Molecular Typing of Multiple Isolates Is Essential to Diagnose Cutibacterium acnes Orthopedic Device-related Infection

Modifiable risk factors for culture positivity after primary Latarjet procedure. Should we change any practice?

BACKGROUND

The prevalence of positive cultures in primarily operated shoulders represents a growing concern. Previous studies have documented high rates of culture positivity in primary prosthetic shoulder surgery, yet the Latarjet procedure has not been specifically explored in this context. The aim of this study was to identify the rate of culture positivity in patients treated with a primary Latarjet procedure and to identify risk factors for culture positivity.

METHODS

This prospective, multicentric study conducted between September 2021 and October 2022 targeted patients undergoing primary open Latarjet procedures. Patients with a history of shoulder surgery were excluded. Six deep peroperative bacteriological samples were collected: 3 from soft tissues (capsulo-labral) and 3 from bony (glenoid) areas. The primary outcome was the rate of culture positivity. Secondary outcomes included the type of germs and the rate of complications. Risk factor analysis for positive cultures was undertaken using both univariate and multivariate analyses.

RESULTS

This study encompassed 122 patients with a mean age of 26.63 ± 7.45. The rates of having at least 1, 2, and 3 cultures positive were 44.8%, 40.16%, and 34.43%, respectively. Predominantly, cultures yielded Cutibacterium acnes in 96.2% of cases. Multivariate analysis identified two main risk factors for culture positivity: preoperative shoulder CT arthrogram (CTA) use (odds ratio [OR] = 4.44, 95% confidence interval [CI] = 1.65-11.9, P = .003) for at least one positive culture. Alcoholic Betadine as skin preparation in a university hospital setting significantly increased the risk (OR = 16.1, 95% CI = 4.57-56.7, P < .001) for at least one positive culture. For at least 2 positive cultures, CTA (OR = 4.17, P = .005) and alcoholic Betadine in a university hospital setting (OR = 12.94, P < .001) remained significant risk factors. Similarly, for at least 3 positive cultures, CTA (OR = 3.88, P = .009) and alcoholic Betadine in a university hospital setting (OR = 8.85, P < .001) were the only significant risk factors. Elimination of preoperative CTA reduced the rate of positive cultures to 29.27%, 24.39%, and 19.51% for at least 1, 2, and 3 positive cultures. One patient who had positive culture experienced early sepsis caused by C acnes.

CONCLUSION

This study showed a high rate of positive cultures in Latarjet patients post surgeries. Analysis highlighted preoperative CTA use as a significant risk factor, increasing positive culture risk 4-fold.

Genomic characterization and clinical evaluation of prosthetic joint infections caused by Cutibacterium acnes

Cutibacterium acnes is a major skin commensal that may act as an opportunistic pathogen. It is difficult to interpret findings of C. acnes in tissue cultures obtained during arthroplasty revision surgery, since they may represent true infection or contamination. This study investigated whether C. acnes obtained from prosthetic joint infections (PJIs) were related and shared common genomic traits that might correlate with clinical courses and patient outcomes. C. acnes isolates from revision surgery of patients with PJIs of the hip, shoulder, and knee were characterized using molecular methods to determine the sequence type (ST) and the presence of possible virulence determinants (Christie-Atkins-Munch-Peterson factors, dermatan sulfate-binding adhesion 1, hyaluronidase lyase, and linear plasmid). A standardized review of the patients' medical charts was performed. The study included 37 patients with C. acnes culture-positive tissue samples where multiple isolates of C. acnes belonged to the same ST. Most of the isolates belonged to phylotype IA1. Phylogenetic analysis of virulence determinants revealed no shared pattern among PJI isolates. Seven patients had a polymicrobial infection. Exchange revision was performed in 70% of the patients, and >50% of all patients received antibiotic treatment for ≥3 months. Failure was noted in seven patients. No specific ST or any identifiable unique feature among virulence determinants were found among C. acnes isolated from PJIs of hips and shoulders. The majority of patients had low inflammatory markers and were treated successfully, even polymicrobial infections. However, failure was more common among shoulder infections compared with hip infections.

