Carbapenem-resistant Klebsiella Pneumoniae Infection Research Articles

Molecular epidemiology, risk factors, and outcomes of carbapenem-resistant Klebsiella pneumoniae infection in a tertiary hospital in eastern China: for a retrospective study conducted over 4 years.

Carbapenem-resistant Klebsiella pneumoniae (CRKP) have been extensively disseminated worldwide, resulting in increased mortality. We performed a retrospective analysis of the epidemiology and risk factors for the outcome of CRKP infection in a general teaching hospital in China. A molecular and clinical study was conducted for 98 CRKP in a tertiary hospital from January 2013 to December 2016. Carbapenemase gene detection, pulsed-field gel electrophoresis (PFGE), and multilocus sequence typing (MLST) were performed. Logistic regression was also used to identify the risk factors associated with 30-day mortality. The production of KPC carbapenemase was the main resistant mechanism, and KPC carbapenemase increased annually with a significant difference. However, the molecular outcome revealed the dominance and diversity in CRKP with 24 sequence types (STs) and 59 PFGE types (PTs). The ST11 CRKP strains, which showed a significant increasing trend year by year, were documented as predominant in our study. Additionally, the predominant ST11 CRKP corresponding to PT10 and PT15 continued to exhibit their characteristic patterns. Importantly, the newly identified PT09 and PT16 strains, corresponding to the ST11 lineage, were only discovered in 2016. Meanwhile, factors affecting 30-day mortality and ST11 proportionality with CRKP infection were assessed, and ST11, appropriate empirical treatment, and hospital stays were found to be independently associated with 30-day mortality. The ST11 CRKP strains played a dominant role in the process; however, the homology of these strains was polymorphic, and the advantage clusters were subject to changes through evolution. Furthermore, in addition to appropriate empirical treatment and hospital stays, ST11 CRKP was independently associated with 30-day mortality. To the best of our knowledge, this association was reported for the first time.

Risk factors and clinical outcomes of carbapenem-resistant Klebsiella pneumoniae bacteraemia in children: a retrospective study

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is increasingly identified in children, but data on the clinical outcomes in this population are limited. The objectives of this study were to characterize the risk factors for 30-day mortality with CRKP bloodstream infection (BSI) in children. We performed a retrospective study from January 2018 to December 2021 at the First Affiliated Hospital of Zhengzhou University. Patients (<18 years old) with CRKP BSI were included. Multivariable Cox and logistic regression were performed to determine risk factors for death and the development of septic shock following CRKP infection, respectively. We identified 33 neonates aged 0-4 weeks and 37 older children. The 30-day mortality rate was 39.4% in neonates and 43.2% in older children. In the neonatal population, a higher Pitt bacteremia score (HR, 1.694; 95% CI, 1.313-2.186; P <0.001) was an independent risk factor for 30-day mortality. In the non-neonatal population, higher platelet count (HR, 0.990; 95% CI, 0.982-0.998; P = 0.010), the use of carbapenems (HR, 0.212; 95% CI, 0.064-0.702; P = 0.011), and appropriate targeted antimicrobial treatment (HR, 0.327; 95% CI, 0.111-0.969; P = 0.044) were associated with decreased 30-day mortality. Monocyte count less than 0.1 × 109 cells/L (OR, 3.615; 95% CI, 1.165-11.444; P = 0.026), and a higher Pitt bacteremia score (OR, 1.330; 95% CI, 1.048-1.688; P = 0.019) were identified as risk factors for the development of septic shock. CRKP BSI was associated with high mortality in children. Appropriate antimicrobial treatment is important to improve survival, but more work is needed to assess the efficacy of specific treatment regimens in children.

Genomic tracking and precise control of Klebsiella pneumoniae transmission in a newly established hospital: a prospective molecular epidemiological study

