Rapid Detection of Ceftazidime/Avibactam Susceptibility/Resistance in Enterobacterales by Rapid CAZ/AVI NP Test.

We developed a novel culture-based test, the Rapid CAZ/AVI NP test, for rapid identification of ceftazidime/avibactam susceptibility/resistance in Enterobacterales. This test is based on glucose metabolization upon bacterial growth in the presence of a defined concentration of ceftazidime/avibactam (128/53 µg/mL). Bacterial growth is visually detectable by a red to yellow color change of red phenol, a pH indicator. A total of 101 well characterized enterobacterial isolates were used to evaluate the test performance. This test showed positive percent agreement of 100% and negative percent agreement of 98.5% with overall percent agreement of 99%, by comparison with the MIC gradient strip test (Etest) taken as the reference standard method. The Rapid CAZ/AVI NP test had only 1.5% major errors and 0% extremely major errors. This test is rapid (result within 2 hours 45 minutes), reliable, affordable, easily interpretable, and easy to implement in clinical microbiology laboratories without requiring any specific equipment.

ALG13-Congenital Disorder of Glycosylation (ALG13-CDG): Updated clinical and molecular review and clinical management guidelines.

ALG13-Congenital Disorder of Glycosylation (CDG), is a rare X-linked CDG caused by pathogenic variants in ALG13 (OMIM 300776) that affects the N-linked glycosylation pathway. Affected individuals present with a predominantly neurological manifestation during infancy. Epileptic spasms are a common presenting symptom of ALG13-CDG. Other common phenotypes include developmental delay, seizures, intellectual disability, microcephaly, and hypotonia. Current management of ALG13-CDG is targeted to address patients' symptoms. To date, less than 100 individuals have been reported with ALG13-CDG. In this article, an international group of experts in CDG reviewed all reported individuals affected with ALG13-CDG and suggested diagnostic and management guidelines for ALG13-CDG. The guidelines are based on the best available data and expert opinion. Neurological symptoms dominate the phenotype of ALG13-CDG where epileptic spasm is confirmed to be the most common presenting symptom of ALG13-CDG in association with hypotonia and developmental delay. We propose that ACTH/prednisolone treatment should be trialed first, followed by vigabatrin, however ketogenic diet has been shown to have promising results in ALG13-CDG. In order to optimize medical management, we also suggest early cardiac, gastrointestinal, skeletal, and behavioral assessments in affected patients.

Frontiers in congenital disorders of glycosylation consortium, a cross-sectional study report at year 5 of 280 individuals in the natural history cohort.

