Small wards in the ICU: a favorable measure for controlling the transmission of carbapenem-resistant Klebsiella pneumoniae

Targeted next-generation sequencing enhances precision and rapid detection in healthcare-associated infection Surveillance: Unveiling multidrug-resistant colonization in ICUs

Objectives

This study aims to evaluate the potential advantages of targeted next-generation sequencing (tNGS) over conventional bacterial culture methods for pathogen detection in hospital-associated infections (HAIs).

Methods

All EICU medical staff and all medical staff from the Physical Examination Centre completed a questionnaire. Nasopharyngeal specimens were collected from medical staff who met all of the inclusion criteria and none of the exclusion criteria. EICU medical staff provided 2 samples each, while Physical Examination Centre staff provided 1 sample each. For EICU medical staff, one of their two nasopharyngeal swabs was subjected to tNGS testing, and the other to bacterial culture testing. For the PEC staff, their nasopharyngeal swabs were subjected to tNGS testing. Additionally, six pairs of spectacles and six keyboards used by EICU medical staff were randomly selected, and the surfaces were swabbed with sterile swabs for tNGS testing.

Results

In 23 nasal swab samples from EICU group, tNGS detected 14 species of microorganism in 29 instances within 19 h. Bacterial culture detected 2 species of microorganism in 4 instances, 2 positive samples within 19 h and confirmed another 2 positive samples within 69 h. A total of 42 samples with 14 different microorganism species were collected from the nasopharyngeal swabs of 23 EICU members and 15 PEC members. Among them, 29 cases (69 %) of 14 different microorganisms were detected in EICU staff, with an average of 1.3 microorganism species detected per person, while 13 cases (28 %) of 6 different microorganisms were detected in PEC staff, with an average of 0.9 microorganism species detected per person. The most common colonizing bacteria included Staphylococcus aureus, Acinetobacter baumannii, and Klebsiella spp. Compared to bacterial culture, tNGS offers advantages in monitoring HAIs, including a broad range of detectable microorganisms, high sensitivity of results, and shorter reporting time for positive results. Bacteria colonizing the EICU carry more antibiotic resistance genes.

Conclusions

tNGS outperforms conventional culture in healthcare-associated infection surveillance, with higher sensitivity and accelerated pathogen identification. Simultaneously, tNGS revealed extensive colonization of multidrug-resistant (MDR) pathogens (e.g., Acinetobacter baumannii, MRSA) in EICU environments, highlighting its utility in monitoring complex antimicrobial resistance patterns.

Diverse modes of ceftazidime/avibactam resistance acquisition in carbapenem-resistant Klebsiella pneumoniae and Pseudomonas aeruginosa from a Chinese intensive care unit

OBJECTIVES

To investigate the mechanisms of ceftazidime/avibactam (CZA) resistance and the nosocomial dissemination of carbapenem-resistant Pseudomonas aeruginosa (CRPA) and carbapenem-resistant Klebsiella pneumoniae (CRKP) in an intensive care unit (ICU) in China.

METHODS

Clinical CRPA and CRKP isolates were obtained from an ICU of a tertiary hospital in China from August 2020 to February 2021. Antimicrobial susceptibility was determined according to CLSI. WGS, cloning experiments and kinetic parameters were conducted to reveal resistance mechanisms, molecular characteristics and dissemination of CRPA and CRKP.

RESULTS

We isolated 32 CZA-resistant strains, including 12 CRPA and 20 CRKP strains from an ICU between August 2020 and February 2021. CZA resistance was associated with the presence of NDM and efflux pumps in CRKP strains, whereas blaAFM-2, blaKPC-87, and blaPER-1 contributed to CZA resistance in CRPA strains. Compared to KPC-2, KPC-87 exhibited a 1.5-fold elevation in kcat/Km for ceftazidime, a 7.5-fold increase in Ki for avibactam, and a loss of carbapenem hydrolysis. blaKPC-87 was located in the NTEKPC-IIa like element based on the Tn3. Insertion of 656 bp ΔblaTEM-1 upstream of blaKPC-87 introduced an additional promoter that increased KPC-87 expression. Cluster 2 and 3 of CRKP represented two different clones of ST11 transmitted between patients. KPC-87-producing ST270 CRPA strains exhibited a small-scale dissemination and cross-regional transfer with the referral of a patient. The evolutionary pathways of AFM-2-producing ST275 CRPA strains were more complex to elucidate the transmission events.

