Carbapenem-resistant Klebsiella Pneumoniae Research Articles

Characterization of ST15-KL112 Klebsiella pneumoniae Co-Harboring Bla oxa-232 and rmtF in China.

This study aimed to investigate the emergence and characteristics of carbapenem-resistant Klebsiella pneumoniae (CRKP) strains that demonstrate resistance to multiple antibiotics, including aminoglycosides and tigecycline, in a Chinese hospital. A group of ten CRKP strains were collected from the nine patients in a Chinese hospital. Antimicrobial Susceptibility Testing (AST) and phenotypic inhibition assays precisely assess bacterial antibiotic resistance. Real-time quantitative PCR (RT-qPCR) was used to analyze the mRNA levels of efflux pump genes (acrA/acrB and oqxA/oqxB) and the regulatory gene (ramA). The core-genome tree and PFGE patterns were analyzed to assess the clonal and horizontal transfer expansion of the strains. Whole-genome sequencing was performed on a clinical isolate of K. pneumoniae named Kpn20 to identify key resistance genes and antimicrobial resistance islands (ARI). The CRKP strains showed high resistance to carbapenems, aminoglycosides (CLSI, 2024), and tigecycline (EUCAST, 2024). The mRNA expression levels of efflux pump genes and regulatory genes were detected by RT-qPCR. All 10 isolates had significant differences compared to the control group of ATCC13883. The core-genome tree and PFGE patterns revealed five clusters, indicating clonal and horizontal transfer expansion. Three key resistance genes (blaoxa-232, blaCTX-M-15 , and rmtF) were observed in the K. pneumoniae clinical isolate Kpn20. Mobile antibiotic resistance islands were identified containing bla CTX-M-15 and rmtF, with multiple insertion sequences and transposons present. The coexistence of bla oxa-232 and rmtF in a high-risk K. pneumoniae strain was reported. Conjugation assay was utilized to investigate the transferability of bla oxa-232-encoding plasmids horizontally. The study highlights the emergence of ST15-KL112 high-risk CRKP strains with multidrug resistance, including to aminoglycosides and tigecycline. The presence of mobile ARI and clonal and horizontal transfer expansion of strains indicate the threat of transmission of these strains. Future research is needed to assess the prevalence of such isolates and develop effective control measures.

Susceptibility evaluation of novel beta-lactam/beta-lactamase inhibitor combinations against carbapenem-resistant Klebsiella pneumoniae from bloodstream infections in hospitalized patients in Brazil

IntroductionNovel beta-lactam/beta-lactamase inhibitor (BIBLI) combinations are commercially available and have been used for treating carbapenem-resistant Klebsiella pneumoniae (CRKP) infections. Continuous surveillance of susceptibility profiles and resistance mechanism identification are necessary to monitor the evolution of resistance within these agents. ObjectiveThe purpose of this study was to evaluate the susceptibility rates of ceftazidime/avibactam, imipenem/relebactam and meropenem/vaborbactam in CRKP isolated from patients with bloodstream infections who underwent screening for a randomized clinical trial in Brazil. MethodsMinimum inhibitory concentrations (MICs) were determined for meropenem, ceftazidime/avibactam, imipenem/relebactam and meropenem/vaborbactam using the gradient diffusion strip method. Carbapenemase genes were detected by multiplex real-time polymerase chain reaction. Klebsiella pneumoniae carbapenemase (KPC)-producing isolates showing resistance to any BLBLI and New Delhi Metallo-beta-lactamase (NDM)-producing isolates with susceptibility to any BLBLI isolates were further submitted for whole-genome sequencing. ResultsFrom a total of 69 CRKP isolates, 39 were positive for blaKPC, 19 for blaNDM and 11 for blaKPC and blaNDM. KPC-producing isolates demonstrated susceptibility rates above 94 % for all BLBLIs. Two isolates with resistance to meropenem/vaborbactam demonstrated a Gly and Asp duplication at the porin OmpK36 as well as a truncated OmpK35. All NDM-producing isolates, including KPC and NDM coproducers, demonstrated susceptibility rates to ceftazidime/avibactam, imipenem/relebactam and meropenem/vaborbactam of 0 %, 9.1–21.1 % and 9.1–26.3 %, respectively. Five NDM-producing isolates that presented susceptibility to BLBLIs also had porin alterations ConclusionsThis study showed that, although high susceptibility rates to BLBLIs were found, KPC-2 isolates were able to demonstrate resistance probably as a result of porin mutations. Additionally, NDM-1 isolates showed susceptibility to BLBLIs in vitro.

