The effect of early broad-spectrum versus delayed narrow-spectrum antibiotic therapy on the primary cure rate of acute infection after osteosynthesis

Risk Factors for Therapeutic Failure and One-Year Mortality in Patients with Intramedullary Nail-Associated Infection after Trochanteric and Subtrochanteric Hip Fracture Repair

Despite the implications of trochanteric and subtrochanteric intramedullary (IM) nail infection for patients with hip fracture, little is known about risk factors for therapeutic failure and mortality in this population. We performed a retrospective observational analysis including patients diagnosed with trochanteric and subtrochanteric IM nail infection at a Spanish academic hospital during a 10-year period, with a minimum follow-up of 22 months. Of 4044 trochanteric and subtrochanteric IM nail implants, we identified 35 cases of infection during the study period (0.87%), 17 of which were chronic infections. Patients with therapeutic failure (n = 10) presented a higher average Charlson Comorbidity Index (CCI) (5.40 vs. 4.21, p 0.015, CI 0.26-2.13) and higher rates of polymicrobial (OR 5.70, p 0.033, CI 1.14-28.33) and multidrug-resistant (OR 7.00, p 0.027, CI 1.24-39.57) infections. Upon multivariate analysis, polymicrobial infection and the presence of multidrug-resistant pathogens were identified as independent risk factors for therapeutic failure. Implant retention was associated with an increased risk of failure in chronic infection and was found to be an independent risk factor for overall one-year mortality in the multivariate analysis. Our study highlights the importance of broad-spectrum empirical antibiotics as initial treatment of trochanteric and subtrochanteric IM nail-associated infection while awaiting microbiological results. It also provides initial evidence for the importance of implant removal in chronic IM-nail infection.

In Vitro Elution of Gentamicin from CERAMENT® G Has an Antimicrobial Effect on Bacteria With Various Levels of Gentamicin Resistance Found in Fracture-related Infection

BACKGROUND

Fracture-related infection is a serious complication after trauma. CERAMENT® G combines dead-space management with local release of gentamicin in a single-stage procedure. Bacterial resistance against antibiotics is increasing. The local effect of CERAMENT® G on bacteria resistant to systemically administered gentamicin is unknown.

QUESTIONS/PURPOSES

(1) What is the in vitro elution pattern of gentamicin from CERAMENT® G using a full washout model? (2) What is the in vitro antimicrobial activity (zone of inhibition) of CERAMENT® G against bacterial isolates found in fracture-related infection with different susceptibility levels toward gentamicin?

METHODS

Elution of gentamicin from CERAMENT® G was determined in vitro over a period of 2 months. Elution experiments were performed in fivefold, with gentamicin being sampled in threefold at 19 different timepoints within 2 months. Antimicrobial activity was determined using the four most-frequently cultured bacterial species found in fracture-related infection: Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Enterobacter cloacae . For each of the species, four different isolates with a different susceptibility to gentamicin were used. According to the European Committee on Antimicrobial Susceptibility Testing, the susceptibility of each isolate was classified into four different groups: fully susceptible (minimum inhibitory concentration 0.064 to 4 mg/L), minimally resistant (minimum inhibitory concentration 4 to 16 mg/L), moderately resistant (minimum inhibitory concentration 8 to 96 mg/L), and highly resistant (minimum inhibitory concentration 24 to 1024 mg/L), depending on each organism. The antimicrobial activity of CERAMENT® G was determined according to the European Committee on Antimicrobial Susceptibility Testing disk protocol. The experiment was performed in fivefold for each isolate. The zone of inhibition was compared between each bacterial isolate and within each of the four separate species. Nonlinear regression statistics were calculated between the zone of interest and logarithmic minimum inhibitory concentration for each bacterial species.

RESULTS

After 24 hours, 95% of all available gentamicin was eluted, and gentamicin was still detectable after 2 months. CERAMENT® G showed antimicrobial activity against all bacterial species; only S taphylococcus aureus (with a minimum inhibitory concentration > 1024 mg/L) was not susceptible. The zone of interest of the different bacterial isolates was correlated with the logarithmic minimum inhibitory concentration.

CONCLUSION

CERAMENT® G offers a bone substitute capable of releasing high levels of gentamicin within a short period of time. This study shows that CERAMENT® G has antimicrobial activity against bacterial isolates that are resistant to gentamicin when systemically administered. This finding raises the question of whether European Committee on Antimicrobial Susceptibility Testing cutoff points for systemic application are useful for the use of local CERAMENT® G. Standardized experiments to determine local antibiotic antimicrobial activity in fracture-related infection treatment are needed to form guidelines for the use of local antibiotics and ultimately improve fracture-related infection treatment.