CONCLUSIONS

In CRKP and CRPA, diverse resistance mechanisms contributed to CZA resistance. These CZA-resistant strains were transmitted among patients in the ICU and even across regions to the other healthcare unit when the patient was transferred.

Clinical and Microbiological Characteristics of Carbapenem-Resistant Klebsiella pneumoniae Associated Recurrent Urinary Tract Infections

Background

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is a major pathogen responsible for urinary tract infections (UTIs). However, its role and characteristics in recurrent urinary tract infections (rUTIs) remain poorly understood. Investigating its features in rUTIs may provide insights into effective prevention strategies.

Methods

We analyzed a cohort of patients with rUTIs caused by Klebsiella pneumoniae from April 2020 to April 2024. Antibiotic susceptibility of the isolates was evaluated. Biofilm Formation Assay and Galleria mellonella infection models were employed to assess the virulence of the strains. Polymerase Chain Reaction (PCR) and whole-genome sequencing (WGS) were utilized to determine multilocus sequence typing (MLST) and capsular serotyping, as well as to identify resistance genes, virulence genes, and plasmid replicons. Phylogenetic relationships among the isolates were also established.

Results

A total of 41 patients with rUTIs were included, with 56.1% caused by CRKP. 97.01% of CRKP carry the blaKPC-2 gene. Compared to patients infected with carbapenem-susceptible Klebsiella pneumoniae (CSKP), those infected with CRKP had a higher prevalence of underlying diseases and complications. Both groups of strains exhibited a high degree of antibiotic resistance. CRKP strains demonstrated enhanced biofilm formation capacity and greater lethality in Galleria mellonella infection models. The predominant phenotype of the CRKP strain was ST11 KL64, whereas the CSKP strain showed multiple phenotypes in different patients. Sequencing analyses revealed that both groups of strains carried a wide range of virulence genes, resistance genes, and plasmid replicons. Among the cases of rUTIs, 31 were identified as relapses caused by the same strain, with no significant differences between the initial and final infection strains.

Conclusion

This study demonstrates that patients with rUTIs caused by CRKP present significant complexity in terms of clinical features, strain resistance and virulence properties. When managing UTIs caused by CRKP, special care needs to be taken to manage recurrent infections.

Impact of healthcare-associated infection on healthcare services and survival of patients with cancer: a propensity score-matched retrospective study

BACKGROUND

Healthcare-associated infections (HAI) lead to poor patient outcomes, including morbidity, mortality, length of hospital stay (LOS) and costs. However, limited data exists on the impact of HAI on LOS, cost at different quantiles and the survival of patients with cancer.

OBJECTIVE

To assess the impact of HAIs on LOS, costs, and survival of cancer patients.

METHODS

This retrospective cohort study used data from January 2017 to December 2018 from a tertiary cancer hospital in Henan. Patient demographic data were sourced from the hospital's electronic medical records. Inclusion criteria were primary cancer diagnoses (ICD codes C00-C97). We balanced the distribution of baseline characteristics between patients with HAI and without using propensity score matching. Quantile regression can estimate how independent variables affect dependent variables at different quantiles. We conducted a quantile regression that assessing the impact of HAI on LOS and costs for patients with cancer and using Kaplan-Meier survival curves to compare the survival.