Global evolutionary dynamics of virulence genes in ST11-KL47 carbapenem-resistant Klebsiella pneumoniae

ST11-KL47 is a hypervirulent carbapenem-resistant Klebsiella pneumoniae (CRKP) that is highly prevalent in China and poses a major public health risk. To investigate the evolutionary dynamics of virulence genes in this subclone, we analysed 78 sequenced isolates obtained from a long-term study across 29 centres from 17 cities in China. Virulence genes were located in large hybrid pNDM-Mar-like plasmids (length: ∼266 kilobases) rather than in classical pK2044-like plasmids. These hybrid plasmids, derived from the fusion of pK2044 and pNDM-Mar plasmids mediated by insertion sequence (IS) elements (such as ISKpn28 and IS26), integrated virulence gene fragments into the chromosome. Analysis of 217 sequences containing the special IncFIB (pNDM-Mar) replicon using public databases indicated that these plasmids typically contained T4SS-related and multiple antimicrobial resistance genes, were present in 24 countries, and were found in humans, animals, and the environment. Notably, the chromosomal integration of virulence genes was observed in strains across five countries across two continents. In vivo and in vitro models showed that the large hybrid plasmid increased the host fitness cost while increasing virulence. Conversely, virulence genes transferred to chromosomes resulted in increased fitness and lower virulence. In conclusion, virulence genes in the plasmids of ST11-KL47 CRKP are evolving, driven by adaptive negative selection, to enable vertical chromosomal inheritance along with conferring a survival advantage and low pathogenicity.

Ceftazidime/avibactam versus polymyxin B in carbapenem-resistant Klebsiella pneumoniae infections: a propensity score-matched multicenter real-world study.

In this retrospective observational multicenter study, we aimed to assess efficacy and mortality between ceftazidime/avibactam (CAZ/AVI) or polymyxin B (PMB)-based regimens for the treatment of Carbapenem-resistant Klebsiella pneumoniae (CRKP) infections, as well as identify potential risk factors. A total of 276 CRKP-infected patients were enrolled in our study. Binary logistic and Cox regression analysis with a propensity score-matched (PSM) model were performed to identify risk factors for efficacy and mortality. The patient cohort was divided into PMB-based regimen group (n = 98, 35.5%) and CAZ/AVI-based regimen group (n = 178, 64.5%). Compared to the PMB group, the CAZ/AVI group exhibited significantly higher rates of clinical efficacy (71.3% vs. 56.1%; p = 0.011), microbiological clearance (74.7% vs. 41.4%; p < 0.001), and a lower incidence of acute kidney injury (AKI) (13.5% vs. 33.7%; p < 0.001). Binary logistic regression revealed that the treatment duration independently influenced both clinical efficacy and microbiological clearance. Vasoactive drugs, sepsis/septic shock, APACHE II score, and treatment duration were identified as risk factors associated with 30-day all-cause mortality. The CAZ/AVI-based regimen was an independent factor for good clinical efficacy, microbiological clearance, and lower AKI incidence. For patients with CRKP infection, the CAZ/AVI-based regimen was superior to the PMB-based regimen.

Inhibitory Potential of Bifidobacterium longum FB1-1 Cell-Free Supernatant against Carbapenem-Resistant Klebsiella pneumoniae Drug Resistance Spread.

The widespread dissemination of carbapenem-resistant Klebsiella pneumoniae (CRKP) and its drug resistance transfer poses a global public health threat. While previous studies outlined CRKP's drug resistance mechanism, there is limited research on strategies inhibiting CRKP drug resistance spread. This study investigates the potential of Bifidobacterium longum (B. longum) FB1-1, a probiotic, in curbing the spread of drug resistance among CRKP by evaluating its cell-free supernatant (CFS) for antibacterial activity. Evaluating the inhibitory effect of FB1-1 CFS on CRKP drug resistance spread involved analyzing its impact on drug resistance and virulence gene expression; drug resistance plasmid transfer FB1-1 CFS exhibited an MIC range of 125 μL/mL against CRKP. After eight hours of co-culture, CFS achieved a 96% and 100% sterilization rate at two and four times the MIC, respectively. At sub-inhibitory concentrations (1/2× MIC), FB1-1 CFS reduced the expression of the bla_KPC gene, which is pivotal for carbapenem resistance, by up to 62.13% across different CRKP strains. Additionally, it markedly suppressed the expression of the uge gene, a key virulence factor, by up to 91%, and the fim_H gene, essential for bacterial adhesion, by up to 53.4%. Our study primarily focuses on determining the inhibitory effect of FB1-1 CFS on CRKP strains harboring the bla_KPC gene, which is a critical resistance determinant in CRKP. Furthermore, FB1-1 CFS demonstrated the ability to inhibit the transfer of drug resistance plasmids among CRKP strains, thus limiting the horizontal spread of resistance genes. This study highlights FB1-1 CFS's inhibitory effect on CRKP drug resistance spread, particularly in strains carrying the bla_KPC gene, thus offering a novel idea and theoretical foundation for developing antibacterial drugs targeting CRKP resistance.

