Search Results (199)

Carbapenem-resistant Klebsiella pneumoniae (CRKP) has become one of the most serious problems confronting modern healthcare, particularly in intensive care units where patients are highly susceptible, procedures are frequent, and antibiotic exposure is often prolonged. In this review, carbapenem resistance in K. pneumoniae is presented not as a fixed feature of individual bacteria, but as a process that is constantly changing and closely interconnected. We bring together evidence showing how the spread of successful bacterial lineages, the exchange of resistance genes, and gradual genetic adjustment combine to drive both the rapid spread and the long-lasting presence of resistance. A major focus is placed on mobile genetic elements, including commonly encountered plasmid backbones, transposons, and insertion sequences that carry carbapenemase genes such as blaKPC, blaNDM, and blaOXA-48-like. These elements allow resistance genes to move easily between bacteria and across different biological environments. The human gut plays a particularly important role in this process. Its microbial community serves as a largely unseen reservoir where resistance genes can circulate and accumulate well before infection becomes clinically apparent, making prevention and control more difficult. This review also discusses the key biological factors that shape resistance levels, including carbapenemase production, changes in the bacterial cell membrane, and systems that expel antibiotics from the cell, and explains how these features work together. Advances in molecular testing have made it possible to identify resistance more quickly, supporting earlier clinical decisions and infection control measures. Even so, current tests remain limited by narrow targets and may miss low-level carriage, hidden genetic reservoirs, or newly emerging resistance patterns. Finally, we look ahead to approaches that move beyond detection alone, emphasizing the need for integrated surveillance, thoughtful antibiotic use, and coordinated system-wide strategies to lessen the impact of CRKP. Full article

Background: In China, Carbapenem-resistant Klebsiella pneumoniae (CRKP) is dominated by sequence type 11 (ST11) harbouring KPC-2, with KL64 displacing KL47 and KL25 emerging. ST859 (ST11 variant) has caused outbreaks, but its epidemiology is unclear. Materials and Methods: A total of 99 non-duplicate CRKP isolates were collected from June to December 2024. Antimicrobial susceptibility was determined by broth microdilution. The genomic sequences of the strains were obtained using next-generation sequencing technology. Resistance genes, virulence loci, and plasmid replicons were identified with Kleborate, Abricate, and MOB-suite, respectively. Results: ST11 accounted for 63.64% and ST859 for 15.15%. All ST859 were KL19, while ST11 were mainly KL25 (60.32%) and KL64 (26.98%). 76.8% co-harbored carbapenemase and extended-spectrum beta-lactamase (ESBL) genes, with KPC-2 and CTX-M-65 being the predominant types. Susceptibility rates were 100% to tigecycline, and 78.79% to ceftazidime/avibactam. ST859 CRKP isolates exhibited higher phenotypic resistance to tetracycline and colistin than ST11 CRKP isolates (p < 0.05), and carrying LAP-2, QnrS1, QnrS10, and tet(A) more frequently. ST11-KL25 showed higher resistance to amikacin, gentamicin, and chloramphenicol, with increased prevalence of CTX-M-65, TEM-1, rmtB, catA2, and dfrA14 compared to ST11-KL64 (p < 0.05). IncF was the most prevalent replicon and both ST859 and ST11 CRKP carry conjugative resistance plasmids, and the host range is predominantly Enterobacterales. Conclusions: ST859-KL19 ranks second to ST11 with higher resistance to tetracyclines and colistin. ST11-KL25 may have already displaced ST11-KL64 as the predominant capsular type in Shanghai, with distinct resistance profiles between KL variants. Long-term, multicenter surveillance is urgently needed to delineate the evolutionary trajectory and clinical impact of these emerging clones. Full article