RESULTS

Our study included 291,535 patients with cancer, among of whom 4,784(1.6%) were diagnosed with HAI and 286,748 were not. Patients with HAI exhibited significantly longer hospital stays, with a mean duration of 26.1 days (range: 17.0 to 40.6 days), compared to their counterparts without HAIs, who had an average stay of 7.2 days (range: 4.0 to 14.0 days) (p < 0.01). Economically, the average hospitalization cost for patients without HAI was $1575.8 (range: 865.6 to 3106.3), substantially lower than the $8710.8 (range: $4073.8 to 13434.0) observed for patients with HAI (p < 0.01). After adjusting for confounders in quantile regression models, HAI was associated with a median increase in LOS of 11.4 (95% confidence interval (CI): 10.9-12.0) days and with excess costs of USD 3449.3 (95% CI: 3281.9-3616.7). The hazard ratio (HR) of death for patients with an HAI was significantly higher than for patients without an HAI (HR: 1.62, 95% CI: 1.50-1.74).

CONCLUSION

HAI prolongs the LOS, increases hospital costs, and worsens the survival of patients with cancer compared with other diseases. Our quantile regression results indicate that the impact of HAI on hospitalization costs and LOS is more pronounced among patients with higher baseline costs and longer LOS (e.g., at the 95th percentile). This suggests that patients with more severe conditions or advanced disease stages are more vulnerable to the adverse effects of HAI.

RELEVANCE TO CLINICAL PRACTICE

Targeted surveillance and preventive interventions, such as early infection screening and strict adherence to infection control protocols, should focus on high-risk patients with prolonged LOS and high costs. By preventing infections in these patients, we can more effectively reduce the additional burden of HAI on costs and LOS. This study informs clinical practice and decision-making for nurses and nursing educators who manage HAI.

PATIENT OR PUBLIC CONTRIBUTION

Patients and healthcare professionals helped in data collection at the Hospital.

A Comprehensive Overview of Klebsiella Pneumoniae: Resistance Dynamics, Clinical Manifestations, and Therapeutic Options

Klebsiella pneumoniae (Kp) is a notable pathogen responsible for various infections. The emergence of hypervirulent and carbapenem-resistant strains has raised global concern. Many novel approaches were developed to combat the current severe situation of antibiotic resistance, and clinical guidelines have also provided corresponding recommendations. This review highlights the critical aspects of Kp, including classification, virulence factors, systemic dissemination, drug resistance progression and the new therapeutic strategies to combat this evolving threat.

Epidemiology and outcomes of carbapenem-resistant Klebsiella pneumoniae infections in patients with hematological malignancies from 2014 to 2022

Background

We aimed to describe the epidemiology, cross-transmission, interventions, and outcomes of carbapenem-resistant Klebsiella pneumoniae (CRKP) infections in the hematological malignancies (HM) department of a hospital in China.

Methods

This prospective study was divided into three stages from 2014 to 2022: Period 1 (from 1 January 2014 to 4 March 2021), Period 2 (from 5 March 2021 to 31 December 2021), and Period 3 (from 1 January 2022 to 31 December 2022), with different measures implemented at each stage to evaluate the rate of new infections. The risk factors, epidemiological characteristics, data from all patients with CRKP, NGS gene sequencing molecular epidemiology analysis, and cross-transmission were described.

Results

A total of 217 patients with K. pneumoniae isolates, including 38 (17.5%) patients with CRKP isolates, were confirmed in the HM department. The total rate of CRKP in KP isolates was 17.5%. The predominant clone in the HM department was ST11 CRKP producing the KPC-2 enzyme (21, 70.0%). A total of 23 cases of HM department-acquired CRKP infections were identified, and five hospital cross-transmission events were observed. Four instances of CRKP dissemination were primarily related to clone ST11. Only one outbreak occurred at the end of Period 1, involving four cases of CRKP healthcare-associated infections (HAIs). After the implementation of outbreak intervention bundles at the end of Period 2, no cross-transmission occurred. The rate of CRKP in KP isolates decreased to 12.9% (only four CRKP isolates) in Period 3, down from a peak of 46.7% in Period 2 (including 14 CRKP isolates). Only one new carrier (0.9%) was identified during the two cross-sectional active screenings of the rectal swab. The 28-day mortality rate was 38.7% (12/31) in CRKP-infected patients.