International and regional spread of carbapenem-resistant Klebsiella pneumoniae in Europe

Carbapenem-resistant Klebsiella pneumoniae (CRKP) are of particular concern due to the spread of antibiotic resistance genes associated with mobile genetic elements. In this study, we collected 687 carbapenem-resistant strains recovered among clinical samples from 41 hospitals in nine Southern European countries (2016-2018). We identified 11 major clonal lineages, with most isolates belonging to the high-risk clones ST258/512, ST101, ST11, and ST307. blaKPC-like was the most prevalent carbapenemase-encoding gene (46%), with blaOXA-48 present in 39% of isolates. Through the combination and comparison of this EURECA collection with the previous EuSCAPE collection (2013-2014), we investigated the spread of high-risk clones circulating in Europe exhibiting regional differences. We particularly found blaKPC-like ST258/512 in Greece, Italy, and Spain, blaOXA-48 ST101 in Serbia and Romania, blaNDM ST11 in Greece, and blaOXA-48-like ST14 in Türkiye. Genomic surveillance across Europe thus provides crucial insights for local risk mapping and informs necessary adaptions for implementation of control strategies.

Synergistic Combination of Aztreonam and Ceftazidime–Avibactam—A Promising Defense Strategy against OXA-48 + NDM Klebsiella pneumoniae in Romania

With the increasing burden of carbapenem-resistant Klebsiella pneumoniae (CR-Kp), including high rates of healthcare-associated infections, treatment failure, and mortality, a good therapeutic strategy for attacking this multi-resistant pathogen is one of the main goals in current medical practice and necessitates the use of novel antibiotics or new drug combinations. Objectives: We reviewed the clinical and microbiological outcomes of seven patients treated at the “Agrippa Ionescu” Clinical Emergency Hospital between October 2023 and January 2024, aiming to demonstrate the synergistic activity of the ceftazidime–avibactam (C/A) plus aztreonam (ATM) combination against the co-producers of blaNDM + blaOXA-48-like CR-Kp. Material and Methods: Seven CR-Kp with blaNDM and blaOXA-48 as resistance mechanisms were tested. Seven patients treated with C/A + ATM were included. The synergistic activity of C/A + ATM was proven through double-disk diffusion in all seven isolates. Resistance mechanisms like KPC, VIM, OXA-48, NDM, IMP, and CTX-M were assessed through immunochromatography. Results: With a mean of nine days of treatment with the synergistic combination C/A + ATM, all patients achieved clinical recovery, and five achieved microbiological recovery. Conclusions: With the emerging co-occurrence of blaOXA-48 and blaNDM among Kp in Romania, the combination of C/A and ATM could be a promising therapeutic option.

High mortality associated with inappropriate initial antibiotic therapy in hematological malignancies with Klebsiella pneumoniae bloodstream infections

Bloodstream infections caused by multidrug-resistant organisms such as Klebsiella pneumoniae are a significant challenge in managing hematological malignancies. This study aims to characterize the epidemiology of Klebsiella pneumoniae bloodstream infections specifically in patients with hematological malignancies, delineate the patterns of initial antibiotic therapy, assess the prevalence of resistant strains, identify risk factors for these resistant strains, and evaluate factors influencing patient outcomes. A retrospective analysis was conducted at a single center from January 2017 to December 2020, focusing on 182 patients with hematological malignancies who developed Klebsiella pneumoniae bloodstream infections. We compared the 30-day mortality rates between patients receiving appropriate and inappropriate antibiotic treatments, including the effectiveness of both single-drug and combination therapies. Kaplan–Meier survival analysis and multivariate logistic and Cox regression were used to identify factors influencing mortality risk. The 30-day all-cause mortality rate was 30.2% for all patients. The 30-day all-cause mortality rates were 77.2% and 8.8% in patients who received inappropriate initial treatment and appropriate initial treatment (p < 0.001). Inappropriate initial treatment significantly influenced mortality and was a key predictor of 30-day mortality, along with septic shock and previous intensive care unit (ICU) stays. Patients with carbapenem-resistant Klebsiella pneumoniae (CRKP) bloodstream infections exhibited more severe clinical symptoms compared to the CSKP group. The study demonstrates a significant association between empirical carbapenem administration and the escalating prevalence of CRKP and multidrug-resistant K. pneumoniae (MDR-KP) infections. Furthermore, the study identified inappropriate initial antibiotic therapy, septic shock, and ICU admission as independent risk factors for 30-day mortality.

