Prosthetic joint infection diagnosis applying the three-level European Bone and Joint Infection Society (EBJIS) approach

Could it be Brucella melitensis? Recognizing and managing a rare pathogen in periprosthetic infections

Periprosthetic joint infections caused by Brucella melitensis are rare and present significant diagnostic and therapeutic challenges, especially in endemic regions such as Anatolia. The indolent nature of Brucella infections often results in subclinical presentations, complicating early detection and management. This case series highlights the importance of recognizing Brucella melitensis as a potential pathogen in periprosthetic joint infection and explores the treatment options for this condition. Herein, we present five cases of Brucella melitensis-associated periprosthetic joint infections involving three hip replacements and two knee replacements. Diagnoses were confirmed through advanced diagnostic techniques, including prolonged cultures and serological testing, as routine methods often yielded negative results. Two patients underwent one-stage revision arthroplasty, two underwent two-stage revision arthroplasty, and one patient was managed conservatively with targeted antibiotics due to the absence of prosthetic loosening. All patients showed excellent functional recovery and infection eradication at follow-up, with normalized inflammatory markers and no evidence of recurrence. This case series emphasizes the importance of clinical suspicion and the use of advanced diagnostics in endemic areas for timely recognition of Brucella-associated periprosthetic joint infections. One-stage revision arthroplasty combined with prolonged antibiotic therapy demonstrated favorable outcomes and may serve as an effective treatment strategy.

A Narrative Review of Fungal Periprosthetic Joint Infections of the Hip and Knee: Risk Factors, Microbiological Profiles, and Treatment Challenges

Fungal periprosthetic joint infections (PJIs) are rare but increasingly recognized complications following total joint arthroplasty (TJA). While Candida albicans remains the most common pathogen, non-albicans Candida species and other fungi, such as Aspergillus, have gained prominence. These infections often present with subtle clinical features and affect patients with significant comorbidities or immunosuppression. Compared to bacterial PJIs, fungal infections pose unique diagnostic and therapeutic challenges, including biofilm formation, limited antifungal susceptibility, and protracted treatment courses. This narrative review synthesizes current evidence from research articles and review/metanalysis papers, focusing on fungal PJIs. The literature search encompassed publications from 2015 to 2024, identifying key insights on epidemiology, risk factors, microbiological profiles, diagnostic methods, therapeutic strategies, and outcomes. Both classical references and recent studies addressing emerging diagnostic biomarkers and biofilm-active therapies were included. It was shown that C. albicans remains the primary fungal pathogen in PJIs but non-albicans Candida species and other fungi are associated with more complex clinical scenarios, higher recurrence rates, and reduced infection-free survival. Patients commonly exhibit multiple comorbidities, compromised immune status, and previous prosthetic revisions. Diagnosis is complicated by slow-growing organisms and nonspecific inflammatory markers, prompting interest in novel diagnostics such as alpha-defensin, calprotectin, and next-generation sequencing. Two-stage revision arthroplasty, supplemented by prolonged targeted antifungal therapy, is considered the gold standard for chronic infections, although outcomes remain inferior to bacterial PJIs. Emerging strategies, including antifungal-impregnated beads and biofilm-disrupting agents, may improve local infection control. In conclusion, fungal PJIs constitute a challenging clinical entity demanding tailored diagnostic and therapeutic approaches. Further research into standardized diagnostic criteria, optimized antifungal regimens, biomarker validation, and refined surgical strategies is essential. Multidisciplinary collaboration, enhanced patient optimization, and innovative biofilm-directed therapies hold promise for improving outcomes and reducing the burden of fungal PJIs.

Insight into antibacterial effect of titanium nanotubular surfaces with focus on Staphylococcus aureus and Pseudomonas aeruginosa

Materials used for orthopedic implants should not only have physical properties close to those of bones, durability and biocompatibility, but should also exhibit a sufficient degree of antibacterial functionality. Due to its excellent properties, titanium is still a widely used material for production of orthopedic implants, but the unmodified material exhibits poor antibacterial activity. In this work, the physicochemical characteristics, such as chemical composition, crystallinity, wettability, roughness, and release of Ti ions of the titanium surface modified with nanotubular layers were analyzed and its antibacterial activity against two biofilm-forming bacterial strains responsible for prosthetic joint infection (Staphylococcus aureus and Pseudomonas aeruginosa) was investigated. Electrochemical anodization (anodic oxidation) was used to prepare two types of nanotubular arrays with nanotubes differing in dimensions (with diameters of 73 and 118 nm and lengths of 572 and 343 nm, respectively). These two surface types showed similar chemistry, crystallinity, and surface energy. The surface with smaller nanotube diameter (TNT-73) but larger values of roughness parameters was more effective against S. aureus. For P. aeruginosa the sample with a larger nanotube diameter (TNT-118) had better antibacterial effect with proven cell lysis. Antibacterial properties of titanium nanotubular surfaces with potential in implantology, which in our previous work demonstrated a positive effect on the behavior of human gingival fibroblasts, were investigated in terms of surface parameters. The interplay between nanotube diameter and roughness appeared critical for the bacterial fate on nanotubular surfaces. The relationship of nanotube diameter, values of roughness parameters, and other surface properties to bacterial behavior is discussed in detail. The study is believed to shed more light on how nanotubular surface parameters and their interplay affect antibacterial activity.

