The microbiological basis for a revised antibiotic regimen in high-energy tibial fractures: preventing deep infections by nosocomial organisms

Microbiological Profile of Fracture Related Infection at a UK Major Trauma Centre

Fracture Related Infection (FRI) represents one of the biggest challenges for Trauma and Orthopaedic surgery. A better understanding of the microbiological profile should assist with decision-making and optimising outcomes. Our primary aim was to report on the microbiological profile of FRI cases treated over a six-year period at one of Europe's busiest trauma centres. Secondarily, we sought to correlate our findings with existing anti-microbiological protocols and report on diagnostic techniques employed in our practice. All adult cases of FRI treated in our institution between 2016 and 2021 were identified, retrospectively. We recorded patient demographics, diagnostic strategies, causative organisms and antibiotic susceptibilities. There were 330 infection episodes in 294 patients. A total of 463 potentially pathogenic organisms (78 different species) were identified from cultures, of which 57.2% were gram-positive and 39.7% gram-negative. Polymicrobial cultures were found in 33.6% of cases and no causative organism was found in 17.5%. The most prevalent organisms were Staphylococcus aureus (24.4%), coagulase-negative Staphylococci (14%), Pseudomonas aeruginosa (8.2%), Enterobacter species (7.8%) and Escherichia coli (6.9%). Resistant gram-positive organisms (methicillin resistant Staphylococcus aureus or vancomycin-resistant Enterococci) were implicated in 3.3% of infection episodes and resistant gram-negatives (extended-spectrum beta-lactamase, ampC or carbapenemase-producing bacteria) in 13.6%. The organisms cultured in 96.3% of infection episodes would have been covered by our empirical systemic antibiotic choice of teicoplanin and meropenem. To our knowledge, this is the largest reported single-centre cohort of FRIs from a major trauma centre. Our results demonstrate patterns in microbiological profiles that should serve to inform the decision-making process regarding antibiotic choices for both prophylaxis and treatment.

Prevalence, Risk Factors and Microbiological Profile of Orthopaedic Surgical Site Infection in North-Eastern Peninsular Malaysia

Introduction

The devastating outcome of orthopaedic surgical site infections (SSI) are largely preventable if its risk factors, causative organisms and antimicrobial susceptibility patterns in the regional area are known.

Materials and methods

We conducted a retrospective study to address the lack of epidemiological and microbiological data on orthopaedic SSI in Malaysia. All the 80 patients diagnosed and treated for microbiologically proven orthopaedic SSIs in a tertiary hospital in Malaysia from April 2015 to March 2019 were included in a 1:2 case control study.

Results

The prevalence of SSI in clean and clean-contaminated surgeries was 1.243%, which is consistent with most of the studies worldwide, but is low compared to other studies done in Malaysia. The most common type of orthopaedics SSI were internal fixation infections (46.25%), superficial SSIs (25.2%) and Prosthetic joint infections (18.75%). Obesity and tobacco use were found to be significant risk factors of orthopaedic SSI. The most common perioperative prophylaxis used was IV cefuroxime. Majority of the cases (86.5%) received prolonged prophylactic antibiotics. The most common causative agent was Staphylococcus aureus (31.25%), followed by Pseudomonas aeruginosa (26.25%) and Enterobacter spp (7.5%). Methicillin-resistant Staphylococcus aureus (MRSA) accounted for 20% of the S. aureus infections. Up to 19.4% of the Gram-negative organisms are multidrug resistant. The higher rate of isolation of organisms resistant to the prophylactic antibiotics being used may be related to the prolonged use of prophylactic antibiotics, which exerted selective pressure for the acquisition of resistant organisms.

Conclusion

Despite its relatively low prevalence in our local institution and worldwide, the prevention of SSI in orthopaedic practice is crucial to avoid morbidity, mortality and high healthcare cost. This may be achieved by control of modifiable risk factors such as obesity and tobacco use, appropriate use of prophylactic antibiotics and implementation of good surgical and infection control practices.

