Infection Of Orthopaedic Implants Research Articles

Combined <em>In vivo</em> Optical and µCT Imaging to Monitor Infection, Inflammation, and Bone Anatomy in an Orthopaedic Implant Infection in Mice

Multimodality imaging has emerged as a common technological approach used in both preclinical and clinical research. Advanced techniques that combine in vivo optical and μCT imaging allow the visualization of biological phenomena in an anatomical context. These imaging modalities may be especially useful to study conditions that impact bone. In particular, orthopaedic implant infections are an important problem in clinical orthopaedic surgery. These infections are difficult to treat because bacterial biofilms form on the foreign surgically implanted materials, leading to persistent inflammation, osteomyelitis and eventual osteolysis of the bone surrounding the implant, which ultimately results in implant loosening and failure. Here, a mouse model of an infected orthopaedic prosthetic implant was used that involved the surgical placement of a Kirschner-wire implant into an intramedullary canal in the femur in such a way that the end of the implant extended into the knee joint. In this model, LysEGFP mice, a mouse strain that has EGFP-fluorescent neutrophils, were employed in conjunction with a bioluminescent Staphylococcus aureus strain, which naturally emits light. The bacteria were inoculated into the knee joints of the mice prior to closing the surgical site. In vivo bioluminescent and fluorescent imaging was used to quantify the bacterial burden and neutrophil inflammatory response, respectively. In addition, μCT imaging was performed on the same mice so that the 3D location of the bioluminescent and fluorescent optical signals could be co-registered with the anatomical μCT images. To quantify the changes in the bone over time, the outer bone volume of the distal femurs were measured at specific time points using a semi-automated contour based segmentation process. Taken together, the combination of in vivo bioluminescent/fluorescent imaging with μCT imaging may be especially useful for the noninvasive monitoring of the infection, inflammatory response and anatomical changes in bone over time.

Combined in vivo optical and µCT imaging to monitor infection, inflammation, and bone anatomy in an orthopaedic implant infection in mice.

Multimodality imaging has emerged as a common technological approach used in both preclinical and clinical research. Advanced techniques that combine in vivo optical and μCT imaging allow the visualization of biological phenomena in an anatomical context. These imaging modalities may be especially useful to study conditions that impact bone. In particular, orthopaedic implant infections are an important problem in clinical orthopaedic surgery. These infections are difficult to treat because bacterial biofilms form on the foreign surgically implanted materials, leading to persistent inflammation, osteomyelitis and eventual osteolysis of the bone surrounding the implant, which ultimately results in implant loosening and failure. Here, a mouse model of an infected orthopaedic prosthetic implant was used that involved the surgical placement of a Kirschner-wire implant into an intramedullary canal in the femur in such a way that the end of the implant extended into the knee joint. In this model, LysEGFP mice, a mouse strain that has EGFP-fluorescent neutrophils, were employed in conjunction with a bioluminescent Staphylococcus aureus strain, which naturally emits light. The bacteria were inoculated into the knee joints of the mice prior to closing the surgical site. In vivo bioluminescent and fluorescent imaging was used to quantify the bacterial burden and neutrophil inflammatory response, respectively. In addition, μCT imaging was performed on the same mice so that the 3D location of the bioluminescent and fluorescent optical signals could be co-registered with the anatomical μCT images. To quantify the changes in the bone over time, the outer bone volume of the distal femurs were measured at specific time points using a semi-automated contour based segmentation process. Taken together, the combination of in vivo bioluminescent/fluorescent imaging with μCT imaging may be especially useful for the noninvasive monitoring of the infection, inflammatory response and anatomical changes in bone over time.

Biofilm Disrupting Technology for Orthopedic Implants: What's on the Horizon?

The use of orthopedic implants in joints has revolutionized the treatment of patients with many debilitating chronic musculoskeletal diseases such as osteoarthritis. However, the introduction of foreign material into the human body predisposes the body to infection. The treatment of these infections has become very complicated since the orthopedic implants serve as a surface for multiple species of bacteria to grow at a time into a resistant biofilm layer. This biofilm layer serves as a protectant for the bacterial colonies on the implant making them more resistant and difficult to eradicate when using standard antibiotic treatment. In some cases, the use of antibiotics alone has even made the bacteria more resistant to treatment. Thus, there has been surge in the creation of non-antibiotic anti-biofilm agents to help disrupt the biofilms on the orthopedic implants to help eliminate the infections. In this study, we discuss infections of orthopedic implants in the shoulder then we review the main categories of anti-biofilm agents that have been used for the treatment of infections on orthopedic implants. Then, we introduce some of the newer biofilm disrupting technology that has been studied in the past few years that may advance the treatment options for orthopedic implants in the future.