OBJECTIVE: Our report describes clinical, genetic, and biochemical features of participants with a molecularly confirmed congenital disorder of glycosylation (CDG) enrolled in the Frontiers in Congenital Disorders of Glycosylation (FCDGC) Natural History cohort at year 5 of the study. METHODS: We enrolled individuals with a known or suspected CDG into the FCDGC Natural History Study, a multicenter prospective and retrospective natural history study of all genetic causes of CDG. We conducted a cross-sectional analysis of baseline study visit data from participants with confirmed CDG who were consented into the FCDGC Natural History Study (5U54NS115198) from October 2019 to November 2023. RESULTS: Three hundred thirty-three subjects consented to the FCDGC Natural History Study. Of these, 280 unique individuals had genetic data available that was consistent with a diagnosis of CDG. These 280 individuals were enrolled into the study between October 8, 2019 and November 29, 2023. One hundred forty-one (50.4%) were female, and 139 (49.6%) were male. Mean and median age at enrollment was 10.1 and 6.5 years, respectively, with a range of 0.22 to 71.4 years. The cohort encompassed individuals with disorders of N-linked protein glycosylation (57%), glycosylphosphatidylinositol anchor disorder (GPI anchor) (15%), disorders of Golgi homeostasis, trafficking and transport (12%), dolichol metabolism disorders (5%), disorders of multiple pathways (6%), and other (5%). The most frequent presenting symptom(s) leading to diagnosis were developmental delay/disability (77%), followed by hypotonia (56%) and feeding difficulties (42%). Mean and median time between first related symptom and diagnosis was 2.7 and 0.8 years, respectively. One hundred percent of individuals in our cohort had developmental differences/disabilities at the time of their baseline visit, followed by 97% with neurologic involvement, 91% with gastrointestinal (GI)/liver involvement, and 88% with musculoskeletal involvement. Severity of disease in individuals was scored on the Nijmegen Progression CDG Rating Scale (NPCRS) with 27% of scores categorized as mild, 44% moderate, and 29% severe. Of the individuals with N-linked protein glycosylation defects, 83% of those with data showed a type 1 pattern on carbohydrate deficient transferrin (CDT) analysis including 82/84 individuals with PMM2-CDG, 6% a type 2 pattern, 1% both type 1 and type 2 pattern and 10% a normal or nonspecific pattern. One hundred percent of individuals with Golgi homeostasis and trafficking defects with data showed a type 2 pattern on CDT analysis, while Golgi transport defect showed a type II pattern 73% of the time, a type 1 pattern for 7%, and 20% had a normal or nonspecific pattern. Most of the variants documented were classified as pathogenic or likely pathogenic using ACMG criteria. For the majority of the variants, the predicted molecular consequence was missense followed by nonsense and splice site, and the majority of the diagnoses are inherited in an autosomal recessive pattern but with disorders of all major nuclear inheritance included. DISCUSSION: The FCDGC Natural History Study serves as an important resource to build future research studies, improve clinical care, and prepare for clinical trial readiness. Herein is the first overview of CDG participants of the FCDGC Natural History Study.

Reduced susceptibility to aztreonam-avibactam conferred by acquired AmpC-type ß-lactamases in PBP3-modified Escherichia coli.

PURPOSE: Carbapenemase-producing Enterobacterales are a growing threat, and very few therapeutic options remain active against those multidrug resistant bacteria. Aztreonam is the molecule of choice against metallo-beta-lactamases (MBL) producers since it is not hydrolyzed by those enzymes, but the co-production of acquired plasmidic cephalosporinases or extended-spectrum ß-lactamases leading to aztreonam resistance may reduce the efficacy of this molecule. Hence, the development of the aztreonam-avibactam (AZA) combination provides an interesting therapeutic alternative since avibactam inhibits the activity of both cephalosporinases and extended-spectrum ß-lactamases. However, structural modifications of penicillin binding protein PBP3, the target of aztreonam, may lead to reduced susceptibility to aztreonam-avibactam. METHODS: Here the impact of various plasmid-encoded AmpC-type ß-lactamases (ACC-1, ACT-7, ACT-17, CMY-2, CMY-42, DHA-1, FOX-1, and FOX-5) on susceptibility to aztreonam-avibactam was evaluated using isogenic E. coli MG1655 strains harboring insertions in PBP3 (YRIN and YRIK). The inhibitory activity of various ß-lactamase inhibitors (clavulanic acid, tazobactam, avibactam, relebactam, and vaborbactam) were also compared against these enzymes. RESULTS: Hence, we showed that reduced susceptibility to AZA was due to the combined effect of both AmpC production and amino acid insertions in PBP3. The highest resistance level was achieved in strains possessing the insertions in PBP3 in association with the production of ACT-7, ACC-1, or CMY-42. CONCLUSION: Although none of the recombinant strains tested displayed clinical resistance to aztreonam-avibactam, our data emphasize that the occurrence of such profile might be of clinical relevance for MBL-producing strains.

Impact of Minor Carbapenemases on Susceptibility to Novel ß-Lactam/ß-Lactamase Inhibitor Combinations and Cefiderocol in Enterobacterales.

