CRISPR-Cas3 and type I restriction-modification team up against blaKPC-IncF plasmid transfer in Klebsiella pneumoniae.

OBJECTIVE: We explored whether the Clustered regularly interspaced short palindromic repeat (CRISPR)-Cas and restriction-modification (R-M) systems are compatible and act together to resist plasmid attacks. METHODS: 932 global whole-genome sequences from GenBank, and 459 K. pneumoniae isolates from six provinces of China, were collected to investigate the co-distribution of CRISPR-Cas, R-M systems, and blaKPC plasmid. Conjugation and transformation assays were applied to explore the anti-plasmid function of CRISPR and R-M systems. RESULTS: We found a significant inverse correlation between the presence of CRISPR and R-M systems and blaKPC plasmids in K. pneumoniae, especially when both systems cohabited in one host. The multiple matched recognition sequences of both systems in blaKPC-IncF plasmids (97%) revealed that they were good targets for both systems. Furthermore, the results of conjugation assay demonstrated that CRISPR-Cas and R-M systems in K. pneumoniae could effectively hinder blaKPC plasmid invasion. Notably, CRISPR-Cas and R-M worked together to confer a 4-log reduction in the acquisition of blaKPC plasmid in conjugative events, exhibiting robust synergistic anti-plasmid immunity. CONCLUSIONS: Our results indicate the synergistic role of CRISPR and R-M in regulating horizontal gene transfer in K. pneumoniae and rationalize the development of antimicrobial strategies that capitalize on the immunocompromised status of KPC-KP.

Cas12a/Guide RNA-Based Platform for Rapidly and Accurately Detecting blaKPC Gene in Carbapenem-Resistant Enterobacterales.

Purpose: Accurate detection and identification of pathogens and their associated resistance mechanisms are essential prerequisites for implementing precision medicine in the management of Carbapenem-resistant Enterobacterales (CRE). Among the various resistance mechanisms, the production of KPC carbapenemase is the most prevalent worldwide. Consequently, this study aims to develop a convenient and precise nucleic acid detection platform specifically for the blaKPC gene. Methods: The initial phase of our research methodology involved developing a CRISPR/Cas12a detection framework, which was achieved by designing highly specific single-guide RNAs (sgRNAs) targeting the blaKPC gene. To enhance the sensitivity of this system, we incorporated three distinct amplification techniques-polymerase chain reaction (PCR), loop-mediated isothermal amplification (LAMP), and recombinase polymerase amplification (RPA)-into the CRISPR/Cas12a framework. Subsequently, we conducted a comparative analysis of the sensitivity and specificity of these three amplification methods when used in combination with the CRISPR/Cas12a system. Additionally, we assessed the clinical applicability of the methodologies by evaluating fluorescence readouts from 80 different clinical isolates. Furthermore, we employed lateral flow assay technology to provide a visual representation of the results, facilitating point-of-care testing. Results: Following a comparative analysis of the sensitivity and specificity of the three methods, we identified the RPA-Cas12a approach as the optimal detection technique. Our findings demonstrated that the limit of detection (LoD) of the RPA-Cas12a platform was 1 aM (~1 copy/µL) for plasmid DNA and 5 × 10³ fg/µL for genomic DNA. Furthermore, both the sensitivity and specificity of the platform achieved 100% upon validation with 80 clinical isolates. Conclusion: These findings suggest that the developed RPA-Cas12a platform represents a promising tool for the cost-effective, convenient, and accurate detection of the blaKPC gene.

Colistin versus polymyxin B for the treatment of carbapenem-resistant Klebsiella pneumoniae bloodstream infections.