CLINICAL RELEVANCE

Local concentrations of gentamicin with CERAMENT® G are much higher than when systemically administered. It seems effective against certain bacterial strains that are not affected by systemically reachable concentrations of gentamicin. CERAMENT® G might still be effective when bacteria that are resistant to systemically administered concentrations of gentamicin are occulated from patients with fracture-related infection.

Mismatch Rate of Empirical Antimicrobial Treatment in Fracture-Related Infections

OBJECTIVES

To evaluate the current standard of care regarding empirical antimicrobial therapy in fracture-related infections (FRIs).

METHODS

DESIGN

Retrospective cohort study.

SETTING

Level I Trauma Center.

PATIENT SELECTION CRITERIA

Adult patients treated for FRI with surgical debridement and empirical antibiotics between September 1, 2014, and August 31, 2022. Patients were excluded if less than 5 tissue samples for culture were taken, culture results were negative, or there was an antibiotic-free window of less than 3 days before debridement.

OUTCOME MEASURES AND COMPARISONS

FRI microbial etiology, antimicrobial resistance patterns (standardized antimicrobial panels were tested for each pathogen), the mismatch rate between empirical antimicrobial therapy and antibiotic resistance of causative microorganism(s), and mismatching risk factors.

RESULTS

In total, 75 patients were included [79% (59/75) men, mean age 51 years]. The most prevalent microorganisms were Staphylococcus aureus (52%, 39/75) and Staphylococcus epidermidis (41%, 31/75). The most frequently used empirical antibiotic was clindamycin (59%, 44/75), followed by combinations of gram-positive and gram-negative covering antibiotics (15%, 11/75). The overall mismatch rate was 51% (38/75) [95% confidence interval (CI), 0.39-0.62] and did not differ between extremities [upper: 31% (4/13) (95% CI, 0.09-0.61), lower: 55% (33/60) (95% CI, 0.42-0.68, P = 0.11)]. Mismatching empirical therapy occurred mostly in infections caused by S. epidermidis and gram-negative bacteria. Combination therapy of vancomycin with ceftazidime produced the lowest theoretical mismatch rate (8%, 6/71). Polymicrobial infections were an independent risk factor for mismatching (OR: 8.38, 95% CI, 2.53-27.75, P < 0.001).

CONCLUSIONS

In patients with FRI, a mismatching of empirical antibiotic therapy occurred in half of patients, mainly due to lack of coverage for S. epidermidis , gram-negative bacteria, and polymicrobial infections. Empirical therapy with vancomycin and ceftazidime produced the lowest theoretical mismatch rates. This study showed the need for the consideration of gram-negative coverage in addition to standard broad gram-positive coverage. Future studies should investigate the effect of the proposed empirical therapy on long-term outcomes.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Time to Positivity in Blood Culture Bottles Inoculated with Sonication Fluid from Fracture-Related Infections

The timely and accurate identification of causative agents is crucial for effectively managing fracture-related infections (FRIs). Among various diagnostic methods, the "time to positivity" (TTP) of cultures has emerged as a valuable predictive factor in infectious diseases. While sonication of implants and inoculation of blood culture bottles with sonication fluid have enhanced sensitivity, data on the TTP of this microbiological technique remain limited. Therefore, patients with ICM criteria for confirmed FRI treated at our institution between March 2019 and March 2023 were retrospectively identified and their microbiological records were analyzed. The primary outcome parameter was TTP for different microorganism species cultured in a liquid culture collected from patients with confirmed FRI. A total of 155 sonication fluid samples from 126 patients (average age 57.0 ± 17.4 years, 68.3% males) was analyzed. Positive bacterial detection was observed in 78.7% (122/155) of the liquid culture pairs infused with sonication fluid. Staphylococcus aureus was the most prevalent organism (42.6%). Streptococcus species exhibited the fastest TTP (median 11.9 h), followed by Staphylococcus aureus (median 12.1 h) and Gram-negative bacteria (median 12.5 h), all of which had a 100% detection rate within 48 h after inoculation. Since all Gram-negative pathogens yielded positive culture results within 24 h, it could be discussed if empirical antibiotic therapy could be de-escalated early and limited towards the Gram-positive germ spectrum if no Gram-negative pathogens are detected up to this time point in the context of antibiotic stewardship.