The in vitro activity of imipenem-relebactam, meropenem-vaborbactam, ceftazidime-avibactam, and cefiderocol was evaluated against both clinical and isogenic enterobacterial isolates producing carbapenemases of the SME, NmcA, FRI, and IMI types. Ceftazidime-avibactam and meropenem-vaborbactam showed the highest activity against all tested isolates; imipenem-relebactam showed only moderate activity. All isolates remained susceptible to cefiderocol. Furthermore, avibactam and vaborbactam have greater inhibitory activity than relebactam against the tested carbapenemases. Overall, ceftazidime-avibactam, meropenem-vaborbactam, and cefiderocol were the most effective therapeutic options for treating infections caused by the tested minor carbapenemase producers.

A Selective Culture Medium for Screening Cefiderocol Resistance in Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter baumannii.

Cefiderocol (FDC) is a siderophore cephalosporin with a broad spectrum of activity against many multidrug-resistant Gram-negative bacteria. Acquired resistance to FDC has been already reported among Gram-negative isolates, thus highlighting the need for rapid and accurate identification of such resistant pathogens, in order to control their spread. Therefore, the SuperFDC medium was developed to screen FDC-resistant Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter baumannii. After testing several culture conditions, a selective medium was set up by supplementing an iron-depleted agar medium with 8 µg/mL of FDC and evaluated with a collection of 68 FDC-susceptible and 33 FDC-resistant Gram-negative isolates exhibiting a variety of ß-lactam resistance mechanisms. The sensitivity and specificity of detection of this medium were evaluated at 97% and 100%, respectively. In comparison with the reference broth microdilution method, only 3% very major errors were found. In addition, excellent detection performances were obtained by testing spiked stools with a lower limit of detection ranging between 100 and 103 CFU/mL. The SuperFDC medium allows detection of FDC-resistant Gram-negative isolates regardless of their corresponding resistance mechanisms.

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.

In vitro activity of cefepime/zidebactam and cefepime/taniborbactam against aztreonam/avibactam-resistant NDM-like-producing Escherichia coli clinical isolates.

BACKGROUND: Aztreonam/avibactam is one of the last therapeutic options for treating infections caused by NDM-like-producing Enterobacterales. However, PBP3-modified and NDM-producing Escherichia coli strains that co-produce CMY-42 have been shown to be resistant to this drug combination. The aim of our study was to assess the in vitro activity of cefepime/taniborbactam and cefepime/zidebactam against such aztreonam/avibactam-resistant E. coli strains. METHODS: MIC values of aztreonam, aztreonam/avibactam, cefepime, cefepime/taniborbactam, cefepime/zidebactam and zidebactam alone were determined for 28 clinical aztreonam/avibactam-resistant E. coli isolates. Those isolates produced either NDM-5 (n = 24), NDM-4 (n = 2) or NDM-1 (n = 2), and they all co-produced CMY-42 (n = 28). They all harboured a four amino acid insertion in PBP-3 (Tyr-Arg-Ile-Asn or Tyr-Arg-Ile-Lys). RESULTS: All strains were resistant to aztreonam/avibactam and cefepime, as expected. The resistance rate to cefepime/taniborbactam was 100%, with MIC50 and MIC90 being at 16 mg/L and 64 mg/L, respectively. Conversely, all strains were susceptible to cefepime/zidebactam, with both MIC50 and MIC90 at 0.25 mg/L. Notably, all strains showed low MICs for zidebactam alone, with MIC50 and MIC90 at 0.5 mg/L and 1 mg/L. CONCLUSIONS: Our data highlighted the excellent in vitro performance of the newly developed ß-lactam/ß-lactamase inhibitor combination cefepime/zidebactam against aztreonam/avibactam-resistant E. coli strains, suggesting that this combination could be considered as an efficient therapeutic option in this context. Our study also highlights the cross-resistance between acquired resistance to aztreonam/avibactam and the cefepime/taniborbactam combination.

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.

Progressive in vivo development of resistance to cefiderocol in Pseudomonas aeruginosa.