BACKGROUND: To assess the effectiveness of colistin (administered as colistimethate sodium-CMS) and polymyxin B (PMB) for the treatment of bloodstream infections (BSIs) caused by carbapenem-resistant Klebsiella pneumoniae (CRKP). MATERIALS AND METHODS: This retrospective cohort included hospitalized adult patients with CRKP BSIs from a single tertiary-care hospital. A univariate analysis comparing CMS and PMB groups was carried out and an inverse-probability propensity score (IPPS) was created. An IPPS-adjusted Cox regression model for 30-day mortality was performed including covariates potentially associated with mortality. RESULTS: A total of 100 patients with CRKP BSI (87 were KPC-producing isolates) were included. The 30-day mortality was 42.0 %:17/46 (38.8 %) and 25/54 (44.6 %) patients of CMS and PMB groups, respectively, P = 0.54 (incidence rate, 18.9 and 21.7/1000 patients-day in CMS and PMB groups, respectively, P = 0.62). No statistically significant difference in 30-day mortality rate was observed in a model adjusted for Pitt bacteremia score, high-risk primary site and IPPS, which included age, intensive care unit admission, minimal inhibitory concentration, previous colonization by CRKP, diabetes mellitus, malignancy, neutropenia, meropenem use before BSI, adjuvant therapy with meropenem and amikacin, and time to start polymyxin. Acute kidney injury (AKI) occurred in 52.0 % of patients, with no significant differences between groups (47.8 % and 57.4 % for CMS and PMB, respectively, P = 0.83). In-hospital mortality was 47,7 % and 50.0 % in CMS and PMB groups, respectively, P = 0.82. CONCLUSION: There was no difference in 30-day mortality and AKI rates among patients with CRKP BSI treated with PMB or CMS.

Meropenem/Vaborbactam: ß-Lactam/ß-Lactamase Inhibitor Combination, the Future in Eradicating Multidrug Resistance.

Due to the fact that there is a steadily increasing trend in the area of antimicrobial resistance in microorganisms, there is a need to look for new treatment alternatives. One of them is the search for new ß-lactamase inhibitors and combining them with ß-lactam antibiotics, with the aim of increasing the low-dose efficacy, as well as lowering the resistance potential of bacterial strains. This review presents the positive effect of meropenem in combination with a vaborbactam (MER-VAB). This latest antibiotic-inhibitor combination has found particular use in the treatment of infections with the etiology of carbapenem-resistant Enterobacterales (CRE), Gram-negative bacteria, with a high degree of resistance to available antimicrobial drugs.

Utilizing Ceftazidime/Avibactam Therapeutic Drug Monitoring in the Treatment of Neurosurgical Meningitis Caused by Difficult-to-Treat Resistant Pseudomonas aeruginosa and KPC-Producing Enterobacterales.

Background: Central nervous system (CNS) infections caused by Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacterales and difficult-to-treat resistant (DTR) Pseudomonas aeruginosa represent a formidable clinical challenge. Antimicrobial regimens that efficiently penetrate the cerebrospinal fluid (CSF) and achieve sufficient concentrations associated with microbiologic and clinical cure are limited. We evaluated therapy with ceftazidime-avibactam (CAZ-AVI) in order to guide precise dosing in the treatment of CNS infections. Methods: Therapeutic drug monitoring (TDM) was performed in 3 patients with health care-associated ventriculitis and meningitis (HAVM) using CAZ-AVI 2.5 g infused intravenously every 8 hours as standard and extended infusion. Simultaneous CSF and plasma samples were obtained throughout the dosing interval in each patient. Concentrations of CAZ and AVI were determined by liquid chromatography/mass spectrometry. Results: Bacterial identification revealed KPC-producing Klebsiella pneumoniae (KPC-Kp), DTR Pseudomonas aeruginosa, and KPC-producing Enterobacter cloacae (KPC-Ent.c). All isolates were resistant to carbapenems. The minimum inhibitory concentrations (MICs) of CAZ-AVI were 0.25/4, 4/4, and 0.25/4 µg/mL, respectively. CAZ and AVI concentrations were determined in CSF samples ranging from 29.0 to 15.0 µg/mL (CAZ component) and 4.20 to 0.92 µg/mL (AVI component), respectively. AVI achieved concentrations ≥1 µg/mL in 11 out of 12 CSF samples collected throughout the dosing interval. Clinical and microbiologic cure were attained in all patients. Conclusions: Postinfusion concentrations of CAZ-AVI were measured in plasma and CSF samples obtained from 3 patients with complicated CNS infections caused by antimicrobial-resistant isolates. The measured concentrations revealed that standard CAZ and AVI exposures sufficiently attained values correlating to 50% fT > MIC, which are associated with efficient bacterial killing.