Carbapenem-resistant Klebsiella pneumoniae (CRKP) pose an emerging clinical threat. We investigated its introduction and transmission in a new hospital, evaluating the effect of whole-genome sequencing (WGS) as an infection control measure. Based on WGS of identified K. pneumoniae (Kpn) strains, a prospective molecular epidemiological study of nosocomial transmission of CRKP in a newly established Chinese hospital was conducted. Between September 2018 and August 2020, 206 Kpn strains were isolated, including 180 CRKP, from 152 patients. The first imported and nosocomial transmission cases were recorded in December 2018 and April 2019, respectively. Overall, 22 nosocomial transmission clusters involving 85 patients were identified, among which 5 were large-size clusters comprising 5-18 patients. Index cases of the large-size clusters were more likely associated with lower Glasgow Coma Scale scores than those of small-size clusters. Furthermore, results of multivariable logistic regression indicated that Kpn tended to transmit more among patients in the ICU [adjusted odds ratio (aOR)=4.96, 95% confidence interval (CI) 1.97-13.47] and those infected with a ST11 strain (aOR=8.04, 95% CI 2.51-29.53) or tetracycline-resistant strains (aOR=17.63, 95% CI 6.32-57.32). However, transmission was less likely in strains bearing the rmpA gene (aOR=0.12, 95% CI 0.03-0.37). The rate of nosocomial CRKP cases decreased by 2.25 with the intervention of WGS-based infection control. Kpn transmission in the newly established hospital originated from several imported cases. Rates of nosocomial CRKP infection were reduced considerably through precise infection control measures.

Pharmacokinetics of YK-1169 in healthy subjects and pharmacokinetic/pharmacodynamic analysis by Monte Carlo simulation.

This study (NCT05588531) aimed to evaluate the safety and pharmacokinetics of cefepime-avibactam (YK-1169) in healthy Chinese subjects and explore the optimal regimen for treating carbapenem-resistant Klebsiella pneumoniae (CRKP) based on the pharmacokinetic/pharmacodynamic evaluation. YK-1169 single-ascending doses (0.5, 1.25, 2.5 or 3.75 g, 2-h infusion) and multiple doses (2.5 or 3.75 g every 8 h [q8h], 2-h infusion) given for 7 days were evaluated in pharmacokinetic studies. Subjects were randomized to receive cefepime (2 g), avibactam (0.5 g) or YK-1169 (2.5 g) to assess drug-drug interactions. The minimum inhibitory concentrations (MICs) of YK-1169 were determined by the broth microdilution method. Monte Carlo simulation was used to evaluate 10 different dose regimens. Cefepime and avibactam both showed a linear pharmacokinetic profile. No accumulation was found after multiple doses. The cefepime Cmax,ss and AUC0-∞,ss were 9.20 and 16.0 μg/mL, 407.2 and 659.45 μg·h/mL in the 2.5 and 3.75 g multiple-dose groups, respectively. The avibactam Cmax,ss and AUC0-∞,ss were 0.545 and 0.837 μg/mL, 53.31 and 79.55 μg·h/mL in the 2.5 and 3.75 g multiple-dose groups, respectively. Cefepime and avibactam did not affect each other's pharmacokinetics. No serious adverse events occurred. All regimens achieved 90% probability of target attainment (PTA) goals when the MIC was ≤8 mg/L. The regimens of 2.5 (q8h, 2-h infusion), 3.75 (q8h, 2-, 3- and 4-h infusions) and 7.5 g (24-h continuous infusion) reached a 90% cumulative fraction of response. YK-1169 had good antibacterial activity against CRKP and could be an option for CRKP infections. The regimen of 2.5 g q8h intravenously guttae (ivgtt)2 h should be considered in future clinical trials.

The Efficacy and Influencing Factors of Polymyxin B in High-Level Carbapenem-Resistant Klebsiella pneumoniae Infections.

Polymyxin B (PMB) is a remedial treatment for carbapenem-resistant Klebsiella pneumoniae (CRKP) infection; however, there is a paucity of reports on the treatment of high-level CRKP infections with polymyxin B. Studies are needed to explore its treatment efficacy and associated influencing factors. Patients with high-level CRKP infections treated with PMB during hospitalization from June 2019 to June 2021 in a hospital were retrospectively studied, and risk factors affecting the efficacy were explored by subgroup analysis. A total of 92 patients were enrolled, and the results showed that the PMB-based regimen had a bacterial clearance rate of 45.7%, an all-cause discharge mortality rate of 22.8%, and an incidence of acute kidney injury (AKI) of 27.2% for high-level CRKP treatment. The combination of β-lactams other than carbapenems facilitated bacterial clearance, and the combination of electrolyte disturbances and higher APACHE II scores was detrimental to microbial clearance. Risk factors for all-cause discharge mortality were advanced age, concomitant antifungal drugs, concomitant tigecycline and incidence of AKI. PMB-based regimens are an effective option for the treatment of high-level CRKP infections. However, the optimal dose of treatment and the choice of combination regimens need to be explored in further studies.

Clinical and Epidemiological Characteristics of Carbapenem-Resistant Klebsiella pneumoniae Infections in a Tertiary Hospital in China.