Conclusion

The prevalence of CRKP in the HM department was relatively low in the studied hospital. We found that interventions, including single-room isolation, enhanced disinfection, and skin decolonization, played a pivotal role in controlling the spread of HM-acquired CRKP infections.

External validation of the ICU-CARB score to predict carbapenem-resistant gram-negative bacteria carriage in critically ill patients upon ICU admission: a multicenter analysis

BACKGROUND

Recognition of carbapenem-resistant gram-negative bacteria (CR-GNB) carriage is frequently delayed, which increases the risk of subsequent infection and transmission. Previously, we developed a scoring system to identify CR-GNB carriage upon intensive care unit (ICU) admission. Although the ICU-CARB score showed satisfactory performance, it has not been externally validated. In this study, therefore, we externally validated the ICU-CARB score.

METHODS

In the previous article, we introduced a risk-scoring system that incorporated seven key variables: neurological disease, high-risk department history, length of stay ≥ 14 days, ICU history, invasive mechanical ventilation, gastrointestinal tube placement, and carbapenem usage. To externally validate the ICU-CARB score, we conducted a study involving patients admitted to the ICUs of four tertiary hospitals between January 2021 and December 2023. Patients from three hospitals were grouped into Cohort I (n = 815) and those from the fourth hospital into Cohort II (n = 1602). Model calibration, discrimination, and performance were then assessed.

RESULTS

A total of 2417 patients were included, among which 289 (12%) carried CR-GNB upon ICU admission. Neurological disease, high-risk department history and length of stay ≥ 14 days were still 3 most important contributing factors in the scoring system. The ICU-CARB score exhibited high calibration, with an area under the receiver operating characteristic curve of 0.825 (95% confidence interval [CI], 0.778-0.873) for Cohort I and 0.823 (95% CI, 0.791-0.855) for Cohort II. The ICU-CARB score showed a highly positive association with CR-GNB carriage in both cohort I (C = 0.315; P < 0.001) and Cohort II (C = 0.381; P < 0.001).

CONCLUSIONS

Despite differences in patient population characteristics, the ICU-CARB score for CR-GNB carriage upon ICU admission exhibited good discrimination in external validation, supporting its potential generalizability to other ICU settings.

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.

Antimicrobial resistance in Klebsiella pneumoniae: an overview of common mechanisms and a current Canadian perspective

Klebsiella pneumoniae is a ubiquitous opportunistic pathogen of the family Enterobacteriaceae. K. pneumoniae is a member of the ESKAPEE pathogens (Enterococcus faecium, Staphylococcus aureus, K. pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp., and Escherichia coli), a group of bacteria that cause nosocomial infections and are able to resist killing by commonly relied upon antimicrobial agents. The acquisition of antimicrobial resistance (AMR) genes is increasing among community and clinical isolates of K. pneumoniae, making K. pneumoniae a rising threat to human health. In addition to the increase in AMR, K. pneumoniae is also thought to disseminate AMR genes to other bacterial species. In this review, the known mechanisms of K. pneumoniae AMR will be described and the current state of AMR K. pneumoniae within Canada will be discussed, including the impact of the coronavirus disease-2019 pandemic, current perspectives, and outlook for the future.

Anti-bacteria, anti-biofilm, and anti-virulence activity of the synthetic compound MTEBT-3 against carbapenem-resistant Klebsiella pneumoniae strains ST3984

PURPOSE

The rise of carbapenem-resistant Klebsiella pneumoniae (CRKP) has led to increased morbidity and mortality in clinical patients, highlighting the urgent need for effective antibacterial agents.

METHODS

We obtained a synthetic compound, MTEBT-3, using hydrophobic triphenylamine as the skeleton and hydrophilic ammonium salts. We determined the MIC of MTEBT-3 using the macro-broth susceptibility testing method. We isolated a clinical CRKP strain ST3984 and performed synergistic antibiotic sensitivity tests, time-kill assays, and resistance evolution studies. Biofilm formation under sub-MIC conditions was evaluated using crystal violet staining and CLSM. Additionally, biofilm proteins and polysaccharides were quantified. We assessed the bactericidal mechanism of MTEBT-3 by examining the integrity of CRKP bacterial cell membranes and analyzing the transcription of virulence-regulating genes via quantitative real-time PCR.

