Outcomes and Risk Factors of Bloodstream Infections Caused by Carbapenem-Resistant and Non-Carbapenem-Resistant Klebsiella pneumoniae in China

Retrospective Case-Control Study of Risk Factors for Carbapenem-Resistant Klebsiella pneumoniae Infection in Children in China

This study aims to investigate the risk factors for infection and mortality associated with carbapenem-resistant Klebsiella pneumoniae (CRKP) in hospitalized children, with the goal of providing valuable insights for the prevention and treatment of these bacterial infections. A retrospective case-control study was conducted, including 153 cases of carbapenem-sensitive K. pneumoniae infection in children and 49 cases of CRKP infection. Among the CRKP cases, 40 children survived and nine died. Logistic regression analysis was used to screen the risk factors for CRKP infection in children, establish a predictive model, and analyze the factors associated with mortality in CRKP-infected children. The results of the multivariate regression analysis showed that hematopoietic malignancies (OR = 28.272, 95% CI: 2.430-328.889), respiratory tract infections (OR = 0.173, 95% CI: 0.047-0.641), mechanical ventilation (OR = 3.002, 95% CI: 1.117-8.071), number of antibiotic agents (OR = 1.491, 95% CI: 1.177-1.889), WBC (OR = 0.849, 95% CI: 0.779-0.926), and neutrophil count (OR = 0.779, 95% CI: 0.677-0.896) were identified as significant factors associated with CRKP infection in children. Specifically, CRKP-infected children with a history of multiple hospitalizations within the past three months, blood stream infections, and decreased WBC and lymphocyte counts should be monitored closely due to poor prognosis. Underlying hematopoietic malignancies in children, non-respiratory tract infections, mechanical ventilation after admission, and use of multiple antibiotics without significant increase in white blood cell and neutrophil counts are major factors influencing CRKP infection. Particularly, CRKP-infected children with blood stream infections and no significant increase in neutrophil count should be closely monitored for potential severity of illness.

Prognostic Value of Computed Tomography-Measured Visceral Adipose Tissue in Patients with Pulmonary Infection Caused by Carbapenem-Resistant Klebsiella pneumoniae

Objective

This study aimed to investigate the correlation between computed tomography (CT) derived body composition and 30-day mortality in patients with pulmonary infections caused by carbapenem-resistant Klebsiella pneumoniae (K. pneumoniae).

Methods

A total of 89 eligible participants from a tertiary teaching hospital, enrolled between January 1, 2016, and December 31, 2020, were included in the study. We analyzed the relationship between visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), total adipose tissue (TAT), and skeletal muscle (SM) and 30-day mortality in patients infected with carbapenem-resistant K. pneumoniae (CRKP) in the pulmonary region. Furthermore, we established Cox regression models and a personalized nomogram model to predict the probability of 30-day mortality in these infected patients.

Results

Individuals with high VAT exhibited a higher likelihood of 30-day all-cause mortality (P<0.01) and 30-day mortality due to CRKP infection (P<0.01) compared to those with low VAT. Similar results were observed for TAT. After adjusting for significant comorbidities and other clinical characteristics, Cox regression analysis revealed that male gender (adjusted HR = 4.37; 95% CI = 0.96-19.92, P=0.06), vasopressor use (adjusted HR = 3.65; 95% CI = 1.04-12.85, P=0.04), and VAT (adjusted HR = 1.16; 95% CI = 1.01-1.34, P=0.03) were independent risk factors for 30-day all-cause mortality among these infectious patients.

Conclusion

The study results highlight the significant prognostic value of CT-quantified visceral adipose tissue in patients with CRKP pulmonary infection. Individuals with high VAT are more prone to mortality within 30 days compared to those with low VAT.

Investigation of the Rapid Emergence of Colistin Resistance in a Newborn Infected with KPC-2-Producing Hypervirulent Carbapenem-Resistant Klebsiella pneumoniae

OBJECTIVES

Hypervirulent carbapenem-resistant Klebsiella pneumoniae (hv-CRKp) poses a significant threat to public health. This study reports an infection related to hv-CRKp in a premature infant and reveals its colistin resistance and evolutionary mechanisms within the host.

METHODS

Three KPC-producing CRKp strains were isolated from a patient with sepsis and CRKp osteoarthritis who had been receiving colistin antimicrobial therapy. The minimum inhibitory concentrations (MICs) of ceftazidime, ceftazidime-avibactam (CAZ-AVI), meropenem, imipenem, tigecycline, amikacin, minocycline, sulfamethoxazole/trimethoprim, ciprofloxacin, levofloxacin, aztreonam, cefepime, cefoperazone/sulbactam, piperacillin/tazobactam, and colistin were determined using the microbroth dilution method. The whole-genome sequencing analysis was conducted to determine the sequence types (STs), virulence genes, and antibiotic resistance genes of the three CRKp strains.