Purpose: Infections caused by carbapenem-resistant Klebsiella pneumoniae (CR-KP) are an important public health problem. This study aimed to evaluate the clinical characteristics of patients with CR-KP. Methods: A retrospective cohort study was conducted of all patients with CR-KP infection. A total of 615 patients with CR-KP infection were identified and 135 patients who did not meet the eligibility criteria were excluded. Clinical characteristics, antimicrobial regimens, and patient outcomes were analyzed. Results: The overall mortality rate of CR-KP infections was 37.3% and the mortality rate in patients with bloodstream infections was 66.2%. Survival analysis revealed that there were statistically significant differences between patients with bloodstream infections and those with pulmonary and drainage fluid infections. Logistics regression analysis showed that hemopathy, age >60 years, solid tumors, diabetes, septic shock, acute kidney injury, and stroke were independent predictors of 30-day mortality rate. The chi-square test showed that treatment with a combination of carbapenems, tigecycline, and polymyxin B was superior to treatment with carbapenems with polymyxin B, without tigecycline. Conclusions: CR-KP infections, especially bloodstream infections, have a high mortality rate. The outcome is strongly dependent on patients' clinical conditions. Antimicrobial regimens combining carbapenems, tigecycline, and polymyxin B might be a better choice.

Epidemiological and Antimicrobial Resistant Patterns, and Molecular Mechanisms of Carbapenem-Resistant Klebsiella pneumoniae Infections in ICU Patients.

To study the epidemiological and antimicrobial resistant patterns, clinical characteristics and risk factors of critically ill patients infected with carbapenem-resistant Klebsiella pneumoniae (CRKP) from intensive care units (ICUs). The potential molecular mechanisms of antimicrobial resistance and virulence of CRKP were investigated through evaluation of associated genes. Totally, 201 ICU patients infected with K. pneumoniae were recruited from January 2020 through January 2021. K. pneumoniae strains were collected from diverse clinical specimens and identified by microbial cultures and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. Antimicrobial resistance was measured through broth micro-dilution or Kirby-Bauer assays. The carbapenemase-, virulence-, and capsular serotype-associated genes of CRKP were individually detected by PCR and sequencing. Demographic and clinical profiles were acquired from hospital databases to evaluate the correlation of CRKP infection incidence with clinical risk factors. Of the 201 K. pneumoniae strains, CRKP accounted for 41.29%. Seasonal bias existed in local prevalence of CRKP infections. CRKP strains mounted significantly strong resistance against major antimicrobial agents except ceftazidime-avibactam, tigecycline and minocycline. Recent exposure to certain antibiotics and prior treatment with invasive interventions were prone to increase CRKP infection risks with worsened infectious outcomes. The local top carbapenemase-encoding and virulence-associated genes of CRKP were blaKPC and irp2, respectively. Nearly half of CRKP isolates harbored a capsular polysaccharide serotype of K14.K64 (wzi-64) which preferentially emerged in the cohort with worse outcomes of infection. Featured epidemiology and typical clinical characteristics existed extensively in K. pneumoniae infections among ICU patients. The CRKP cohort exhibited substantially high antimicrobial resistance. Distinctive carbapenemase-, virulence-, and serotype-associated genes were intensively involved in the spread and pathogenesis of CRKP. These findings supported careful management of critically ill patients potentially infected with virulent CRKP in the ICUs.

Clinical and Genomic Evolution of Carbapenem-Resistant Klebsiellapneumoniae Bloodstream Infections over Two Time Periods at a Tertiary Care Hospital in South India: A Prospective Cohort Study.

The objective of this study was to examine the evolution of carbapenem-resistant Klebsiellapneumoniae (CRKp) infections and their impact at a tertiary care hospital in South India. A comparative analysis of clinical data from two prospective cohorts of patients with CRKp bacteremia (C1, 2014-2015; C2, 2021-2022) was carried out. Antimicrobial susceptibilities and whole genome sequencing (WGS) data of selected isolates were also analyzed. A total of 181 patients were enrolled in the study, 56 from C1 and 125 from C2. CRKp bacteremia shifted from critically ill patientswith neutropenia toothers (ICU stay: C1, 73%; C2, 54%; p = 0.02). The overall mortality rate was 50% and the introduction of ceftazidime-avibactam did not change mortality significantly (54% versus 48%; p = 0.49). Oxacillinases (OXA) 232 and 181 were the most common mechanisms of resistance. WGS showed the introduction of New Delhi metallo-β-lactamase-5 (NDM-5), higher genetic diversity, accessory genome content, and plasmid burden, as well as increased convergence of hypervirulence and carbapenem resistance in C2. CRKp continues to pose a significant clinical threat, despite the introduction of new antibiotics. The study highlights the evolution of resistance and virulence in this pathogen and the impact on patient outcomes in South India, providing valuable information for clinicians and researchers.