RESULTS

MTEBT-3 exhibited broad-spectrum antibacterial activity with a low resistance rate, achieving an MIC of 8 μg/mL. The compound displayed additive effects with meropenem and imipenem and synergistic effects with tigecycline. It maintained its efficacy over multiple bacterial generations, with no significant increase in resistance observed. Under sub-MIC conditions, the biomass of biofilms was significantly reduced, and the levels of proteins and polysaccharides within the biofilms were markedly lowered in a concentration-dependent manner. The bactericidal mechanism of MTEBT-3 involved disrupting the integrity of CRKP bacterial cell membranes, leading to increased permeability. Quantitative real-time PCR results showed that MTEBT-3 effectively suppressed the expression of key virulence genes, including fimH, wbbM, rmpA, and rmpA2, which are associated with biofilm formation and bacterial adhesion.

CONCLUSION

The significant antimicrobial activity of MTEBT-3 against clinically isolated CRKP, along with its synergistic or additive effects with commonly used antibiotics, positions it as a promising candidate for treatment. Its ability to disrupt biofilm formation and reduce virulence factor expression further underscores its potential in managing CRKP infections.

Disinfectants efficacy in reducing pathogens related to health-care infection associated in universities hospitals of Gorgan, North of Iran

BACKGROUND

Disinfection has a fundamental role in the control of pathogens in the hospital environment. This study was designed to assess the efficacy and functional impact of disinfectants in reducing pathogens related to healthcare associated infections (HAIs) in hospitals.

METHODS

This observation study was conducted at three university hospitals in Gorgan, Iran, from May to Oct 2023. The data including used disinfectants and microbiological examination were obtained from the infection control unit of each hospital.

RESULTS

The results showed that a variety of disinfectants from intermediate to high levels were employed in accordance with the World Health Organization (WHO) protocols. The microbial result revealed that 31.6% (286 out of 906) of the sample had at least one microorganism. Among identified organisms, Bacillus spp. were the predominant species followed by Staphylococcus epidermis, fungus genera, Enterobacter spp., Enterococcus spp., Pseudomonas spp., Escherichia coli, Alcaligenes spp., Staphylococcus aureus, Citrobacter spp., Corynebacterium spp., Klebsiella spp., Acinetobacter spp., Micrococcus spp., Staphylococcus saprophyticus, and Serratias spp. The highest prevalence rates of microorganisms were observed in the wards of ICU, emergency, internal medicine, and women's ward. The chi-square test revealed a significant relationship between the presence of organisms and hospital wards (P < 0.05).

CONCLUSION

The presence of pathogens indicates a defect in the disinfection process, probably due to both little attention to disinfection protocols and multidrug resistance. It is not yet possible to eliminate pathogens from the hospital environment, but it can be minimized by education intervention, standardizing disinfecting processes, and monitoring by the infection control committee.

Genomic study substantiates the intensive care unit as a reservoir for carbapenem-resistant Klebsiella pneumoniae in a teaching hospital in China

Carbapenem-resistant Klebsiella pneumoniae (CRKP) has recently emerged as a notable public health concern, while the underlying drivers of CRKP transmission among patients across different healthcare facilities have not been fully elucidated. To explore the transmission dynamics of CRKP, 45 isolates were collected from both the intensive care unit (ICU) and non-ICU facilities in a teaching hospital in Guangdong, China, from March 2020 to August 2023. The collection of clinical data and antimicrobial resistance phenotypes was conducted, followed by genomic data analysis for these isolates. The mean age of the patients was 75.2 years, with 18 patients (40.0%) admitted to the ICU. The predominant strain in hospital-acquired CRKP was sequence type 11 (ST11), with k-locus type 64 and serotype O1/O2v1 (KL64:O1/O2v1), accounting for 95.6% (43/45) of the cases. The CRKP ST11 isolates from the ICU exhibited a low single nucleotide polymorphism (SNP) distance when compared to isolates from other departments. Genome-wide association studies identified 17 genes strongly associated with SNPs that distinguish CRKP ST11 isolates from those in the ICU and other departments. Temporal transmission analysis revealed that all CRKP isolates from other departments were genetically very close to those from the ICU, with fewer than 16 SNP differences. To further elucidate the transmission routes among departments within the hospital, we reconstructed detailed patient-to-patient transmission pathways using hybrid methods that combine TransPhylo with an SNP-based algorithm. A clear transmission route, along with mutations in potential key genes, was deduced from genomic data coupled with clinical information in this study, providing insights into CRKP transmission dynamics in healthcare settings.