Whole genome sequencing analysis of seven unknown resistance mechanisms of carbapenem-resistant Klebsiella pneumoniae strains resistance to ceftazidime-avibactam.

To investigate alternative resistance mechanisms among seven ceftazidime-avibactam (CZA)-resistant carbapenem-resistant Klebsiella pneumoniae (CRKP) strains lacking common antimicrobial resistance genes (ARGs) using whole genome sequencing. ARG and virulence factors (VFs) were screened using the ARG database CARD and the VF database, respectively, and identified using genomic annotation data with BLAST+. Six strains were ST11 sequence types (STs), and one was ST2123. ST11 strains harbored more ARGs than the ST2123 strains. All seven strains carried multiple ARGs with efflux-mediated antibiotic resistance, including oqxA, oqxB, tet (A), qacEdltal, CRP, H-NS, Kpn-E, F, G, H, acrA, LptD, acrB, acrD, cpxA, mdtB, and mdtC. These efflux-mediated ARGs were identified in most strains and even all strains. Whole genome sequencing revealed that the ST11 strain carried multiple potential prophages, genomic islands, and integrative and conjugative elements, while the ST2123 strain carried an independent potential prophages and a genomic island. Whole genome sequencing analysis revealed that these seven CZA-resistant CRKP strains lacking common ARGs exhibited efflux-mediated antibiotic resistance-associated ARGs. The main mechanism by which CRKP resists CZA is antibiotic inactivation. Except for tet (A), no ARGs and validation experiments related to efflux were found. This study's results provide a new possibility for the resistance mechanism of CRKP to CZA, and we will verify this conclusion through experiments in the future.

Study of the Epidemiological and Mechanistic Differences Between Carbapenem-Resistant Klebsiella pneumoniae Infections in Children and Adults.

The emergence of carbapenem-resistant Klebsiella pneumoniae (CRKP) has garnered international concern due to its significant antibiotic resistance. Notably, children exhibit distinct resistance mechanisms compared to adults, necessitating a differential approach to antibiotic selection. A thorough analysis of CRKP's epidemiology and drug resistance mechanisms is essential for establishing a robust foundation for clinical anti-infection strategies and precise prevention and control measures. This study involved the collection of 31 non-repetitive strains from pediatric and adult patients at a tertiary hospital in China, spanning from July 2016 to July 2022, testing for resistance genes, antimicrobial susceptibility, and homology analysis. Infants (0-1 year) were the largest pediatric CRKP group, with 61.3% of cases. The neonatal intensive care unit (NICU) and pediatrics were the main departments affected. Adults with CRKP had a mean age of 67 years, with the highest prevalence in neurology and emergency ICU. Antimicrobial susceptibility testing revealed that adult CRKP strains exhibited higher resistance to amikacin, ciprofloxacin, cotrimoxazole, and aztreonam compared to pediatric strains. Conversely, pediatric strains showed a higher rate of resistance to ceftazidime/avibactam. The predominant resistance genes identified were bla NDM-5 in children (58.1%) and bla KPC-2 in adults (87.1%), with over 93% of both groups testing positive for extended-spectrum beta-lactamase (ESBL) genes. Multilocus Sequence Typing (MLST) indicated ST2735 and ST11 as the predominant types in children and adults, respectively. Pulsed-field gel electrophoresis (PFGE) identified clonal transmission patterns of ST11 bla KPC-2 and ST15 bla OXA-232 across both age groups. Notably, this study reports the first instance of ST1114-type CRKP co-producing bla NDM-5 and bla OXA-181 in the NICU. This study reveals distinct resistance mechanisms and epidemiology in CRKP from children and adults. The identified clonal transmission patterns emphasize the need for improved infection control to prevent the spread of resistant strains.