IMPORTANCE

Prosthetic joint infection (PJI) is a rare complication after arthroplasty surgery. The infection seldom resolves without a combination of both surgical and antibiotic treatment and can cause significant suffering among affected patients. Cutibacterium acnes is a common skin bacterium that is most often found in shoulder PJIs but can also infect other prostheses. In this study, we conducted a review of patients with previously verified PJIs involving C. acnes in hip or shoulder prostheses, along with a genomic analysis of the bacteria causing the infections. The majority of patients had successful outcomes. We did not identify any specific phylogenetic lineage or specific molecular signature of virulence factors among these PJI-associated C. acnes isolates that seemed to be associated with increased potential to cause infection among this species. This indicates that C. acnes isolated from PJIs originates from the patients' own skin microbiome and is inoculated during the arthroplasty surgery.

Whole genome sequencing distinguishes skin colonizing from infection-associated Cutibacterium acnes isolates

Introduction

Cutibacterium acnes can both be a helpful colonizer of the human skin as well as the causative agent of acne and purulent infections. Until today, it is a moot point whether there are C. acnes strains exclusively devoted to be part of the skin microbiome and others, that carry special features enabling them to cause disease. So far, the search for the molecular background of such diverse behavior has led to inconsistent results.

Methods

In the present study, we prospectively collected C. acnes strains from 27 infected persons and 18 healthy controls employing rigid selection criteria to ensure their role as infectious agent or colonizer. The genome sequences from these strains were obtained and carefully controlled for quality.

Results

Deduced traditional phylotyping assigned almost all superficial isolates to type IA1, while the clinical strains were evenly distributed between types IA1, IB, and II. Single locus sequence typing (SLST) showed a predominance of A1 type for the control strains, whereas 56% of the clinical isolates belonged to types A1, H1 and K8. Pangenome analysis from all the present strains and 30 published genomes indicated the presence of an open pangenome. Except for three isolates, the colonizing strains clustered in clades separate from the majority of clinical strains, while 4 clinical strains clustered with the control strains. Identical results were obtained by a single nucleotide polymorphism (SNP) analysis. However, there were no significant differences in virulence gene contents in both groups.

Discussion

Genome-wide association studies (GWAS) from both the pangenome and SNP data consistently showed genomic differences between both groups located in metabolic pathway and DNA repair genes. Thus, the different behavior of colonizing and infectious C. acnes strains could be due to special metabolic capacities or flexibilities rather than specific virulence traits.

Increased biofilm formation in dual-strain compared to single-strain communities of Cutibacterium acnes

Cutibacterium acnes is a known opportunistic pathogen in orthopedic implant-associated infections (OIAIs). The species of C. acnes comprises distinct phylotypes. Previous studies suggested that C. acnes can cause single- as well as multi-typic infections, i.e. infections caused by multiple strains of different phylotypes. However, it is not known if different C. acnes phylotypes are organized in a complex biofilm community, which could constitute a multicellular strategy to increase biofilm strength and persistency. Here, the interactions of two C. acnes strains belonging to phylotypes IB and II were determined in co-culture experiments. No adverse interactions between the strains were observed in liquid culture or on agar plates; instead, biofilm formation in both microtiter plates and on titanium discs was significantly increased when combining both strains. Fluorescence in situ hybridization showed that both strains co-occurred throughout the biofilm. Transcriptome analyses revealed strain-specific alterations of gene expression in biofilm-embedded cells compared to planktonic growth, in particular affecting genes involved in carbon and amino acid metabolism. Overall, our results provide first insights into the nature of dual-type biofilms of C. acnes, suggesting that strains belonging to different phylotypes can form biofilms together with additive effects. The findings might influence the perception of C. acnes OIAIs in terms of diagnosis and treatment.

