Multiplex microarray PCR Unyvero BCU system to accelerate relevant antimicrobial treatment in polymicrobial bloodstream infection.

PURPOSE: To evaluate the performance of a rapid multiplex microarray-based method (Unyvero BCU system, BCU) to identify microorganisms and detect antimicrobial resistance directly from positive blood culture (BC) bottles with polymicrobial growth, and to assess relevance of information provided for timely guidance of polymicrobial bloodstream infection treatment. METHODS: Accuracy, time-to-actionable results and potential impact of BCU on antimicrobial treatment were compared with those of standard of care during a prospective study for the sample analysis (November 2017-November 2018) and a retrospective study for the clinical data analysis and the time-to-result analysis. The study was complemented with an experimental study, based on spiked blood cultures to assess the ability of the method to detect antimicrobial resistance genes. RESULTS: Sixty-five clinical polymicrobial BC samples (163 total microorganisms) and 30 simulated polymicrobial BC samples (60 strains) were included. BCU reported 84.6% samples as polymicrobial, correctly identified all the bacteria of the mix for 72.3% samples (47/65) and detected bacteria that were missed by the conventional culture for 13.8% samples. All identifications and antimicrobial resistances were accurately detected for 61.5% (40/65) samples. Limitations concerned the detection of anaerobes, enterococci and enterobacterial susceptibility to third generation cephalosporins. BCU results would have guided antimicrobial treatment for 50.8% of the cases (33/65) in a timely and relevant manner, had no impact for 27.7% (18/65) and been misleading for 18.5% (12/65). CONCLUSIONS: Despite some limitations, the Unyvero BCU system is a rapid and reliable method for polymicrobial BC sample analysis.

Ruling out underlying infection in 200 presumed aseptic knee and hip revision arthroplasties using a multiplex PCR system.

Ruling out an infection in one-stage knee and hip revisions for presumed aseptic failure by conventional tissue cultures takes up to 14 days. Multiplex polymerase chain reaction (mPCR) is a quick test (4-5 h) for detecting pathogens. The purpose of this study was to evaluate the diagnostic accuracy of an automated mPCR of synovial fluid obtained intraoperatively in unsuspected knee and hip revisions. A prospective study was conducted with 200 patients undergoing a one-stage knee or hip revision. Synovial fluid was analyzed with the mPCR Unyvero implant and tissue infection G2 cartridge (U-ITI G2) system and compared to intraoperative tissue cultures. The primary outcome measure was the diagnostic accuracy, including sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), of the mPCR U-ITI G2 system compared to conventional cultures. In the knee revision group, there were no patients with a positive mPCR in combination with positive cultures. This resulted in a non-calculable sensitivity and PPV. The specificity and NPV in the knee revision group of the mPCR compared to tissue cultures was 96.8% and 96.8%, respectively. In the hip revision group, the sensitivity, specificity, PPV, and NPV of the mPCR compared to tissue cultures was 36.4%, 96.6%, 57.1%, and 92.5%, respectively. Sixteen mismatches occurred between the mPCR and tissue cultures. The mPCR U-ITI G2 system is a quick and reliable synovium fluid test for ruling out infection in presumed aseptic knee and hip revisions with a high NPV compared with tissue cultures, although some mismatches were observed. Periprosthetic tissue cultures are still advised as back-up for false negative and positive mPCR test results.

Is the Unyvero i60 ITI multiplex PCR system a promising test in the diagnosis of infective endocarditis from heart valves?

The aim of this study was to evaluate the new commercial Unyvero i60 ITI multiplex PCR system (Curetis, Holzgerlingen, Germany) on native cardiac valves in comparison with made in-house 16S rRNA PCR amplification (91E/13BS primers) and conventional microbiological techniques. Forty-four patients (30 men, 14 women) with suspected infective endocarditis (IE) were included in this evaluation corresponding to 30 aortic valves and 14 mitral valves. IE was definite for 40 patients using the modified Duke criteria. 16S rRNA PCR amplification was successful in 22 patients (55%). The Unyvero i60 ITI cartridge yielded a positive result in 16 patients (40%). Among the 40 cases, the etiological agent was not included in the panel of Unyvero i60 ITI cartridge for 14 cases. Moreover, for S. aureus, the Unyvero i60 ITI cartridge quickly yielded the susceptibility to meticillin. The result of the experiment was available after 5 hours whereas 16S rRNA PCR amplification-sequencing needs 14 hours of manipulation. If the manufacturer incorporates new targets able to detect more endocarditis agents such as viridans streptococci, the Unyvero i60 ITI cartridge may be a promising and easy-to-use test.

Diagnostic performances and therapeutic impact of the Unyvero Implant and Tissue Infection multiplex PCR in periprosthetic joint infections.

Aim: We evaluated the diagnostic performances of Unyvero Implant and Tissue Infection multiplex PCR (mPCR) (Curetis) and the clinical impact of this PCR on therapeutic decisions. Materials & methods: A mPCR was performed on 33 joint fluids in addition to standard culture. A group of experts analyzed a posteriori the impact of the mPCR in the patient management. Results: The rate of concordance with culture was 74% (20/27). The sensitivity of the PCR was 59% and the specificity 90%. Clinicians would have started an appropriate treatment sooner for six patients (from 2 to 22 days earlier). Conclusion: The PCR would improve the management of 22% of the patients. For other patients, mPCR results have to be completed with the culture.