Osteomyelitis

Despite promising advances in antibiotic and surgical therapy osteomyelitis remians a severe disease with a high morbidity. Nowadays it occurs mainly after traumata. Typical clinical manifestations are signs of local infection, non-healing wounds, pathological fractures or loosening of orthopedic implants. Besides the clinical judgement the diagnosis is consolidated by imaging procedures, histopathological and microbiological examinations. Ideally, the treatment plan is based on an interdisciplinary approach. Besides the radical surgical debridement a test appropriate antibiotic therapy is essential. Defect reconstruction after surgical debridement and optimization of local microcirculation is essential to preserve limbs and to obtain a good functional result. Microsurgical free tissue transfer is often necessary to achieve healing. An optimal therapeutic management with stable long-term clinical results can be achieved by the interaction of different surgical and medical disciplines.

Prevention of Orthopaedic Implant Infection in Patients Undergoing Dental Procedures

The Prevention of Orthopaedic Implant Infection in Patients Undergoing Dental Procedures evidence-based clinical practice guideline was codeveloped by the American Academy of Orthopaedic Surgeons (AAOS) and the American Dental Association. This guideline replaces the previous AAOS Information Statement, "Antibiotic Prophylaxis in Bacteremia in Patients With Joint Replacement," published in 2009. Based on the best current evidence and a systematic review of published studies, three recommendations have been created to guide clinical practice in the prevention of orthopaedic implant infections in patients undergoing dental procedures. The first recommendation is graded as Limited; this recommendation proposes that the practitioner consider changing the long-standing practice of routinely prescribing prophylactic antibiotic for patients with orthopaedic implants who undergo dental procedures. The second, graded as Inconclusive, addresses the use of oral topical antimicrobials in the prevention of periprosthetic joint infections. The third recommendation, a Consensus statement, addresses the maintenance of good oral hygiene.

Some Comments on Orthopaedic Implant Infection: Biomaterials Issues

Some Comments on Orthopaedic Implant Infection: Biomaterials Issues

Infection of orthopedic implants with emphasis on bacterial adhesion process and techniques used in studying bacterial-material interactions.

Staphylococcus comprises up to two-thirds of all pathogens in orthopedic implant infections and they are the principal causative agents of two major types of infection affecting bone: septic arthritis and osteomyelitis, which involve the inflammatory destruction of joint and bone. Bacterial adhesion is the first and most important step in implant infection. It is a complex process influenced by environmental factors, bacterial properties, material surface properties and by the presence of serum or tissue proteins. Properties of the substrate, such as chemical composition of the material, surface charge, hydrophobicity, surface roughness and the presence of specific proteins at the surface, are all thought to be important in the initial cell attachment process. The biofilm mode of growth of infecting bacteria on an implant surface protects the organisms from the host immune system and antibiotic therapy. The research for novel therapeutic strategies is incited by the emergence of antibiotic-resistant bacteria. This work will provide an overview of the mechanisms and factors involved in bacterial adhesion, the techniques that are currently being used studying bacterial-material interactions as well as provide insight into future directions in the field.

The need to assess drugs selected from cancer genomic data prior to patient treatment.