In Vitro Activity of New ß-Lactamase Inhibitor Combinations against blaNDM, blaKPC, and ESBL-Producing Enterobacteriales Uropathogens.

Antibiotic resistance in uropathogens has increased substantially and severely affected treatment of urinary tract infections (UTIs). Lately, some new formulations, including meropenem/vaborbactam (MEV), ceftazidime/avibactam (CZA), and ceftolozane/tazobactam (C/T) have been introduced to treat infections caused by drug-resistant pathogens. This study was designed to screen Enterobacteriales isolates from UTI patients and to assess their antimicrobial resistance pattern, particularly against the mentioned (new) antibiotics. Phenotypic screening of extended-spectrum ß-lactamase (ESBL) and carbapenem resistance was followed by inhibitor-based assays to detect K. pneumoniae carbapenemase (KPC), metallo-ß-lactamase (MBL), and class D oxacillinases (OXA). Among 289 Enterobacteriales, E. coli (66.4%) was the most predominant pathogen, followed by K. pneumoniae (13.8%) and P. mirabilis (8.3%). The isolates showed higher resistance to penicillins and cephalosporins (70-87%) than to non-ß-lactam antimicrobials (33.2-41.5%). NDM production was a common feature among carbapenem-resistant (CR) isolates, followed by KPC and OXA. ESBL producers were susceptible to the tested new antibiotics, but NDM-positive isolates appeared resistant to these combinations. KPC-producers showed resistance to only C/T. ESBLs and carbapenemase encoding genes were located on plasmids and most of the genes were successfully transferred to recipient cells. This study revealed that MEV and CZA had significant activity against ESBL and KPC producers.

Uso de ceftazidima-avibactam en una recién nacida prematura con infección urinaria bacteriémica por Klebsiella pneumoniae productora de carbapenemasa / Use of ceftazidime-avibactam in a preterm infant with urinary tract infection with bacteremia caused by carbapenemase-producing Klebsiella pneumoniae

Los recién nacidos tienen un alto riesgo de morbimortalidad asociada a infecciones durante su estancia en unidades de cuidado intensivo neonatal, a lo que se asocia un aumento progresivo de infecciones por microorganismos multi-resistentes que requiere el uso de nuevos antimicrobianos. Presentamos el caso de una recién nacida de pretérmino de 36 semanas que cursó con una infección del tracto urinario bacteriémica por Klebsiella pneumoniae productora de carbapenemasa tratada de forma efectiva con 14 días de cefazi- dima-avibactam, sin efectos adversos observados. Según nuestro conocimiento, este es el primer caso reportado en nuestro país del uso de este antimicrobiano en población neonatal. Se necesita más información sobre la eficacia y seguridad de ceftazidima-avibactam en este grupo de pacientes.

Neonates are high risk patients regarding morbimortality secondary to infections during their neonatal intensive care unit stay, which is associated to a progressive increase in the report of multidrug resistant organism infections, that require the use of new antimicrobial. We report the case of a 36-week preterm with an urinary tract infection with bacteriemia caused by carbapenemase- producing Klebsiella pneumoniae treated effectively with 14 day of ceftazidime-avibactam, without observed adverse effects. To our knowledge, this is the first case report in our country of the use of this antibiotic in neonatal population. More information is needed regarding efficacy and safety of ceftazidime-avibactam in this group of patients.

Carbapenem-resistant gram-negative bacterial prevention practice in nosocomial infection and molecular epidemiological characteristics in a pediatric intensive care unit.