Direct prediction of carbapenem-resistant, carbapenemase-producing, and colistin-resistant Klebsiella pneumoniae isolates from routine MALDI-TOF mass spectra using machine learning and outcome evaluation

The objective of this study was to develop a rapid prediction method for carbapenem-resistant Klebsiella pneumoniae (CRKP) and colistin-resistant K. pneumoniae (ColRKP) based on routine MALDI-TOF mass spectrometry (MS) results in order to formulate a suitable and rapid treatment strategy. A total of 830 CRKP and 1462 carbapenem-susceptible K. pneumoniae (CSKP) isolates were collected; 54 ColRKP isolates and 1592 colistin-intermediate K. pneumoniae (ColIKP) isolates were also included. Routine MALDI-TOF MS, antimicrobial susceptibility testing, NG-Test CARBA 5, and resistance gene detection were followed by machine learning (ML). Using the ML model, the accuracy and area under the curve for differentiating CRKP and CSKP were 0.8869 and 0.9551, respectively, and those for ColRKP and ColIKP were 0.8361 and 0.8447, respectively. The most important MS features of CRKP and ColRKP were m/z 4520-4529 and m/z 4170-4179, respectively. Of the CRKP isolates, MS m/z 4520-4529 was a potential biomarker for distinguishing KPC from OXA, NDM, IMP, and VIM. Of the 34 patients who received preliminary CRKP ML prediction results (by texting), 24 (70.6%) were confirmed to have CRKP infection. The mortality rate was lower in patients who received antibiotic regimen adjustment based on the preliminary ML prediction (4/14, 28.6%). In conclusion, the proposed model can provide rapid results for differentiating CRKP and CSKP, as well as ColRKP and ColIKP. The combination of ML-based CRKP with preliminary reporting of results can help physicians alter the regimen approximately 24 h earlier, resulting in improved survival of patients with timely antibiotic intervention.

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.

Association between Intestinal Colonization and Extraintestinal Infection with Carbapenem-Resistant Klebsiella pneumoniae in Children.

Carbapenem-resistant Klebsiella pneumoniae (CRKP) has become a critical public health threat. However, the association between intestinal colonization and parenteral infection among pediatric patients has not been elucidated. We collected 8 fecal CRKP strains and 10 corresponding CRKP strains responsible for extraintestinal infection from eight patients who did not manifest infection upon admission to the hospital. Paired isolates showed identical resistance to antimicrobials and identical virulence in vitro and in vivo. wzi capsule typing, multilocus sequence typing, and whole-genome sequencing (WGS) indicated high similarity between paired colonizing and infecting isolates. Mutations between colonizing and infecting isolate pairs found by WGS had a distinctive molecular signature of a high proportion of complex structural variants. The mutated genes were involved in pathways associated with infection-related physiological and pathogenic functions, including antibiotic resistance, virulence, and response to the extracellular environment. The latter is important for bacterial infection of environmental niches. Various mutations related to antibiotic resistance, virulence, and colonization that were not associated with any particular mutational hot spot correlated with an increased risk of extraintestinal infection. Notably, novel subclone carbapenem-resistant hypervirulent K. pneumoniae (CR-hvKP) KL19-ST15 exhibited hypervirulence in experimental assays that reflected the severe clinical symptoms of two patients infected with the clonal strains. Taken together, our findings indicate the association between CRKP intestinal colonization and extraintestinal infection, suggesting that active screening for colonization on admission could decrease infection risk in children. IMPORTANCE Carbapenem-resistant Klebsiella pneumoniae (CRKP) causes an increasing number of nosocomial infections, which can be life-threatening, as carbapenems are last-resort antibiotics. K. pneumoniae is part of the healthy human microbiome, and this provides a potential advantage for infection. This study demonstrated that CRKP intestinal colonization is strongly linked to extraintestinal infection, based on the evidence given by whole-genome sequencing data and phenotypic assays of antimicrobial resistance and virulence. Apart from these findings, our in-depth analysis of point mutations and chromosome structural variants in patient-specific infecting isolates compared with colonizing isolates may contribute insights into bacterial adaptation underlying CRKP infection. In addition, a novel subclone of carbapenem-resistant hypervirulent K. pneumoniae (CR-hvKP) was observed in the study. This finding highlights the importance of CRKP active surveillance among children, targeting in particular the novel high-risk CR-hvKP clone.