Personalized MedicineVol. 9, No. 5 EditorialThe need to assess drugs selected from cancer genomic data prior to patient treatmentPeter ToliasPeter ToliasDepartment of Chemistry, Chemical Biology & Biomedical Engineering, Interdepartmental Bioinnovation Program, Stevens Institute of Technology, 507 River Street, Castle Point on Hudson, McLean Hall Room 515, Hoboken NJ 07030, USA. Search for more papers by this authorEmail the corresponding author at ptolias@stevens.eduPublished Online:30 Jul 2012https://doi.org/10.2217/pme.12.51AboutSectionsView ArticleView Full TextPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinkedInRedditEmail View articleKeywords: 3D microfluidic culturecancerdrug selection and assessmenttumor biopsywhole-genome sequencingReferences1 Sennino B, Ishiguro-Oonuma T, Wei Y et al. Suppression of tumor invasion and metastasis by concurrent inhibition of c-Met and VEGF signaling in pancreatic neuroendocrine tumors. Cancer Discov.2(3),270–287 (2012).Crossref, Medline, CAS, Google Scholar2 Gerlinger M, Rowan AJ, Horswell S et al. Intratumor heterogeneity and branched evolution revealed by multiregion sequencing. N. Engl. J. Med.366,883–892 (2012).Crossref, Medline, CAS, Google Scholar3 Wang L, Lawrence MS, Wan Y et al.SF3B1 and other novel cancer genes in chronic lymphocytic leukemia. N. Engl. J. Med.365(26),2497–2506 (2011).Crossref, Medline, CAS, Google Scholar4 Stark MS, Woods SL, Gartside MG et al. Frequent somatic mutations in and MAP3K9 in metastatic melanoma identified by exome sequencing. Nat. Genet.44,165–169 (2011).Crossref, Medline, Google Scholar5 Dancey JE, Bedard PL, Onetto N, Hudson TJ. The genetic basis for cancer treatment decisions. Cell148,409–420 (2012).Crossref, Medline, CAS, Google Scholar6 Lipson D, Capelletti M, Yelensky R et al. Identification of new ALK and RET gene fusions from colorectal and lung cancer biopsies. Nat. Med.18,382–384 (2012).Crossref, Medline, CAS, Google Scholar7 Perel P, Roberts I, Sena E et al. Comparison of treatment effects between animal experiments and clinical trials: systematic review. BMJ334(7586),197 (2007).Crossref, Medline, CAS, Google Scholar8 Hyman AH, Simons K. The new cell biology: beyond HeLa cells. Nature480,34 (2011).Crossref, Medline, CAS, Google Scholar9 Chapman S, Liu X, Meyers C, Schlegel R, McBride AA. Human keratinocytes are efficiently immortalized by a Rho kinase inhibitor. J. Clin. Invest.120,2619–2626 (2010).Crossref, Medline, CAS, Google Scholar10 Liu X, Ory V, Chapman S et al. ROCK inhibitor and feeder cells induce the conditional reprogramming of epithelial cells. Am. J. Pathol.180(2),599–607 (2012).Crossref, Medline, CAS, Google Scholar11 Bell E. Why 3D is better than 2D. Nat. Rev. Immunol.6,87 (2006).Crossref, Google Scholar12 Lee JH, Wang H, Kaplan JB, Lee WY. Microfluidic approach to create three- dimensional tissue models for biofilm-related infection of orthopaedic implants. Tissue Eng. Part C Methods17,39–48 (2011).Crossref, Medline, CAS, Google Scholar13 Lee JH, Gu Y, Wang H, Lee WY. Microfluidic 3D bone tissue model for high-throughput evaluation of wound-healing and infection-preventing biomaterials. Biomaterials33,999–1006 (2012).Crossref, Medline, CAS, Google Scholar14 Desrochers TM, Shamis Y, Alt-Holland A et al. The 3D tissue microenvironment modulates DNA methylation and E-cadherin expression in squamous cell carcinoma. Epigenetics7,34–46 (2012).Crossref, Medline, CAS, Google Scholar101 The International Cancer Genome Consortium. https://www.icgc.orgGoogle ScholarFiguresReferencesRelatedDetailsCited ByWell plate-based perfusion culture device for tissue and tumor microenvironment replication1 January 2015 | Lab on a Chip, Vol. 15, No. 13A possible future for the pharmaceutical industryPeter Tolias1 December 2014 | Personalized Medicine, Vol. 11, No. 8 Vol. 9, No. 5 Follow us on social media for the latest updates Metrics Downloaded 129 times History Published online 30 July 2012 Published in print July 2012 Information© Future Medicine LtdKeywords3D microfluidic culturecancerdrug selection and assessmenttumor biopsywhole-genome sequencingFinancial & competing interests disclosureThe author is a co-inventor on two provisional patent applications dealing with the design of microfluidic devices that can culture cells in 3D (US 61/566,261 and US 61/568,681). The author has no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.No writing assistance was utilized in the production of this manuscript.PDF download

In-vitro adhesion of Staphylococcus spp. tocertain orthopedic biomaterials and expression ofadhesion genes