Introduction: The increasing prevalence of carbapenem-resistant gram-negative bacilli infection has emerged as a substantial threat to human health. Methodology: In January 2017, a screening program for carbapenem-resistant gram-negative bacilli colonization was performed in a pediatric intensive care unit (PICU). Subsequently, different strategies for carbapenem-resistant gram-negative bacilli cohorting and patient placements were introduced in January 2018. Results: The increase in the single room isolation (type A) and the resettlement of the same area placement (type B) resulted in a significant decrease in the nosocomial infection rate from 2.57% (50/1945) in 2017 to 0.87% (15/1720) in 2021 (P < 0.001). Notably, the incidence of nosocomial carbapenem-resistant gram-negative bacilli infections decreased in 2019 (P = 0.046) and 2020 (P = 0.041) compared with that in the respective previous year. During 2019 and 2020, a statistically significant increasing trend of type A and type B placements was observed (P < 0.05, each), which may have contributed to the decline of carbapenem-resistant gram-negative bacilli infection. The primary carbapenemase genes identified in carbapenem-resistant isolates of Klebsiella pneumoniae and Acinetobacter baumannii were blaKPC-2 from sequence type 11 and blaOXA-23 from sequence type 1712. Conclusion: The integration of various placements for patients with carbapenem-resistant gram-negative bacilli infection with active screening has been demonstrated as an effective preventive strategy in the management of carbapenem-resistant gram-negative bacilli infection.

Evaluation of the Ability to Form Biofilms in KPC-Producing and ESBL-Producing Klebsiella pneumoniae Isolated from Clinical Samples.

The appearance of Klebsiella pneumoniae strains producing extended-spectrum ß-lactamase (ESBL), and carbapenemase (KPC) has turned into a significant public health issue. ESBL- and KPC-producing K. pneumoniae's ability to form biofilms is a significant concern as it can promote the spread of antibiotic resistance and prolong infections in healthcare facilities. A total of 45 K. pneumoniae strains were isolated from human infections. Antibiograms were performed for 17 antibiotics, ESBL production was tested by Etest ESBL PM/PML, a rapid test was used to detect KPC carbapenemases, and resistance genes were detected by PCR. Biofilm production was detected by the microtiter plate method. A total of 73% of multidrug resistance was found, with the highest resistance rates to ampicillin, trimethoprim-sulfamethoxazole, cefotaxime, amoxicillin-clavulanic acid, and aztreonam. Simultaneously, the most effective antibiotics were tetracycline and amikacin. blaCTX-M, blaTEM, blaSHV, aac(3)-II, aadA1, tetA, cmlA, catA, gyrA, gyrB, parC, sul1, sul2, sul3, blaKPC, blaOXA, and blaPER genes were detected. Biofilm production showed that 80% of K. pneumoniae strains were biofilm producers. Most ESBL- and KPC-producing isolates were weak biofilm producers (40.0% and 60.0%, respectively). There was no correlation between the ability to form stronger biofilms and the presence of ESBL and KPC enzymes in K. pneumoniae isolates.

A comparative study of intestinal Pseudomonas aeruginosa in healthy individuals and ICU inpatients.

The human intestinal tract is considered the most important reservoir of the opportunistic pathogens, including Pseudomonas aeruginosa, which is often overlooked but critical due to its antimicrobial resistance and virulence. Public health interventions to control this pathogen require a comprehensive understanding of its epidemiology and genomics.  In the current study, we identified P. aeruginosa strains from 2,605 fecal samples collected between 2021 to 2022. Among these samples, 574 were from ICU inpatients in Zhejiang province, while 2,031 were obtained from healthy individuals residing in ten different provinces in China. The prevalence of P. aeruginosa intestinal carriage was found to be higher in ICU inpatients (10.28%, 95% CI: 7.79%-12.76%) than that in healthy individuals (3.99%, 81/2,031, 95% CI: 3.14%-4.84%). Similarly, the prevalence of carbapenem-resistant P. aeruginosa (CRPA) was higher in ICU inpatients (32.2%) compared to healthy individuals (7.41%). The population structure analysis of our isolates revealed a predominantly non-clonal distribution, with 41 distinct sequence types identified among 59 P. aeruginosa isolates from ICU inpatients and 38 different STs among 81 P. aeruginosa isolates from healthy individuals. These findings suggest that the individual acquisition of P. aeruginosa is more frequent than patient-to-patient transmission, as evidenced by the polyclonal population structure. Antimicrobial susceptibility testing and genome analysis indicated that P. aeruginosa strains from ICU inpatients exhibited significantly higher resistance rates to most antimicrobials and harbored a greater number of acquired resistance genes compared to strains from healthy individuals. Notably, in ICU inpatients, we identified three isolates of ST463, all of which shared the conserved Tn3-TnpR-ISKpn8-blaKPC-ISKpn6 genetic context. Additionally, five isolates carrying the qacE gene were also identified, these findings suggest that small-scale transmission events may still occur within the ICU setting, posing significant challenges for clinical management. With regard to virulence factors, we observed similar profiles between the two groups, except for phzA2, phzB2, and pilA, which were statistically higher in isolates from healthy individuals. This may be because the accumulating resistance mutations in ICU-derived P. aeruginosa are linked to a decrease in virulence.