Clinical Management of a Pandrug-Resistant OXA-48 Klebsiella pneumoniae Infection in the Pediatric Intensive Care Unit.

Background: Carbapenem-resistant Klebsiella pneumoniae (CRKP) is one of the serious forms of health care-associated infection. Pan-drug resistant (PDR) CRKP infections can cause severe infections. Mortality and treatment costs in the pediatric intensive care unit (PICU) are high. This study aims to share our experience regarding the treatment of oxacillinase (OXA)-48-positive PDR-CRKP infection in our 20-bed tertiary PICU with isolated rooms and 1 nurse for every 2-3 patients. Methods: Patient demographic characteristics, underlying diseases, previous infections, source of infection PDR-CRKP, treatment modalities, measures used, and outcomes were recorded. Findings: Eleven patients (eight men and three women) were found to have PDR OXA-48-positive CRKP. Because of the simultaneous detection of PDR-CRKP in three patients and the rapid spread of the disease, it was classified as a clinical outbreak, and strict infection control measures were taken. Combination therapy with double carbapenemase (meropenem and imipenem), amikacin, colistin, and tigecycline was used for treatment. The mean duration of treatment and isolation was 15.7 and 65.4 days, respectively. No treatment-related complication was observed, only one patient died, and the mortality rate was 9%. Conclusions: This severe clinical outbreak can be successfully treated with effective treatment with combined antibiotics and strict adherence to infection control measures. ClinicalTrial.gov ID: 28/01/2022 - 1/5.

Relationship between antibiotic exposure and carbapenem-resistant Klebsiella pneumoniae infection within four types of control patients: A systematic review and meta-analysis

This study attempted to identify the relationship between antibiotic exposure and carbapenem-resistant Klebsiella pneumoniae (CRKP) infection. Antibiotic exposure were chosen as the risk factors for CRKP infection, which were extracted from research articles indexed in PubMed, EMBASE and Cochrane Library. Relevant studies published until January 2023 were reviewed, and a meta-analysis was conducted on antibiotic exposure within the four types of control groups, which comprised of 52 studies. The meta-analysis was performed within four types of control groups: patients infected with carbapenem-susceptible Klebsiella pneumoniae (comparison 1), other infection especially without CRKP infection (comparison 2), CRKP colonization (comparison 3) and no infection (comparison 4). The two risk factors were common to the four comparisons according to Carbapenem and Aminoglycoside exposure. Compared to Carbapenem-susceptible Klebsiella pneumoniae (CSKP) infection, Tegacyclin exposure in bloodstream infection and Quinolone exposure within 30 days were associated with increased risk for CRKP infection. However, Tegacyclin exposure in MIX infection (MIX infection included two or more different infection sites) and Quinolone exposure within 90 days possessed a similar risk for both CRKP and CSKP infection. Carbapenem and Aminoglycoside exposure serve as likely risk factors for CRKP infection. Meanwhile, antibiotic exposure time as continuous variables was not relatedtoCRKP infection compared to CSKP infection. Tigecycline exposure in MIX infection and Quinolone exposure within 90 days may not increase the risk of CRKP infection.

Clinical distribution and drug resistance characteristics of carbapenem-resistant Klebsiella pneumoniae