Drug-resistant Klebsiella pneumoniae and related Enterobacterales represent an escalating global public health threat, increasingly limiting therapeutic options in both healthcare- and community-associated infections. This review summarizes how resistance in K. pneumoniae emerges from the synergy of intrinsic barriers and acquired determinants. Key molecular mechanisms include reduced permeability via porin remodeling (notably OmpK35/OmpK36), multidrug efflux (e.g., AcrAB-TolC and OqxAB), and enzymatic drug inactivation driven by extended-spectrum beta-lactamases and carbapenemases (e.g., KPC, OXA-48-like enzymes, and metallo-beta-lactamases). We also highlight clinically meaningful pathways underlying polymyxin/colistin resistance, including mgrB inactivation and PhoPQ/PmrAB-mediated lipid A modification. In addition to stable genetic resistance, adaptive programs can shape transient tolerance and persistence, including stress responses that modulate gene expression under antibiotic and host-imposed pressures. The ability of these organisms to form biofilms, particularly on medical devices, further complicates treatment and eradication. Finally, we discuss therapeutic implications and current options and limitations—including novel beta-lactam/beta-lactamase inhibitor combinations and siderophore cephalosporins—and emphasize the importance of aligning therapy and surveillance with the underlying resistance mechanisms and circulating high-risk lineages. Full article

Carbapenem-resistant Enterobacterales (CREs) pose a critical threat to global public health, largely driven by the enzymatic activity of Klebsiella pneumoniae carbapenemase-2 (KPC-2), a class A serine β-lactamase that hydrolyzes most β-lactam antibiotics. While β-lactamase inhibitors like avibactam offer temporary relief, emerging KPC variants demand novel, sustainable inhibitory scaffolds. This study aimed to identify and characterize potential natural inhibitors of KPC-2 from Pongamia pinnata, leveraging a comprehensive in silico workflow. A curated library of 86 phytochemicals was docked against the active site of KPC-2 (PDB ID: 3DW0). The top-performing ligands were subjected to ADMET profiling (pkCSM), and 100 ns molecular dynamics simulations (GROMACS) to evaluate structural stability and interaction persistence, using avibactam as control. Ponganone V exhibited the most favorable binding energy (−9.0 kcal/mol), engaging Ser70 via a hydrogen bond and forming π–π interactions with Trp105. Glabrachromene II demonstrated a broader interaction network but reduced long-term stability. ADMET analysis confirmed high intestinal absorption, non-mutagenicity, and absence of hERG inhibition for both ligands. Molecular dynamics simulations revealed that Ponganone V maintained compact structure and stable hydrogen bonding throughout the 100 ns trajectory, closely mirroring the behavior of avibactam, whereas Glabrachromene II displayed increased fluctuation and loss of compactness beyond 80 ns. Principal Component Analysis (PCA) further supported these findings, with Ponganone V showing restricted conformational motion and a single deep free energy basin, while avibactam and Glabrachromene II exhibited broader conformational sampling and multiple energy minima. The integrated computational findings highlight Ponganone V as a potent and pharmacologically viable natural KPC-2 inhibitor, with strong binding affinity, sustained structural stability, and minimal toxicity. This study underscores the untapped potential of Pongamia pinnata phytochemicals as future anti-resistance therapeutics and provides a rational basis for their experimental validation. Full article