Developing an antibiogram for empiric antibiotic prescribing for adult non-spinal orthopaedic infections in a developing world setting

PURPOSE

Empiric antibiotic strategies in the treatment of fracture-related infections, chronic osteomyelitis, prosthetic joint infection, and septic arthritis should be based on local microbiological antibiograms. This study aims to describe the microbiology and review the antibiogram profiles of bacterial isolates from patients undergoing surgical treatment for non-spinal orthopaedic infections, to identify the most appropriate empiric antibiotic strategy.

METHODS

A retrospective review was performed of all cases of non-spinal orthopaedic infections treated surgically from 1 January 2018 to 31 December 2018. The National Health Laboratory Service microbiology database was used to identify all intra-operative microbiological specimens obtained from orthopaedic patients, and data were correlated with the orthopaedic surgical database. Cases were divided into fracture-related infections, chronic osteomyelitis, prosthetic joint infection, and septic arthritis. Antibiotic susceptibility data were used to predict the efficacy of different empiric antibiotic regimens.

RESULTS

A total of 107 cases were included in the study; 184 organisms were cultured. Overall, the most common organism cultured was Staphylococcus aureus (25%) followed by Acinetobacter baumannii (9%), Enterococcus faecalis (7%) and Enterobacter cloacae (5%). Across all categories the oral antibiotic combination with the highest effectiveness (81%) would have been a combination of co-trimoxazole, ciprofloxacin and amoxicillin. The most effective intravenous antibiotic combination would have been either piperacillin-tazobactam, amikacin and vancomycin or meropenem and vancomycin; 90% of tested isolates were susceptible to either of these combinations.

CONCLUSION

Antibiogram profiles can serve to guide to empiric antibiotic choice in the management of different categories of non-spinal orthopaedic infections.

[Antibiotic use for prophylaxis and empirical therapy of fracture-related infections in Germany : A survey of 44 hospitals]

BACKGROUND

Antibiotics play an important role in the prophylaxis and treatment of infections in orthopedic trauma surgery; however, there seems to be remarkable differences in the clinical antibiotic practice between hospitals, particularly for open fractures and for the empirical therapy of fracture-related infections (FRI).

METHODS

Therefore, we intended to evaluate the current clinical praxis in university and workers' compensation hospitals in Germany with a questionnaire on prophylaxis and empirical treatment of FRI. The results were compared with the resistance profile of 86 FRI patients in order to analyze the hypothetical effectiveness of the empirical treatment.

RESULTS

A total of 44 hospitals (62.0%) responded. A homogeneous antibiotic prophylaxis (95.5% of all hospitals) with cephalosporins was reported for perioperative prophylaxis of internal fixation of closed fractures. For open fractures, eight different monotherapy and combination treatment concepts were reported. In empirical treatment of FRI, 12 different therapeutic concepts were reported, including aminopenicillins/beta lactamase inhibitors (BLI) (31.8%), cephalosporins (31.8%), and ampicillin/sulbactam + vancomycin (9.1%). In terms of the hypothetical effectiveness of these antibiotic regimes, low sensitivity rates of 65.1% and 74.4% for cephalosporins and aminopenicillins/BLI, respectively, were found. For the combination vancomycin + meropenem, the highest hypothetical sensitivity (91.9%) was detected.

DISCUSSION

Based on the existing, institution-specific pathogen spectrum, the combination therapy including meropenem and vancomycin seems to be of value but should be restricted to patients with multiple revision procedures or a septic course of infection in order to prevent the selection of highly resistant pathogens.

Analyzing risk factors for treatment failure in fracture-related infection

INTRODUCTION

Fracture-related infection (FRI) represents a challenging clinical scenario. Limited evidence exists regarding treatment failure after initial management of FRI. The objective of our investigation was to determine incidence and risk factors for treatment failure in FRI.

MATERIALS AND METHODS

We conducted a retrospective review of patients treated for FRI between 2011 and 2015 at three level 1 trauma centers. One hundred and thirty-four patients treated for FRI were identified. Demographic and clinical variables were extracted from the medical record. Treatment failure was defined as the need for repeat debridement or surgical revision seven or more days after the presumed final procedure for infection treatment. Univariate comparisons were conducted between patients who experienced treatment failure and those who did not. Multivariable logistic regression was conducted to identify independent associations with treatment failure.