First evaluation of the automated-multiplex-PCR Unyvero ITI G2 cartridge for rapid diagnosis of osteo-articular infections.

OBJECTIVE: Conventional microbiological methods (CMM), including long-term culture, for the diagnosis of osteo-articular infections (OAI) fail in at least 5% of all cases. Only one IOA dedicated molecular method has been commercialized, and only the first version of this kit has been studied. The aim of this work was to evaluate the concordance between test results obtained with the second version of the Unyvero ITI G2 cartridge (Curetis) and CMM. The cartridge, combining one-step automated lysis/DNA extraction with multiplex PCR and amplicon detection by array hybridization, allows for the detection of 102 prevalent pathogens and their antibiotic resistance markers directly in clinical specimens (liquid [n=8] or solid [n=32]). MATERIAL AND METHODS: Frozen samples from 40 patients who underwent orthopedic surgery at Pitié-Salpêtrière hospital were tested retrospectively with the cartridge: 5 were culture-negative, 25 revealed monomicrobial and 10 polymicrobial OAI. The 2 main surgical sites were hip (22.5%) and knee (17.5%). RESULTS: Extraction, amplification and hybridization reactions were completed in 28 of the 40 cases, failed in all cartridge chambers in 6 cases, and in 1 or 2 chambers in an additional 6 cases. Overall sensitivity and specificity for microorganism identification were estimated at 67.6% and 98.2%, when complete and partial failures were excluded. CONCLUSIONS: These results show that the performances of the second version of the Unyvero ITI G2 cartridge should be further enhanced before considering avoiding conventional microbiological methods.

Evaluation of the Unyvero i60 ITI® multiplex PCR for infected chronic leg ulcers diagnosis.

OBJECTIVES: Unyvero i60 ITI multiplex PCR (mPCR) may identify a large panel of bacteria and antibiotic resistance genes. In this study, we compared results obtained by mPCR to standard bacteriology in chronic leg ulcer (CLU) infections. METHODS: A prospective study, part of the interventional-blinded randomized study "ulcerinfecte" (NCT02889926), was conducted at Saint Joseph Hospital in Paris. Fifty patients with a suspicion of infected CLU were included between February 2017 and September 2018. Conventional bacteriology and mPCR were performed simultaneously on deep skin biopsies. RESULTS: Staphylococcus aureus and Pseudomonas aeruginosa were the most detected pathogens. Regarding the global sensitivity, mPCR is not overcome to the standard culture. Anaerobes and slow growing bacteria were detected with a higher sensitivity rate by mPCR than standard culture. CONCLUSION: Unyvero i60 ITI multiplex PCR detected rapidly pathogenic bacteria in infected CLU especially anaerobes and slow growing bacteria and was particularly effective for patients previously treated with antibiotics.

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

OBJECTIVES: This 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). RESULTS: 72 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.

Performance of the automated multiplex PCR Unyvero implant and tissue infections system in the management of diabetic foot osteomyelitis.

AIM: We evaluated the performance of Unyvero implant and tissue infections system (ITI) application (Curetis) to diagnose Diabetic Foot Osteomyelitis (DFOM). PATIENTS & METHODS: The study was conducted in the Diabetic Foot reference center of Nîmes University Hospital (France) from 1 December 2016 to 31 May 2017. We compared the Unyvero ITI PCR to conventional culture and alternative molecular approaches. RESULTS: A total of 79 patients with DFOM were included: 177 microorganisms were isolated by culture, 146 detected by PCR, resulting in a concordance level of 66.7% (65.0-68.4). Discrepant results were obtained for 45 samples, with 59 microorganisms being detected by PCR only (18 samples) or by culture only (27 samples). CONCLUSION: Unyvero ITI PCR represents an interesting additional diagnosis solution to manage DFOM.

Assessment of the automated multiplex-PCR Unyvero i60 ITI® cartridge system to diagnose prosthetic joint infection: a multicentre study.

OBJECTIVES: Prosthetic joint infections (PJI) are responsible for significant morbidity and mortality and their number continues to rise. Their management remains complex, especially the microbiological diagnosis. Besides 'homemade' tests developed by several teams, new molecular biology methods are now available with different analytical performance and usability. METHODS: We studied the performances of one of these tests: ITI® multiplex PCR (mPCR) by the Curetis® company and compared it to either 'optimized' culture or 16S rRNA PCR. We performed a retrospective multicentre study to assess the contributions of mPCR in the diagnosis of PJI. We randomly selected 484 intraoperative specimens among 1252 of various types (biopsy, bone, tissue around the prosthesis, synovial fluid) from 251 patients in seven different hospitals. Each sample was treated according to the recommendations of the manufacturer. RESULTS: In all, 154 out of 164 (93.9%) samples negative in culture were negative with the mPCR. Among the 276 positive samples in culture, 251 (90.9%) were monomicrobial, of which 119 (47.4%) were positive with the mPCR, and 25 (9.1%) were polymicrobial, of which 12 (48%) were positive with the mPCR. The concordance rate of mPCR with culture was 58.1% (53.6%-62.7%) and the concordance rate with 16S rRNA PCR was 70.1% (65.5%-74.6%). CONCLUSION: This new standardized molecular test showed a lack of detection when the bacterial inoculum was low (number of positive media per sample and number of colonies per media) but can be useful when patients have received antibiotic therapy previously.