Time and antibiotic concentration had a negative linear correlation coefficient (r = -0.501). Most of the reference MIC levels were reached at 4 hours. However, at 24 hours, a considerable percentage of patients had concentrations below the MIC for many common pathogens, including Staphylococcus epidermidis (gentamicin: 65% to 100% of patients; tobramycin: 50% to 85%), methicillin-sensitive Staphylococcus aureus (gentamicin: 5% to 90%; tobramycin: 5% to 50%), methicillin-resistant S . aureus (gentamicin: 5% to 65%; tobramycin: 50%), Streptococcus species (gentamicin: 10% to 100%), and Cutibacterium acnes (gentamicin: 10% to 65%; tobramycin: 100%). The aforementioned ranges reflect variation in the MIC among different strains of each organism. Gentamicin concentrations reached MBEC threshold values at 4 hours only for the least virulent strains of S . aureus and Escherichia coli. Tobramycin concentrations did not reach the MBEC threshold for any of the bacteria at either time point.

CONCLUSIONS

The elution of antibiotics from commercially available ALBC decreased rapidly following TKA, and only at 4 hours postoperatively did the mean antibiotic concentrations exceed the MIC for most of the pathogens. Use of commercially available ALBC may not provide substantial antimicrobial coverage following TKA.

LEVEL OF EVIDENCE

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

DISCUSSION

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

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.

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.

Cutibacterium acnes phylogenetic type IC and II isolated from patients with non-acne diseases exhibit high-level biofilm formation

Cutibacterium (formerly Propionibacterium) acnes is an important for not only exacerbating factor of acne vulgaris but also pathogen of surgical site infections (SSIs) in orthopedics and plastic surgery. Although biofilm-forming (BF) C. acnes are associated with intractable SSI, characteristics of these strains were still unknown. Here, we explored detailed molecular epidemiological features of BF C. acnes isolated as causative pathogen of infectious diseases. Phylogenetic types of 205 C. acnes strains isolated between 2013 and 2018 from 18 clinical departments of a university hospital in Japan were determined by single-locus sequence type (SLST). Clade H (traditional type IC) and K (type II) which are less relevant with healthy skin and acne vulgaris, were detected in 26.8% (55/205) and 16.1% (33/205) of the strains, respectively. The incidence of them was significantly higher than that of acne patients (H and K, each 2.9%, P < 0.05). In addition, SLST distribution of C. acnes strains differed by each department and isolation site. When biofilm formation was quantified, 51 strains (24.9%) were defined as high-BF strains. Notably, most high-BF strains were classified into the strains of clade H (56.4%, 31/55) and clade K (54.4%, 18/33), and these strains were frequently found in the strains isolated from patients of medical emergency center and plastic surgery. Similarly, high-BF strains were frequently found among the isolates from blood (35.7%) and catheters (30.0%), with a high proportion belonging to clades H and K. Compared to C. acnes strains isolated from acne patients, antimicrobial-resistant strains were less identified in non-acne patients. Our findings showed that pathogenicity of C. acnes strains differs by their phylogenetic types. Furthermore, we showed clade H and K have the ability of high biofilm formation and suggest that these strains have potential to become a risk factor for SSI.

Antibiotic loaded β-tricalcium phosphate/calcium sulfate for antimicrobial potency, prevention and killing efficacy of Pseudomonas aeruginosa and Staphylococcus aureus biofilms

This study investigated the efficacy of a biphasic synthetic β-tricalcium phosphate/calcium sulfate (β-TCP/CS) bone graft substitute for compatibility with vancomycin (V) in combination with tobramycin (T) or gentamicin (G) evidenced by the duration of potency and the prevention and killing efficacies of P. aeruginosa (PAO1) and S. aureus (SAP231) biofilms in in vitro assays. Antibiotic loaded β-TCP/CS beads were compared with antibiotic loaded beads formed from a well characterized synthetic calcium sulfate (CS) bone void filler. β-TCP/CS antibiotic loaded showed antimicrobial potency against PAO1 in a repeated Kirby-Bauer like zone of inhibition assay for 6 days compared to 8 days for CS. However, both bead types showed potency against SAP231 for 40 days. Both formulations loaded with V + T completely prevented biofilm formation (CFU below detection limits) for the 3 days of the experiment with daily fresh inoculum challenges (P < 0.001). In addition, both antibiotic loaded materials and antibiotic combinations significantly reduced the bioburden of pre-grown biofilms by between 3 and 5 logs (P < 0.001) with V + G performing slightly better against PAO1 than V + T. Our data, combined with previous data on osteogenesis suggest that antibiotic loaded β-TCP/CS may have potential to stimulate osteogenesis through acting as a scaffold as well as simultaneously protecting against biofilm infection. Future in vivo experiments and clinical investigations are warranted to more comprehensively evaluate the use of β-TCP/CS in the management of orthopaedic infections.

Debridement, antibiotic pearls, and retention of the implant in the treatment of infected total hip arthroplasty

In this article the authors describe a modified surgical technique developed to enhance the classical irrigation and debridement procedure to improve the possibilities of retaining a total hip arthroplasty (THA) undergoing acute periprosthetic joint infection (PJI). This technique, debridement antibiotic pearls and retention of the implant (DAPRI), aims to remove the intra-articular biofilm allowing a higher and prolonged local antibiotic concentration by using calcium sulphate antibiotic-added beads. The combination of 3 different surgical techniques (tumour-like synovectomy, Argon Beam application and chlorhexidine gluconate brushing) might enhance the disruption and removal of the bacterial biofilm which is the main responsible of antibiotics and antibodies resistance. The timing of the diagnosis (6 weeks from the original surgery or 1 week from clinical symptoms appearance in the case of an hematogenous infection) and the preoperative isolation of the germ are fundamental in order to obtain a satisfactory outcome. A 12-week course of postoperative antibiotic therapy (6 weeks I.V. and 6 weeks oral) complete the postoperative protocol used by the authors.The DAPRI technique might represent a safe and more conservative treatment for acute and early hematogenous PJI.