RESULTS

Of the 134 FRI patients, 51 (38.1%) experienced treatment failure. Patients who failed were more likely to have had an open injury (31% versus 17%; p = 0.05), to have undergone implant removal (p = 0.03), and additional index I&D procedures (3.3 versus 1.6; p < 0.001). Most culture results identified a single organism (62%), while 15% were culture negative. Treatment failure was more common in culture-negative infections (p = 0.08). Methicillin-resistant Staphylococcus aureus (MRSA) was the most common organism associated with treatment failure (29%; p = 0.08). Multivariate regression demonstrated a statistically significant association between treatment failure and two or more irrigation and debridement (I&D) procedures (OR 13.22, 95% CI 4.77-36.62, p < 0.001) and culture-negative infection (OR 4.74, 95% CI 1.26-17.83, p = 0.02).

CONCLUSIONS

The rate of treatment failure following FRI continues to be high. Important risk factors associated with treatment failure include open fracture, implant removal, and multiple I&D procedures. While MRSA remains common, culture-negative infection represents a novel risk factor for failure, suggesting aggressive treatment of clinically diagnosed cases remains critical even without positive culture data.

LEVEL OF EVIDENCE

Retrospective cohort study; Level III.

The Microbiological Etiology of Fracture-Related Infection

Purpose

Fracture-related infection (FRI) is an important complication related to orthopaedic trauma. Although the scientific interest with respect to the diagnosis and treatment of FRI is increasing, data on the microbiological epidemiology remains limited. Therefore, the primary aim of this study was to evaluate the microbiological epidemiology related to FRI, including the association with clinical symptoms and antimicrobial susceptibility data. The secondary aim was to analyze whether there was a relationship between the time to onset of infection and the microbiological etiology of FRI.

Methods

FRI patients treated at the University Hospitals of Leuven, Belgium, between January 1st 2015 and November 24th 2019 were evaluated retrospectively. The microbiological etiology and antimicrobial susceptibility data were analyzed. Patients were classified as having an early (<2 weeks after implantation), delayed (2-10 weeks) or late-onset (> 10 weeks) FRI.

Results

One hundred ninety-one patients with 194 FRIs, most frequently involving the tibia (23.7%) and femur (18.6%), were included. Staphylococcus aureus was the most frequently isolated pathogen, regardless of time to onset (n=61; 31.4%), followed by S. epidermidis (n=50; 25.8%) and non-epidermidis coagulase-negative staphylococci (n=35; 18.0%). Polymicrobial infections (n=49; 25.3%), mainly involving Gram negative bacilli (GNB) (n=32; 65.3%), were less common than monomicrobial infections (n=138; 71.1%). Virulent pathogens in monomicrobial FRIs were more likely to cause pus or purulent discharge (n=45;54.9%; p=0.002) and fistulas (n=21;25.6%; p=0.030). Susceptibility to piperacillin/tazobactam for GNB was 75.9%. Vancomycin covered 100% of Gram positive cocci.

Conclusion

This study revealed that in early FRIs, polymicrobial infections and infections including Enterobacterales and enterococcal species were more frequent. A time-based FRI classification is not meaningful to estimate the microbiological epidemiology and cannot be used to guide empiric antibiotic therapy. Large multicenter prospective studies are necessary to gain more insight into the added value of (broad) empirical antibiotic therapy.

What Is the Most Effective Empirical Antibiotic Treatment for Early, Delayed, and Late Fracture-Related Infections?

Antibiotic treatment strategies for fracture-related infections (FRI) are often extrapolated from periprosthetic joint infections (PJI), although, in contrast to PJI, detailed analysis of pathogens and their antibiotic resistance is missing. Therefore, this study aimed to investigate antibiotic susceptibility profiles to identify effective empiric antibiotic treatment for early-, delayed-, and late-onset FRI. Patients treated for FRI from 2013 to 2020 were grouped into early (<2 weeks), delayed (3−10 weeks), and late (>10 weeks) onset of infection. Antibiotic susceptibility profiles were examined with respect to broadly used antibiotics and antibiotic combinations. In total, 117 patients (early n = 19, delayed n = 60, late n = 38) were enrolled. In early-onset FRI, 100.0% efficacy would be achieved by meropenem + vancomycin, gentamicin + vancomycin, co-amoxiclav + glycopeptide, ciprofloxacin + glycopeptide and piperacillin/tazobactam + glycopeptide. For patients with delayed FRI, the highest susceptibility was revealed for meropenem + vancomycin, gentamicin + vancomycin and ciprofloxacin + glycopeptide (96.7%). Meropenem + vancomycin was the most effective empiric antimicrobial in patients with late-onset of infection with 92.1% coverage. No subgroup differences in antibiotic sensitivity profiles were observed except for the combination ciprofloxacin + glycopeptide, which was significantly superior in early FRI (F = 3.304, p = 0.04). Across all subgroups meropenem + vancomycin was the most effective empiric treatment in 95.7% of patients with confirmed susceptibility. Meropenem + vancomycin, gentamicin + vancomycin, co-amoxiclav + glycopeptide are the best therapeutic options for FRI, regardless of the onset of infection. To avoid multidrug resistance, established antibiotic combinations such as co-amoxiclav with a glycopeptide seem to be reasonable as a systemic antibiotic therapy, while vancomycin + gentamicin could be implemented in local antibiotic therapy to reduce adverse events during treatment.