We report in vivo development of cefiderocol (FDC) resistance among four sequential Pseudomonas aeruginosa clinical isolates ST244 recovered from a single patient, without exposure to FDC, which raises concern about the effectiveness of this novel drug. The first recovered P. aeruginosa isolate (P-01) was susceptible to FDC (2 µg/mL), albeit this MIC value was higher than that of a wild-type P. aeruginosa (0.12-0.25 µg/ml). The subsequent isolated strains (P-02, P-03, P-04) displayed increasing levels of FDC MICs (8, 16, and 64 µg/ml, respectively). Those isolates also showed variable and gradual increasing levels of resistance to most ß-lactams tested in this study. Surprisingly, no acquired ß-lactamase was identified in any of those isolates. Whole-genome sequence analysis suggested that this resistance was driven by multifactorial mechanisms including mutational changes in iron transporter proteins associated with FDC uptake, ampC gene overproduction, and mexAB-oprM overexpression. These findings highlight that a susceptibility testing to FDC must be performed prior to any prescription.

Impact of Acquired Broad-Spectrum ß-Lactamases on Susceptibility to Cefiderocol and Newly Developed ß-Lactam/ß-Lactamase Inhibitor Combinations in Escherichia coli and Pseudomonas aeruginosa.

The ability of broad-spectrum ß-lactamases to reduce the susceptibility to ceftazidime-avibactam (CZA), ceftolozane-tazobactam (C/T), imipenem-relebactam, meropenem-vaborbactam, aztreonam-avibactam (AZA), and cefiderocol (FDC) was evaluated both in Pseudomonas aeruginosa and in Escherichia coli using isogenic backgrounds. Although metallo-ß-lactamases conferred resistance in most cases, except for AZA, several clavulanic-acid-inhibited extended-spectrum ß-lactamases (PER, BEL, SHV) had a significant impact on the susceptibility to CZA, C/T, and FDC.

NDM-35-Producing ST167 Escherichia coli Highly Resistant to ß-Lactams Including Cefiderocol.

A multidrug-resistant (carbapenems, aztreonam + avibactam, and cefiderocol) ST167 Escherichia coli clinical isolate recovered from a patient hospitalized in Switzerland produced NDM-35 showing ca. 10-fold increased hydrolytic activity toward cefiderocol compared to NDM-1. The isolate co-produced a CMY-type ß-lactamase, exhibited a four amino-acid insertion in PBP3, and possessed a truncated iron transporter CirA protein. Our study identified an association of unrelated resistance mechanisms leading to resistance to virtually all ß-lactams in a high-risk E. coli clone.

Selective Culture Medium for Screening of Fosfomycin Resistance in Enterobacterales.

A selective medium for screening fosfomycin (FOS)-resistant Enterobacterales was developed. Performances of this medium were first evaluated by using cultures of a collection of 84 enterobacterial clinical strains (42 FOS susceptible and 42 FOS resistant). The SuperFOS medium showed excellent sensitivity and specificity of detection (100%) in those conditions. Then, by testing spiked stool and spiked urine specimens, it revealed excellent performances, with lower limits of identification ranging from 101 to 102 CFU/ml. This screening medium allows easy and accurate detection of FOS-resistant isolates regardless of their resistance mechanisms.

Rapid cefiderocol NP test for detection of cefiderocol susceptibility/resistance in Enterobacterales.