Molecular Dynamic Analysis of Carbapenem-Resistant Klebsiella pneumonia's Porin Proteins with Beta Lactam Antibiotics and Zinc Oxide Nanoparticles.

To prevent the rapidly increasing prevalence of bacterial resistance, it is crucial to discover new antibacterial agents. The emergence of Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae has been associated with a higher mortality rate in gulf union countries and worldwide. Compared to physical and chemical approaches, green zinc oxide nanoparticle (ZnO-NP) synthesis is thought to be significantly safer and more ecofriendly. The present study used molecular dynamics (MD) to examine how ZnO-NPs interact with porin protein (GLO21), a target of ß-lactam antibiotics, and then tested this interaction in vitro by determining the zone of inhibition (IZ), minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC), as well as the alteration of KPC's cell surface. The nanoparticles produced were characterized by UV-Vis spectroscopy, zetasizer, Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). In silico investigation was conducted using a variety of computational techniques, including Autodock Vina for protein and ligand docking and Desmond for MD simulation. The candidate ligands that interact with the GLO21 protein were biosynthesized ZnO-NPs, meropenem, imipenem, and cefepime. Analysis of MD revealed that the ZnO-NPs had the highest log P value (-9.1 kcal/mol), which indicates higher permeability through the bacterial surface, followed by cefepime (-7.9 kcal/mol), meropenem (-7.5 kcal/mol), and imipenem (-6.4 kcal/mol). All tested compounds and ZnO-NPs possess similar binding sites of porin proteins. An MD simulation study showed a stable system for ZnO-NPs and cefepime, as confirmed by RMSD and RMSF values during 100 ns trajectories. The test compounds were further inspected for their intersection with porin in terms of hydrophobic, hydrogen, and ionic levels. In addition, the stability of these bonds were measured by observing the protein-ligand contact within 100 ns trajectories. ZnO-NPs showed promising results for fighting KPC, represented in MIC (0.2 mg/mL), MBC (0.5 mg/mL), and ZI (24 mm diameter). To draw the conclusion that ZnO-NP is a potent antibacterial agent and in order to identify potent antibacterial drugs that do not harm human cells, further in vivo studies are required.

Comparison of Broth Microdilution, Disk Diffusion and Strip Test Methods for Cefiderocol Antimicrobial Susceptibility Testing on KPC-Producing Klebsiella pneumoniae.

The aim of this study was to compare the reference broth microdilution (BMD) method with the Disk Diffusion (DD) test and strip test against a collection of 75 well-characterized Klebsiella pneumoniae carbapenemase (KPC)-producing Klebsiella pneumoniae (KPC-Kp) clinical strains to assess cefiderocol (CFD) antimicrobial activity. Whole-genome sequencing was performed on KPC-Kp strains by Illumina iSeq100 platform. The Categorical Agreement (CA) between the BMD method and DD test was 92% (69/75) with a Major Error (ME) of 16.7% (6/36). Additionally, the CA between the BMD method and test strip was 90.7% (68/75) with a Very Major Error (VME) of 17.9% (7/39) and 82.7% (62/75) between the strip test and DD with a ME of 30.2%. KPC-Kp strains showing resistance to CFD were 27 out of 75 (36%) by three methods. Specifically, 51.9% (14/27) of KPC-Kp resistant to CFD harbored blaKPC-3, while 48.1% (13/27) harbored mutated blaKPC-3. Moreover, KPC-Kp strains carrying a mutated blaKPC-3 gene exhibited high MIC values (p value < 0.001) compared to wild-type blaKPC-3. In conclusion, the DD test resulted as a valid alternative to the BMD method to determine the in vitro susceptibility to CFD, while the strip test exhibited major limitations.