Systemic Inflammation Response Index (SIRI) and Monocyte-to-Lymphocyte Ratio (MLR) Are Predictors of Good Outcomes in Surgical Treatment of Periprosthetic Joint Infections of Lower Limbs: A Single-Center Retrospective Analysis

BACKGROUND

Periprosthetic joint infection (PJI) is a devastating complication that develops after total joint arthroplasty (TJA), whose incidence is expected to increase over the years. Traditionally, surgical treatment of PJI has been based on algorithms, where early infections are preferably treated with debridement, antibiotics, and implant retention (DAIR) and late infections with two-stage revision surgery. Two-stage revision is considered the "gold standard" for treatment of chronic prosthetic joint infection (PJI) as it enables local delivery of antibiotics, maintenance of limb-length and mobility, and easier reimplantation. Many studies have attempted to identify potential predicting factors for early diagnosis of PJI, but its management remains challenging. In this observational retrospective study, we investigated the potential role of inflammatory blood markers (neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), platelet-to-lymphocyte ratio (PLR), systemic inflammatory index (SII), systemic inflammatory response index (SIRI), and aggregate index of systemic inflammation (AISI)) as prognostic factors in two-stage exchange arthroplasty for PJI.

METHODS

A single-center retrospective analysis was conducted, collecting clinical data and laboratory parameters from patients submitted to prosthetic explantation (EP) for chronic PJI. Laboratory parameters (PCR, NLR, MLR, PLR, SIRI, SII, and AISI) were evaluated at the explantation time; at 4, 6, and 8 weeks after surgery; and at reimplantation time. The correlation between laboratory parameters and surgery success was evaluated and defined as infection absence/resolution at the last follow-up.

RESULTS

A total of 57 patients with PJI were evaluated (62% males; average age 70 years, SD 12.14). Fifty-three patients with chronic PJI were included. Nine patients underwent DAIR revision surgery and chronic suppressive therapy; two patients died. Nineteen patients completed the two-stage revision process (prosthetic removal, spacer placement, and subsequent replanting). Among them, none showed signs of reinfection or persistence of infection at the last available follow-up. The other twenty-three patients did not replant due to persistent infection: among them, some (the most) underwent spacer retention; others (fewer in number) were submitted to resection arthroplasty and arthrodesis (Girdlestone technique) or chronic suppressive antibiotic therapy; the remaining were, over time, lost to follow-up. Of the patients who concluded the two-stage revision, the ones with high SIRI values (mean 3.08 SD 1.7 and p-value 0.04) and MLR values (mean 0.4 SD 0.2 and p-value 0.02) at the explantation time were associated with a higher probability of infection resolution. Moreover, higher variation in the SIRI and PCR, also defined, respectively, as delta-SIRI (mean -2.3 SD 1.8 and p-value 0.03) and delta-PCR (mean -46 SD 35.7 and p-value 0.03), were associated with favorable outcomes.

CONCLUSIONS

The results of our study suggest that, in patients with PJI undergoing EP, the SIRI and MLR values and delta-SIRI and delta-PCR values could be predictive of a favorable outcome. The evaluation of these laboratory indices, especially their determination at 4 weeks after removal, could therefore help to determine which patients could be successfully replanted and to identify the best time to replant. More studies analyzing a wider cohort of patients with chronic PJI are needed to validate the promising results of this study.

Diagnosis and Prevention of Periprosthetic Joint Infections by Staphylococcus aureus after Hip Fracture: A Systematic Review of the Literature

Hip arthroplasties are surgical procedures widely performed all over the world, seeking to return functionality, relieve pain, and improve the quality of life of patients affected by osteoarthritis, femoral neck fractures, osteonecrosis of the femoral head, among other etiologies. Periprosthetic joint infections are one of the most feared complications due to the high associated morbidity and mortality, with a high number of pathogens that may be associated with its etiology. The aim of the present study was to analyze aspects correlated with the occurrence of infection, diagnosis and prevention of periprosthetic joint infections in the hip associated with Staphylococcus aureus after corrective surgery for hip fractures. This is a systematic review of the literature carried out in the databases indexed in the Medical Literature Analysis and Retrieval System Online (MEDLINE) carried out in accordance with the precepts established by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology. Twenty studies that addressed the diagnosis and prevention of periprosthetic joint infections after hip fractures were selected for analysis. It is observed that there is no consensus in the literature on preventive measures for the occurrence of such infectious processes. Among the risk factors for the occurrence and severity of infections by S. aureus after hip arthroplasties, obesity, longer surgical time, older age, immunosuppression, recent use of antibiotics, and multicomorbidities were mentioned. The use of biomarkers for early diagnosis, as well as screening, decolonization, and antibiotic prophylaxis processes are among the preventive procedures proposed in the literature.