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.

Molecular epidemiology of clinical isolation of carbapenem-resistant Enterobacterales and application of carbapenemase inhibitor enhancement test. / ä¸´åºŠåˆ†ç¦»ç¢³é’éœ‰çƒ¯ç±»è€è¯è‚ æ†èŒç›®ç»†èŒèŒæ ªçš„åˆ†å­æµè¡Œç— å­¦åŠç¢³é’éœ‰çƒ¯é ¶æŠ‘åˆ¶å‰‚å¢žå¼ºè¯•éªŒçš„åº”ç”¨.

OBJECTIVES: The prevalence of carbapenem-resistant Enterobacterales (CRE) presents a significant challenge in clinical anti-infective treatment. This study aims to investigate drug resistance and the molecular epidemiological characteristics of CRE in our area. Additionally, we seek to evaluate practicality of utilizing carbapenemase inhibitor enhancement test in clinical laboratory. METHODS: Non-repeated CREs isolated from clinical specimens at Xiangya Hospital, Central South University, were collected. Minimum inhibitory concentration (MIC) combined with Kirby-Bauer (KB) assay was used to detect the drug susceptibility of the strains, and 13 carbapenemase-producing genes were detected by PCR. The phenotype of 126 strains of carbapenemase-producing Enterobacterales identified by PCR was detected by the carbapenemase inhibitor enhancement test to understand the agreement between the method and the gold standard PCR results. RESULTS: Among 704 CRE strains examined, we observed significant drug resistance in 501 strains dentified as carbapenemase-producing Enterobacterales (CPE). Klebsiella pneumoniae was the predominant CPE strain, followed by Enterobacter cloacae and Escherichia coli. A total of 9 carbapenemase types were detected, including Klebsiella pneumoniae carbapenemase (KPC), New Delhi metallo-ß-lactamase (NDM), Verona integron- encoded metallo-ß-lactamases (VIM), imipenemase (IMP), oxacillinase-48 (OXA-48), and rare imipenem-hydrolyzing ß-lactamase (IMI), adelaide imipenemase (AIM), Bicêtre carbapenemase (BIC), and guiana extended-spectrum ß-lactamase (GES). The detection rate of KPC serine carbapenemase was 61.7% (309/501). The carbapenemase inhibitor enhancement test exhibited a 100% consistency rate for the strains producing Class A serine carbapenemase and/or Class B metallo-ß-lactamases. CONCLUSIONS: CRE strains in Changsha, Hunan, China, are wide distribution and exhibit carbapenemase production. The main mechanism of carbapenem resistance in these bacterias is predominatly attributed to the production of KPC serine carbapenemase. The presence of GES and IMI genes carried by Enterobacterales has been detected for the first time in this region. The carbapenemase inhibitor enhancement test has been proven to be an accurate method for detecting CRE producing Class A serine carbapenemase and/or Class B metallo-ß-lactamases. This method offers simpicity of operation and ease of results interpretation, making it weel-suited meeting the clinical microbiology laboratory's reguirements for the detection of serine carbapenemase and metallo-ß-lactamases.

Genomic and clinical characterization of Klebsiella pneumoniae carrying the pks island.

Background: The pks island and its production of the bacterial secondary metabolite genotoxin, colibactin, have attracted increasing attention. However, genomic articles focusing on pks islands in Klebsiella pneumoniae, as well as comparative genomic studies of mobile genetic elements, such as prophages, plasmids, and insertion sequences, are lacking. In this study, a large-scale analysis was conducted to understand the prevalence and evolution of pks islands, differences in mobile genetic elements between pks-negative and pks-positive K. pneumoniae, and clinical characteristics of infection caused by pks-positive K. pneumoniae. Methods: The genomes of 2,709 K. pneumoniae were downloaded from public databases, among which, 1,422 were from NCBI and 1,287 were from the China National GeneBank DataBase (CNGBdb). Screening for virulence and resistance genes, phylogenetic tree construction, and pan-genome analysis were performed. Differences in mobile genetic elements between pks-positive and pks-negative strains were compared. The clinical characteristics of 157 pks-positive and 157 pks-negative K. pneumoniae infected patients were investigated. Results: Of 2,709 K. pneumoniae genomes, 245 pks-positive genomes were screened. The four siderophores, type VI secretion system, and nutritional factor genes were present in at least 77.9% (191/245), 66.9% (164/245), and 63.3% (155/245) of pks-positive strains, respectively. The number and fragment length of prophage were lower in pks-positive strains than in pks-negative strains (p < 0.05). The prevalence of the IS6 family was higher in pks-negative strains than in pks-positive strains, and the prevalence of multiple plasmid replicon types differed between the pks-positive and pks-negative strains (p < 0.05). The detection rate of pks-positive K. pneumoniae in abscess samples was higher than that of pks-negative K. pneumoniae (p < 0.05). Conclusion: The pks-positive strains had abundant virulence genes. There were differences in the distribution of mobile genetic elements between pks-positive and pks-negative isolates. Further analysis of the evolutionary pattern of pks island and epidemiological surveillance in different populations are needed.