The real-world impact of the BioFire FilmArray blood culture identification 2 panel on antimicrobial stewardship among patients with bloodstream infections in intensive care units with a high burden of drug-resistant pathogens

BackgroundThe increasing prevalence of drug-resistant pathogens leads to delays in adequate antimicrobial treatment in intensive care units (ICU). The real-world influence of the BioFire FilmArray Blood Culture Identification 2 (BCID2) panel on pathogen identification, diagnostic concordance with conventional culture methods, and antimicrobial stewardship in the ICU remains unexplored. MethodsThis retrospective observational study, conducted from July 2021 to August 2023, involved adult ICU patients with positive blood cultures who underwent BCID2 testing. The concordance between BCID2 and conventional culture results was examined, and its impact on antimicrobial stewardship was assessed through a comprehensive retrospective review of patient records by intensivists. ResultsA total of 129 blood specimens from 113 patients were analysed. Among these patients, a high proportion of drug-resistant strains were noted, including carbapenem-resistant Klebsiella pneumoniae (CRKP) (57.1%), carbapenem-resistant Acinetobacter calcoaceticus-baumannii complex (100%), methicillin-resistant Staphylococcus aureus (MRSA) (70%), and vancomycin-resistant Enterococcus faecium (VRE) (100%). The time from blood culture collection to obtaining BCID2 results was significantly shorter than conventional culture (46.2 h vs. 86.9 h, p < 0.001). BCID2 demonstrated 100% concordance in genotype–phenotype correlation in antimicrobial resistance (AMR) for CRKP, carbapenem-resistant Escherichia coli, MRSA, and VRE. A total of 40.5% of patients received inadequate empirical antimicrobial treatment. The antimicrobial regimen was adjusted or confirmed in 55.4% of patients following the BCID2 results. ConclusionsIn the context of a high burden of drug-resistant pathogens, BCID2 demonstrated rapid pathogen and AMR detection, with a noticeable impact on antimicrobial stewardship in BSI in the ICU.

Virulence gene distribution and molecular epidemiological characteristics of carbapenem-resistant Klebsiella pneumoniae in the ICU.

The drug-resistant genes carried by carbapenem-resistant Klebsiella pneumoniae (CRKP) limit clinical treatment options, and its virulence genes severely affect patient prognosis. This study aims to investigate the distribution of virulence genes, capsular serotypes, and molecular epidemiological characteristics of CRKP in ICU, to understand the characteristics of CRKP infections in ICU, and to provide a scientific basis for effective monitoring and control of CRKP infections in ICU. A total of 40 non-duplicate strains of CRKP isolated from the ICU of Guangdong Provincial People's Hospital between January 2021 and December 2022 were collected and analyzed. Whole-genome sequencing was used to analyze the distribution of resistance genes, virulence genes, and capsular serotypes of the strains. The sequences of 7 housekeeping genes of CRKP genome were uploaded to the Klebsiella pneumoniae (KPN)multilocus sequence typing (MLST) database to determine the sequence types (STs) of the strains. The age of the 40 ICU CRKP-infected patients was (69.03±17.82) years old, with various underlying diseases, and there were 20 patients with improved clinical outcome and 20 patients with death. The isolated strains primarily originated from mid-stream urine and bronchoalveolar lavage fluid. Whole-genome sequencing results revealed that the strains predominantly carried blaKPC-1 (29 strains, 72.5%) and blaNDM-1 (6 strains, 15.0%), with 5 strains carrying both blaKPC-1 and blaNDM-1. Various virulence genes were detected, among which the carriage rates of genes such as entA, entB, entE, entS, fepA, fepC, fepG, yag/ecp, and ompA reached 100%, while the carriage rates of genes such as entD, fimB, iroB, iroD, fes,and pla were low. The CRKP strains isolated from ICU were predominantly ST11 (27 cases, 67.5%), with KL64 being the main capsular serotype (29 cases, 72.5%). A total of 23 ST11-KL64 CRKP strains were detected, accounting for 57.5%. The main type of ICU CRKP is ST11-KL64, carrying various virulence genes, primarily those related to iron absorption. Furthermore, blaKPC has shifted from blaKPC-2 to blaKPC-1. Therefore, close monitoring of the molecular epidemiological changes of CRKP is necessary, and strict control measures should be implemented to effectively curb the occurrence of CRKP infections.

Genome sequence of a sequence type 1 NDM-5-producing carbapenem-resistant Klebsiella pneumoniae in China