Is There a Difference in Microbiological Epidemiology and Effective Empiric Antimicrobial Therapy Comparing Fracture-Related Infection and Periprosthetic Joint Infection? A Retrospective Comparative Study

This study aims to investigate (1) microbial patterns in fracture-related infections (FRIs) in comparison to microbiological patterns of periprosthetic joint infections (PJIs), (2) the identification of effective empiric antibiotic therapy for FRIs and PJIs and (3) analysis of difficult-to-treat (DTT) pathogens. Patients treated for FRIs or PJIs from 2017 to 2020 were evaluated for pathogens detected during treatment. Antibiotic susceptibility profiles were examined with respect to broadly used antibiotics and antibiotic combinations. Resistance rates to rifampicin or fluoroquinolone were determined. A total of 81 patients with PJI and 86 with FRI were included in the study. For FRIs Staphylococcus aureus was the most common infection-causing pathogen (37.4% vs. 27.9% for PJI). Overall, there was no statistical difference in pathogen distribution (p = 0.254). For FRIs, combinations of gentamicin + vancomycin (93.2%), co-amoxiclav + glycopeptide and meropenem + vancomycin (91.9% each) would have been effective for empiric therapy, similar to PJIs. Difficult to treat pathogens were more frequently detectable in PJIs (11.6% vs. 2.3%). Empiric therapy combinations such as gentamicin + vancomycin, co-amoxiclav + glycopeptide or meropenem + vancomycin, are effective antibiotic strategies for both FRI and PJI patients. More DTT pathogens were detectable in PJIs compared to FRIs.

Outcome of Debridement, Antibiotics, and Implant Retention for Staphylococcal Hip and Knee Prosthetic Joint Infections, Focused on Rifampicin Use: A Systematic Review and Meta-Analysis

The treatment of staphylococcal prosthetic joint infection (PJI) with debridement, antibiotics, and retention of the implant (DAIR) often results in failure. An important evidence gap concerns the treatment with rifampicin for PJI. A systematic review and meta-analysis were conducted to assess the outcome of staphylococcal hip and/or knee PJI after DAIR, focused on the role of rifampicin. Studies published until September 2, 2020 were included. Success rates were stratified for type of joint and type of micro-organism. Sixty-four studies were included. The pooled risk ratio for rifampicin effectiveness was 1.10 (95% confidence interval, 1.00-1.22). The pooled success rate was 69% for Staphylococcus aureus hip PJI, 54% for S aureus knee PJI, 83% for coagulase-negative staphylococci (CNS) hip PJI, and 73% for CNS knee PJI. Success rates for MRSA PJI (58%) were similar to MSSA PJI (60%). The meta-analysis indicates that rifampicin may only prevent a small fraction of all treatment failures.

[Management of suspected early infection after osteosynthesis]

The infection rate after fracture osteosynthesis depends on many factors. The postoperative infection rate after osteosynthesis (inpatient treatment) was between 1.15% and 2.04% for the years 2017-2019. The total number of postoperative wound infections was estimated at around 225,000 annually in 2018. Essential factors for reducing the infection rate after osteosynthesis are the favorable choice of the timing of the operation and the surgical procedure as well as the treatment of relevant secondary diseases. If a postoperative wound infection is suspected critical assessment of the wounds in the postoperative course is essential in order to be able to identify and treat this complication at an early stage. After osteosynthesis, early diagnosis of a peri-implant infection and differentiated surgical and antibiotic treatment are the prerequisites for the best possible treatment success.