Development of a prognostic nomogram for patients with malignant mesothelioma with bone metastasis.

Malignant mesothelioma (MM) is a rare aggressive tumor, and bone metastasis often occurs in later stages of this disease. This study aimed to establish a nomogram to predict the prognosis of bone metastasis of patients with MM. Data from the Surveillance, Epidemiology, and End Results database were screened and retrieved. This study included 311 patients with MM with bone metastases. Prognostic factors were analyzed using the Kaplan-Meier method and Cox proportional hazards model. A nomogram for overall survival (OS) was established and evaluated using statistically significant prognostic factors, and cancer-specific survival (CSS) analysis was performed to investigate its prognostic factors. In addition, the metastasis patterns of patients with MM were investigated, and the effects of different sites of metastasis on survival were compared using the Kaplan-Meier method. Age, sex, histological type, and chemotherapy were identified as the independent risk factors for OS. The 1-, 2-, and 3-year areas under the curve of the nomogram were 0.792, 0.774, and 0.928, and 0.742, 0.733, and 0.733 in the training and validation sets, respectively. Compared to OS, histological type, radiotherapy, and chemotherapy were independent risk factors for CSS. Different metastatic sites in MM have significantly different effects on prognosis.

Molecular epidemiology and clinical characteristics of the type VI secretion system in Klebsiella pneumoniae causing abscesses.

Purpose: The type VI system (T6SS) has the potential to be a new virulence factor for hypervirulent Klebsiella pneumoniae (hvKp) strains. This study aimed to characterize the molecular and clinical features of T6SS-positive and T6SS-negative K. pneumoniae isolates that cause abscesses. Patients and methods: A total of 169 non-duplicate K. pneumoniae strains were isolated from patients with abscesses in a tertiary hospital in China from January 2018 to June 2022, and clinical data were collected. For all isolates, capsular serotypes, T6SS genes, virulence, and drug resistance genes, antimicrobial susceptibility testing, and biofilm formation assays were assessed. Multilocus sequence typing was used to analyze the genotypes of hvKp. T6SS-positive hvKp, T6SS-negative hvKp, T6SS-positive cKP, and T6SS-negative cKP (n = 4 strains for each group) were chosen for the in vivo Galleria mellonella infection model and in vitro competition experiments to further explore the microbiological characteristics of T6SS-positive K. pneumoniae isolates. Results: The positive detection rate for T6SS was 36.1%. The rates of hvKp, seven virulence genes, K1 capsular serotype, and ST23 in T6SS-positive strains were all higher than those in T6SS-negative strains (p < 0.05). Multivariate logistic regression analysis indicated that the carriage of aerobactin (OR 0.01) and wcaG (OR 33.53) were independent risk factors for T6SS-positive strains (p < 0.05). The T6SS-positive strains had a stronger biofilm-forming ability than T6SS-negative strains (p < 0.05). The T6SS-positive and T6SS-negative strains showed no significant differences in competitive ability (p = 0.06). In the in vivo G. mellonella infection model, the T6SS(+)/hvKP group had the worst prognosis. Except for cefazolin and tegacyclin, T6SS-positive isolates displayed a lower rate of antimicrobial resistance to other drugs (p < 0.05). The T6SS-positive isolates were more likely to be acquired from community infections (p < 0.05). Conclusion: Klebsiella pneumoniae isolates causing abscesses have a high prevalence of T6SS genes. T6SS-positive K. pneumoniae isolates are associated with virulence, and the T6SS genes may be involved in the hvKp virulence mechanism.