ObjectiveThe emergence of carbapenem-resistant Klebsiella pneumoniae (CRKP) presents significant health challenges. Here, we present the structural genome sequence of an NDM-5-producing K. pneumoniae (HZKP2) in China. MethodsAntimicrobial susceptibility tests were conducted via broth microdilution. Whole-genome sequencing (WGS) was performed for genomic analysis. Wzi and capsular polysaccharide (KL) were analysed using Kaptive. Resistance genes, virulence factors, and comparative genomics analyses were also conducted. Multilocus sequence typing (MLST), replicons type, and core genome multilocus sequence typing (cgMLST) analysis were further conducted using BacWGSTdb server. ResultsHZKP2 was resistant to cefepime, ceftazidime, ciprofloxacin, ciprofloxacin, meropenem, and ertapenem. It harbored fosA, blaSHV-187, oqxA, oqxB, sul1, dfrA1, tet(A), floR, aph(6)-Id, aph(3′')-Ib, sul2, blaCTX-M-55, and blaNDM-5. Based on the RAST results, 5563 genes that belonged to 398 subsystems were annotated. The complete genome sequence of HZKP2 was characterized as ST1, wzi 19, and KL19, with five contigs totaling 5,654,446 bp, including one chromosome and four plasmids. Further analysis found that blaNDM-5 was located in a 46,161 bp IncX3 plasmid (pHZKP2-3). The genetic structure of blaNDM-5 gene was ISKox3-IS26-bleMBL-blaNDM-5-IS5-ISAb125-IS3000. Further analysis revealed that insertion sequences mediated the dissemination of blaNDM-5 from other species of Enterobacterales. Phylogenetic analysis showed that the closest relative was from a human stool specimen in China, which differed by 53 cgMLST alleles. ConclusionOur study provides the first structural perspective of the ST1 K. pneumoniae isolate producing NDM-5 in China. These results could provide valuable insights into the genetic characteristics, antimicrobial resistance mechanisms, and transmission dynamics of CRKP in clinical settings.

Implications of deduplication on the detection rates of multidrug-resistant organism (MDRO) in various specimens: insights from the hospital infection surveillance program

BackgroundCurrently, different guidelines recommend using different methods to determine whether deduplication is necessary when determining the detection rates of multidrug-resistant organisms (MDROs). However, few studies have investigated the effect of deduplication on MDRO monitoring data. In this study, we aimed to investigate the influence of deduplication on the detection rates of MDROs in different specimens to assess its impact on infection surveillance outcomes.MethodsSamples were collected from hospitalized patients admitted between January 2022 and December 2022; four types of specimens were collected from key monitored MDROs, including sputum samples, urine samples, blood samples, and bronchoalveolar lavage fluid (BALF) samples. In this study, we compared and analysed the detection rates of carbapenem-resistant Klebsiella pneumoniae (CRKP), carbapenem-resistant Escherichia coli (CRECO), carbapenem-resistant Acinetobacter baumannii (CRAB), carbapenem-resistant Pseudomonas aeruginosa (CRPA), and methicillin-resistant Staphylococcus aureus (MRSA) under two conditions: with and without deduplication.ResultsWhen all specimens were included, the detection rates of CRKP, CRAB, CRPA, and MRSA without deduplication (33.52%, 77.24%, 44.56%, and 56.58%, respectively) were significantly greater than those with deduplication (24.78%, 66.25%, 36.24%, and 50.83%, respectively) (all P < 0.05). The detection rates in sputum samples were significantly different between samples without duplication (28.39%, 76.19%, 46.95%, and 70.43%) and those with deduplication (19.99%, 63.00%, 38.05%, and 64.50%) (all P < 0.05). When deduplication was not performed, the rate of detection of CRKP in urine samples reached 30.05%, surpassing the rate observed with deduplication (21.56%) (P < 0.05). In BALF specimens, the detection rates of CRKP and CRPA without deduplication (39.78% and 53.23%, respectively) were greater than those with deduplication (31.62% and 42.20%, respectively) (P < 0.05). In blood samples, deduplication did not have a significant impact on the detection rates of MDROs.ConclusionDeduplication had a significant effect on the detection rates of MDROs in sputum, urine, and BALF samples. Based on these data, we call for the Infection Prevention and Control Organization to align its analysis rules with those of the Bacterial Resistance Surveillance Organization when monitoring MDRO detection rates.

Clinical Characteristics and Risk Factors for Mortality in Children with Carbapenem-Resistant Klebsiella pneumoniae-Induced Bloodstream Infections

Background: Klebsiella pneumoniae (KP) is commonly found in human intestinal and respiratory tracts. Objectives: This study aimed to investigate the clinical characteristics and risk factors associated with mortality in children suffering from carbapenem-resistant Klebsiella pneumoniae (CRKP)-induced bloodstream infections. Methods: We collected clinical data from 160 children diagnosed with CRKP-induced bloodstream infections. These children were divided into two groups based on their outcomes 30 days post-infection: A death group (n = 61) and a survival group (n = 99). Clinical symptoms and outcomes were meticulously documented. Results: The death group experienced a significantly shorter hospital stay than the survival group. Additionally, higher incidence rates of sepsis, malignant tumors, renal diseases, infectious shock, surgical site infections, higher acute physiology and chronic health evaluation II (APACHE II) scores, and elevated procalcitonin levels were observed in the death group (P &lt; 0.05). These factors were all identified as independent risk factors for mortality among children with CRKP-induced bloodstream infections (P &lt; 0.05). The areas under the receiver operating characteristic (ROC) curves for the length of hospital stay, presence of malignant tumors, sepsis, renal diseases, APACHE II score, procalcitonin levels, infectious shock, and surgical site infections all exceeded 0.700, indicating their high predictive value for mortality. Conclusions: The mortality rate among children with CRKP-induced bloodstream infections is high. Factors such as a brief hospital stay, presence of malignant tumors, sepsis, renal diseases, infectious shock, elevated APACHE II score, and high procalcitonin levels significantly contribute to the risk of death.