Clinical and Molecular Characteristics of Patients with Bloodstream Infections Caused by KPC and NDM Co-Producing Carbapenem-Resistant Klebsiella pneumoniae

Purpose

Klebsiella pneumoniae carbapenemase (KPC) and New Delhi metallo-β-lactamase (NDM) co-producing carbapenem-resistant Klebsiella pneumoniae (KPC-NDM-CRKP) isolates have been increasingly reported worldwide but have not yet been systematically studied. Thus, we have conducted a study to compare the risk factors, molecular characteristics, and mortality involved in clinical bloodstream infections (BSIs) caused by KPC-NDM-CRKP and KPC-CRKP strains.

Methods

A retrospective study was conducted on 231 patients with BSIs caused by CRKP at Jinling Hospital in China from January 2020 to December 2022. Antimicrobial susceptibility testing, carbapenemase genes detection and whole-genome sequencing were performed subsequently.

Results

Overall, 231 patients were included in this study: 25 patients with KPC-NDM-CRKP BSIs and 206 patients with KPC-CRKP BSIs. Multivariate analysis implicated ICU-acquired BSI, surgery within 30 days, and longer stay of hospitalization prior to CRKP isolation as independent risk factors for KPC-NDM-CRKP BSIs. The 30-day mortality rate of the KPC-NDM-CRKP BSIs group was 56% (14/25) compared with 32.5% (67/206) in the KPC-CRKP BSIs control group (P = 0.02). The ICU-acquired BSIs, APACHE II score at BSI onset, and BSIs caused by KPC-NDM-CRKP were independent predictors for 30-day mortality in patients with CRKP bacteremia. The most prevalent ST in KPC-NDM-CRKP isolates was ST11 (23/25, 92%), followed by ST15 (2/25, 8%).

Conclusion

In patients with CRKP BSIs, KPC-NDM-CRKP was associated with an excess of mortality. The likelihood that KPC-NDM-CRKP will become the next "superbug" highlights the significance of epidemiologic surveillance and clinical awareness of this pathogen.

Fei-Yan-Qing-Hua decoction decreases hyperinflammation by inhibiting HMGB1/RAGE signaling and promotes bacterial phagocytosis in the treatment of sepsis

ETHNOPHARMACOLOGICAL RELEVANCE

Fei-Yan-Qing-Hua decoction (FYQHD), derived from the renowned formula Ma Xing Shi Gan tang documented in Zhang Zhong Jing's "Treatise on Exogenous Febrile Disease" during the Han Dynasty, has demonstrated notable efficacy in the clinical treatment of pneumonia resulting from bacterial infection. However, its molecular mechanisms underlying the therapeutic effects remains elusive.

AIM OF THE STUDY

This study aimed to investigate the protective effects of FYQHD against lipopolysaccharide (LPS) and carbapenem-resistant Klebsiella pneumoniae (CRKP)-induced sepsis in mice and to elucidate its specific mechanism of action.

MATERIALS AND METHODS

Sepsis models were established in mice through intraperitoneal injection of LPS or CRKP. FYQHD was administered via gavage at low and high doses. Serum cytokines, bacterial load, and pathological damage were assessed using enzyme-linked immunosorbent assay (ELISA), minimal inhibitory concentration (MIC) detection, and hematoxylin and eosin staining (H&E), respectively. In vitro, the immunoregulatory effects of FYQHD on macrophages were investigated through ELISA, MIC, quantitative real-time PCR (Q-PCR), immunofluorescence, Western blot, and a network pharmacological approach.