Outer Membrane Vesicles Transmitting blaNDM-1 Mediate the Emergence of Carbapenem-Resistant Hypervirulent Klebsiella pneumoniae.

Dissemination of hypervirulent and carbapenem-resistant Klebsiella pneumoniae (CRKP) has been reported worldwide, posing a serious threat to antimicrobial therapy and public health. Outer membrane vesicles (OMVs) act as vectors for the horizontal transfer of virulence and resistance genes. However, K. pneumoniae OMVs that transfer carbapenem resistance genes into hypervirulent K. pneumoniae (hvKP) have been insufficiently investigated. Therefore, this study investigates the transmission of the blaNDM-1 gene encoding resistance via OMVs released from CRKP and the potential mechanism responsible for the carbapenem-resistant hypervirulent K. pneumoniae (CR-hvKP) emergence. OMVs were isolated via ultracentrifugation from CRKP with or without meropenem selective pressure. OMVs were then used to transform classical K. pneumoniae (ckp) ATCC 10031, extended-spectrum ß-lactamase (ESBL)-producing K. pneumoniae ATCC 700603, and hvKP NTUH-K2044. Our results showed that meropenem treatment resulted in changes in the number and diameter of OMVs secreted by CRKP. OMVs derived from CRKP mediated the transfer of blaNDM-1 to ckp and hvKP, thereby increasing the carbapenem MIC of transformants. Further experiments confirmed that NTUH-K2044 transformants exhibited hypervirulence. Our study demonstrates, for the first time, that OMVs derived from CRKP can carry blaNDM-1 and deliver resistance genes to other K. pneumoniae strains, even hvKP. The transfer of carbapenem genes into hypervirulent strains may promote the emergence and dissemination of CR-hvKP. This study elucidates a new mechanism underlying the formation of CR-hvKP.

Genome sequence and genomic analysis of liver abscess caused by hypervirulent Klebsiella pneumoniae.

Hypervirulent Klebsiella pneumoniae (hvKp) is an important pathotype with enhanced virulence features compared with classical K. pneumoniae (cKp). hvKp usually causes life-threatening infections in the community, often affecting young and healthy individuals. During the past few decades, hvKp-induced liver abscess has been increasingly reported in Asia and is emerging as a global disease. To better comprehend the molecular characteristics of hvKp-induced liver abscess and recognize the global dissemination of hypervirulent strains with resistance determinants, we sequenced the whole genome of 26 K. pneumoniae strains from patients with liver abscess (KLA) and investigated the clinical factors related to different phenotype groups. The epidemiology, virulence-related factors, and antimicrobial resistance determinants were also discussed. The age, gender, and whether being hospitalized showed no differences among the string-positive and -negative groups were also studied. The assembly and annotation suggested that most of the 26 new liver abscess-causing hvKp strains were ST23-K1 or ST86-K2, and only one of the strains exhibited multidrug resistance. Compared with the existing 36 global liver abscess genome sequences, higher sequence type and virulence gene diversity were found in the new genomes. The clinical characteristics and genomic data of the isolated strains will enrich our knowledge for comparative genomic studies, allowing the better understanding of hvKp characteristics and evolution.

The Clinical Characteristic and Management of Patients with Nocardiosis in a Tertiary Hospital in China.