Enhancing resistance, but not virulence attributed to the high mortality caused by carbapenem-resistant Klebsiella pneumoniae

Carbapenem-resistant Klebsiella pneumoniae (CRKP) has emerged as a global threat due to its high mortality in clinical patients. However, the specific mechanisms underlying this increased mortality remain unclear. The objective of this study is to investigate how the development of a resistance phenotype contributes to the significantly higher mortality associated with this pathogen. To achieve this, a collection of isogeneic strains was generated. The clinical carbapenem-susceptible K. pneumoniae (CSKP) strain HKU3 served as the control isolate, while HKU3-KPC was created through conjugation with a blaKPC-2-bearing plasmid and served as clinical CRKP strain. Using a sepsis model, it was demonstrated that both HKU3 and HKU3-KPC exhibited similar levels of virulence. Flow cytometry, RNA-seq, and ELISA analysis were employed to assess immune cell response, M1 macrophage polarization, and cytokine storm induction, revealing that both strains elicited comparable types and levels of these immune responses. Subsequently, meropenem was utilized to treat K. pneumoniae infection, and it was found that meropenem effectively reduced bacterial load, inhibited M1 macrophage polarization, and suppressed serum cytokine production during HKU3 (CSKP) infection. However, these effects were not observed in the case of HKU3-KPC (CRKP) infection. These findings provide evidence that the high mortality associated with CRKP is attributed to its enhanced survival within the host during antibiotic treatment, resulting in a cytokine storm and subsequent host death. The development of an effective therapy for CRKP infections could significantly reduce the mortality caused by this pathogen.

Performance comparison of BD Phoenix CPO detect panel with Cepheid Xpert Carba-R assay for the detection of carbapenemase-producing Klebsiella pneumoniae isolates

BackgroundWe aimed to compare the performance of carbapenemase classification in carbapenem-resistant Klebsiella pneumoniae (CRKP) obtained using the BD Phoenix CPO Detect panel (CPO panel) and Cepheid Xpert Carba-R assays. We analyzed 55 CRKP strains from clinical specimens collected between November 2020 and November 2022. The CPO panel was used to detect both antibiotic susceptibility and phenotypic carbapenemase classes, while Xpert Carba-R was employed to identify KPC, NDM, VIM, OXA-48, and IMP genes. Due to the limited availability of molecular kits, we arbitrarily selected 55 isolates, identified as carbapenemase-producing according to the CPO panel and with meropenem minimum inhibitory concentration values > 8 mg/L.ResultsAccording to the Xpert Carba-R assay, 16 of the 55 isolates (29.1%) were categorised as Ambler Class A (11 of which matched CPO panel Class A identification); three isolates (5.5%) were identified as Class B and 27 isolates (49.1%) as Class D (in both cases consistent with CPO panel B and D classifications). A further eight isolates (14.5%) exhibited multiple carbapenemase enzymes and were designated as dual-carbapenemase producers, while one isolate (1.8%) was identified as a non-carbapenemase-producer. The CPO panel demonstrated positive and negative percent agreements of 100% and 85.7% for Ambler Class A, 100% and 100% for Class B, and 96.4% and 100% for Class D carbapenemase detection, respectively.ConclusionWhile the CPO panel’s phenotypic performance was satisfactory in detecting Class B and D carbapenemases, additional confirmatory testing may be necessary for Class A carbapenemases as part of routine laboratory procedures.

Molecular epidemiology and antimicrobial resistance profiles of Klebsiella pneumoniae isolates from hospitalized patients in different regions of China.