Radial Extracorporeal Shock Wave Therapy Against Cutibacterium acnes Implant-Associated Infections: An in Vitro Trial

BACKGROUND

Antibiotic management of low-virulent implant-associated infections induced by Cutibacterium acnes may be compromised by multi-drug resistance development, side effects, and increased cost. Therefore, we sought to assess the effects of shock wave therapy against the above pathogen using an in vitro model of infection.

METHODS

We used a total of 120 roughened titanium alloy disks, simulating orthopedic biomaterials, to assess the results of radial extracorporeal shock wave therapy (rESWT) against C. acnes (ATCC 11827) biofilms relative to untreated control. In particular, we considered 1.6 to 2.5 Bar with a frequency ranging from 8-11 Hz and 95 to 143 impulses per disk to investigate the antibacterial effect of rESWT against C. acnes planktonic (free-floating) and biofilm forms.

RESULTS

Planktonic bacteria load diminished by 54% compared to untreated control after a 1.8-bar setting with a frequency of 8 Hz and 95 impulses was applied (median absorbance (MA) for intervention vs. control groups was 0.9245 (IQR= 0.888 to 0.104) vs. 0.7705 (IQR = 0.712 to 0.864), respectively, p = 0.001). Likewise, a statistically significant reduction in the amount of biofilm relative to untreated control was documented when the above setting was considered (MA for treatment vs biofilm control groups was 0.244 (IQR= 0.215-0.282) and 0.298 (IQR = 0.247-0.307), respectively, p = 0.033).

CONCLUSION

A 50% biofilm eradication was documented following application of low-pressure and low-frequency radial shock waves, so rESWT could be investigated as an adjuvant treatment to antibiotics, but it cannot be recommended as a standalone treatment against device-associated infections induced by C. ances.

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.

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.

Regulation of Monospecies and Mixed Biofilms Formation of Skin Staphylococcus aureus and Cutibacterium acnes by Human Natriuretic Peptides

Staphylococcus aureus and Cutibacterium acnes are common representatives of the human skin microbiome. However, when these bacteria are organized in biofilm, they could be involved in several skin disorders such as acne or psoriasis. They inhabit in hollows of hair follicles and skin glands, where they form biofilms. There, they are continuously exposed to human hormones, including human natriuretic peptides (NUPs). We first observed that the atrial natriuretic peptide (ANP) and the C-type natriuretic peptide (CNP) have a strong effect S. aureus and C. acnes biofilm formation on the skin. These effects are significantly dependent on the aero-anaerobic conditions and temperature. We also show that both ANP and CNP increased competitive advantages of C. acnes toward S. aureus in mixed biofilm. Because of their temperature-dependent effects, NUPs appear to act as a thermostat, allowing the skin to modulate bacterial development in normal and inflammatory conditions. This is an important step toward understanding how human neuroendocrine systems can regulate the cutaneous microbial community and should be important for applications in fundamental sciences, medicine, dermatology, and cosmetology.

Quantification of Propionic Acid in the Bovine Spinal Disk After Infection of the Tissue With Propionibacteria acnes Bacteria

STUDY DESIGN

Research.

OBJECTIVE

The goal of this study was to investigate whether Propionibacteria acnes infection of the intervertebral disc can be detected noninvasively by nuclear magnetic resonance (NMR) spectroscopy.

SUMMARY OF BACKGROUND DATA

Microbiological studies of surgical samples suggest that a significant subpopulation of back pain patients may have occult disc infection with P. acnes bacteria. This hypothesis is further supported by a double-blind clinical trial showing that back pain patients with Modic type 1 changes may respond to antibiotic treatment. Because significant side effects are associated with antibiotic treatment, there is a need for a noninvasive method to detect whether specific discs in back pain patients are infected with P acnes bacteria.

METHODS

P. acnes bacteria were obtained from human patients. NMR detection of a propionic acid (PA) in the bacteria extracts was conducted on 500 MHz high-resolution spectrometer, whereas in vivo NMR spectroscopy of an isolated bovine disk tissue infected with P. acnes was conducted on 7 T magnetic resonance imaging scanner.

RESULTS

NMR spectra of P. acnes metabolites revealed a distinct NMR signal with identical chemical shits (1.05 and 2.18 ppm) as PA (a primary P. acne metabolite). The 1.05 ppm signal does not overlap with other bacteria metabolites, and its intensity increases linearly with P. acnes concentration. Bovine disks injected with P. acnes bacteria revealed a very distinct NMR signal at 1.05 ppm, which linearly increased with P. acnes concentration.

CONCLUSION

The 1.05 ppm NMR signal from PA can be used as a marker of P. acnes infection of discs. This signal does not overlap with other disc metabolites and linearly depends on P. acnes concentration. Consequently, NMR spectroscopy may provide a noninvasive method to detect disc infection in the clinical setting.

LEVEL OF EVIDENCE

N/A.

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.