BACKGROUND: Cefiderocol is among the latest generation of commercialized antibiotics against a large variety of MDR Gram-negative bacteria including carbapenem-resistant Enterobacterales and non-fermenters such as Pseudomonas aeruginosa and Acinetobacter baumannii. Cefiderocol susceptibility testing, a key element for implementing rapidly a cefiderocol-based treatment, might be still challenging. OBJECTIVES: To develop a rapid culture-based test, Rapid Cefiderocol NP test, for the identification of cefiderocol resistance among MDR Enterobacterales. METHODS: The Rapid Cefiderocol NP test is based on glucose metabolization when bacterial growth occurs and the detection of bacterial growth in the presence of cefiderocol at 64 mg/L using iron-depleted CAMHB. Bacterial growth is visually detectable by a red-to-yellow colour change of red phenol, a pH indicator. A total of 74 clinical enterobacterial isolates from various clinical sources and of worldwide origin, among which 42 isolates were cefiderocol resistant, were used to evaluate the test performance. RESULTS: The sensitivity and specificity of the test were found to be 98% and 91%, respectively, by comparison with the reference broth microdilution (BMD) method. All positive results were obtained within 3 h after incubation at 35°C ±â€Š2°C, that is a gain of time of ca. 18 h (1 day) compared with currently used techniques for susceptibility testing (BMD method). CONCLUSIONS: This novel test is rapid, highly sensitive, specific, easily interpretable, and easy to implement in routine microbiology laboratories. Such a test may rapidly and accurately provide the information needed for the implementation of adequate cefiderocol-based treatment.

Co-resistance to ceftazidime-avibactam and cefiderocol in clinical isolates producing KPC variants.

Cefiderocol (FDC) and ceftazidime-avibactam (CZA) are among the latest generation of commercialized antibiotics against carbapenem-resistant Gram negatives. However, emergence of CZA resistance is being increasingly reported, involving different KPC variants in Enterobacterales. By analyzing two CZA-resistant KPC-3 clinical variants, KPC-41 and KPC-50, we showed that KPC-41, and to a lesser extent KPC-50, may also have an impact on susceptibility to FDC leading to a cross-resistance. This feature highlights that a susceptibility testing to FDC is mandatory prior any clinical use of FDC for treating infections due to KPC producers.

Contribution of PER-Type and NDM-Type ß-Lactamases to Cefiderocol Resistance in Acinetobacter baumannii.

Cefiderocol (FDC) is a recently developed siderophore cephalosporin showing excellent antibacterial activity against Gram-negative bacteria, including Acinetobacter baumannii. By investigating a series of A. baumannii clinical isolates with elevated MICs of FDC, we showed that PER-like ß-lactamases and, to a lesser extent, NDM-like ß-lactamases, significantly contributed to reduced susceptibility to that antibiotic. Interestingly, we showed that combination of FDC with avibactam exhibited excellent activity against all multidrug-resistant isolates coproducing OXA-23 and PER-type ß-lactamases.

Rapid ResaImipenem/Acinetobacter NP Test for Detection of Carbapenem Susceptibility/Resistance in Acinetobacter baumannii.

The rapid ResaImipenem/Acinetobacter NP test was developed for the identification of carbapenem resistance among Acinetobacter baumannii isolates. The principle of this test is based on the reduction of resazurin (a viability colorant) by metabolically active bacterial cells, hence detecting bacterial growth, in the presence of a defined concentration of imipenem chosen to be slightly above that defining imipenem resistance (6 µg/ml). Bacterial growth is visually detected by a color change from blue (resazurin) to purple or pink (resorufin product). A total of 110 A. baumannii isolates, among which 61 were imipenem resistant, were used to evaluate test performance. The sensitivity and specificity of the test were found to be 100%, in comparison with broth microdilution taken as the reference standard method. The rapid ResaImipenem/Acinetobacter NP test is highly specific and sensitive and is easy to implement in routine microbiology laboratories, and results are obtained within 2 h 30 min. It does not require any specific equipment.

Cross-Border Emergence of Escherichia coli Producing the Carbapenemase NDM-5 in Switzerland and Germany.