Timing of antibiotic administration, wound debridement, and the stages of reconstructive surgery for open long bone fractures of the upper and lower limbs

BACKGROUND

Open fractures of the major long bones are complex limb-threatening injuries that are predisposed to deep infection. Treatment includes antibiotics and surgery to debride the wound, stabilise the fracture and reconstruct any soft tissue defect to enable infection-free bone repair. There is a need to assess the effect of timing and duration of antibiotic administration and timing and staging of surgical interventions to optimise outcomes.

OBJECTIVES

To assess the effects (risks and benefits) of the timing of antibiotic administration, wound debridement and the stages of surgical interventions in managing people with open long bone fractures of the upper and lower limbs.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase and clinical trial registers in February 2021. We also searched conference proceedings and reference lists of included studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) or quasi-RCTs that recruited adults with open fractures of the major long bones, comparing: 1) timings of prophylactic antibiotic treatment, 2) duration of prophylactic antibiotic treatment, 3) timing of wound debridement following injury or 4) timing of the stages of reconstructive surgery.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. We aimed to collect data for the following outcomes: limb function, health-related quality of life (HRQoL), deep surgical site infection, delayed or non-union, adverse events (in the short- and long-term course of recovery), and resource-related outcomes.

MAIN RESULTS

We included three RCTs of 613 randomised participants with 617 open fractures. Studies were conducted in medical and trauma centres in the USA and Kenya. Where reported, there was a higher proportion of men and a mean age of participants between 30 and 34 years old. Fractures were in the upper and lower limbs in one study, and were tibia fractures in two studies; where reported, these were the result of high-energy trauma such as road traffic accidents. No studies compared the timing of antibiotic treatment or wound debridement. Duration of prophylactic antibiotic treatment (1 study, 77 participants available for analysis) One study compared antibiotic treatment for 24 hours with antibiotic treatment for five days. We are very uncertain about the effects of different durations of antibiotic treatment on superficial infections (risk ratio (RR) 1.19, 95% CI 0.49 to 2.87, favours 5 day treatment; 1 study, 77 participants); this was very low-certainty evidence derived from one small study with unclear and high risks of bias, and with an imprecise effect estimate. This study reported no other review outcomes. Reconstructive surgery: timing of the stages of surgery (2 studies, 458 participants available for analysis) Two studies compared the timing of wound closure, which was completed immediately or delayed. In one study, the mean time of delay was 5.9 days; in the other study, the time of delay was not reported. We are very uncertain about the effects of different timings of wound closure on deep infections (RR 0.82, 95% CI 0.37 to 1.80, favours immediate closure; 2 studies, 458 participants), delayed union or non-union (RR 1.13, 95% CI 0.83 to 1.55, favours delayed closure; 1 study, 387 participants), or superficial infections (RR 6.45, 95% CI 0.35 to 120.43, favours delayed closure; 1 study, 71 participants); this was very low-certainty evidence. We downgraded the certainty of the evidence for very serious risks of bias because both studies had unclear and high risks of bias. We also downgraded for serious imprecision because effect estimates were imprecise, including the possibility of benefits as well as harms, and very serious imprecision when the data were derived from single small study. These studies reported no other review outcomes.

AUTHORS' CONCLUSIONS

We could not determine the risks and benefits of different treatment protocols for open long bone fractures because the evidence was very uncertain for the two comparisons and we did not find any studies addressing the other possible comparisons. Well-designed randomised trials with adequate power are needed to guide surgical and antibiotic treatment of open fractures, particularly with regard to timing and duration of antibiotic administration and timing and staging of surgery.

Bacterial Identification and Visualization of Bacterial Biofilms Adjacent to Fracture Sites After Internal Fixation