Epidemiology and Mortality Analysis Related to Carbapenem-Resistant Enterobacterales in Patients After Admission to Intensive Care Units: An Observational Study.

Purpose: The prevalence of carbapenem-resistant Enterobacterales (CRE) is rapidly increasing worldwide. Patients in the intensive care unit (ICU) are susceptible to CRE infections, and the related mortality rate is increased. It is necessary to understand CRE strains and risk factors for CRE infection in the ICU, to facilitate development of effective prophylactic strategies and treatments for ICU patients. Patients and Methods: This observational study was conducted in a tertiary hospital between 2016 and 2021. The subjects were patients with CRE cultured from specimens obtained after ICU admission. Genotypes of strains of CRE and carbapenemase-producing Enterobacterales (CPE) were identified, CRE infection was distinguished from mere colonization, and the clinical course of these patients was investigated. Results: Among 327 CRE cases, 84 (25.7%) showed infection and 243 (74.3%) showed colonization. Of these patients, 138 (42.2%) died. The CRE strains were Klebsiella pneumoniae (253 cases, 77.4%), Enterobacter cloacae (44 cases, 13.5%), and Escherichia coli (15 cases, 4.6%). Among CRE cases, CPE was found in 249 (76.1%), including Klebsiella pneumoniae carbapenemase (KPC) in 164 (65.9%), and Guiana extended-spectrum (GES) in 64 (25.7%). A bedridden state, longer ICU stay, chronic kidney disease, malignancy, connective tissue disease, ICU admission for cardiac arrest, and CRE infection were associated with higher mortality, but cerebrovascular disease and ICU admission for trauma were associated with lower mortality. GES outbreak was caused by person-to-person transmission and was controlled through active surveillance. Conclusion: The frequency of K. pneumoniae and KPC was the highest, but E. cloacae and GES was characteristically high in this study. Active CRE surveillance can be helpful for controlling outbreak.

Baicalein Inhibits Plasmid-Mediated Horizontal Transmission of the blaKPC Multidrug Resistance Gene from Klebsiella pneumoniae to Escherichia coli.

Carbapenem-resistant bacterial infections pose an urgent threat to public health worldwide. Horizontal transmission of the ß-lacatamase Klebsiella pneumoniae carbapenemase (blaKPC) multidrug resistance gene is a major mechanism for global dissemination of carbapenem resistance. Here, we investigated the effects of baicalein, an active ingredient of a Chinese herbal medicine, on plasmid-mediated horizontal transmission of blaKPC from a meropenem-resistant K. pneumoniae strain (JZ2157) to a meropenem-sensitive Escherichia coli strain (E600). Baicalein showed no direct effects on the growth of JZ2157 or E600. Co-cultivation of JZ2157 and E600 caused the spread of meropenem resistance from JZ2157 to E600. Baicalein at 40 and 400 µg/mL significantly inhibited the spread of meropenem resistance. Co-cultivation also resulted in plasmid-mediated transmission of blaKPC from JZ2157 to E600, which was inhibited by baicalein. Therefore, baicalein may be used in clinical practice to prevent or contain outbreaks of carbapenem-resistant infections by inhibiting the horizontal transfer of resistance genes across bacteria species.

A novel KPC-113 variant conferring carbapenem and ceftazidime-avibactam resistance in a multidrug-resistant Pseudomonas aeruginosa isolate.