Nocardiosis is an uncommon opportunistic bacterial infection which becomes a significant health problem due to its increasing incidence and high mortality rate. However, many nocardiosis patients are underdiagnosed by physicians. To summarize the clinical characteristics and management of nocardiosis would help with better diagnosis and prognosis of nocardiosis. This retrospective study was conducted based on the medical records of nocardiosis patients between January 2015 and December 2021 in a tertiary hospital in China. Overall, 44 nocardiosis patients with 54 specimens were included. The patients consisted of 26 males and 18 females with a mean age of 50.4 ± 13.2 years. Among 44 patients, 26 (59.1%) were previously given immunosuppressive therapy. Connective tissue diseases (CTDs) were the most common underlying disease (16/44). The most frequent infection sites were the lungs (17/44) and skin or soft tissues (8/44). Common symptoms included cough (23/44), expectoration (18/44), fever (15/44), and subcutaneous abscesses (15/44). Forty-five out of 54 specimens (83.3%) required over 48 hours of culture time for nocardiosis detection. Thirty-six patients were cured or improved, 5 patients were discharged from the hospital due to poor prognosis, and 1 patient died. The average diagnosis time of poor prognosis cases was 19.7 days, which was significantly longer than those of improved or cured patients (7.3 days). Immunosuppressed patients comprise a large part of nocardiosis cases, which is worth attention in clinical practice. Early diagnosis, specifically through prolonged cultivation time of specimen, could help achieve better prognosis of nocardiosis patients.

Clinical value of lymphocyte count in autoimmune diabetic nephropathy. / æ·‹å·´ç»†èƒžè®¡æ•°åœ¨è‡ªèº«å ç–«æ€§ç³–å°¿ç— è‚¾ç— ä¸­çš„ä¸´åºŠä»·å€¼ï¼ˆè‹±æ–‡ï¼‰.

OBJECTIVES: In recent years, the prevalence of diabetic nephropathy (DN) has increased significantly. An increasing number of studies have shown that lymphocyte-associated inflammatory responses play a role in DN. This study aims to investigate the relationship between lymphocytes and DN in patients with autoimmune diabetes. METHODS: The clinical data of 226 patients with Type 1 diabetes (T1D) and 79 patients with latent autoimmune diabetes in adults (LADA) were retrospectively studied and stratified according to the urinary albumin to creatinine ratio (ACR). Risk factors associated with DN were analyzed using correlation analysis and logistic regression. RESULTS: In T1D and LADA patients, systolic blood pressure (SBP), uric acid duration, and diabetes duration in patients with normoalbuminuria were lower or shorter than those in patients with macroalbuminuria (P<0.05). The lymphocyte count of T1D patients was significantly higher than that in LADA patients (P<0.05), while the neutrophil to lymphocyte ratio (NLR) of T1D patients was significantly lower than that in LADA patients (P<0.05). The lymphocyte count in the T1D patients with normoalbuminuria was lower than that those with macroalbuminuria (P<0.05). The NLR was lower in the T1D patients with macroalbuminuria than those with microalbuminuria and normoproteinuria (all P<0.01). Based on logistic regression analysis, lymphocytes were independently associated with DN in T1D after adjusting for various known risk factors such as course of disease, age, gender, dyslipidemia, hypertension, and smoking status. Analysis of the receiver operating characteristic curve of subjects predicting lymphocytes in normoalbuminuria showed that the area under the curve was 0.601 (95% CI 0.510 to 0.693, P=0.039), and when the cutoff value of lymphocytes was 2.332, the sensitivity was 37.0%, and the specificity was 82.5%. CONCLUSIONS: Lymphocyte counts in autoimmune diabetic patients are closely associated with DN, suggesting that lymphocyte-mediated inflammation may be involved in the pathogenesis of DN in autoimmune diabetic patients. This study provides a possible perspective for using lymphocytes as a potential biomarker for the early identification of individuals at risk for DN and potential therapeutic targets for DN.

Molecular epidemiology and clinical characteristics of Clostridioides difficile infection in patients with inflammatory bowel disease from a teaching hospital.