RESULTS

Whole-genome sequencing revealed that all three CRKp strains belonged to the ST11 clone and carried a plasmid encoding blaKPC-2. The three strains all possessed the iucABCDiutA virulence cluster, peg-344 gene, and rmpA/rmpA2 genes, defining them as hv-CRKp. Further experiments and whole-genome analysis revealed that a strain of K. pneuomniae had developed resistance to colistin. The mechanism found to be responsible for colistin resistance was a deletion mutation of approximately 9000 bp including the mgrB gene.

CONCLUSION

This study characterizes colistin resistance of the ST11 clone hv-CRKp during colistin treatment and its rapid evolution within the host.

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.

Alkyl deoxyglycoside-polymyxin combinations against critical priority carbapenem-resistant gram-negative bacteria

The escalating antimicrobial resistance crisis urges the development of new antibacterial treatments with innovative mechanisms of action, particularly against the critical priority carbapenem-resistant Acinetobacter baumannii (CRAB), Pseudomonas aeruginosa (CRPA) and Enterobacteriaceae (CRE). Membrane-disrupting dodecyl deoxyglycosides have been reported for their interesting phosphatidylethanolamine-associated bactericidal activity against Gram-positive strains; however, their inability to penetrate the Gram-negative outer membrane (OM) renders them useless against the most challenging pathogens. Aiming to repurpose alkyl deoxyglycosides against Gram-negative bacteria, this study investigates the antimicrobial effects of five reference compounds with different deoxygenation patterns or anomeric configurations in combination with polymyxins as adjuvants for enhanced OM permeability. The generation of the lead 4,6-dideoxy scaffold was optimized through a simultaneous dideoxygenation step and applied to the synthesis of a novel alkyl 4,6-dideoxy C-glycoside 5, herein reported for the first time. When combined with subtherapeutic colistin concentrations, most glycosides demonstrated potent antimicrobial activity against several multidrug-resistant clinical isolates of CRAB, CRE and CRPA exhibiting distinct carbapenem resistance mechanisms, together with acceptable cytotoxicity against human HEK-293T and Caco-2 cells. The novel 4,6-dideoxy C-glycoside 5 emerged as the most promising prototype structure for further development (MIC 3.1 μg/mL when combined with colistin 0.5 μg/mL against CRPA or 0.25 μg/mL against several CRE and CRAB strains), highlighting the potential of C-glycosylation for an improved bioactive profile. This study is the first to show the potential of IM-targeting carbohydrate-based compounds for the treatment of infections caused by MDR Gram-negative pathogens of clinical importance.

Bloodstream Infections Caused by Multidrug Resistant Bacteria: Clinical and Microbiological Features and Mortality

Objectives

Bloodstream infections (BSI) are associated with high morbidity and mortality. The aim of our study is to determine whether there is a relationship between certain risk factors such as the underlying disease, patient's medical history, or interventional procedures and multidrug resistant (MDR) bacterial infection and to determine the risk factors for mortality.

Methods

Two hundred and twenty-two outpatients and inpatients who were diagnosed with bacteremia over a 6-month period were included in the study. 232 agents from 222 patients were isolated and tested for antimicrobial susceptibility. The relationship between patients demographic and clinical data and MDR was analyzed.

Results

The most common microorganisms were Gram-negative bacteria (59.4%), Gram-positive bacteria (36.9%), Candida species (2.2%), and anaerobic bacteria (1.35%). The most common isolates were Escherichia coli 53 (22.8%), Staphylococcus aureus 35 (%15.1), Klebsiella pneumoniae 26 (11.2%), Pseudomonas spp. (n=17, 7.3%), Acinetobacter spp 17 (7.3%), and Enterococcus spp 14 (6%). Microorganisms with the highest antimicrobial resistance observed were 82.3% in Acinetobacter baumannii, 64.5% in coagulase-negative staphylococci, 60.3% in E. coli, 50% in K. pneumoniae, and 27.2% in Enterobacterales spp. Most patients with BSI caused by MDR bacteria were in the intensive care unit (64%). Sepsis diagnosis, urinary catheter use, history of surgery, and use of broad-spectrum antibiotics as well as risk factors for antibiotic-resistant bacteremia, coronary artery disease, inappropriate empirical therapy, healthcare-associated infections, urinary catheterization, and stay in the ICU were determined as risk factors for mortality.