OBJECTIVES: This study aimed to characterize a novel KPC-113 variant from a clinical Pseudomonas aeruginosa isolate R20-14. METHODS: Genomic DNA of R20-14 was subjected to Illumina and Oxford Nanopore sequencing. The horizontal transmission of plasmid was evaluated with conjugation experiments. Minimum inhibitory concentrations of bacterial strains were obtained using broth microdilution methods. KPC-113 detectability of different carbapenemase detection methods was tested. The kinetic parameters of KPC-113 were compared with those of KPC-2 by a spectrophotometer. Structure modelling and molecular docking of KPC-2 and KPC-113 were performed using Schrödinger. RESULTS: R20-14, a sequence type 3903 multidrug-resistant strain, was resistant to carbapenems and ceftazidime-avibactam (CZA) concurrently. S1-nuclease pulsed-field gel electrophoresis and genomic analysis revealed a blaKPC-113-carrying plasmid pR20-14, which resembled the previously reported type I KPC-encoding P. aeruginosa plasmids and exhibited a high conjugation frequency. KPC-113, with a glycine residue insertion between Ambler positions 266 and 267 in KPC-2, conferred both carbapenem and CZA resistance in DH5α and PAO1 transformants. Diagnostic tests showed that KPC-113 acted in a similar manner to KPC-2. Compared with KPC-2, KPC-113 presented reduced catalytic ability to carbapenems and ceftazidime, meanwhile responding poorly to avibactam inhibition. Modelling structure revealed that KPC-113 possibly had a more flattened binding pocket than KPC-2, leading to the change of ligand binding modes. CONCLUSIONS: KPC-113 is a novel KPC variant mediating both CZA resistance and carbapenem resistance. It is of great concern that blaKPC-113 could transfer horizontally with great efficiency and inactivate carbapenems and CZA simultaneously. Great efforts should be made to prevent its spread in clinical settings.

Molecular phenotyping approaches for the detection and monitoring of carbapenem-resistant Enterobacteriaceae by mass spectrometry.

Antimicrobial resistance is increasing in prevalence and there is a clear need for the development of rapid detection methods in clinical diagnostics. This review explores -omics studies utilising mass spectrometry to investigate the molecular phenotype associated with carbapenem resistance. Whilst the specific mechanisms of carbapenem resistance are well characterised, the resistant phenotype is poorly understood. Understanding how the acquisition of resistance affects cellular physiology and cell metabolism through molecular phenotyping is a necessary step towards detecting resistance by diagnostic means. In addition, this article examines the potential of mass spectrometry for the identification of resistance biomarkers through molecular profiling of bacteria. Developments in mass spectrometry platforms are expanding the biomarker-based diagnostic landscape. Targeted measures, such as high-resolution mass spectrometry coupled with chromatographic separation show considerable promise for the identification of molecular signatures and the development of a rapid diagnostic assay for the detection of carbapenem resistance.

Demographic, clinical, and outcome characteristics of carbapenem-resistant Enterobacteriaceae over a 10-year period (2010-2020) in Oman.

Purpose: The incidence of carbapenem-resistant Enterobacteriaceae (CRE) has increased in the last two decades, causing significant morbidity and mortality. Our study investigated the factors associated with mortality from CRE bloodstream infection in a single center in Oman. Methods: Data from adult patients with CRE bacteremia, over a 10-year period, were retrospectively collected. Demographic and clinical characteristics were compared according to intensive care unit (ICU) admission status and mortality. A logistic regression model was used to evaluate factors associated with mortality. Results: 169 cases of CRE bacteremia were identified, of whom 93 (55%) required ICU admission and 96 (56.8%) died. Patients who required ICU care were more likely to require organ transplant (15% vs 4.0%; p = 0.02), be on immunosuppressants (31% vs 17%; p = 0.035), be transferred from other hospitals (40% vs 14%; p < 0.001), be colonized with CRE (73% vs 43%; p < 0.001), have vascular lines (85% vs 42%; p < 0.001), be on mechanical ventilation (91% vs 9.2%; p < 0.001), require a longer stay (37 vs 17 days; p < 0.001), and have increased mortality (80% vs 29%; p < 0.001). In the multivariate analysis, mechanical ventilation (adjusted odds ratio (aOR) 15.3; 95% confidence interval 5.39-43.2; p < 0.001) and prior use of the broad-spectrum antibiotics meropenem (p = 0.01) and piperacillin/tazobactam (p = 0.026) were associated with CRE mortality. Conclusion: CRE bacteremia carries a high mortality rate in patients requiring ICU care. Implementation of infection control measures and antimicrobial stewardship programs are essential in reducing the rates of CRE BSI.