One-stage revision for infected shoulder arthroplasty: prospective, observational study of 37 patients

Background

Periprosthetic joint infection is a severe complication of joint replacement surgery. Thus two-stage exchange remains the gold standard, one-stage exchange is now widely recommended. We hypothesized that, for patients with chronic periprosthetic shoulder infection (PSI), treatment with a one-stage exchange would be an effective approach to eradicate infection, relieve pain, and restore function to the involved shoulder.

Materials and methods

This monocenter cohort study in a Bone and Joint Infection Referral Center (11/2003-05/2020) included all patients with confirmed PSI treated by one-stage revision. Data were extracted from the prospective database, including demographics, infection characteristics, and functional evaluations (range of motion and Constant Score at admission and last follow-up). The primary outcome was the 2-year reinfection-free rate.

Results

We included 37 patients. The refection-free rate was 5%. The most commonly isolated pathogen was Cutibacterium acnes (68%), isolated alone (15 patients, 41%) or as polymicrobial infections (10 patients, 27%). The Constant Score increased significantly from 24 to 53 (P = .001). Range of motion (forward elevation, abduction) was also significantly improved after surgery. Mean active forward elevation increased significantly by 45° from 60° to 105° postoperatively (P < .001), mean abduction increased by 42° from 55° to 97° (P < .001).

Discussion

Results from our prospective cohort-extracted series suggest that one-stage revision is a reliable treatment with a low infection recurrence rate. Improved functional outcomes can be achieved with one-stage exchange. Our patients' overall functional results were similar to those previously reported for one-stage revision and better than those reported after two-stage exchange. Patients with multiple previous surgeries seem to have worse functional outcomes than the subgroup without surgery before the index arthroplasty.

Conclusions

Our results and literature search findings suggest that one-stage revisions effectively eradicate PSIs, with good functional outcomes.

Novel Role of Biomedical Sensors and CT/MRI Scanning Image Segmentation Algorithms in Orthopedic Diseases

We aimed to evaluate the efficacy of medical image segmentation algorithms in conjunction with biomedical sensors for the diagnosis and treatment of orthopedic diseases. The two-dimensional image data of orthopedic patients were obtained by using CT/MRI scanning along with the biomedical sensors. Patients are divided into: control group (n = 140 cases) and experimental group (106 cases). The control group has received the traditional orthopedic surgery analysis method, while the experimental group has adopted the medical image segmentation, biomedical sensors and MRI scanning for the treatment/surgery of orthopedic patients. There is a apparently different level of performance between two groups (P <0.05). The analgesic and sedative effect of the experimental group is observed at 2 h, 6 h, and after 12 h respectively and it is found that the experimental group exhibits better results with statistical significance (P < 0.05). The experimental group has better rates of fracture, fracture nonunion, osteoporosis, and femoral head necrosis, and a substantial difference in various disease classifications is observed between two groups (P <0.05). There is a considerable gap between two groups in the rate of subsequent operations. The experimental group has much higher rate of subsequent operations than the control group (P <0.05). The proposed innovative non-invasive medical treatment methods can not only enhance the accuracy of orthopedic surgeries.

Microbiological Characterization of Cutibacterium acnes Strains Isolated from Prosthetic Joint Infections

Aims: This study aimed to characterize 79 Cutibacterium acnes strains isolated from prosthetic joint infections (PJIs) originated from eight European hospitals. Methods: Isolates were phylotyped according to the single-locus sequence typing (SLST) scheme. We evaluated the ability of the biofilm formation of C. acnes strains isolated from PJIs and 84 isolates recovered from healthy skin. Antibiotic susceptibility testing of planktonic and biofilm cells of PJI isolates and skin isolates was performed. Results: Most of the isolates from PJIs belonged to the SLST class H/phylotype IB (34.2%), followed by class D/phylotype IA1 (21.5%), class A/phylotype IA1 (18.9%), and class K/phylotype II (13.9%). All tested isolates were biofilm producers; no difference in biofilm formation was observed between the healthy skin group and the PJI group of strains. Planktonic and sessile cells of C. acnes remained highly susceptible to a broad spectrum of antibiotics, including beta-lactams, clindamycin, fluoroquinolones, linezolid, rifampin, and vancomycin. The minimal inhibitory concentrations (MICs) for planktonic and biofilm states coincided in most cases. However, the minimal biofilm eradication concentration (MBEC) was high for all antimicrobial drugs tested (>32 mg/L), except for rifampin (2 mg/L). Conclusions: C. acnes strains isolated from healthy skin were able to produce biofilm to the same extent as isolates recovered from PJIs. All C. acnes strains in planktonic and sessile states were susceptible to most antibiotics commonly used for PJI treatment, although rifampin was the only antimicrobial agent able to eradicate C. acnes embedded in biofilm.

