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

BACKGROUND: Recently developed therapeutics against Gram-negative bacteria include the ß-lactam-ß-lactamase inhibitor combinations ceftazidime-avibactam (CZA), meropenem-vaborbactam (MEV), and imipenem-relebatam (IPR), and the siderophore cephalosporin cefiderocol (FDC). The aim of this study was to develop a test for rapid identification of susceptibility/resistance to CZA, MEV, IPR, and FDC for Enterobacterales in a single test for rapid clinical decision making. METHODS: The MultiRapid ATB NP test is based on the detection of glucose metabolism occurring after bacterial growth in the presence of defined concentrations of CZA, MEV, IPR, and FDC, followed by visual detection of colour change of the pH indicator red phenol (red to yellow) generated by the acidification of the medium upon bacterial growth. This test is performed in 96-well microplates. The MultiRapid ATB NP test was evaluated using 78 Enterobacterales isolates and compared to the reference method broth microdilution. RESULTS: The MultiRapid ATB NP test displayed 97.0% (confidence interval [CI] 92.6-98.8) sensitivity, 97.7% (CI 94.3-99.1) specificity, and 97.4% (CI 95.0-98.7) 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. CONCLUSION: The MultiRapid ATB NP test provided accurate results for the concomitant detection of susceptibility/resistance to CZA, MEV, IPR, and FDC in Enterobacterales, independent of the resistance mechanism. This test may be suitable for implementation in any microbiology routine laboratory.

Rapid detection of cefiderocol susceptibility/resistance in Acinetobacter baumannii.

PURPOSE: 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). MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Rapid Aztreonam/Avibactam NP test for detection of aztreonam/avibactam susceptibility/resistance in Enterobacterales.

Aztreonam-avibactam (AZA), a newly developed ß-lactam/ß-lactamase inhibitor combination, is a treatment option for infections due to carbapenem-resistant Enterobacterales (CRE), including metallo-ß-lactamase producers, regardless of additional production of broad-spectrum serine-ß-lactamases. However, AZA-resistance has already been reported in Enterobacterales and its early detection could be a valuable tool for faster and more accurate clinical decision-making. We therefore developed a rapid culture-based test for the identification of AZA resistance among multidrug-resistant Enterobacterales. The Rapid Aztreonam/Avibactam NP test is based on resazurin reduction when bacterial growth occurs in the presence of AZA at 8/4 µg/mL (protocol 1) or 12/4 µg/mL (protocol 2). Given the absence of guidelines on AZA susceptibility testing, two tentative breakpoints were indeed used to categorize AZA-susceptible isolates: ≤4 µg/mL in protocol 1 and ≤ 8 µg/mL in protocol 2. Bacterial growth was visually detectable by a blue-to-purple or blue-to-pink color change of the medium. A total of 78 enterobacterial isolates (among which 34 AZA-resistant and 13 AZA-resistant according to protocols 1 and 2, respectively) were used to evaluate the test performance using protocol 1 or protocol 2. The sensitivity and specificity of the test were found to be 100% and 97.7%, respectively, following protocol 1 and 100% and 100%, respectively, following protocol 2, in comparison with broth microdilution. All results were obtained within 4.5 hours corresponding to a time saving of ca. 14 hours compared with currently available methods for AZA susceptibility testing. The Rapid Aztreonam/Avibactam NP test is rapid, highly sensitive, specific, easily interpretable, and easy to implement in routine.

Resist Acineto rapid immunological test for the detection of acquired carbapenemase producers among Acinetobacter spp.

The Resist Acineto from Coris Bioconcept is a novel immunochromatographic test for detection of the major acquired carbapenemases (OXA-23, OXA-40, OXA-58, and NDM) identified in Acinetobacter spp. This rapid and easy-to-perform test showed an excellent specificity and sensitivity, with positive and negatives predictive values of 100% in both cases.

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

BACKGROUND: 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. OBJECTIVES: To develop a rapid test, namely the Rapid MEV NP, for the identification of meropenem/vaborbactam resistance in Enterobacterales. METHODS: 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. RESULTS: 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 ±â€Š2°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. CONCLUSIONS: 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.

Dissemination of ArmA- and OXA-23-co-producing Acinetobacter baumannii Global Clone 2 in Switzerland, 2020-2021.

Following the observation of an increased number of isolation of OXA-23- and ArmA-producing Acinetobacter baumannii at the national level, our aim was to evaluate whether some given clone(s) might actually be spreading and/or emerging in Switzerland. To evaluate this possibility, our study investigated and characterized all A. baumannii isolates harboring both the blaOXA-23 and armA genes that had been collected at the Swiss National Reference Center for Emerging Antibiotic Resistance (NARA) from 2020 to 2021. Most isolates were obtained from infections rather than colonization with the majority being obtained from respiratory specimens. Pulsed-field gel electrophoresis (PFGE) analysis of 56 isolates identified nine profiles. Then, whole-genome sequencing that was performed on a subset of 11 isolates including at least one representative isolate of each PFGE profile identified three STs; one each of ST25 and ST1902, and nine ST2 (a member of Global Clone 2 (GC-2). The blaOXA-23 gene was always found embedded within Tn2006 structures, as commonly described with GC-2 (ST2) isolates. Susceptibility testing showed that most of those isolates, despite being highly resistant to all carbapenems and all aminoglycosides, remained susceptible to colistin (94.6%), sulbactam-durlobactam (87.5%), and cefiderocol (83.9% or 91.1% according to EUCAST or CLSI breakpoints, respectively). Overall, this study identified that the A. baumannii co-producing OXA-23 and ArmA are increasing in incidence in Switzerland, largely due to the dissemination of the high-risk GC-2. This highlights the importance of the monitoring of such MDR A. baumannii strains, in order to contribute to reduce their potential further spread.

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

OBJECTIVES: 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. METHODS: 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. RESULTS: 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. DISCUSSION: 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.

Evaluation of novel immunological rapid test (K.N.I.V.O. Detection K-Set) for rapid detection of carbapenemase producers in multidrug-resistant gram negatives.

The K.N.I.V.O Detection K-Set is a novel immunochromatographic test for detection of the 5 major carbapenemases (KPC, NDM, IMP, VIM, and OXA-48-like). This test is rapid, easy to perform, and shows a good specificity and sensitivity (96.8% and 100%, respectively), being suitable for microbiology laboratories together with biochemical rapid tests.