The present study evaluated biofilm forming capacity, the adherence of Staphylococci spp. to different orthopedic biomaterials and the presence of both icaA and icaD genes among staphylococci strains isolated from patients suffering from orthopedic implant infections. We studied 53 Staphylococcal strains from infections related to orthopedic implants, as regards their ability to form biofilm by using microtitre plate method (MTP), in vitro evaluation of the ability of the biofilm forming strains to adhere to certain biomaterials that used in orthopedic surgery and detection of ica A and ica D among the isolates. 90.9% of S. aureus strains were biofilm positive while, 95% of Coagulase negative staph. were biofilm forming, PMMA demonstrated a significantly highest adherence (P<0.05) followed by stainless steel while, the lowest adherence exhibited by titanium and Biofilm producing strains were positive for icaA and icaD genes while, biofilm negative strains were negative for both genes. Staphylococcus spp. are the major pathogens in orthopedic implants infections. Titanium biomaterials are less susceptible for adherence by bacteria . Biofilms are considered the key factor in the development of implantrelated infections.

Orthopaedic-implant infections by Escherichia coli: Molecular and phenotypic analysis of the causative strains

Little is known about Escherichia coli Orthopaedic Implant Infections (OII) pathogenesis. Thus, we compared 30 clinical strains isolated in this context with 30 clinical strains of faecal origin, in order to identify phenotypic and genetic features related to E. coli OII. Phylogenetic analysis and detection of 19 virulence genes were performed by PCR. Ability to form biofilm was studied using the crystal violet reference method and the innovative BioFilm Ring Test(®). Most of the OII isolates (56.7%) belonged to the virulence-associated phylogenetic group B2, but did not present a specific set of virulence factors. S fimbriae was the only adhesin significantly associated with OII isolates. Isolates varied greatly in their ability to form biofilm but OII isolates did not produce significantly more biofilm in vitro than isolates of faecal origin, whatever the method used. Neither a specific pathogenic signature nor an increased ability to form biofilm in vitro was detected in E. coli strains isolated from OII. Nevertheless, genetic properties of these isolates could provide a clue to their origin. Hence, we found that virulence factors of uropathogenic strains and urological disorders were frequently detected among our OII cohort.

Hard implant coatings with antimicrobial properties

Infection of orthopaedic implants often leads to inflammation immediately after surgery and increases patient morbidity due to repetitive operations. Silver ions have been shown to combine good biocompatibility with a low risk of inducing bacterial resistance. In this study a physical vapour deposition system using both arc deposition and magnetron sputtering has been utilized to produce silver ion doped TiN coatings on Ti substrates. This biphasic system combines the advantages of silver induced bactericidity with the good mechanical properties of TiN. Crystallographic analysis by X-ray diffraction showed that silver was deposited as well in its elementary form as it was incorporated into the crystal lattice of TiN, which resulted in increasing hardness of the TiN-coatings. Elution experiments revealed a continuous release of Ag ions in phosphate buffered saline. The coatings showed significant inhibitory effects on the growth of Staphylococcus epidermidis and Staphylococcus aureus and practically no cell-toxicity in cytocompatibility tests.

Concise Survey of Staphylococcus Aureus Virulence Factors that Promote Adhesion and Damage to Peri-Implant Tissues

Staphylococcus aureus is the leading cause of infection in orthopedic implants and of osteomyelitis consequent to it. Here we focus on the wide array of virulence factors that endow S. aureus with its abilities to colonize peri-prosthesis tissues and to attack and damage them. Following an infective strategy orchestrated by agr locus, Staphylococcus aureus first deploys virulence factors for adhesion to the prosthesis and peri-prosthesis tissues and then launches its attack by delivering destructive factors.

The Additional Value of Tc 99m HMPAO White Blood Cell SPECT in the Evaluation of Bone and Soft Tissue Infections

Objective: The aim of this prospective study was to evaluate the additional value of Tc 99m HMPAO white blood cell (WBC) SPECT for bone and soft tissue infections.Materials and Methods: Thirty-eight patients with suspected bone and joint infection were included in the study. Patients were assigned into 2 groups according to the presence of orthopedic implants. All patients had multiphase bone scan (BS) with Tc 99m methylene diphosphonate and WBC scintigraphy. The planar images of BS and WBC images were evaluated together. SPECT WBC images were evaluated separately.Results: Group 1 had 30 patients including 12 patients with diabetic foot, 17 patients with suspected relapse of chronic osteomyelitis and 1 with septic arthritis. In 19 of 30 patients, BS and planar WBC images were similar with SPECT images in terms of final diagnosis. In the remaining 11 patients, planar BS+planar WBC images and SPECT WBC images were discordant. Group 2 included 8 patients with suspected infection of orthopedic implants. There was no difference between planar BS+planar WBC images and SPECT WBC in 6 of 8 patients. SPECT WBC images changed the diagnosis of 13 (34.2%) patients in the whole group. SPECT WBC images did not have any contribution in the evaluation of the 6 patients who had reactive changes. Conclusion: SPECT images made significant contribution in discriminating soft tissue infection from osteomyelitis and improved diagnosis in terms of localization and the extent of disease.Conflict of interest:None declared.