Clindamycin Efficacy for Cutibacterium acnes Shoulder Device-Related Infections

Clindamycin is an antibiotic with high bioavailability and appropriate bone diffusion, often proposed as an alternative in guidelines for C. acnes prosthetic joint infections. We aimed to evaluate the efficacy of clindamycin in the treatment of C. acnes shoulder implant joint infections (SIJI). Methods: A retrospective analysis was conducted at the University Hospital of Nice (France) between 2010 and 2019. We included patients with one shoulder implant surgical procedure and at least one C. acnes positive sample. We selected the C. acnes SIJI according to French and international recommendations. The primary endpoint was favorable outcome of C. acnes SIJI treatment after at least 1-year follow-up in the clindamycin group compared to another therapeutic group. Results: Forty-eight SIJI were identified and 33 were treated with clindamycin, among which 25 were treated with monotherapy. The median duration of clindamycin antibiotherapy was 6 weeks. The average follow-up was 45 months; one patient was lost to follow-up. Twenty-seven patients out of 33 (82%) were cured with clindamycin, compared to 9/12 (75%) with other antibiotics. The rate of favorable outcomes increased to 27/31 (87%) with clindamycin and to 9/10 (90%) for other antibiotics when no septic revision strategies were excluded (P = 1.00). Conclusions: The therapeutic strategy based on one- or two-stage revision associated with 6 weeks of clindamycin seems to be effective.

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.

Cutibacterium acnes clonal complexes display various growth rates in blood culture vials used for diagnosing orthopedic device-related infections

OBJECTIVES

Blood culture bottles (BCBs) are commonly used for the diagnosis of infections associated with orthopedic devices. Although Cutibacterium acnes is an important pathogen in orthopedics, relatively little is known about its growth characteristics in BCBs. This prompted us to analyze the influence of bacterial genotype and clinical significance on time-to-detection (TTD) in BCBs.

METHODS

We reviewed 59 cases of orthopedic device-related infections in which at least one intraoperative specimen yielded a pure C. acnes culture from anaerobic BCBs (BD Bactec Lytic/10 Anaerobic/F; Lytic-Ana) and/or solid media. A strain was considered infectant if the same genotype was present in two or more intraoperative samples. From these cases, we isolated a total of 72 unique C. acnes strains belonging to four multilocus sequence type clonal complexes (CCs): CC18, CC28, CC36 and CC53. Growth rate and TTD in Lytic-Ana BCB were studied under experimental conditions (inoculation of standard inoculum) and in clinical samples (inoculation of periprosthetic tissue samples).

RESULTS

Median TTD values were shorter for CC53 compared to other CCs under experimental conditions (69 vs. 103 h; p < 0.001) and from clinical specimens (70 vs. 200 h; p = 0.02). Infectant strains had a shorter median TTD compared to contaminant strains in a clinical situation, while the difference was not observed under experimental conditions.

CONCLUSIONS

The detection dynamics of C. acnes in Lytic-Ana BCBs were associated with genotype. Thus, TTD not only reflects the bacterial load in clinical samples, but may also reflect the intrinsic properties of the clonal complex of C. acnes.