To explore the clinical distribution and drug resistance characteristics of carbapenem-resistant Klebsiella pneumoniae (CRKP), in order to provide reference for the prevention and treatment of CRKP infection. Retrospective analysis was performed on 510 clinical isolates of CRKP from January 2017 to December 2021, and strain identification and drug sensitivity tests were conducted by MALDI-TOF mass spectrometer and VITEK-2 Compact microbial drug sensitivity analyzer. The carbapenemase phenotype of CRKP strain was detected by carbapenemase inhibitor enhancement test. The CRKP strain was further categorized by immunochromogenic method and polymerase chain reaction (PCR) was used for gene detection. The results showed that 302 strains (59.2%) were derived from sputum, 127 strains (24.9%) from urine and 47 strains (9.2%) from blood. 231 (45.3%) were mainly distributed in intensive care, followed by 108 (21.2%) in respiratory medicine and 79 (15.5%) in neurosurgery. Drug susceptibility test result shows that the resistant rate of tigecycline increased from 1.0% in 2017 to 10.1% in 2021, the difference was statistically significant (χ2=14.444,P<0.05). The results of carbapenemase inhibitor enhancement test showed that 461 carbapenemase strains (90.4%) of 510 CRKP strains, including 450 serinase strains (88.2%), 9 metalloenzyme strains (1.8%), and 2 strains (0.4%) produced both serine and metalloenzyme. 49 strains (9.6%) did not produce enzymes. Further typing by immunochromogenic assay showed that 461 CRKP strains were KPC 450 (97.6%) and IMP 2 (0.4%). 7 NDM (1.5%); 2 strains of KPC+NDM (0.4%); PCR results were as follows: 450 strains of blaKPC (97.6%), 2 strains of blaIMP (0.4%), 7 strains of blaNDM (1.5%), and 2 strains of blaKPC+NDM (0.4%). In conclusion, CRKP strains mainly originated from sputum specimens and distributed in intensive care department, and the drug resistance characteristics were mainly KPC type in carbapenemase production. Clinical microbiology laboratory should strengthen the monitoring of CRKP strains, so as to provide reference for preventing CRKP infection and reducing the production of bacterial drug resistance.

Analysis of risk factors associated with healthcare-associated carbapenem-resistant Klebsiella pneumoniae infection in a large general hospital: a case-case-control study.

Carbapenem-resistant Klebsiella pneumoniae (CRKP) infection is a major public health threat in the world. To inform the prevention and control of CRKP infection in hospitals, this study analyzed the factors associated with CRKP infection and resistance to carbapenems in K. pneumoniae. This case-case-control study was carried out in a large general hospital in China from January 2016 to December 2018, comprising 494 hospitalized patients infected with CRKP (case group 1) and 2429 hospitalized patients infected with carbapenem-susceptible K. pneumoniae (CSKP, case group 2). We selected control groups from hospitalized patients without K. pneumoniae infections for the two case groups separately, with a 1:3 case-control ratio, to analyze the risk factors of the two case groups using the conditional logistic regression. Multivariate analysis showed that the risk factors of CRKP infection were intensive care unit (ICU) admission (odds ratio [OR], 6.85; 95% confidence interval [CI], 4.90-9.58; P < 0.001), respiratory failure (OR, 1.93; 95% CI, 1.34-2.77; P < 0.001), age-adjusted Charlson comorbidity index (aCCI; OR, 1.08; 95% CI, 1.02-1.15; P = 0.007), admission from the Emergency (OR, 1.37; 95% CI, 1.02-1.85; P = 0.036), and imipenem use (OR, 1.80; 95% CI, 1.30-2.49; P < 0.001). Among the aforementioned five risk factors, aCCI (OR, 1.09; 95% CI, 1.06-1.13; P < 0.001) was also identified as a risk factor of CSKP infections in multivariate analysis. The risk factors for resistance to carbapenems in K. pneumoniae were ICU admission, respiratory failure, admission from the Emergency, and imipenem use.

Genomic Analysis Revealed the International and Domestic Transmission of Carbapenem-Resistant Klebsiella pneumoniae in Chinese Pediatric Patients.

Carbapenem-resistant Klebsiella pneumoniae (CRKP) poses a severe threat to public health worldwide. Based on the genomic analysis of 198 CRKP isolates collected at Shanghai Children's Medical Center over the last 8 years (2013 to 2021), we reported the clinical risk, genetic diversity, and prevalence of antimicrobial resistance (AMR) of CRKP in pediatric patients at the genomic level. We found that the blaNDM genes were the predominant carbapenemase genes, followed by blaKPC-2 and blaIMP. All of the carbapenemases were disseminated mainly by four main types of plasmids, among which one plasmid was associated with a higher risk of bloodstream infections. Notably, we tracked disease outbreaks caused by recent introductions of ST14 CRKP from southeast Asia or western countries, and we reported frequent, repetitive introductions of ST11 from other domestic hospitals that were associated interhospital movement of the patients. The cocirculation of K. pneumoniae and AMR plasmids in hospitals highlights the importance of genome sequencing for monitoring and controlling CRKP infections. IMPORTANCE Carbapenem-resistant Klebsiella pneumoniae (CRKP) infection in pediatric patients differs from that in adults patients in terms of both genetic and phenotypic features, which remain to be elucidated. We present a summary of prevalent CRKP isolates from Chinese pediatric patients over 8 years, demonstrating the prevalence and clinical importance of New Delhi metallo-β-lactamase genes in pediatric patients, mainly describing the genomic features of two predominant CRKP clones (ST11 and ST14) in Chinese children, and identifying four carbapenemase-encoding plasmids that contribute to the transmission of most carbapenemase genes in hospitals. Overall, our research provides valuable information about the international and domestic transmission of CRKP isolates that are prevalent in Chinese children and shows the urgent need for genome sequencing-based surveillance systems for monitoring the transmission of CRKP.