Objectives: The primary aims of this study were to determine if any correlation exists in cases of fracture fixation among: (1) bacterial profiles recovered from the instrumentation and adjacent tissues; (2) the type of orthopedic injury; and (3) the clinical outcome-union versus nonunion. A secondary goal was to compare culture and molecular diagnostics for identifying the bacterial species present following fracture fixation. Design: Single-institution, prospective case-control cohort study. Setting: Single level 1 trauma center. Patients: Forty-nine bony nonunion cases undergoing revision internal fixation and 45 healed fracture controls undergoing removal of hardware. Intervention: Bacterial infection was detected by standard microbial culture methods and by a pan-eubacterial domain, molecular diagnostic (MDx) assay. Confirmation of culture and MDx results was achieved with bacterial ribosomal 16S rRNA fluorescence in situ hybridization (FISH) to visualize bacterial biofilms. Main Outcome Measurements: MDx and microbial culture methods results were the primary study outcomes. Results: Ninety-four percent of the nonunion cohort and 93% of the union cohort had bacteria detected by the MDx. Seventy-eight percent of the nonunion cases and 69% of the controls were culture negative, but MDx positive. Although no significant differences in bacterial composition were observed between the cases and controls, differences were observed when cases were divided by comorbidities. Conclusion: The MDx is more sensitive than microbial culture in detecting bacterial presence. The lack of significantly different findings with regard to bacterial profile identified between the cases and controls suggests that host factors and environmental conditions are largely responsible for determining if bony union will occur. Level of Evidence: Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Bacterial Epidemiology of Surgical Site Infections after Open Fractures of the Lower Limb: A Retrospective Cohort Study

Open lower limb fractures are common injuries, and the occurrence of infectious complications after open fractures is a usual problem. The rate of surgical site infections (SSIs) and the nature and resistance of the germs responsible for SSIs remain poorly described. Our aim was to describe the bacterial epidemiology of SSIs after surgical management of an open lower limb fracture. We conducted a retrospective monocentric cohort study from 1 January 2012 to 31 December 2020 based on the analysis of inpatient records in a non-university hospital of Ile de France region. All patients who underwent surgery for an open lower limb fracture were included. A total of 149 patients were included. In our population, 19 (12.7%) patients developed an SSI. Of these 19 patients, the sample was polymicrobial in 9 (47.4%) patients. In 9 (45%) cases, the samples identified a group 3 enterobacteria, Enterobacter cloacae being the main one in 7 (36.9%) cases. Staphylococci were identified in 11 patients, with Staphylococcus aureus in 9 (47.4%). All Staphylococcus aureus were susceptible to methicillin, and all enterobacteria were susceptible to C3G. Among all SSI, 10 (58.8%) contained at least one germ resistant to amoxicillin/clavulanic acid (AMC). The SSIs rate was 12.7%. The main pathogens identified were Enterobacter cloacae and Staphylococcus aureus. The presence of early SSI caused by group 3 Enterobacteriaceae renders current antibiotic prophylaxis protocols inadequate with AMC in half the cases.

Infection after Open Long Bone Fractures: Can we Improve on Prophylaxis?

INTRODUCTION

Current standards recommend antibiotic prophylaxis administered after open fracture injury. The purpose of this study was to assess culture results in patients with open fracture-associated infections, hypothesizing that cultures obtained do not vary by Gustilo-Anderson (GA) classification.

METHODS

We examined cultured bacterial species from patients with open long bone fractures that underwent irrigation and debridement at a Level 1 trauma center (2008-2016), evaluating our current and two hypothetical antibiotic protocols to assess whether they provided appropriate coverage. The antibiotic protocols included protocols 1 (cefazolin, with gentamicin added for type III fractures), 2 (vancomycin and cefepime) and 3 (ceftriaxone).

RESULTS

GA classification was not associated with bacterial gram stain (P = 0.161), nor was it predictive of mono- versus polymicrobial infection (P = 0.094). Of 42 culture-positive infections, 31 were type III and 11 were type I or II fractures. 27% of the infections for type I or II fractures were caused by organisms targeted by protocol 1 (OR 0.18, 95% CI 0.04-0.82; P = 0.027). There was no difference in coverage by fracture type among protocol 2 (P = 0.771) or protocol 3 (P = 0.891). For type III fractures, protocol 2 provided 94% appropriate coverage compared to 68% and 61% coverage by protocols 1 and 3, respectively.

CONCLUSION

For open fractures complicated by infection, isolated bacterial organisms do not correlate with GA open fracture classification, suggesting that hypothetical protocol 2 should be used for all fracture types. Protocol 2's broad coverage, across all GA fracture types, may prevent infection by organisms not covered by current antibiotic prophylaxis.