BACKGROUND: Clostridioides difficile infection (CDI) in patients with inflammatory bowel disease (IBD) is of increasing concern. This study aimed to investigate the molecular epidemiology and antimicrobial susceptibilities of toxigenic C. difficile isolated from IBD patients and to evaluate the risk factors for CDI in IBD population. METHODS: Loose or watery stools from IBD patients were tested for glutamate dehydrogenase, C. difficile toxins A&B and anaerobic culture. Toxigenic C. difficile isolates were characterized by multi-locus sequence typing, ribotyping and antimicrobial susceptibility testing. RESULTS: The prevalence of CDI in IBD patients was 13.6% (43/317). The dominant sequence types (STs) were ST35 (20.9%), ST2 (18.6%) and ST37 (16.3%). The most common ribotypes (RTs) were RT 017 (18.6%), RT 012 (14.0%), and RT 220 (14.0%), whereas RT 027 and RT 078 were not detected in this study. All the isolates were susceptible to vancomycin and metronidazole. The multidrug resistance rate of C. difficile RT 017 was higher (p < 0.01) than that of other RT strains. Recent hospitalization, use of corticosteroids and proton pump inhibitors were related to increased risk of CDI in IBD patients; of these, recent hospitalization and proton pump inhibitors use were independent risk factors. CONCLUSION: Patients with IBD have a relatively high incidence rate of CDI. C. difficile RT 017 is most frequently isolated from IBD patients in this region and warrants more attention to its high resistance rate. Clinicians should pay greater attention to CDI testing in IBD patients with diarrhea to ensure early diagnosis and initiation of effective treatment.

Genome-wide association study of Klebsiella pneumoniae identifies variations linked to carbapenems resistance.

Klebsiella pneumoniae (KP) is one of the microorganisms that can acquire carbapenem-resistance (CR), and few antimicrobial therapy options exist for infections caused by Carbapenem-Resistant KP (CRKP). In recent years, with the increase of carbapenem resistance rates, treating CRKP has become a serious public health threat in clinical practice. We have collected 2,035 clinical KP isolates from a tertiary hospital in China. Whole genome sequencing data coupled with their binary antimicrobial susceptibility testing data were obtained to conduct the genome-wide association study using a bayesian-based method, including single nucleotide polymorphisms (SNPs) and genes. We identified 28 and 37 potential maker genes associated with imipenem and meropenem resistance, respectively. Among which 19 of them were selected in both drugs by genome-wide association study (GWAS), 11 genes among them were simultaneously validated in independent datasets. These genes were likely related to biofilm formation, efflux pump, and DNA repairing. Moreover, we identified 13 significant CR related SNPs in imipenem or meropenem, with one SNP located in the non-coding region and validated in the independent datasets. Our study indicates complex mechanisms of carbapenems resistance and further investigation of CRKP-related factors are warranted to better understand their contributions to carbapenems resistance. These identified biomarkers may provide targets for future drug interventions or treatments.

Enhanced chiral sensing in achiral nanostructures with linearly polarized light.

Chiral plasmonic nanostructures can generate large superchiral near fields owing to their intrinsic chirality, leveraging applications for molecule chirality sensing. However, the large structural chirality of chiral nanostructures poses the risk of overshadowing molecular chiral signals, hampering the practical application of chiral nanostructures. Herein, we propose an achiral nanorod that shows no structural chirality and presents strong superchiral near-fields with linearly polarized incidence. The mechanism of the strong superchiral near-field originates from the coupling between the evanescent fields of the localized surface plasmon resonance and incident light. The enhanced near-field optical chirality at the corners of the nanorods reached 25 at a wavelength of 790 nm. Meanwhile, the sign of optical chirality can be tuned by the polarization of the incident light, which provides a convenient way to control the handedness of the light. Furthermore, the enantiomers of D- and L-phenylalanine molecules were experimentally characterized using an achiral platform, which demonstrated a promising nanophotonic platform for chiral biomedical sensing.

Risk factors for carbapenem-resistant Enterobacterales infection among hospitalized patients with previous colonization.

BACKGROUND: We aimed to identify the risk factors for subsequent carbapenem-resistant Enterobacterales (CRE) infections in patients with initial rectal colonization with CRE. METHODS: We conducted a retrospective case-control study on inpatients with rectal CRE colonization between January 2019 and December 2020. Clinical and microbiological data were extracted from hospital patients' medical records and the clinical microbiology laboratory. Risk factors were assessed and compared between patients with CRE colonization who had subsequent infections and those who did not have infections. RESULTS: Among 1064 patients screened for CRE, we enrolled 205 patients with rectal CRE colonization. Among the 205 colonized bacteria, 78.5% were Klebsiella pneumoniae, with 62.9% of them producing Klebsiella pneumoniae carbapenemase (KPC). Multivariate logistic regression analysis revealed that more than three times hospitalization (p = 0.026), being in a coma (p = 0.019), and exposure to carbapenems (p = 0.015) were independent risk factors for CRE clinical infection among CRE rectal carriers. CONCLUSION: This is the first study to report that more than three times hospitalization is an independent risk factor for subsequent CRE clinical infection in CRE intestinal carriers. Carbapenem-resistant Klebsiella pneumoniae is the most important species isolated from hospitalized CRE rectal carriers and is the most common cause of subsequent infections.