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

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

Novel strategies to diagnose prosthetic or native bone and joint infections

INTRODUCTION

Bone and Joint Infections (BJI) are medically important, costly and occur in native and prosthetic joints. Arthroplasties will increase significantly in absolute numbers over time as well as the incidence of Prosthetic Joint Infections (PJI). Diagnosis of BJI and PJI is sub-optimal. The available diagnostic tests have variable effectiveness, are often below standard in sensitivity and/or specificity, and carry significant contamination risks during the collection of clinical samples. Improvement of diagnostics is urgently needed.

AREAS COVERED

We provide a narrative review on current and future diagnostic microbiology technologies. Pathogen identification, antibiotic resistance detection, and assessment of the epidemiology of infections via bacterial typing are considered useful for improved patient management. We confirm the continuing importance of culture methods and successful introduction of molecular, mass spectrometry-mediated and next-generation genome sequencing technologies. The diagnostic algorithms for BJI must be better defined, especially in the context of diversity of both disease phenotypes and clinical specimens rendered available.

EXPERT OPINION

Whether interventions in BJI or PJI are surgical or chemo-therapeutic (antibiotics and bacteriophages included), prior sensitive and specific pathogen detection remains a therapy-substantiating necessity. Innovative tests for earlier and more sensitive and specific detection of bacterial pathogens in BJI are urgently needed.

Genomic Analysis of Cutibacterium acnes Strains Isolated from Prosthetic Joint Infections

Cutibacterium acnes is a common cause of prosthetic joint infections (PJIs). The C. acnes population can be divided into six main phylotypes (IA₁, IA₂, IB, IC, II and III) that are associated with different clinical conditions and normal skin. A single-locus sequence typing (SLST) scheme can distinguish ten main SLST types: A-E (all IA₁), F (IA₂), G (IC), H (IB), K (II), L (III). We genome-sequenced and compared 16 strains of C. acnes isolated from healthy skin (n = 4) and PJIs (n = 12), including six PJI cases with a good outcome (four shoulder PJIs, one hip PJI, one knee PJI) and six with infection relapse (three shoulder PJIs, three hip PJIs). The sequenced strains belonged to four different phylotypes (IA₁, IA₂, IB and II) and seven different SLST types. All five type IB strains (all SLST type H1) were PJI isolates (three hip PJIs, two shoulder PJIs), and four of these caused infection relapse (three hip PJIs, one shoulder PJI). Isolates from PJI cases with a good outcome belonged to three different phylotypes (IA, IB, II). Interestingly, four strains (three strains from PJI cases with good outcome and one strain from healthy skin) contained a linear plasmid; these strains belonged to different SLST types (A1, C1, F4, H1) and were isolated in three different hospitals. This study suggests that type IB strains have the potential to cause infection relapse, in particular regarding hip PJIs. Moreover, our study revealed that strains belonging to the same SLST type can differ in their accessory genome in different geographic locations, indicative of microevolution.

Cutibacterium spp. isolated from orthopaedic implant-associated infection: A not-so-slowly growing organism

INTRODUCTION

It has been reported that microbiological diagnosis of Cutibacterium spp. infection requires a prolonged incubation time (up to 14 days). We present our experience with regard to incubation time for detection of Cutibacterium spp. in orthopaedic samples over a 10-year period.

METHODS

One hundred and nineteen samples were included in this retrospective study. Fifty-three were implants (having previously undergone sonication), 64 were periprosthetic tissue biopsies and two were synovial fluids. Atkins's criteria were used for interpreting the isolates. Quantification and number of days until a culture became positive for Cutibacterium spp. were evaluated.

RESULTS

The median number of days to detection of a clinically significant isolate and a contaminant was 4 days. No clinically significant isolates grew after day eight.

CONCLUSION

Most clinically significant isolates of Cutibacterium spp. are detected in the first 7 days of incubation, although a recommendation of prolonged incubation (up to 14 days) appears to be necessary for detecting other organisms.

