Rapid diagnostics of orthopedic implant-associated infections using Unyvero ITI implant and tissue infection application is not optimal for Staphylococcus species identification

Abstract

ObjectivesThis pilot study aimed to compare the commercial Unyvero ITI multiplex PCR application (U-ITI, Curetis GmbH) with conventional culturing concerning (a) detection of pathogens, (b) time to detection of pathogens and (c) time to and quality of antibiotic treatment recommendation in diagnostics of orthopedic implant-associated infections (OIAI).Results72 tissue biopsies from 15 consecutive patients with deep OIAI infections were analyzed with conventional culturing including phenotypic antibiotic susceptibility testing and the U-ITI. U-ITI showed lower sensitivity than conventional culturing concerning detection of pathogens (73% vs 93%). 4/15 patients would have been given false negative results by U-ITI, all of which were culture-positive for Staphylococcus species. Median time to detection of pathogens was 47 h and antibiotic resistance 89 h by conventional methods compared to 13.5 h with the U-ITI. The U-ITI did not detect antibiotic resistance, whereas conventional culturing showed resistance to antibiotics covered by the U-ITI panel in 2 patients. Time to detection of pathogens was improved, but the detection limit for staphylococci was unsatisfactory. Although the time to antibiotic treatment recommendation was significantly reduced, the U-ITI would have resulted in incorrect antibiotic recommendation in 2 patients. Our data do not support use of this assay in diagnostics.

Are conventional microbiological diagnostics sufficiently expedient in the era of rapid diagnostics? Evaluation of conventional microbiological diagnostics of orthopedic implant-associated infections (OIAI)

“…Conventional culturing was performed by homogenizing up to 5 tissue samples individually with mortar and pistil in heart infusion broth (HIB) in a type 2 microbiological safety cabinet with subsequent seeding as previous described (Aamot et al. 2019 ). Incubation was terminated after 5 days following consensus (Parvizi et al.…”

“… 2017 , Jun and Jianghua 2018 , Aamot et al. 2019 ).…”

Rapid Diagnostics of Orthopaedic-Implant-Associated Infections Using Nanopore Shotgun Metagenomic Sequencing on Tissue Biopsies

“…Cultivation results have previously been reported [ 5 ]. In addition, biopsies from 15 of the patients have been analysed on a rapid molecular diagnostics platform [ 8 ]. Three patients’ biopsy shotgun metagenomic sequencing results have been previously published ( Supplementary Materials, Table S1 , IDs 117, 127, 130) [ 11 ].…”

“…There are a few culture-independent rapid diagnostic tools on the market. However, these are targeted approaches, limited to the detection of a pre-conceived set of microbes and antibiotic resistance genes [ 6 , 7 , 8 ]. Shotgun metagenomic sequencing is an untargeted method, free of these limitations.…”

Culture-Independent Genotyping, Virulence and Antimicrobial Resistance Gene Identification of Staphylococcus aureus from Orthopaedic Implant-Associated Infections

“…Each patient biopsy was divided into two segments. One segment was cultivated following conventional microbiological diagnostics including pathogen identification with MALDI-TOF (Matrix-Assisted Laser Desorption/Ionization-Time of Flight) mass spectrometry and antimicrobial susceptibility testing in accordance with EUCAST (European Committee on Antimicrobial Susceptibility Testing) guidelines, as described in earlier work [ 17 ]. The other segment was initially frozen in −80 °C awaiting DNA extraction and subsequent nanopore sequencing.…”