Genomic characterization of colistin resistance in Klebsiella spp. under the pressure of colistin.

Introduction. Carbapenem-resistant Klebsiella pneumoniae (CRKP) has become a serious threat to global public health. Colistin is regarded as the last-resort antibiotic for CRKP infections, but colistin resistance among CRKP is increasingly being reported, making clinical treatment for CRKP infections more difficult.Hypothesis/Gap Statement. The molecular mechanisms of colistin resistance in Klebsiella spp. under the pressure of colistin have not been fully investigated.Aim. We aimed to investigate the phenotypic and genetic variation in two colistin-susceptible Klebsiella spp. strains under selective pressure of colistin.Methodology. One hundred microlitres of overnight cultures of the CRKP clinical strain CRKP12-130 and of ATCC 700603 was spread on five Mueller-Hinton Agar (MHA) plates with colistin concentrations of 2, 4, 8, 16 and 32 µg ml-1, and growth of colonies was observed for five consecutive days. Colonies collected from plates were passaged daily for 10 days on MHA plates without colistin and susceptibility testing of colistin was performed by broth microdilution. Thirty-four colistin-resistant strains randomly selected were submitted to whole genome sequencing (WGS). Transcriptional levels of genes involved in colistin resistance (mgrB, phoP, phoQ, pmrA, pmrB, pmrD, pmrE and pmrK) were measured by quantitative real-time PCR.Results. A total of 114 and 119 colistin-resistant colonies were obtained from CRKP12-130 and ATCC 700603 in this study, among which 16 and 18 colonies were submitted to WGS, respectively. Among these 34 sequenced isolates, mutation in phoQ (13/16, 81.25 %) was the main genetic factor mediating colistin resistance in strains from CRKP12-130, while for strains from ATCC 700603, mutation associated with mgrB (8/18, 44.44 %) was found to be the commonest. Mutation of mgrB led to a significant increase in the MIC for colistin (from 64 to >128 µg ml-1), and a novel mutation C28R in mgrB was first reported in this study.Conclusion. Colistin-resistant Klebsiella spp. could be easily selected under pressure of different concentrations of colistin. Mutations of mgrB, phoP, phoQ and pmrB genes were the main mechanisms leading to chromosomally mediated colistin resistance in Klebsiella spp.

Molecular and Clinical Characteristics of Carbapenem-Resistant Klebsiella pneumoniae Isolates at a Tertiary Hospital in Wuhan, China.

Carbapenem resistant Klebsiella pneumoniae (CRKP) is an independent risk factor for nosocomial infection which poses a serious threat to human health. How to prevent and suppress CRKP infection and explore its drug resistance mechanisms have become a huge challenge and possesses immediate significance. A total of 45 CRKP strains isolated from hospitalized patients in Zhongnan Hospital of Wuhan University were collected from August 2018-December 2020. The strain's identification and antimicrobial susceptibility tests were performed using the VITEK 2 automated identification instrument. Single molecule DNA sequencing of 45 CRKP isolates was performed by the third generation high-throughput sequencing technology. The results were analyzed by multi locus sequence typing (MLST) and phylogenetic analysis. Antimicrobial susceptibility showed that 45 CRKP isolates were multi-drug resistant strains, and the resistance rates to common antibiotics were as high as 68%. Whole genome sequencing results showed that the CRKP strains carried multiple drug resistance genes and virulence factors. MLST analysis found two different sequence types (ST), of which 44 were ST11 and 1 was ST1049. Through whole genome sequencing (WGS), we found multiple drug-resistant genes and virulence factors, and there was obvious dominant microbiota. The source was mainly related to nosocomial infection. The ST11-KPC Klebsiella pneumoniae was the main type, which was consistent with the most common type in China. We identified several dominant microbiotas which may serve as a target in the clinical prevention and treatment of severe bacterial infections. Our finding may have a role for guiding clinical antibiotic choosing.