Antibiotic Prophylaxis in Open Fractures: Evidence, Evolving Issues, and Recommendations

Open fractures are often associated with high-energy trauma and have an increased risk of infection because of surrounding soft-tissue damage and the introduction of environmental contaminants that may communicate with the fracture site. The Gustilo-Anderson classification of open fractures has been used to guide prophylactic antibiotic therapy because different types of open fracture have been shown to have varying rates of surgical site infections with different combinations of pathogens. Prophylactic treatment with various classes of antibiotics, including penicillins and cephalosporins, aminoglycosides, and fluoroquinolones, has evolved over the past half century. More recently, broader spectrum agents including monobactams and glycopeptides have been used for additional coverage. Duration of antibiotic therapy remains variable between institutions, and antibiotic choice is not standardized. Coverage for nosocomial and multidrug-resistant organisms is an ongoing area of clinical research.

Outcomes and Risk Factors for Polymicrobial Posttraumatic Osteomyelitis

Background: We hypothesized that polymicrobial posttraumatic osteomyelitis (PTO) may be associated with worse outcomes when compared to monomicrobial PTO. We therefore attempted to show the outcomes and predisposing factors associated with polymicrobial PTO.

Methods: A single-center case-control study was carried out from 2007 to 2012. The outcome variables analyzed were: the need for additional surgical and antibiotic treatments, rates of amputation, and mortality associated with the infection. Univariate and multivariable analyses using multiple logistic regression were performed to identify risk factors associated with polymicrobial PTO, and p < 0.05 was considered significant.

Results: Among the 193 patients identified, polymicrobial PTO was diagnosed in 37.8%, and was significantly associated with supplementary surgical debridement (56.1% vs. 31%; p < 0.01), a higher consumption of antibiotics, and more amputations (6.5% vs 1.3%; p < 0.01). Factors associated with polymicrobial PTO in the multivariable analysis were older age (odds ratio [OR] = 1.02, 95% confidence interval [CI] = 1.01 to 1.03, p = 0.04), working in agriculture (OR = 2.86, 95% CI = 1.05 to 7.79, p = 0.04), open fracture Gustilo type III (OR = 2.38, 95% CI = 1.02 to 5.56, p = 0.04), need for blood transfusion (OR = 2.15, 95% CI = 1.07 to 4.32, p = 0.03), and need for supplementary debridement (OR = 2.58, 95% CI = 1.29 to 5.16, p = 0.01).

Conclusions: PTO is polymicrobial in more than one-third of patients, associated with extra surgical and clinical treatment, and worse outcomes including higher rates of amputation.

Complications of Open Tibial Fracture Management: Risk Factors and Treatment

Open tibial fractures result in high rates of complications. This study aims to elucidate the risk factors causing these complications, and suggest antimicrobial regimens based on the organisms grown in post-operative infections. Over a period of five years, 173 patients had sustained open tibial fractures and undergone operative treatment at a single institution. All surgical data was gathered retrospectively through online medical records. Thirty-one patients (17.9%) had sustained post-operative bony complications, while infective complications were reported in 37 patients (21.4%). Patients with Gustilo type III fractures were found to be more than three times as likely to sustain post-operative infective (p=0.007) or bony (p=0.015) complications, compared to Gustilo type I or II fractures. The fracture location and time taken to fixation did not significantly affect the complication rate, but results were trending towards significance. The commonest cause of infective complications were hospital-acquired organisms, such as Methicillin-resistant staphylococcus aureus (40.5%). Closer monitoring of patients sustaining high grade Gustilo open fractures, as well as antimicrobial prophylaxis for both hospital-acquired organisms and environmental contaminants, will result in the best outcome for patients. Further studies with larger sample sizes are warranted, to determine the significance of fracture location and time taken to fixation on complication rates.

Meta-analysis of antibiotics for simple hand injuries requiring surgery

BACKGROUND

Simple hand trauma is very common, accounting for 1·8 million emergency department visits annually in the USA alone. Antibiotics are used widely as postinjury prophylaxis, but their efficacy is unclear. This meta-analysis assessed the effect of antibiotic prophylaxis versus placebo or no treatment on wound infection rates in hand injuries managed surgically.