RESULTS

The application of FYQHD in the treatment of LPS or CRKP-induced septic mouse models revealed significant outcomes. FYQHD increased the survival rate of mice exposed to a lethal dose of LPS to 33.3%, prevented hypothermia (with a rise of 3.58 °C), reduced pro-inflammatory variables (including TNF-α, IL-6, and MCP-1), and mitigated tissue damage in LPS or CRKP-induced septic mice. Additionally, FYQHD decreased bacterial load in CRKP-infected mice. In vitro, FYQHD suppressed the expression of inflammatory cytokines in macrophages activated by LPS or HK-CRKP. Mechanistically, FYQHD inhibited the PI3K/AKT/mTOR/4E-BP1 signaling pathway, thereby suppressing the translational level of inflammatory cytokines. Furthermore, it reduced the expression of HMGB1/RAGE, a positive feedback loop in the inflammatory response. Moreover, FYQHD was found to enhance the phagocytic activity of macrophages by upregulating the expression of phagocytic receptors such as CD169 and SR-A1.

CONCLUSION

FYQHD provides protection against bacterial sepsis by concurrently inhibiting the inflammatory response and augmenting the phagocytic ability of immune cells.

Development and application of a nomogram model for the prediction of carbapenem-resistant Klebsiella pneumoniae infection in neuro-ICU patients

IMPORTANCE

Patients in neuro-ICU are at a high risk of developing nosocomial CRKP infection owing to complex conditions, critical illness, and frequent invasive procedures. However, studies focused on constructing prediction models for assessing the risk of CRKP infection in neurocritically ill patients are lacking at present. Therefore, this study aims to establish a simple-to-use nomogram for predicting the risk of CRKP infection in patients admitted to the neuro-ICU. Three easily accessed variables were included in the model, including the number of antibiotics used, surgery, and the length of neuro-ICU stay. This nomogram might serve as a useful tool to facilitate early detection and reduction of the CRKP infection risk of neurocritically ill patients.

A preliminary exploration on the mechanism of the carbapenem-resistance transformation of Serratia marcescens in vivo

BACKGROUND

The infection of carbapenem-resistant organisms was a huge threat to human health due to their global spread. Dealing with a carbapenem-resistant Serratia marcescens (CRSM) infection poses a significant challenge in clinical settings. This study aims to provide insights into strategies for controlling CRSM infection by exploring the transformation mechanism of carbapenem-resistance.

METHODS

We used whole genome sequencing (WGS) to investigate the mechanism of carbapenem resistance in 14 S. marcescens isolates in vivo. The expression level of related genes and the minimum inhibitory concentration of meropenem (MICMEM) were also evaluated to confirm the mechanism of carbapenem resistance.

RESULTS

Seven groups of S. marcescens, each consisting of two strains, were collected from a hospital and displayed a shift in MICMEM from low to high levels. Homology analysis revealed that the isolates in five groups were significantly different from the remaining two. WGS and experimental evidence indicated that four groups of strains developed carbapenem resistance by acquiring the blaKPC (obtaining group), while two groups (persisting group) increased the expression level of the blaKPC. In contrast, isolates in the last group (missing group) did not carry the blaKPC. All strains possessed multiple β-lactamase genes, including blaCTX-M-14, blaSRT-1, and blaSRT-2. However, only in the missing group, the carbapenem-resistant strain lost an outer membrane protein-encoding gene, leading to increased blaCTX-M-14 expression compared to the carbapenem-susceptible strain.

CONCLUSION

The study findings suggest that S. marcescens strains developed diverse carbapenem resistance in vivo through the evolution of drug resistance, rather than through clone replacement. We hypothesize that carbapenem resistance in S. marcescens was due to certain clonal types with a distinct mechanism.

