Empiric antibiotic therapy in early periprosthetic joint infection: a retrospective cohort study

Novel Method for the Rapid Establishment of Antibiotic Susceptibility Profiles in Bacterial Strains Linked to Musculoskeletal Infections Using Scattered Light Integrated Collector Technology

Bacterial antibiotic resistance is an important challenge that the healthcare system is continually battling and a major problem in the treatment of musculoskeletal infections such as periprosthetic joint infections. Current methods to identify infectious microbes and define susceptibility to antibiotics require two to ten days from isolation to the establishment of an antibiogram. This slow process limits advances in antimicrobial drug discovery and, in the clinical context, delays the delivery of targeted treatments, with potentially devastating outcomes for patients. With this in mind, we strived to establish a quicker and more sensitive method to deliver antibiotic susceptibility profiles of clinically relevant microbes using Scattered Light Integrated Collector (SLIC) technology. We established antibiotic panels to obtain an approximate identification of a wide variety of microbes linked to periprosthetic joint infections and determine their susceptibility to antibiotics. We challenged microbes isolated from patients with our tailored antibiotic panels and found that SLIC detects perturbations in bacterial growth accurately and reproducibly within minutes of culture. Indeed, we could show that SLIC can be used to measure the dose-dependent inhibitory or bacteriolytic activity of broad classes of antibiotics. Our panel design enabled us to establish a profile similar to an antibiogram for the tested bacteria within 90 min. Our method can provide information on the class of bacteria tested and potential treatment avenues in parallel. Our proof-of-principle experiments using isolated clinical strains of bacteria demonstrate that SLIC, together with our specifically designed antibiotic panels, could be used to rapidly provide information on the identity of an infecting microbe, such as those associated with periprosthetic joint infections, and guide physicians to prescribe targeted antibiotic treatment early-on. The constant emergence of resistant strains of bacteria pushes the pharmaceutical industry to develop further effective drugs. Our optimized method could significantly accelerate this work by characterizing the efficacy of new classes of compounds against bacterial viability within minutes, a timeframe far shorter than the current standards.

Modern Microbiological Methods to Detect Biofilm Formation in Orthopedy and Suggestions for Antibiotic Therapy, with Particular Emphasis on Prosthetic Joint Infection (PJI)

Biofilm formation is a serious problem that relatively often causes complications in orthopedic surgery. Biofilm-forming pathogens invade implanted foreign bodies and surrounding tissues. Such a condition, if not limited at the appropriate time, often requires reoperation. This can be partially prevented by selecting an appropriate prosthesis material that prevents the development of biofilm. There are many modern techniques available to detect the formed biofilm. By applying them we can identify and visualize biofilm-forming microorganisms. The most common etiological factors associated with biofilms in orthopedics are: Staphylococcus aureus, coagulase-negative Staphylococci (CoNS), and Enterococcus spp., whereas Gram-negative bacilli and Candida spp. also deserve attention. It seems crucial, for therapeutic success, to eradicate the microorganisms able to form biofilm after the implantation of endoprostheses. Planning the effective targeted antimicrobial treatment of postoperative infections requires accurate identification of the microorganism responsible for the complications of the procedure. The modern microbiological testing techniques described in this article show the diagnostic options that can be followed to enable the implementation of effective treatment.

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.

Microbiological profiles and antibiotic resistance of periprosthetic joint infection after hip replacement in patients with fracture or non-fracture: A comparative study

BACKGROUND

Periprosthetic joint infection (PJI) is one of the worst complications following total joint arthroplasty (TJA). Unfortunately, effective prevention strategies to reduce the burden of PJI have not been fully determined in hip replacement patients with fracture and non-fracture.

OBJECTIVE

This study aimed to analyze and compare the demographic characteristics, microbiological profiles and antibiotic resistance of PJI after hip replacement between patients with fracture and non-fracture.

METHODS

We retrospectively analyzed the data of 132 patients who treated PJI. There were divided into two groups: non-fracture group (64 patients infected after hip replacement for fracture) and non-fracture group (68 patients infected after hip replacement for non-fracture). Microorganisms were obtained from the synovial fluid and infected necrotic tissue in the joint capsule, medullary cavity, or acetabulum in all patients, and microbiological profiles and antibiotic resistance were evaluated.

RESULTS

Coagulase-negative staphylococci (CoNS) were the most common pathogenic microorganisms in all patients. Methicillin-resistant Staphylococcus (MRS) accounted for 25% in all pathogenic microbes. Staphylococci showed high drug resistance rates to clindamycin, levofloxacin, and all of the first- and second-generation cephalosporins. MRS isolates in non-fracture group had higher drug resistance rates to clindamycin and levofloxacin than than those in fracture group. Gram-negative bacilli (GNB) showed high drug resistance rates to Aztreonam, gentamicin and all of the third- and fourth-generation cephalosporins. Furthermore, GNB isolates in the non-fracture group showed higher resistance rates to gentamicin and all of the third- and fourth-generation cephalosporins.

CONCLUSIONS

MRS isolates in the non-fracture group showed higher drug resistance rates to clindamycin and levofloxacin, and GNB isolates in non-fracture group showed higher drug resistance rates to gentamicin and all of the third- and fourth-generation cephalosporins.

Assessment of antimicrobial mismatches in empirical treatment in early PJI after aseptic revision arthroplasty

Background

In early periprosthetic joint infection (PJI), 'debridement, antibiotics and implant retention' (DAIR) is a widely accepted form of treatment. Empirical antimicrobial treatment is started while culture results of tissue samples taken during debridement are pending.

Objectives

In this retrospective study we assessed the antimicrobial mismatch rate between empirical treatment and the susceptibility of the causative microorganisms of PJI after aseptic revision arthroplasty. We analysed risk factors for antimicrobial mismatches and the impact of mismatches on the outcome of PJI treatment.

Results

A total of 119 patients were included in the analysis. In 72% (86/119) of the cases there was an antimicrobial mismatch in empirical treatment. Most of the antimicrobial mismatches were caused by multidrug-resistant (MDR) Staphylococcus spp. (77%, 66/86). In multivariable analysis, polymicrobial PJI was significantly associated with antimicrobial mismatch (OR: 6.89; 95% CI: 2.38-19.53; P < 0.001), and antimicrobial mismatch was significantly associated with reduced success rate of PJI treatment (OR: 0.20; 95% CI: 0.05 ± 0.82; P = 0.026). There was no difference in successful outcome between PJI caused by Gram-negative bacilli (61%) and Gram-positive bacteria (69%, P = 0.516).

Conclusions

Mismatching empirical antimicrobial treatment after DAIR following aseptic revision arthroplasty was significantly associated with failure of PJI treatment. Polymicrobial PJI is a risk factor for antimicrobial mismatch of the empirical treatment of PJI. Antimicrobial mismatch and delay in targeted treatment should be integrated in the approach to optimize antibiotic treatment to improve clinical outcomes, while minimizing unintended side effects of antimicrobial use (antimicrobial stewardship).