Background: There are many methods of identifying microbial resistance to therapeutic agents; however, they can generally be classified into two main categories: phenotypic and genotypic. The study aims to determine drug sensitivity and to analyze the correlation between the results obtained from cultures on commercial chromogenic media Brilliance^TM CRE (OXOID) and Brilliance^TM ESBL (OXOID) and the occurrence of specific resistance genes carbapenemase (IMP, NDM, VIM, KPC, OXA), ESBL β-lactamase (TEM, SHV, CTX-M), and AmpC (CMY, DHA), which will be used in drug sensitivity tests. Methods: The present study used bacteria, including Klebsiella pneumoniae, Acinetobacter baumannii, and Escherichia coli, obtained from patients hospitalized in military hospitals in Poland. All strains were plated on the commercial chromogenic media and subjected to antimicrobial susceptibility testing. Additionally, molecular assays detecting three main classes according to the mechanism of action, enzyme type carbapenemase (IMP, NDM, VIM, KPC, OXA), ESBL β-lactamase (TEM, SHV, CTX-M), and AmpC (CMY, DHA) were performed using the real-time PCR method. Results: The results of the studies indicate the presence of carbapenemases and ESBL genes. Among K. pneumoniae strains, the dominant gene was CTX-M-15 (88.89%), followed by the SHV (84.12%), NDM (46.03%), TEM (41.26%), KPC (34.92%), and OXA-48 (19.04%). In contrast, A. baumanii was dominated by carbapenemases from the OXA family (OXA-51 in 96.00% and OXA-24/40 in 84.00%). E. coli exhibits a high prevalence of CTX-M-15 (53.85%), TEM (46.15%), NDM (38.46%), and CMY-2 (30.77%). It was observed that the CTX-M-15 gene was commonly co-identified with SHV (n = 43). All tested strains grew on chromogenic Brilliance^TM CRE medium. In the case of Brilliance^TM ESBL medium, the genes determining the resistance mechanism were detected in 41.7% for A. baumannii, 53.8% for E. coli, and 100% for K. pneumoniae. Chromogenic media perfectly differentiate strains to species. A moderate positive correlation of the occurrence of the antibiotic resistance genes was observed for OXA-51 and OXA-24/40 genes, which were resistant to meropenem (rho = 0.45, p < 0.001). K-means cluster analysis performed on integrated genotype–phenotype data allowed for the identification of three distinct clusters characterized by distinct resistance gene profiles. These results demonstrate that selective agar media enable faster identification compared to other conventional techniques; however, the obtained results should be confirmed by other validated phenotypic methods, and, if possible, by a molecular assay. Full article

Background: Rapid antimicrobial susceptibility testing (RAST) allows early detection of resistance directly from positive blood cultures, potentially improving outcomes in bloodstream infections (BSIs). We evaluated the performance of EUCAST RAST for Gram-negative ESKAPEEc pathogens and characterized carbapenemase genes in carbapenem-resistant Klebsiella pneumoniae (CRKP). Methods: A total of 354 positive blood cultures were screened, including 51 monomicrobial Gram-negative ESKAPEEc isolates. RAST results at 4, 6, 8, and 16–20 h were compared with standard antimicrobial susceptibility testing (AST) obtained using the BD Phoenix™ system. Categorical agreement (CA) and error frequency were calculated. Multiplex PCR and Sanger sequencing were performed on 15 CRKP isolates to identify carbapenemase genes and allelic variants. Results: 51 Gram-negative ESKAPEEc isolates met the inclusion criteria for RAST (15 E. coli, 19 K. pneumoniae, 11 A. baumannii, and 6 P. aeruginosa). Overall performance varied markedly by species and antibiotic. E. coli showed frequent unreadable or ATU zones at early timepoints and wide CA variability (50–100%), with high very major error (VME) rates for AMP, TZP, and CAZ, particularly at 6–8 h. K. pneumoniae displayed consistently high CA (mostly 100%) for carbapenems, CAZ, and TZP. A. baumannii demonstrated excellent agreement (100% for most agents), except for GEN at 6–8 h. P. aeruginosa could be evaluated only at 16–20 h, showing high CA for AMK, CAZ, and CIP; lower CA for MEM (83%); non-calculable CA for IMI due to universal ATU readings; and a CA value of 0% for TZP due to the predominance of the ATU results. VMEs ranged from 0% to 26.1% across species and reading times, but carbapenems did not generate VMEs. Molecular analysis revealed bla_KPC in 66.7%, bla_NDM in 46.7%, and bla_OXA-48 in 33.3% of isolates, with co-occurrence in several strains. Sequencing identified bla_KPC-2 and bla_NDM-1 as the predominant variants, with one isolate harboring bla_NDM-5. Conclusions: EUCAST RAST markedly accelerates susceptibility reporting from positive blood cultures, but its accuracy is species- and time-dependent. Performance was excellent for K. pneumoniae (including CRKP) and A. baumannii and acceptable for P. aeruginosa at 16–20 h. In contrast, E. coli showed frequent ATU results at early timepoints and high ME/VME rates, making readings before 8 h unreliable for clinical decisions. Overall, RAST can effectively support rapid antimicrobial stewardship when species-specific limitations are recognized, and early-timepoint results are interpreted with caution. Full article