421. In vitro and in vivo synergistic antimicrobial activities of the combinations of meropenem, colistin, tigecycline, and ceftolozane/tazobactam against carbapenem-resistant Klebsiella pneumoniae

Abstract Background The aim of this study was to evaluate the in vitro and in vivo activities of various antimicrobial combinations against carbapenem-resistant Klebsiella pneumoniae (CRKP). Methods The in vitro activity of six two-drug combinations against CRKP isolates collected from the rectal swab samples of patients with intestinal CRKP colonization was evaluated using the checkerboard method and time-kill assay to identify potential synergistic and bactericidal two-drug combinations against CRKP isolates. The in vivo efficacy of the combinations of colistin, meropenem and ceftolozane/tazobactam (C/T) as therapeutic options, was assessed in a mouse model of intraperitoneal CRKP sepsis. Antimicrobial susceptibility and genotypes of carbapenem-resistance were also analyzed. Results A total of 5 clinical isolates of CRKP were collected from nonduplicate patients with CRKP infection. Of 5 CRKP isolates, 4 carried the blaKPC-2-type carbapenem-hydrolyzing enzymes except 1 blaNDM-1-type. Antimicrobial susceptibility rates were tigecycline 80%, colistin 40%, and C/T 0%, respectively. The checkerboard assay showed that in vitro synergistic activity against CRKP isolates was 90% for the meropenem-tigecycline combinations and 20% for colistin-C/T combinations. None of the various combinations of the six antibiotics showed a synergistic effect in the time-kill assay. However, the meropenem-colistin (100%) and colistin-C/T (100%) combinations showed bactericidal effects in the time-kill assay (using an antibiotic concentration of 1× MIC) (Table). The survival rates of the mice was 80% (4/5) at 48 h in the treated group using low dose combinations of colistin (10 mg/kg) and C/T (25 mg/kg), unlike both antibiotics, which were 60% in a monotherapy with the same dose (Figure). Comparison of checkerboard assay and time-kill assay Comparison of checkerboard assay and time-kill assay associated with the bactericidal activity of two-drug combinations (1 × MIC) against each carbapenem-resistant Klebsiella pneumoniae isolate In vivo survival tests for antimicrobial combinations Comparison of the survival rates of the mice in the treated group using antimicrobial combinations Conclusion In conclusion, the present in vivo study demonstrated that the low-dose combination of colistin and C/T may be a promising alternative to nephrotoxic high-dose colistin alone for treating CRKP infections. However, it was difficult to predict this possibility in in vitro tests, and even there is great discordance of antimicrobial synergistic activities between the checkerboard microdilution and time-kill assays. Disclosures All Authors: No reported disclosures.

Clinical Outcomes and Risk Factors for Death following Carbapenem-Resistant Klebsiella pneumoniae Infection in Solid Organ Transplant Recipients.

Infections caused by carbapenem-resistant Klebsiella pneumoniae (CRKP) are associated with significant morbidity and mortality. Among solid organ transplant recipients (SOTRs), clinical outcomes and risk factors for death following such infections remain not well documented. A single-center retrospective study was performed. All SOTRs with a CRKP infection at the First Affiliated Hospital of Zhengzhou University between 1 January 2018 and 31 December 2021 were included. Multivariable Cox regression was performed to determine risk factors for death following CRKP infection. We identified 94 SOTRs with CRKP infection, with a median age of 50 years old. CRKP infections resulted in 38.3% of overall 30-day mortality. On multivariable analysis, independent risk factors for death following CRKP infection included older age (hazard ratio [HR], 1.044; 95% confidence interval [CI], 1.007 to 1.083; P = 0.02), allograft failure (HR, 3.962; 95% CI, 1.628 to 9.644; P = 0.002), and septic shock (HR, 8.512; 95% CI, 3.294 to 21.998; P < 0.001). Receiving appropriate targeted therapy was associated with a reduced hazard of death (HR, 0.245; 95% CI, 0.111 to 0.543; P = 0.001). Our study characterized the clinical features and mortality in SOTRs with CRKP infection. The protective effects of appropriate targeted therapy highlight the importance of assessing how antibiotic choices affect the clinical outcomes among SOTRs. IMPORTANCE Carbapenem-resistant Klebsiella pneumoniae (CRKP) infections are increasingly identified in solid organ transplant recipients (SOTRs), but data on the clinical outcomes and risk factors for death following such infections remain limited. Here, we reported CRKP infection was associated with 38.3% of overall 30-day mortality in SOTRs. Independent risk factors for death after CRKP infection included older age, allograft failure, and septic shock. Appropriate targeted therapy was important for alleviating the impact of CRKP infections on these SOTRs.