Clinical Characteristics and Molecular Epidemiology of ST23 Klebsiella pneumoniae in China

Purpose

In clinical settings, CG23 Klebsiella pneumoniae (Kp) is the most virulent clonal group of Kp. Continuous fusions of hypervirulent (Hv) and highly resistant strains have been reported; however, few studies have analysed the molecular epidemiology and clinical characteristics of CG23 strains, especially MDR-sequence type ST23 strains. In this study, we investigated the molecular characteristics of ST23 Kp and analysed the clinical characteristics of ST23 Kp infections in a large teaching hospital of the third class in China.

Methods

ST23 Kp isolates were screened using whole-genome sequencing data from a large single centre. We compared the clinical characteristics of ST23 strains isolated from community-acquired infections (CAI) and hospital acquired infection (HAI). In addition, the infection characteristics of MDR and poor-prognosis isolates were investigated. We analysed genetic characteristics of ST23 Kp and further investigated the evolutionary relationship based on single-nucleotide polymorphism phylogenetic trees.

Results

We detected 184 ST23 strains between 2013 and July of 2018. There were no significant differences between the isolation rates of pulmonary, bloodstream, urinary tract, and cutaneous soft tissue infections in the community and hospitals, except for abscess infections. MDR strains primarily cause pulmonary infections and abscesses; infections with a poor prognosis are typically bloodstream and pulmonary infections. Fourteen MDR strains producing extended-spectrum or class C beta-lactamases, resulting in resistance to third-generation cephalosporins. In 3.8% of ST23 Kp strains, the clb locus was absent. The phylogenetic tree revealed that the isolates were primarily divided into three clades, and based on clinical data, it is inferred that three clonal transmission events have occurred, mainly in ICU causing lung infection.

Conclusion

This study demonstrates that virulence and drug-resistance fusion events of ST23 strains occur gradually, and that the hypervirulent clones facilitate the widespread dissemination of CAI and HAI, particularly pulmonary. Monitoring genomics and developing antivirulence strategies are essential.

Clinical Characteristics and Prognosis of Hospital-Acquired Klebsiella pneumoniae Bacteremic Pneumonia versus Escherichia coli Bacteremic Pneumonia: A Retrospective Comparative Study

Objective

This research aimed to investigate the variations in clinical features and prognosis of HABP caused by E. coli and K. pneumoniae. We also aimed to evaluate the risk variables related to 30-day death in the investigated groups.

Methods

A single-center retrospective cohort research lasting four years was performed. A total of 117 patients with HABP were involved in this research. The primary prognosis was 30-day death.

Results

Among 117 patients with HABP, 60 patients were infected with K. pneumoniae (KP-HABP), and 57 patients were infected with E. coli (E. coli-HABP). A higher proportion of males, ICU admission, undergoing tracheotomy and trachea cannulation, carbapenem-resistant strains, inappropriate empirical therapy (IET), immune compromise, diabetes mellitus, and sepsis were observed in the patients with KP-HABP (all P < 0.05). Meanwhile, the median SOFA score and Pitt score were significantly (P < 0.001) higher in the KP-HABP group compared to the E. coli-HABP group. The 30-day death was 48.33% in the KP-HABP group and 24.56% in the E. coli-HABP group (P = 0.008). After adjusting for the main covariates, the hazard ratios for 30-day mortality in KP-HABP were 1.58 (95% CI:0.80-3.12), 3.24 (95% CI:1.48-7.06), 5.67 (95% CI:2.00-16.07), and 5.99 (95% CI:2.10-17.06), respectively. Multivariate logistic regression models revealed that IET, hypoproteinaemia, cerebral vascular disease (CVD), and SOFA score ≥ 5.0 were the independent risk variables for 30-day death in KP-HABP. Simultaneously, SOFA score ≥ 4.0 and Pitt score ≥ 2.0 were independent risk factors for 30-day mortality in E. coli-HABP.

Conclusion

The clinical features of HABP vary depending on whether it is caused by Escherichia coli or K. pneumoniae. KP-HABP patients have higher 30-day mortality than E. coli-HABP patients. To ensure greater validity, it is necessary to further verify this conclusion using a larger sample size.