Current Concepts of Fracture-Related Infection

Pathogens in FRI - Do bugs matter? - An analysis of FRI studies to assess your enemy

Fracture-related infection (FRI) is a devasting complication for both patients and their treating Orthopaedic surgeon that can lead to loss of limb function or even amputation. The unique and unpredictable features of FRI make its diagnosis and treatment a significant challenge. It has substantial morbidity and financial implications for patients, their families and healthcare providers. In this article, we perform an in-depth and comprehensive review of FRI through recent and seminal literature to highlight evolving definitions, diagnostic and treatment approaches, focusing on common pathogens such as Staphylococcus aureus, polymicrobial infections and multi-drug-resistant organisms (MDRO). Furthermore, multiple resistance mechanisms and adaptations for microbial survival are discussed, as well as modern evidence-based medical and surgical advancements in treatment strategies in combating FRI.

Multiplexed bacterial pathogen detection and clinical characteristics of orthopedic infection in hospitalized patients

Introduction

Accurate identification of the etiology of orthopedic infection is very important for correct and timely clinical management, but it has been poorly studied. In the current study we explored the association of multiple bacterial pathogens with orthopedic infection.

Methods

Hospitalized orthopedic patients were enrolled in a rural hospital in Qingdao, China. Wound or exudate swab samples were collected and tested for twelve bacterial pathogens with both culture and multiplex real time PCR.

Results and discussion

A total of 349 hospitalized orthopedic patients were enrolled including 193 cases presenting infection manifestations upon admission and 156 with no sign of infection. Orthopedic infection patients were mainly male (72.5%) with more lengthy hospital stay (median 15 days). At least one pathogen was detected in 42.5% (82/193) of patients with infection while 7.1% (11/156) in the patients without infection (P < 0.001). S. aureus was the most prevalent causative pathogen (15.5%). Quantity dependent pathogen association with infection was observed, particularly for P. aeruginosa and K. pneumoniae, possibly indicating subclinical infection. Most of the patients with detected pathogens had a previous history of orthopedic surgery (odds ratio 2.8, P = 0.038). Pathogen specific clinical manifestations were characterized. Multiplex qPCR, because of its high sensitivity, superior specificity, and powerful quantification could be utilized in combination with culture to guide antimicrobial therapy and track the progression of orthopedic infection during treatment.

Efficacy of lysostaphin-coated titanium plates on implant-associated MRSA osteitis in minipigs

PURPOSE

The growing incidence of implant-associated infections (IAIs) caused by biofilm-forming Staphylococcus aureus in combination with an increasing resistance to antibiotics requires new therapeutic strategies. Lysostaphin has been shown to eliminate this biofilm. Own studies confirm the effectiveness in a murine model. The current study characterizes the effects of lysostaphin-coated plates in an IAI minipig model.

METHODS

The femur of 30 minipigs was stabilized with a five-hole plate, a bone defect was created, and in 20 cases methicillin-resistant Staphylococcus aureus was applied. Ten animals served as control group. After 14 days, local debridement, lavage, and plate exchange (seven-hole plate) were performed. Ten of the infected minipigs received an uncoated plate and 10 a lysostaphin-coated plate. On day 84, the minipigs were again lavaged, followed by euthanasia. Bacterial load was quantified by colony-forming units (CFU). Immunological response was determined by neutrophils, as well as interleukins. Fracture healing was assessed radiologically.

RESULTS

CFU showed significant difference between infected minipigs with an uncoated plate and minipigs with a lysostaphin-coated plate (p = 0.0411). The infection-related excessive callus formation and calcification was significantly greater in the infected animals with an uncoated plate than in animals with a lysostaphin-coated plate (p = 0.0164/p = 0.0033). The analysis of polymorphonuclear neutrophils and interleukins did not reveal any pioneering findings.

CONCLUSION

This study confirms the minipig model for examining IAI. Furthermore, coating of plates using lysostaphin could be a promising tool in the therapeutic strategies of IAI. Future studies should focus on coating technology of implants and on translation into a clinical model.

Fracture-related infection: Analysis of healthcare utilisation and associated costs

AIMS

A consensus definition of fracture related infection (FRI) has been created with the aim of standardising diagnosis and eliminating heterogeneity that prevents accurate comparison between existing studies. FRI remains one of the most challenging complications in musculoskeletal trauma surgery and carries with it a significant cost burden. A review of UK finances has not been completed utilising consensus diagnostic criteria. The goal of this study was to investigate the hospital-associated healthcare cost related to the treatment of FRI within an NHS major trauma centre.

METHOD

Through retrospective case-control analysis, 1240 patients with close fractures were identified. Of those, 21 patients with FRI were compared to 63 uninfected patients. Patients were matched based on fracture location, type of procedure and proximity in age. The costs assessed included hospitalisation, imaging, outpatient consultation, pharmaceuticals and procedure charges. Cost data was retrieved from healthcare resource group (HRG) guidelines, NHS Business Service Authority's (NBSA) prescription rates and internal costing.

RESULTS

The FRI group were found to incur a 2.51 increase in total medial healthcare cost compared to the control group (£22,058 vs £8798 [p < 0.001]), which was primarily due to increased procedural costs (£13,020 vs £6291 [p < 0.001]) and length of hospital stay (£7552 vs £2124 [p < 0.001]).

CONCLUSION

Whilst diagnosis of FRI has a more rigorous definition following the new consensus, prevalence and cost outcomes are similar to previous studies. Given the deficiency in funding and ongoing challenges of resource allocation to the NHS, it is prudent to incorporate studies such as this into stratifying departmental budgets and quality improvement.

LEVEL OF EVIDENCE

III.

Fibrinogen, albumin-to-globulin ratio, and fibrinogen to albumin-to-globulin ratio may be potential diagnostic biomarkers for infected tibial nonunion

AIM

The accurate preoperative diagnosis of infected tibial nonunion remains challenging. Hence, we evaluated the diagnostic potential of novel biomarkers for infected tibial nonunion.

METHODS

This single-center retrospective study was conducted in 252 patients divided into two groups: infected tibial nonunion (67 patients) and aseptic tibial nonunion (185 patients). The preoperative clinical biomarkers included D-dimer, fibrinogen, albumin, globulin, total protein, and C-reactive protein (CRP) levels; albumin-to-globulin ratio (AGR); erythrocyte sedimentation rate (ESR); and white blood cell (WBC) count. Receiver operating characteristic (ROC) curves, sensitivity, and specificity were utilized to compare the biomarkers' diagnostic potential.

RESULTS

The area under the curve (AUC) values for fibrinogen and AGR were 0.829 and 0.821, respectively, suggesting similarly good diagnostic potentials for infected tibial nonunion. Fibrinogen and AGR were better diagnostic biomarkers for infected tibial nonunion than the WBC count; ESR; D-dimer, albumin, globulin, CRP, and total protein levels, whose AUC values were 0.623, 0.684, 0.741, 0.797, 0.765, 0.715, and 0.554, respectively. The sensitivity and specificity of fibrinogen with a cut-off value of 3.35 g/L were 71.64% and 84.86%, respectively. The corresponding values for AGR with a cut-off value of 1.33 were 73.13% and 86.49%. Moreover, the fibrinogen-AGR (FAGR), i.e., the combination of fibrinogen and AGR, had the highest diagnostic accuracy for infected tibial nonunion (AUC = 0.906). The optimal FAGR cut-off was 2.69, with fair sensitivity (74.63%) but the highest specificity (94.59%).

CONCLUSION

Fibrinogen, AGR, and FAGR are promising biomarkers for the diagnosis of infected tibial nonunion.