Carbapenem-resistant Klebsiella pneumoniae isolates harbouring double carbapenemases, from patients in a surgical and transplantation ICU, were investigated to better understand the dispersion of the pathogen. Twenty-three carbapenem-resistant K. pneumoniae isolates harbouring at least two different carbapenemases (by immunochromatography screening), were consecutively collected during a seven-month period from patients in a surgical and transplantation ICU. Identification and susceptibility testing were performed using the MALDI-TOF Vitek MS and the Vitek2 system (BioMerieux), respectively. Whole genome sequencing (WGS) was performed in an Illumina NextSeq2000 platform and MLST and resistome analysis of assembled genomes were performed by ResFinder, through the Center for Genomic Epidemiology platform. All isolates were resistant to ertapenem, imipenem, meropenem, and most to meropenem–varbobactam. Seventeen isolates belonged to the ST11 type and were positive for the OXA-48/NDM combination (by immunochromatography and NGS). Four isolates belonged to the ST39 type and were positive for the KPC/NDM combination (by immunochromatography and NGS). Finally, two isolates belonged to the ST258 type. One of them was positive for the OXA-48/KPC/NDM combination (by immunochromatography), but only bla_KPC was detected by WGS, and the second was positive for the OXA-48/KPC combination (by immunochromatography) and confirmed by WGS. This is the first report of an outbreak in Greece due to two simultaneous carbapenem-resistant populations harbouring double carbapenemases: a larger one comprising ST11 isolates harbouring the combination bla_NDM-1/bla_OXA-48, coupled by a smaller one comprising ST39 isolates harbouring the combination bla_KPC-2/bla_NDM-1. The implications of this particular situation regarding public health as well as intra-nosocomial infection prevention and control should be further monitored and studied. Full article

The production of β-lactamases is the main mechanism underlying carbapenem resistance. This study combined in silico and in vitro approaches to identify potential polyphenols as carbapenemase inhibitors. Molecular docking, molecular dynamics, and ADMET prediction were performed to assess the binding affinity, stability, and safety of quercetin, kaempferol, caffeic acid, and 3,4-dihydroxybenzoic acid against KPC-2, NDM-1, and OXA-48 carbapenemases. In vitro antibacterial assays and checkerboard analyses were conducted against Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa to assess antibacterial and synergistic effects. Then, the inhibition of the β-lactam hydrolytic activity was confirmed. In silico results showed that quercetin, kaempferol, and caffeic acid exhibited strong binding affinity and consistent stability towards the targets. Therefore, quercetin and kaempferol showed the strongest affinities (−8.0 kcal/mol) and stable interactions with key catalytic residues. ADMET profiles indicated good pharmacokinetic behavior and low acute toxicity. In vitro assays revealed that the polyphenols exhibited MIC values ranging from 12.5 to 25 mg/L and MBC values of 25–50 mg/L. Combined with cefotaxime, they enhanced bacterial susceptibility and inhibited β-lactam hydrolysis, with quercetin achieving complete inhibition at 200 mg/L. These findings highlight the potential of the four polyphenols as natural β-lactamase inhibitors. Further enzyme kinetics and in vivo studies are needed to confirm their therapeutic relevance. Full article