The increasing incidence of Klebsiella pneumoniae and carbapenem-resistant Klebsiella pneumoniae (CRKP) has posed great challenges for the clinical anti-infective treatment. Here, we describe the molecular epidemiology and antimicrobial resistance profiles of K. pneumoniae and CRKP isolates from hospitalized patients in different regions of China. A total of 219 K. pneumoniae isolates from 26 hospitals in 19 provinces of China were collected during 2019-2020. Antimicrobial susceptibility tests, multilocus sequence typing were performed, antimicrobial resistance genes were detected by polymerase chain reaction (PCR). Antimicrobial resistance profiles were compared between different groups. The resistance rates of K. pneumoniae isolates to imipenem, meropenem, and ertapenem were 20.1%, 20.1%, and 22.4%, respectively. A total of 45 CRKP isolates were identified. There was a significant difference in antimicrobial resistance between 45 CRKP and 174 carbapenem-sensitive Klebsiella pneumoniae (CSKP) strains, and the CRKP isolates were characterized by the multiple-drug resistance phenotype.There were regional differences among antimicrobial resistance rates of K. pneumoniae to cefazolin, chloramphenicol, and sulfamethoxazole,which were lower in the northwest than those in north and south of China.The mostcommon sequence type (ST) was ST11 (66.7% of the strains). In addition, we detected 13 other STs. There were differences between ST11 and non-ST11 isolates in the resistance rate to amikacin, gentamicin, latamoxef, ciprofloxacin, levofloxacin, aztreonam, nitrofurantoin, fosfomycin, and ceftazidime/avibactam. In terms of molecular resistance mechanisms, the majority of the CRKP strains (71.1%, 32/45) harbored blaKPC-2, followed by blaNDM (22.2%, 10/45). Strains harboring blaKPC or blaNDM genes showed different sensitivities to some antibiotics. Our analysis emphasizes the importance of surveilling carbapenem-resistant determinants and analyzing their molecular characteristics for better management of antimicrobial agents in clinical use.

Genetic, virulence, and antimicrobial resistance characteristics associated with distinct morphotypes in ST11 carbapenem-resistant Klebsiella pneumoniae

ABSTRACT ST11 is the most common lineage among carbapenem-resistant Klebsiella pneumoniae (CRKP) infections in Asia. Diverse morphotypes resulting from genetic mutations are associated with significant differences in microbial characteristics among K. pneumoniae isolates. Here, we investigated the genetic determinants and critical characteristics associated with distinct morphotypes of ST11 CRKP. An ST11-KL47 CRKP isolate carrying a pLVPK-like virulence plasmid was isolated from a patient with a bloodstream infection; the isolate had the “mcsw” morphotype. Two distinct morphotypes (“ntrd” and “msdw”) were derived from this strain during in vitro passage. Whole genome sequencing was used to identify mutations that cause the distinct morphotypes of ST11 CRKP. Transmission electron microscopy, antimicrobial susceptibility tests, growth assays, biofilm formation, virulence assays, membrane permeability assays, and RNA-seq analysis were used to investigate the specific characteristics associated with different morphotypes of ST11 CRKP. Compared with the parental mcsw morphotype, the ntrd morphotype resulted from mutation of genes involved in capsular polysaccharide biosynthesis (wza, wzc, and wbaP), a result validated by gene knockout experiments. This morphotype showed capsule deficiency and lower virulence potential, but higher biofilm production. By contrast, the msdw morphotype displayed competition deficiency and increased susceptibility to chlorhexidine and polymyxin B. Further analyses indicated that these characteristics were caused by interruption of the sigma factor gene rpoN by insertion mutations and deletion of the rpoN gene, which attenuated membrane integrity presumably by downregulating the phage shock protein operon. These data expand current understanding of genetic, virulence, and antimicrobial resistance characteristics associated with distinct morphotypes in ST11 CRKP.

Exploring the immune characteristions of CRKP pneumonia at single-cell level

The immune dysregulation associated with carbapenem-resistant Klebsiella pneumoniae (CRKP) severity was investigated through single-cell RNA sequencing (scRNA-seq) of 5 peripheral blood samples from 3 patients with moderate and severe CRKP pneumonia. Additionally, scRNA-seq datasets from two individuals with COVID-19 were included for comparative analysis. The dynamic characterization and functional properties of each immune cell type were examined by delineating the transcriptional profiles of immune cells throughout the transition from moderate to severe conditions. Overall, most immune cells in CRKP patients exhibited a robust interferon-α response and inflammatory reaction compared to healthy controls, mirroring observations in COVID-19 patients. Furthermore, cell signatures associated with NK cells, macrophages, and monocytes were identified in CRKP progression including PTPRCAP for NK cells, C1QB for macrophages, and S100A12 for both macrophages and monocytes. In summary, this study offers a comprehensive scRNA-seq resource for illustrating the dynamic immune response patterns during CRKP progression, thereby shedding light on the associations between CRKP and COVID-19.