Conclusion

Our study identified the risk factors of BSI caused by MDR bacteria and helped to reveal the relationship between these factors and mortality.

Genomic Insights Into Molecular Characteristics and Phylogenetic Linkage Between the Cases of Carbapenem-Resistant Klebsiella pneumoniae From a Non-tertiary Hospital in China: A Cohort Study

Background: Carbapenem-resistant Klebsiella pneumoniae (CRKP) strains have been listed as one of the major clinical concerns. Objectives: We investigated CPKP isolates from non-tertiary hospitals to find disseminated clones and analyze extensive phenotypic and genetic diversity in this study. Methods: In this cohort study, a total of 49 CRKP isolates from 3 hospitals in the same region were collected in 2021. The prevalence and antimicrobial susceptibility patterns were analyzed. Clinical data were retrieved from electronic medical record systems. The molecular types, antimicrobial resistance (AMR) profiles, plasmid replicons, and virulence factors were analyzed. The maximum-likelihood phylogenetic tree and transmission networks were constructed using single-nucleotide polymorphisms (SNPs). Results: The median age of patients (N = 49) was 66.0 years, and 85.7% were male. The most common CRKP infection was nosocomial pneumonia (75.5%), followed by bacteremia (10.2%). More than 53% of isolates were resistant to ceftazidime-avibactam (CAZ/AVI). Forty-five isolates were successfully sequenced; the predominant carbapenem-resistant gene was blaKPC-2 (93.3%). The 30-day mortality in our cohort was 24.5%. The most dominant sequence type (ST) was ST11 (60.0%), followed by ST15 (13.3%). Whole genome sequencing (WGS) analysis exhibited dissemination of ST11 strain clones, ST420, and ST15 clones, both within and outside the given hospital. Conclusions: In this surveillance study, several dissemination chains of CRKP were discovered in the hospital and the region, as ST11 was the main epidemic clone. Our findings suggest that effective infection control practices and antimicrobial stewardship are needed in non-tertiary hospitals in China.

Genomic Characteristics and Phylogenetic Analyses of a Multiple Drug-Resistant Klebsiella pneumoniae Harboring Plasmid-Mediated MCR-1 Isolated from Tai'an City, China

Klebsiella pneumoniae is a clinically common opportunistic pathogen that causes pneumonia and upper respiratory tract infection in humans as well as community-and hospital-acquired infections, posing significant threats to public health. Moreover, the insertion of a plasmid carrying the mobile colistin resistance (MCR) genes brings obstacles to the clinical treatment of K. pneumoniae infection. In this study, a strain of colistin-resistant K. pneumoniae (CRKP) was isolated from sputum samples of a patient who was admitted to a tertiary hospital in Tai'an city, China, and tested for drug sensitivity. The results showed that KPTA-2108 was multidrug-resistant (MDR), being resistant to 21 of 26 selected antibiotics, such as cefazolin, amikacin, tigecycline and colistin but sensitive to carbapenems via antibiotic resistance assays. The chromosome and plasmid sequences of the isolated strain KPTA-2108 were obtained using whole-genome sequencing technology and then were analyzed deeply using bioinformatics methods. The whole-genome sequencing analysis showed that the length of KPTA-2108 was 5,306,347 bp and carried four plasmids, pMJ4-1, pMJ4-2, pMJ4-3, and pMJ4-4-MCR. The plasmid pMJ4-4-MCR contained 30,124 bp and was found to be an IncX4 type. It was the smallest plasmid in the KPTA-2108 strain and carried only one resistance gene MCR-1. Successful conjugation tests demonstrated that pMJ4-4-MCR carrying MCR-1 could be horizontally transmitted through conjugation between bacteria. In conclusion, the acquisition and genome-wide characterization of a clinical MDR strain of CRKP may provide a scientific basis for the treatment of K. pneumoniae infection and epidemiological data for the surveillance of CRKP.

Metagenomic Next-Generation Sequencing (mNGS) for the Timely Diagnosis of Carbapenem-Resistant Klebsiella pneumoniae in Leukemia Patients

This report shows the contribution of metagenomic next-generation sequencing (mNGS) as an alternative to challenging diagnostic infection in immunosuppressed individuals. Herein, we report two leukemia patients who developed severe infections due to carbapenem-resistant Klebsiella pneumoniae (CrKP). The mNGS can be strongly recommended as an alternative investigation for patients who are at high risk of infection without positivity on body fluid culture. This can provide the opportunity for adequate therapy.