The global rise of multi-drug resistant (MDR) pathogens, including the widespread resistance to beta-lactams through the production of β-lactamases, like extended spectrum β-lactamases (ESBLs), has led to the increasing use of last-line antibiotics such as carbapenems. Subsequently, the worldwide emergence of carbapenemase-producing pathogens poses a formidable challenge. The combination ceftazidime/avibactam (CAZ/AVI) has emerged as a pivotal agent in the management of multidrug-resistant Gram-negative infections. Avibactam, a novel β-lactamase inhibitor, demonstrates a wider spectrum of activity against Ambler Class A, C, and partially D β-lactamases in comparison to older inhibitors, thus enhancing the antimicrobial activity of ceftazidime against organisms producing ESBL and carbapenemases, such as oxacillinase (OXA)-type and Klebsiella pneumoniae Carbapenemase (KPC). This review synthesizes findings from randomized controlled trials and cohort studies, evaluating the efficacy of CAZ/AVI across diverse clinical settings, including complicated intra-abdominal infections, urinary tract infections, nosocomial pneumonia, skin and soft tissue infections, and bloodstream infections. The non-inferiority of CAZ-AVI with respect to carbapenems and superiority over polymyxins in terms of both clinical outcomes and safety are outlined, along with evidence supporting the use of CAZ/AVI in high-risk populations such as immunocompromised and critically ill patients. Overall, CAZ/AVI represents a compelling therapeutic option with favorable efficacy and safety, thus appearing as a reasonable frontline treatment for resistant Gram-negative infections. Full article

In recent decades, the problem of resistant strains, which present resistance to different types of antimicrobials, has increased. Klebsiella pneumoniae is one of the most important species that exhibits an acquired resistance phenotype to at least one agent in three or more classes of antimicrobials and is thus characterized as a multidrug-resistant bacterium (MDR). 98 nosocomial strains of K. pneumoniae were isolated during the pre-COVID-19 period, and more specifically, from February 2015 to March 2019, were analyzed for the detection of class A, D, and B carbapenemase genes. The existence of KPC, OXA-48 like, IMP, VIM, and NDM carbapenemases has been examined. The immunochromatography showed that NDM carbapenemases are more frequently detected in the samples, reaching a percentage of 30.7%, while correspondingly the percentage for VIM carbapenemases was 7.68% among the strains with resistant phenotypes. No strain with carbapenemase IMP was found. Real-time multiplex polymerase chain reaction (PCR) showed, in contrast to immunochromatography kits, that a high percentage of bacterial isolates (94.26%) carry NDM and VIM carbapenemase genes, while no IMP carbapenemase genes were detected. Regarding the KPC enzymes, the immunochromatography kits showed that KPC positive strains are reaching 53.1%, and OXA-48 positive strains are reaching 3.1% among the strains with resistant phenotypes. Real-time multiplex polymerase chain reaction revealed a much higher percentage of 89.6% KPC positive isolates and a percentage of 14.6% OXA-48 carbapenemase producers. The aforementioned results indicate the dominance of the Multiplex Real-Time PCR as a “gold standard” method. This study could not fully support the usefulness of rapid immunochromatographic tests as a fast and useful diagnostic tool in the laboratory daily routine, as per the results of previous studies. Thus, more studies need to be conducted in this field to introduce these rapid tests safely into the daily laboratory workflow as a screening tool. Additionally, this study underlines the predominance of KPC enzymes from clinical isolates of ICUs and a significant shift over the OXA-48 like enzymes that are not limited to the ICU environment. Full article

