Rapid detection of imipenem/relebactam susceptibility/resistance in Enterobacterales.

The treatment options for infections caused by carbapenem-resistant Enterobacterales are scarce and the development of new antibiotics is an urgent necessity. Imipenem/relebactam (IPR) has been recently introduced for treating severe infections related to multidrug-resistant bacteria. However, IPR resistance has already been reported in Enterobacterales, thus its rapid detection may be interesting for clinical decision-making. The aim of the study was to develop a rapid and accurate test, namely the Rapid IPR Nordmann Poirel (NP) test, for the identification of IPR resistance among multidrug-resistant Enterobacterales. The Rapid IPR NP test is based on the detection of glucose metabolization because of bacterial growth in the presence of IPR. Bacterial growth is visually detectable by a colour change of the red phenol pH indicator, turning from red to yellow subsequent to the acidification of the medium upon bacterial growth. Cultures of a total of 94 Enterobacterales isolates were selected for evaluating the performance of the Rapid IPR NP test. The sensitivity and specificity of the test were found to be 95.2% (95.2%, CI 84.2-98.7%) and 100% (100%, CI 93.1-100%), respectively. All the results were obtained within 3 hours incubation time at 35°C ± 2°C, which is a gain of time of at least 15 hours when compared with currently used antimicrobial susceptibility. The test showed two very major errors corresponding to OXA-48-producing Klebsiella pneumoniae isolates with MICs of IPR at 8 mg/L. The Rapid IPR NP test is simple to perform and interpret, and shows excellent performances. Thus, it may suitable for implementation in clinical microbiology routine laboratories

MultiRapid ATB NP test for detecting concomitantly susceptibility and resistance of last resort novel antibiotics available to treat multidrug-resistant Enterobacterales infections.

Among the recently developed antibacterial therapeutics against Gram-negatives, there are the β-lactam-β-lactamase inhibitor combinations ceftazidime-avibactam (CZA), meropenem-vaborbactam (MEV), and imipenem-relebatam (IPR), and there is the siderophore cephalosporin cefiderocol (FDC). This study is aimed to develop a rapid test, namely the MultiRapid ATB NP test, for rapid identification of susceptibility/resistance to CZA, MEV, IPR, and FDC for Enterobacterales.in a single test for rapid clinical decision making. The MultiRapid ATB NP test is based on the detection of glucose metabolization occurring after bacterial growth in the presence of defined concentrations of CZA, MEV, IPR, and FDC. Followed by visual detection of color change of the pH indicator red phenol (red to yellow) generated by the acidification of the medium upon bacterial growth. It is performed in 96-well microplates. The Multi Rapid ATB NP test was evaluated with 78 Enterobacterales isolates, and its performances compared to the reference method broth microdilution. The MultiRapid ATB NP test displayed 97.0% (97.0%, CI 92.6 - 98.8%) of sensitivity, 97.7% (97.7%, CI 94.3 - 99.1%) of specificity, and 97.4% (97.4%, CI 95.0% - 98.7%) of accuracy. The results were obtained after 3 h of incubation at 35°C ± 2°C, representing at least a 15 h gain-of-time compared with currently used antimicrobial susceptibility testing methods. The MultiRapid ATB NP test was capable of providing accurate results for a concomitant detection of susceptibility/resistance to CZA, MEV, IPR, and FDC in Enterobacterales, independent from its resistance mechanism. It may be suitable for implementation in any microbiology routine laboratory

Rapid meropenem/vaborbactam NP test for detecting susceptibility/resistance in Enterobacterales.

The treatment options for infections caused by carbapenem-resistant Enterobacterales (CRE) are extremely scarce nowadays and the development of new antibiotics does not follow the exponential increase in the dissemination of carbapenem resistance determinants worldwide. Meropenem/vaborbactam was recently approved for clinical use and it has been indicated for treating several infections. Although relatively rare, meropenem/vaborbactam resistance has already been reported in Enterobacterales and its early detection could be a valuable tool for faster clinical decision-making. To develop a rapid test, namely the Rapid MEV NP, for the identification of meropenem/vaborbactam resistance in Enterobacterales. The Rapid MEV NP test is based on detection of glucose metabolization occurring upon bacterial growth in the presence of meropenem/vaborbactam at a concentration of 16/8 mg/L. Bacterial growth is detectable by a colour change of phenol red (from red to yellow) subsequent of the acidification of the medium upon bacterial growth. A total of 75 Enterobacterales isolates were randomly selected for evaluating the performance of the Rapid MEV NP test. The test showed 97.2% sensitivity and 93.8% specificity when compared with the reference method. The results are obtained after 3 h of incubation at 35°C ± 2°C, which is a gain of time of at least 15 h (one day in practice) compared with currently used antimicrobial susceptibility testing including broth microdilution methods. The Rapid MEV NP test, easy to perform and to interpret, showed remarkable performance while providing fast results, and is therefore suitable for implementation in routine clinical microbiology laboratories

Rapid detection of cefiderocol susceptibility/resistance in Acinetobacter baumannii.

Due to its ability to disseminate worldwide and its multiple resistance trait, Acinetobacter baumannii is becoming a threat for public health worldwide. Cefiderocol (FDC) is a promising broad-spectrum cephalosporin recently approved for treating Gram-negative infection. The aim of this study was to develop a rapid test, namely the rapid FDC Acinetobacter baumannii NP test, for the detection of FDC susceptibility/resistance in A. baumannii since the current FDC susceptibility tests are rather time-consuming (at least 24 h). The rapid test is based on the reduction of resazurin to resorufin product by bacterial viable cells, thus detecting bacterial growth in the presence of FDC (38.4 mg/L). A color change from blue (resazurin) to violet or pink (resorufin) represents visual detection of bacterial growth. 95 randomly selected A. baumannii isolates were used to evaluate the performance of the rapid FDC Acinetobacter baumannii NP test. The test showed 95.5% (95% CI 78.2-99.2%) and 100.0% (95% CI 95.0-100.0%) of sensitivity and specificity, respectively. All the results were obtained within 4 h30-4 h45 incubation time at 35 °C ± 2 °C, saving virtually one day when compared with currently-used antimicrobial susceptibility tests. The test showed only a single very major error, an isolate with a MIC of 8 mg/L. The rapid FDC Acinetobacter baumannii NP test can be a valuable method which is easier and faster to interpret when compared with the gold standard broth microdilution method. The test showed remarkable performances; hence, it may be suitable for implementation in clinical microbiology routine laboratories