Angeliki Banousi1, Dimitrios S Evangelopoulos2, Antonios Stylianakis3, Emmanouil Fandridis4, Sofia Chatziioannou5,6, Nikolaos V Sipsas7, Spyridon G Pneumaticos2. 1. 3rd Department of Orthopaedics, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece. anbanousi@gmail.com. 2. 3rd Department of Orthopaedics, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece. 3. Laboratory of Implant Associated Infections, Department of Microbiology, General Hospital KAT, Athens, Greece. 4. Hand-Upper Limb and Microsurgery Department, General Hospital KAT, Athens, Greece. 5. Nuclear Medicine Division, PET/CT section, Foundation for Biomedical Research of the Academy of Athens, Athens, Greece. 6. 2nd Department of Radiology, Medical School, National and Kapodistrian University of Athens, General University Hospital "ATTIKON", Athens, Greece. 7. Department of Pathophysiology, Medical School, National and Kapodistrian University of Athens, Athens, Greece.
Abstract
BACKGROUND: "Heterogeneity" describes a phenomenon where subpopulations of seemingly isogenic bacteria exhibit a range of susceptibilities to a particular antibiotic. We aim to investigate the frequency of heterogeneity among microbes isolated from infected prostheses, and its possible correlation with microbial resistance. METHODS: Between May 2014 and June 2019, we investigated 234 patients, at our institution, undergoing revision arthroplasty because of loosening of the prostheses or because of periprosthetic joint infection. All patients had periprosthetic tissue culture, sonication of prosthesis and direct inoculation of Sonication fluid into blood culture bottles. We assessed the presence of heterogeneity among all pathogens isolated from infected prostheses. RESULTS: Using standard non-microbiological criteria to determine periprosthetic joint infection, it was found that 143 patient (61.1%) had aseptic loosening while 91 patients (38.9%) had periprosthetic joint infection. Comparing the two methods, the results of our study showed that the method of sonication was significantly more sensitive than tissue culture [91% (83-96) vs. 43% (33-54); p < 0.005]. In this study, heterogeneity was reported in 15 cases, 16.5% of all infections and 6.4% in the total population. In our study, Staphylococcus epidermidis was the most commonly isolated strain followed by Staphylococcus aureus, at a rate of 35.2% and 19.8%, respectively. Antibiotics in which the microorganisms exhibited heterogeneous bacterial behavior most frequently were Gendamicin (5.3%), Vancomycin (4.9%). CONCLUSION: There is increasing evidence that heterogeneity can lead to therapeutic failure and that the detection of this phenotype is a prerequisite for a proper antibiotic choice to have a successful therapeutic effect.
BACKGROUND: "Heterogeneity" describes a phenomenon where subpopulations of seemingly isogenic bacteria exhibit a range of susceptibilities to a particular antibiotic. We aim to investigate the frequency of heterogeneity among microbes isolated from infected prostheses, and its possible correlation with microbial resistance. METHODS: Between May 2014 and June 2019, we investigated 234 patients, at our institution, undergoing revision arthroplasty because of loosening of the prostheses or because of periprosthetic joint infection. All patients had periprosthetic tissue culture, sonication of prosthesis and direct inoculation of Sonication fluid into blood culture bottles. We assessed the presence of heterogeneity among all pathogens isolated from infected prostheses. RESULTS: Using standard non-microbiological criteria to determine periprosthetic joint infection, it was found that 143 patient (61.1%) had aseptic loosening while 91 patients (38.9%) had periprosthetic joint infection. Comparing the two methods, the results of our study showed that the method of sonication was significantly more sensitive than tissue culture [91% (83-96) vs. 43% (33-54); p < 0.005]. In this study, heterogeneity was reported in 15 cases, 16.5% of all infections and 6.4% in the total population. In our study, Staphylococcus epidermidis was the most commonly isolated strain followed by Staphylococcus aureus, at a rate of 35.2% and 19.8%, respectively. Antibiotics in which the microorganisms exhibited heterogeneous bacterial behavior most frequently were Gendamicin (5.3%), Vancomycin (4.9%). CONCLUSION: There is increasing evidence that heterogeneity can lead to therapeutic failure and that the detection of this phenotype is a prerequisite for a proper antibiotic choice to have a successful therapeutic effect.