Wound infections pose a significant challenge in modern medicine, driven by multimorbidity, weakened immunity, microbial virulence factors, and resistance to antibiotics and antiseptics. This study aims to evaluate the antibacterial properties of carvacrol (CAR), its impact on biofilm formation, and its capacity to trigger oxidative stress in clinical strains of Pseudomonas aeruginosa, Klebsiella pneumoniae, and Enterobacter cloacae. Carbapenemases in the studied bacteria were detected using culture on CarbaId agar. The presence of genes encoding bacterial virulence factors and carbapenemase production was confirmed using the PCR method. The antimicrobial activity of carvacrol was evaluated using the broth microdilution method. The ability of strains to form biofilm was determined using a modified crystal violet assay. Oxidative stress levels in bacterial cells in response to carvacrol treatment were measured using 2′,7′-dichlorofluorescein diacetate. Real-TimePCR was used to confirm the presence of NDM family carbapenemase genes in K. pneumoniae strains, KPC genes in E. cloacae strains, and VIM genes in P. aeruginosa strains. CAR exhibited a broad spectrum of antibacterial activity against the tested bacteria, with MIC values ranging from 125 to 1000 μg/mL. Treatment with 1/2 MIC of CAR did not significantly influence biofilm formation, except in a K. pneumoniae isolate. At 1/2 MIC, CAR induced an increase in intracellular ROS in most tested strains, with the exception of P. aeruginosa 25521221. This study provides insights into the antimicrobial efficacy of carvacrol against carbapenemase-producing pathogens isolated from wound infections—specifically P. aeruginosa, K. pneumoniae, and E. cloacae. CAR demonstrated promising bactericidal properties, likely mediated through the induction of oxidative stress, as evidenced by increased ROS generation in most studied isolates. Full article

Antimicrobial resistance (AMR) poses a critical global health challenge, with carbapenemase-producing Enterobacterales (CPE) representing one of the most urgent threats. While Klebsiella pneumoniae and Escherichia coli have been the focus of most surveillance programs, Enterobacter spp., members of the Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp., and Escherichia coli (ESKAPEE) group, remain an underrecognized but increasingly important reservoir of carbapenemase genes in Europe. Despite being categorized by the World Health Organization (WHO) as “critical-priority” pathogens, Enterobacter spp. are largely excluded from major AMR surveillance frameworks, creating blind spots in detection and control. This review summarizes the taxonomy, intrinsic resistance mechanisms, and clinical relevance of Enterobacter spp., with a particular focus on carbapenemase epidemiology across Europe. We highlight the distribution and genetic context of major carbapenemases, including VIM, OXA-48-like, KPC, and NDM, and discuss emerging or minor enzymes such as IMI, FRI, GES, and IMP. Epidemiological data reveal shifting dominance patterns over time, with VIM enzymes consolidating their prevalence after 2015, while OXA-48-like and KPC declined, and NDM gained ground. The genetic diversity of Enterobacter spp., coupled with their ability to act as both nosocomial pathogens and silent intestinal or environmental reservoirs, facilitates the dissemination of carbapenemase genes via epidemic plasmids and clonal expansion. Addressing the growing impact of carbapenemase-producing Enterobacter spp. requires their systematic inclusion in national and international monitoring programs, expanded use of genomic epidemiology in clinical microbiology, and better alignment between research, clinical practice, and policy. A One Health approach is essential to curb the spread of carbapenemases across human, environmental, and animal reservoirs, and to safeguard the remaining therapeutic options. Full article

Background: Carbapenem-resistant Klebsiella pneumoniae (CRKP) poses a significant therapeutic challenge, particularly when multiple resistance mechanisms, such as metallo-β-lactamases (MBLs) and Klebsiella pneumoniae carbapenemase (KPC), coexist. Case description: We describe a case of a 51-year-old male with a post-sternotomy surgical site infection and concurrent bacteremia caused by a CRKP. Sternal swab and mediastinal liquid culture results highlighted CRKP harboring bla_NDM and bla_KPC genes, while the blood isolate showed bla_CTX and bla_KPC, indicating phenotypic resistance to ceftazidime-avibactam. All the strains exhibited phenotypic susceptibility to meropenem-vaborbactam (MEV), despite having a high minimum inhibitory concentration. Following clinical failure of MEV-based therapy, combination treatment with aztreonam (ATM) and imipenem/cilastatin/relebactam (IMI/REL), plus gentamicin, was initiated. Therapy was well tolerated and resulted in microbiological eradication and full clinical recovery. The patient completed 49 days of ATM and IMI/REL without relapse over a 3-month follow-up period. This is, to the best of our knowledge, the first reported case of IMI/REL being used in combination with ATM. Full article