METHODS

Embase, MEDLINE, PubMed, Cochrane Central, ClinicalTrials.gov and the World Health Organization International Clinical Trials Portal were searched for published and unpublished studies in any language from inception to September 2015. The primary outcome was the effect of antibiotic prophylaxis on wound infection rates. Open fractures, crush injuries and bite wounds were excluded. Study quality was assessed using the Cochrane risk-of-bias tool. Data were pooled using random-effects meta-analysis, and risk ratios (RRs) and 95 per cent c.i. obtained.

RESULTS

Thirteen studies (2578 patients) were included, comprising five double-blind randomized clinical trials, five prospective trials and three cohort studies. There was no significant difference in infection rate between the antibiotic and placebo/no antibiotic groups (RR 0·89, 95 per cent c.i. 0·65 to 1·23; P = 0·49). Subgroup analysis of the five double-blind randomized clinical trials (864 patients) again found no difference in infection rates (RR 0·66, 0·36 to 1·21; P = 0·18).

CONCLUSION

There was moderate-quality evidence that routine use of antibiotics does not reduce the infection rate in simple hand wounds that require surgery.

Current Concepts and Ongoing Research in the Prevention and Treatment of Open Fracture Infections

Significance: Open fractures are fractures in which the bone has violated the skin and soft tissue. Because of their severity, open fractures are associated with complications that can result in increased lengths of hospital stays, multiple operative interventions, and even amputation. One of the factors thought to influence the extent of these complications is exposure and contamination of the open fracture with environmental microorganisms, potentially those that are pathogenic in nature. Recent Advances: Current open fracture care aims to prevent infection by wound classification, prophylactic antibiotic administration, debridement and irrigation, and stable fracture fixation. Critical Issues: Despite these established treatment paradigms, infections and infection-related complications remain a significant clinical burden. To address this, improvements need to be made in our ability to detect bacterial infections, effectively remove wound contamination, eradicate infections, and treat and prevent biofilm formation associated with fracture fixation hardware. Future Directions: Current research is addressing these critical issues. While culture methods are of limited value, culture-independent molecular techniques are being developed to provide informative detection of bacterial contamination and infection. Other advanced contamination- and infection-detecting techniques are also being investigated. New hardware-coating methods are being developed to minimize the risk of biofilm formation in wounds, and immune stimulation techniques are being developed to prevent open fracture infections.

The ortho-plastic approach to soft tissue management in trauma

Fractures with associated soft tissue injuries, or those termed 'open,' are not uncommon. There has been much discussion regarding there management, with the guidance from the combined British Orthopaedic Association and British Association and Aesthetic Surgeons teams widely accepted as the gold level of therapy. We aim to discuss the current evidence about the initial management of this group of injuries, taking a journey from arrival in the accident and emergency department through to the point of definitive closure. Other modes of therapy are also reviewed.

Pretibial lacerations: experience from a lower limb trauma centre and systematic review

BACKGROUND

Pretibial lacerations are an important and neglected problem among the elderly. Poor management leads to prolonged hospitalisation and terminal decline. This study summarises our experience and evidence from the literature to ascertain an evidence-based rationale for referral and management.

METHODS

Our data were obtained from review of a prospectively gathered database. Additionally, Pubmed, Embase, Medline, and the Cochrane Database of Systematic Reviews were searched through July 2013, with eligible studies evaluated using standard methodology.

RESULTS

Seventy-three pretibial lacerations in 73 patients (63 females) were identified. Mean age was 78 ± 14, 1SD. Sixty patients were managed operatively with a mean length of stay of 11 ± 7 days, 1SD when uncomplicated by medical co-morbidity. Seven deaths occurred (4 in-hospital; 2 treated surgically and 2 treated conservatively) and 3 deaths occurred within 3 months of discharge; a death rate more than twice that of matched controls. Donor site "over-grafting" was performed in 19 cases and resulted in accelerated donor site healing (11 ± 9 days, 1SD vs. 29 ± 42 days, 1SD; P < 0.001). Negative pressure wound therapy delayed discharge (21 ± 23 days, 1SD vs. 15 ± 14 days, 1SD; P = 0.028). Microbiological sampling is unhelpful. Bed rest is unnecessary. "De-fatting" the flap is unproven.