Molecular epidemiology characteristics and detecting transmission of carbapenemase-producing enterobacterales in southwestern China.

BACKGROUND: To investigate the genotype and clinical characteristics of carbapenem-resistant Enterobacteriaceae (CRE) strains in southwest China and provide information on the treatment stopping the spread of the infection. METHODS: The clinical information of CRE isolates was collected from 19 hospitals in 12 cities across Sichuan Province, China, between June 2018 and April 2019. The isolates were detected by DNA sequencing of genes encoding carbapenem enzymes and multilocus sequence types (MLSTs). RESULTS: A total of 166 nonrepetitive CRE isolates were isolated during the study period from sputum, blood, urine, and other samples. Klebsiella pneumoniae carbapenemase (KPC) was dominant in Klebsiella pneumoniae (53.9%), followed by New Delhi metallo-ß-lactamase (NDM) (42.1%). A total of 43 STs were detected. The most common ST of K. pneumoniae was ST11, and that of Escherichia coli was ST410. Pairwise single nucleotide polymorphism (SNP) distances and the likelihood of local transmission by epidemiology were plotted for each species. About 65% of these pairs had ≤ 20 pairwise SNPs. CONCLUSION: A large number of CRE strains carried carbapenemase. Although NDM-ST12 K. pneumoniae should not be disregarded, KPC-ST11is the predominant strain. Thus, the possibility of transmission between E. coli and K. pneumoniae could not be ignored.

A Post-Neurosurgical Infection due to KPC-Producing Klebsiella pneumoniae Treated with Meropenem-Vaborbactam: A Case Report.

This case report describes a patient with post-neurosurgical infection and bacteremia caused by Klebsiella pneumoniae carbapenemase-producing Klebsiella pneumoniae. There is limited evidence to guide antibiotic treatment decisions for such infections. The patient was treated with meropenem-vaborbactam (MEV). MEV monotherapy was associated with bacteremia clearance.

Impact of a Rapid Molecular Test for Klebsiella pneumoniae Carbapenemase and Ceftazidime-Avibactam Use on Outcomes After Bacteremia Caused by Carbapenem-Resistant Enterobacterales.

BACKGROUND: Patients with bacteremia due to carbapenem-resistant Enterobacterales (CRE) experience delays until appropriate therapy and high mortality rates. Rapid molecular diagnostics for carbapenemases and new ß-lactam/ß-lactamase inhibitors may improve outcomes. METHODS: We conducted an observational study of patients with CRE bacteremia from 2016 to 2018 at 8 New York and New Jersey medical centers and assessed center-specific clinical microbiology practices. We compared time to receipt of active antimicrobial therapy and mortality between patients whose positive blood cultures underwent rapid molecular testing for the Klebsiella pneumoniae carbapenemase (KPC) gene (blaKPC) and patients whose cultures did not undergo this test. CRE isolates underwent antimicrobial susceptibility testing by broth microdilution and carbapenemase profiling by whole-genome sequencing. We also assessed outcomes when ceftazidime-avibactam and polymyxins were used as targeted therapies. RESULTS: Of 137 patients with CRE bacteremia, 89 (65%) had a KPC-producing organism. Patients whose blood cultures underwent blaKPC PCR testing (n = 51) had shorter time until receipt of active therapy (median: 24 vs 50 hours; P = .009) compared with other patients (n = 86) and decreased 14-day (16% vs 37%; P = .007) and 30-day (24% vs 47%; P = .007) mortality. blaKPC PCR testing was associated with decreased 30-day mortality (adjusted odds ratio: .37; 95% CI: .16-.84) in an adjusted model. The 30-day mortality rate was 10% with ceftazidime-avibactam monotherapy and 31% with polymyxin monotherapy (P = .08). CONCLUSIONS: In a KPC-endemic area, blaKPC PCR testing of positive blood cultures was associated with decreased time until appropriate therapy and decreased mortality for CRE bacteremia, and ceftazidime-avibactam is a reasonable first-line therapy for these infections.