A series of clinical NDM-5-producing Escherichia coli isolates obtained from two surveillance networks for carbapenem-producing Enterobacterales from 2018 to 2019, namely, Switzerland (NARA) and Germany (SurvCARE), were analyzed. The 33 NDM-5-producing E. coli isolates were highly resistant to ß-lactams, including novel ß-lactam/ß-lactamase inhibitor combinations (ceftazidime-avibactam, imipenem-relebactam, and meropenem-vaborbactam), and remained susceptible to fosfomycin, colistin, and tigecycline. These isolates were assigned to different sequence types (STs) and indicated a predominance of isolates exhibiting ST167 in Switzerland and Germany (n = 10) (phylogenetic group C), followed by ST405 (n = 4) (phylogenetic group E), ST1284 (n = 4) (phylogenetic group C), and ST361 (n = 4) (phylogenetic group C). The blaNDM-5 gene was predominantly present on an IncF-type plasmid (n = 29) and, to a lesser extent, on the narrow-host-range IncX3 plasmid (n = 4). Sequence analyses of eight NDM-5 plasmids indicated that NDM-5-encoding F-type plasmids varied in size between 86 and 132 kb. The two IncX3 plasmids pCH8NDM5 and pD12NDM5 were 46 and 45 kb in size, respectively. The highly conserved blaNDM-5 genetic surrounding structures (ΔISAba125-blaNDM-5-bleMBL-trpT-dsbD-IS26) of both the F-type and IncX3 plasmids suggested a common genetic origin. The emergence of the NDM-5 carbapenemase was evidenced in particular for the E. coli ST167 clone, which is a successful epidemic clone known to be associated with both multiresistance and virulence traits and is therefore of high public health concern. The occurrence of clonally related NDM-5-producing E. coli isolates in Switzerland and Germany further indicates the international spread of this multidrug-resistant superbug at least throughout Europe.

Genetic Features Leading to Reduced Susceptibility to Aztreonam-Avibactam among Metallo-ß-Lactamase-Producing Escherichia coli Isolates.

Metallo-ß-lactamase (MBL)-producing Escherichia coli isolates resistant to the newly developed ß-lactam/ß-lactamase inhibitor drug combination aztreonam-avibactam (ATM-AVI) have been reported. Here, we analyzed a series of 118 clinical MBL-producing E. coli isolates of various geographical origins for susceptibility to ATM-AVI. The nature of the PBP3 protein sequence and the occurrence of blaCMY genes for susceptibility to ATM-AVI were investigated. We showed here that elevated MICs of ATM-AVI among MBL-producing E. coli isolates resulted from a combination of different features, including modification of PBP3 protein sequence through specific amino acid insertions and production of CMY-type enzymes, particularly, CMY-42. We showed here that those insertions identified in the PBP3 sequence are not considered the unique basis of resistance to ATM-AVI, but they significantly contribute to it.

NitroSpeed-Carba NP Test for Rapid Detection and Differentiation between Different Classes of Carbapenemases in Enterobacterales.

A biochemical test (NitroSpeed-Carba NP test) was developed to identify carbapenemase production in Enterobacterales and to discriminate between the different types of clinically significant carbapenemases (Ambler classes A, B, and D). It is based on two main features, namely, the hydrolysis by all ß-lactamases, including carbapenemases of the nitrocefin substrate, and the capacity of ertapenem to prevent this hydrolysis for all ß-lactamases except carbapenemases. Specific carbapenemase inhibitors of class A (avibactam, vaborbactam), class B (dipicolinic acid), and class D (avibactam) were used to inhibit the nitrocefin hydrolysis and to allow the identification of the carbapenemase types with a turnaround time of ca. 30 min. The test was evaluated with a collection of 248 clinical enterobacterial isolates, including 148 carbapenemase producers and 100 non-carbapenemase producers. Its overall sensitivity and specificity were 100% and 97%, respectively, including detection of all types of OXA-48-like carbapenemases. For the detection of the carbapenemase type, including strains that produce double carbapenemases, the sensitivity was 100%, 97%, and 100% for the detection of classes A, B, and D, respectively. This easy-to-implement test may contribute to optimization of the choice of the ß-lactam/ß-lactamase inhibitor combinations for treating infection due to carbapenemase producers.