Microfluidic Approach to Create Three-Dimensional Tissue Models for Biofilm-Related Infection of Orthopaedic Implants

With conventional in vitro culture methods, it is difficult to study complex interactions of host cells with pathogens and drugs in physiologically relevant microenvironments. To simulate orthopaedic implant-associated infection, a multi-channel microfluidic device was used to (1) observe in real-time the development of osteoblasts into three-dimensional (3D) tissue-like structures and (2) study how this development was influenced by phenotypes of Staphylococcus epidermidis. In the absence of bacteria, osteoblasts formed a confluent layer on the bottom channel surface, gradually migrated to the side and top surfaces, and formed calcified 3D nodular structures in 8 days. The delivery timing and concentration of an antibiotic were controlled to produce small colony variants, sessile biofilms, or dead cells of S. epidermidis. In the presence of the small colony variants, osteoblasts initially adhered, and spread, but were killed within 2 days. In contrast, the sessile biofilms and dead bacteria cells did not significantly interfere with the formation of tissue-like structures. The results suggest the possibility of creating in vitro tissue-biofilm-biomaterial interfaces and therefore 3D tissue models, as an entirely new method of studying biofilm-related infection of orthopaedic implants with physiological relevance.

Specific Distribution within the Enterobacter cloacae Complex of Strains Isolated from Infected Orthopedic Implants

Bacteria belonging to the Enterobacter genus are frequently isolated from clinical samples but are unusual causative agents of orthopedic implant infections. Twelve genetic clusters (clusters I to XII) and one sequence crowd (sequence crowd xiii) can be distinguished within the Enterobacter cloacae nomenspecies on the basis of hsp60 sequence analysis, and until now, none of these clusters could be specifically associated with a disease. In order to investigate if specific genetic clusters would be involved in infections of orthopedic material, two series of bacterial clinical isolates identified as E. cloacae by routine phenotypic identification methods were collected either from infected orthopedic implants (n = 21) or from randomly selected samples of diverse anatomical origins (control; n = 52). Analysis of the hsp60 gene showed that genetic clusters III, VI, and VIII were the most frequent genetic clusters detected in the control group, whereas cluster III was poorly represented among the orthopedic implant isolates (P = 0.006). On the other hand, E. hormaechei (clusters VI and VIII), but not cluster III, is predominantly associated with infections of orthopedic implants and, more specifically, with infected material in the hip (P = 0.019). These results support the hypothesis that, among the isolates within the E. cloacae complex, E. hormaechei and hsp60 gene sequencing-based cluster III are involved in pathogenesis in different ways and highlight the need for more accurate routine Enterobacter identification methods.

Study of Bacteria Isolated from Orthopedic Implant Infections and their Antimicrobial Susceptibility Pattern

Study of Bacteria Isolated from Orthopedic Implant Infections and their Antimicrobial Susceptibility Pattern

Rifampin as adjuvant treatment of Gram-positive bacterial infections: a systematic review of comparative clinical trials

We reviewed the bibliographic evidence from comparative trials regarding the role of rifampin as adjuvant treatment in the treatment of Gram-positive infections [PubMed (1/1950-7/2006)]. Only studies reporting comparative outcome data in patients treated with an antibiotic regimen with the addition or not of rifampin were included. Eight comparative studies were identified [all were randomized controlled trials (RCTs)], five reporting on infections caused by staphylococci (S. aureus in 97% of patients) and three by streptococci. There was no statistically significant difference in mortality between the treatment arms (with and without rifampin) in any of the included studies. Clinical cure was achieved more commonly (p < 0.05) in the rifampin treatment arm in 3/8 studies; in staphylococcal infections of orthopedic stable implants and in beta-hemolytic streptococcal pharyngitis in children (one RCT each), and in one RCT that reported on patients with various staphylococcal infections. However, no statistically significant difference in cure of the infection between the two groups was found after pooling data from two RCTs (121 patients) that reported on patients with various staphylococcal infections (odds ratio = 0.57; 95% confidence interval 0.27-1.17). No differences were noted between the two groups regarding relapse of infection or adverse events. There is only limited evidence from comparative trials regarding the role of rifampin as adjuvant therapeutic agent for infections caused by Gram-positive bacteria, not allowing for definitive conclusions on this important management question. More controlled trials are necessary for better evaluation of this practice.