Background/Objectives: Carbapenem-resistant Klebsiella pneumoniae (CRKP) threatens Intensive Care Units (ICU), particularly in settings where serine (KPC) and metallo-β-lactamases (NDM) co-circulate. The aim of this study was to assess CRKP susceptibility especially to novel β-lactam/β-lactamase inhibitor combinations, characterize the genetic determinants of resistance, and contribute to the understanding of local epidemiology in the ICU of our hospital. Methods: We studied 32 non-duplicate CRKP isolates (30 ICU, 2 wards) collected at Hippokration General Hospital, Thessaloniki (May–Oct 2023). Bacterial identification and Antimicrobial susceptibility testing (AST) were performed by VITEK-2; Minimum inhibitory concentrations (MICs) for ceftazidime/avibactam (CAZ/AVI), meropenem/vaborbactam (MER/VAB), and imipenem/relebactam (IMI/REL) were determined by E-tests. Colistin MICs were performed by broth microdilution. Carbapenemases were screened phenotypically and by immunochromatography and confirmed by multiplex PCR. One bronchial isolate co-harboring bla_NDM and bla_KPC genes underwent WGS. Results: All isolates were carbapenem-resistant and showed extensive resistance to β-lactams and fluoroquinolones. By PCR, 8/32 (25%) carried bla_KPC alone, 8/32 (25.0%) bla_NDM alone, and 16/32 (50%) co-harbored bla_KPC and bla_NDM. KPC-only isolates were generally susceptible in vitro to CAZ/AVI, MER/VAB, and IMI/REL, whereas dual KPC-NDM producers were resistant to all three combinations. Tigecycline showed the highest retained activity; colistin remained active in a minority. WGS of one ST512 (CG258) isolate revealed co-harboring bla_NDM-1 and bla_KPC-3 with additional resistance determinants and plasmid replicons, consistent with high-risk spread. Conclusions: Half of CRKP isolates in this ICU-predominant series co-produced KPC and NDM, severely limiting β-lactam/β-lactamase inhibitor options. These data support routine screening for carbapenemases, strict infection prevention, antimicrobial stewardship, and access to agents active against MBLs. Full article

Background: Carbapenem-resistant Klebsiella pneumoniae (CRKp) is a critical global health threat due to its multidrug resistance, primarily driven by carbapenemase production. Rapid and accurate detection of carbapenemases is essential for effective treatment and infection control. This study evaluates the validity of the NG-Test CARBA 5, a rapid immunochromatographic assay, for detecting five major carbapenemases (KPC, NDM, VIM, IMP, OXA-48-like) in clinical CRKp isolates. Methods: Clinical isolates of CRKp were collected from various clinical specimens at the Military Medical Academy in Belgrade, Serbia, between January 2023 and October 2024. Detection of carbapenemases was performed using NG-Test CARBA 5, while PCR served as the reference method. Diagnostic performance was assessed by calculating sensitivity, specificity, and Cohen’s kappa coefficient. Results: Among 312 isolates, OXA-48-like was the most prevalent carbapenemase. NG-Test CARBA 5 showed high sensitivity (98.7%) and specificity (100%) overall, with excellent agreement for NDM (κ = 0.947), OXA-48-like (κ = 0.957), and KPC (κ = 0.978). However, it failed to detect VIM in five PCR-positive isolates, suggesting potential limitations. Conclusions: NG-Test CARBA 5 is a rapid and reliable tool for detecting major carbapenemases in CRKp, though its performance for VIM detection requires further investigation. This assay has the potential to improve clinical diagnostics and strengthen infection control in settings with high antimicrobial resistance. Full article