CONCLUSION

Admissions expose the elderly to physical/functional decline and death. Our findings support a change of practice, minimising admissions for minor (Dunkin type I/II) injuries and rapid, protocol-driven surgical intervention and discharge for Dunkin type III/IV injuries with avoidance of negative pressure wound therapy in all but selected cases.

What is the rate of methicillin-resistant Staphylococcus aureus and Gram-negative infections in open fractures?

BACKGROUND

There have been increasing reports of methicillin-resistant Staphylococcus aureus (MRSA) infections in the community, but it is unclear whether infectious organisms in open fracture infections have changed and if our current regimen of antibiotic prophylaxis is therefore obsolete.

QUESTIONS/PURPOSES

We determined the recent incidence of MRSA and Gram-negative organism infections after open fractures.

METHODS

We performed a retrospective cohort study on 189 patients with 202 open fractures treated from 2009 to 2010. During the followup, patients were evaluated for signs of infection using the Centers for Disease Control and Prevention criteria. We determined the organisms using routine microbiology culture. The minimum followup was 3 months (median, 47 months; range, 3-108 months).

RESULTS

Of the 202 open fractures, 20 (10%) developed infections. The most common organism was Staphylococcus, whereas five (25%) of those infected were positive for MRSA, and 11 (55%) of those with infection were cultured for at least one Gram-negative organism. Six (30%) open fractures had infections that grew out multiple organisms. The incidence of MRSA infections in our open fracture population was 2.5%.

CONCLUSIONS

There is a high incidence of MRSA and Gram-negative infections after open fractures, which may indicate that current antibiotic regimens need to be changed.

LEVEL OF EVIDENCE

Level IV, retrospective case-series. See the Guidelines for Authors for a complete description of levels of evidence.

Delayed amputation following trauma increases residual lower limb infection

INTRODUCTION

Residual limb infection following amputation is a devastating complication, resulting in delayed rehabilitation, repeat surgery, prolonged hospitalisation and poor functional outcome. The aim of this study was to identify variables predicting residual limb infection following non-salvageable lower limb trauma.

METHODS

All cases of non-salvageable lower limb trauma presenting to a specialist centre over 5 years were evaluated from a prospective database and clinical and management variables correlated with the development of deep infection.

RESULTS

Forty patients requiring 42 amputations were identified with a mean age of 49 years (±19.9, 1SD). Amputations were performed for 21 Gustilo IIIB injuries, 12 multi-planar degloving injuries, seven IIIC injuries and one open Schatzker 6 fracture. One limb was traumatically amputated at the scene and surgically revised. Amputation level was transtibial in 32, through-knee in one and transfemoral in nine. Median time from injury to amputation was 4 days (range 0-30 days). Amputation following only one debridement and within 5 days resulted in significantly fewer stump infections (p = 0.026 and p = 0.03, respectively, Fisher's exact test). The cumulative probability of infection-free residual limb closure declined steadily from day 5. Multivariate analyses revealed that neither the nature of the injury nor pre-injury patient morbidity independently influenced residual limb infection.

CONCLUSION

Avoiding residual limb infection is critically dependent on prompt amputation of non-salvageable limbs.

Antimicrobial prophylaxis in open lower extremity fractures

Clinical question:

Based on the grade of open fracture, which antibiotic should be selected for antimicrobial prophylaxis, and what is the optimal timing and duration of administration?

Results:

For Grade I and II open fractures, a first-generation cephalosporin (eg, cefazolin) should be administered within 3 hours of initial injury and be continued for 24 hours after initial injury. Grade III open fractures require coverage with an aminoglycoside in addition to a first-generation cephalosporin within 3 hours of initial injury, and antibiotics should be continued for 48–72 hours after initial injury but no more than 24 hours after wound closure. If a fracture is at risk of contamination with clostridium species, such as a farm-related injury, penicillin should be added to the antibiotic regimen.

Implementation:

Pitfalls to avoid when using antibiotics for infection prophylaxis in open fractures include utilizing cultures immediately postinjury to direct choice of agent for antimicrobial prophylaxis, because infecting pathogens do not typically correlate to pathogens initially cultured after injury; failure to consider patients’ medication allergy history or reconcile allergy records; and failure to obtain a thorough history to determine injury exposure (eg, farm, water).