Efficacy and tolerability of prolonged linezolid therapy in the treatment of orthopedic implant infections

The aim of the study presented here was to assess the efficacy and tolerability of linezolid in the treatment of orthopedic implant infections (OII). Eighty-five patients with an OII treated with linezolid were prospectively followed up for a minimum of 12 months from the end of antibiotic therapy. Outcome was evaluated in relation to the duration and type of symptoms (acute or chronic) and the retention or removal of the implant. For acute and chronic infections, the respective success rates were 100 and 92.3% when the implant was removed and 72.2 and 42.8% when it was not. The median length of linezolid treatment in acute and chronic infections was 47 and 60 days, respectively. Thrombocytopenia was observed in four (4.7%) patients and anemia in five (5.8%). The results suggest oral linezolid is an effective and well-tolerated alternative for treating OII.

Automated Ribotyping to Distinguish the Different nonSau/ nonSep Staphylococcal Emerging Pathogens in Orthopedic Implant Infections

Several species belonging to Staphylococcus genus, other than Staphylococcus aureus and Staphylococcus epidermidis (non Sau/ non Sep species), exhibit increasing abilities as opportunistic pathogens in the colonisation of periprosthetic tissues. Consequently, the availability of means for accurate identification is crucial to assess the pathogenic characteristics and to clarify clinical relevance of the individual species. Here, 146 clinical staphylococcal isolates belonging to non Sau/ non Sep species from prosthesis-associated orthopedic infections were analyzed by conventional enzymatic galleries and by automated ribotyping. Twelve different species were recognised: S. capitis, S. caprae, S. cohnii, S. equorum, S. haemolyticus, S. hominis, S. lugdunensis, S. pasteuri, S. sciuri, S. simulans, S. warneri, S. xylosus. Ribotype identifications were compared with the phenotypes obtained by the Api 20 Staph system and/or ID 32 Staph system. ID 32 Staph profiles were more consistent with ribotyping results than Api Staph profiles. Across the different staphylococcal species investigated, correct identifications with Api Staph were 45%, while with ID 32 Staph they were 59%. It has, however, to be mentioned that ID 32 Staph was mostly applied to discriminate unmatched ribotyping and Api Staph identifications, thus to a subpopulation of strains with ""atypical"" metabolic profile. Automated ribotyping provided a correct identification for 91% of the isolates. These results confirm automated ribotyping as a convenient rapid technique, still subject to improvements, which will accurately and rapidly recognise the newly emerging staphylococcal pathogens in implant-related orthopedic infections.

Arthroplastic and osteosynthetic infections due to Propionibacterium acnes: a retrospective study of 52 cases, 1995–2002

The cases of 52 patients with Propionibacterium acnes infection of orthopaedic implants are summarized: 20 patients with definite infection (sepsis, with P. acnes recovered from multiple specimens per patient), 15 with probable infection (sepsis, with P. acnes recovered from one specimen), and 17 with possible infection (signs of prosthetic malfunction or pseudo-osteoarthritis, with P. acnes recovered from one specimen). The patient population consisted of 37 males and 15 females with a mean age of 51.8 years (range 17-88). Besides bone surgery, 21% of these patients had severe coexisting illness. The study population was very heterogeneous and clinical presentation very polymorphic; infections became clinically apparent through sepsis, prosthetic malfunction, or a delay in consolidation. The diagnosis was highly dependent on the quality of the samples taken and the methodology used by the microbiology laboratory to isolate this bacterium. Culture time was long, on average 11.4 days. Treatment involved a combination of antibiotic treatments (67% of cases) and ablation of the material (83% of cases). Although P. acnes is considered to be weakly pathogenic, this bacterium may be responsible for infections in patients with implanted orthopaedic material. Ablation of the arthroplastic or osteosynthetic material is necessary in the majority of cases.