One Health Analysis of mcr-Carrying Plasmids and Emergence of mcr-10.1 in Three Species of Klebsiella Recovered from Humans in China.

The global dissemination of the mobile colistin resistance (mcr) gene illustrates how the use of colistin in veterinary medicine can affect human health, exemplifying the concept of One Health. This study screened for the existence of mcr variants (from mcr-1 to mcr-10) in a 5-year collection of clinical Klebsiella short-read whole-genome sequencing (WGS) data from a tertiary hospital in China (2013 to 2018) and aimed to identify the mechanisms of mcr spread. MICs were measured for the mcr-positive isolates, and long-read sequencing was performed to complete the mcr-positive genome sequences. Six variants (mcr-1.1, mcr-8.1, mcr-8.2, mcr-9.1, mcr-9.2, and mcr-10.1) were identified in 20 genomes, with plasmids from the IncFIIK, IncHI2, IncI2, and IncX4 groups. Highly similar plasmids (coverage, >75%; nucleotide identity, >98.5%) isolated from silver gulls, chickens, pigs, wastewater treatment plants, and hospital sewage were identified in GenBank. The MICs of the mcr-1- and mcr-8-carrying isolates were ≥4 µg/mL; however, the MICs of the mcr-9- and mcr-10-carrying isolates ranged from 0.5 µg/mL to 1 µg/mL (colistin susceptible). The variants mcr-1 to mcr-9 were found only in Klebsiella pneumoniae, while mcr-10.1 was found in K. pneumoniae, Klebsiella quasipneumoniae subsp. quasipneumoniae, and Klebsiella variicola. A pair of inverted repeats (IRs) was identified for hsdSMR-ISEc36-mcr-10.1-xerC; IR-1 (5'-TCAAACGTA) was inside the attL site of xerC, indicating that mcr-10.1 was originally integrated by xerC and mobilized by ISEc36 afterwards. In conclusion, this is the first report of mcr-10.1 susceptible to colistin in three species of Klebsiella. This study shows the genetic events that happened to mcr-10.1 in a stepwise manner, with the first step being XerC integration and the second being ISEc36 mobilization. Finally, this study also highlights mcr transmission between humans and nature. IMPORTANCE Reports of mcr-1 and mcr-8 are common in China; however, few studies have reported mcr-9 and mcr-10. One reason is that the newly described variants can be phenotypically colistin susceptible and thus may not be identified. This study identified the mcr-positive clinical isolates by investigating WGS data for 2,855 Klebsiella isolates (including K. pneumoniae, K. quasipneumoniae subsp. quasipneumoniae, and K. variicola) and found three mcr-9 and three mcr-10 cases (MICs, 0.5 µg/mL to 1 µg/mL; colistin susceptible). This study also reveals a pair of perfect 9-bp IRs of ISEc36 and the precise mcr-10.1 integration and insertion events that happened to the IncFIIK plasmids. A One Health analysis of highly similar plasmid structures from human and nonhuman sources emphasizes the plasmid transmission and evolution process.

Prevalence of Escherichia coli ST1193 Causing Intracranial Infection in Changsha, China.