A Janus-Faced Bacterium: Host-Beneficial and -Detrimental Roles of Cutibacterium acnes

The bacterial species Cutibacterium acnes (formerly known as Propionibacterium acnes) is tightly associated with humans. It is the dominant bacterium in sebaceous regions of the human skin, where it preferentially colonizes the pilosebaceous unit. Multiple strains of C. acnes that belong to phylogenetically distinct types can co-exist. In this review we summarize and discuss the current knowledge of C. acnes regarding bacterial properties and traits that allow host colonization and play major roles in host-bacterium interactions and also regarding the host responses that C. acnes can trigger. These responses can have beneficial or detrimental consequences for the host. In the first part of the review, we highlight and critically review disease associations of C. acnes, in particular acne vulgaris, implant-associated infections and native infections. Here, we also analyse the current evidence for a direct or indirect role of a C. acnes-related dysbiosis in disease development or progression, i.e., reduced C. acnes strain diversity and/or the predominance of a certain phylotype. In the second part of the review, we highlight historical and recent findings demonstrating beneficial aspects of colonization by C. acnes such as colonization resistance, immune system interactions, and oxidant protection, and discuss the molecular mechanisms behind these effects. This new insight led to efforts in skin microbiota manipulation, such as the use of C. acnes strains as probiotic options to treat skin disorders.

Effects of different tissue specimen pretreatment methods on microbial culture results in the diagnosis of periprosthetic joint infection

Aims

Microbiological culture is a key element in the diagnosis of periprosthetic joint infection (PJI). However, cultures of periprosthetic tissue do not have optimal sensitivity. One of the main reasons for this is that microorganisms are not released from the tissues, either due to biofilm formation or intracellular persistence. This study aimed to optimize tissue pretreatment methods in order to improve detection of microorganisms.

Methods

From December 2017 to September 2019, patients undergoing revision arthroplasty in a single centre due to PJI and aseptic failure (AF) were included, with demographic data and laboratory test results recorded prospectively. Periprosthetic tissue samples were collected intraoperatively and assigned to tissue-mechanical homogenization (T-MH), tissue-manual milling (T-MM), tissue-dithiothreitol (T-DTT) treatment, tissue-sonication (T-S), and tissue-direct culture (T-D). The yield of the microbial cultures was then analyzed.

Results

A total of 46 patients were enrolled, including 28 patients in the PJI group and 18 patients in the AF group. In the PJI group, 23 cases had positive culture results via T-MH, 22 cases via T-DTT, 20 cases via T-S, 15 cases via T-MM, and 13 cases via T-D. Three cases under ongoing antibiotic treatment remained culture-negative. Five tissue samples provided the optimal yield. Any ongoing antibiotic treatment had a relevant influence on culture sensitivity, except for T-DTT.

Conclusion

T-MH had the highest sensitivity. Combining T-MH with T-DTT, which requires no special equipment, may effectively improve bacterial detection in PJI. A total of five periprosthetic tissue biopsies should be sampled in revision arthroplasty for optimal detection of PJI.

Cite this article: Bone Joint Res 2021;10(2):96–104.

Cutibacterium spp. isolated from orthopaedic implant-associated infection: A not-so-slowly growing organism

INTRODUCTION

It has been reported that microbiological diagnosis of Cutibacterium spp. infection requires a prolonged incubation time (up to 14 days). We present our experience with regard to incubation time for detection of Cutibacterium spp. in orthopaedic samples over a 10-year period.

METHODS

One hundred and nineteen samples were included in this retrospective study. Fifty-three were implants (having previously undergone sonication), 64 were periprosthetic tissue biopsies and two were synovial fluids. Atkins's criteria were used for interpreting the isolates. Quantification and number of days until a culture became positive for Cutibacterium spp. were evaluated.

RESULTS

The median number of days to detection of a clinically significant isolate and a contaminant was 4 days. No clinically significant isolates grew after day eight.

CONCLUSION

Most clinically significant isolates of Cutibacterium spp. are detected in the first 7 days of incubation, although a recommendation of prolonged incubation (up to 14 days) appears to be necessary for detecting other organisms.