ST1193 is an emerging new virulent and resistant clone among Escherichia coli with a tendency to spread rapidly across the globe. However, the prevalence of intracranial infection-causing E. coli ST1193 is rarely reported. This study aimed at determining the prevalence of E. coli ST1193 isolates, causing intracranial infections in Changsha, central China. A total of 28 E. coli isolates were collected from the cerebrospinal fluid of patients with intracranial infection over a four-year period. All isolates were differentiated using multilocus sequence typing (MLST), and phylogenetic grouping, and tested for antibiotic resistance. MLST analysis showed 11 sequence types (ST) among the 28 E. coli isolates. The most prevalent ST was B2-ST1193 (28.6%, 8/28), followed by B2-ST131 (21.4%, 6/28) and F-ST648 (10.7%, 3/28). Of the eight ST1193 isolates, three carried CTX-M-55, and one carried CTX-M-27. All eight ST1193 isolates were resistant to Ciprofloxacin, showing gyrA1AB/parC4A mutations. Two ST1193 isolates carried the aac(6')-Ib-cr gene. All ST1193 isolates were recovered from infants with meningitis, with a fatal outcome for one three-month-old infant. ST1193 has emerged as the predominant type of E. coli strain causing intracranial infections in Changsha, China. This study highlights the importance of implementing appropriate surveillance measures to prevent the spread of this emerging public health threat.

Community Fecal Carriage and Molecular Epidemiology of Extended-Spectrum ß-Lactamase- and Carbapenemase-Producing Escherichia coli from Healthy Children in the Central South China.

Background: Fecal carriage of extended-spectrum ß-lactamase-producing Escherichia coli (ESBL-EC) and carbapenemase-producing E. coli (CP-EC) is well reported among hospitalized adults and children. However, there are few studies on the carriage prevalence and ESBL-EC and CP-EC genotypes among healthy children in China. Patients and Methods: Stool samples were collected from 330 students in 2021 from three randomly selected primary schools in Changsha, China. ESBL-EC and CP-EC were screened using CHROMagarTM chromogenic plates. ESBL and carbapenemase production was confirmed using the double-disc synergy test and a modified carbapenem inactivation method, respectively. Antimicrobial susceptibility was tested using the broth microdilution method. Resistance determinants, virulence factors, and phylogenetic groups were determined by PCR and sequencing. Multi-locus sequence typing (MLST) was performed (seven housekeeping genes were amplified and sequenced) on the phylogenic group B2 E. coli to detect high-risk clonal strains such as ST131 E. coli. Then, ST131 E. coli were characterized based on ST131 clades, O-type, and fimH alleles. Results: In total, 118 (35.8%) ESBL-EC and 3 (0.9%) CP-EC were isolated. bla CTX-M was the most common genotype (27.1%), identified in all ESBL-EC, except one, which carried bla SHV-12. One isolate with mcr-1 was found amongst ESBL-EC, whereas all three CP-EC carried bla NDM-1. The predominant sequence type (ST) clones in group B2 were ST131 and ST1193. The prevalence of ST131 E. coli was 9.9%, displaying serotypes O16 and O25b, fimH alleles 30, 41, and 89, and ST131 clades A and C1-M27. Conclusion: In this study, high carriage rate of ESBL-EC was found among healthy children, and the dominant ESBL was CTX-M-14. In addition, high-risk clones (ST131 and ST1193) were also detected. This emphasizes the importance of monitoring ESBL-EC in community settings.

Large-Scale Genomic Epidemiology of Klebsiella pneumoniae Identified Clone Divergence with Hypervirulent Plus Antimicrobial-Resistant Characteristics Causing Within-Ward Strain Transmissions.

Global dissemination of K. pneumoniae clones poses health hazards to the public. Genomic epidemiology studies with comprehensive data set further revealed clone divergence, showing a high complexity in evolution. Moreover, clones carrying both acquired virulent and antimicrobial-resistant genes emerged and might replace the carbapenem-resistant clones. Co-occurrence of virulence and resistance is emerging. An unbiased collection of 3,061 clinical K. pneumoniae isolates (January 5, 2013 to July 24, 2018) underwent whole-genome sequencing. Pairwise core-genome single-nucleotide polymorphism (cgSNP) distances identified clone divergence and transmission events. A sum of 2,193 nonduplicated genomes clustered into four phenotypically indistinguishable species complexes. 93% (n = 2,035) were KpI with its largest clonal group (CG) being CG11 (n = 406). Three hundred ninety-three were ST11 and three hundred seventy-four carried blaKPC-2. Noticeably, CG11 is divided into two main subclones based on the capsule synthesis K loci (KL). CG11-KL64 showed a clear hypervirulent plus antimicrobial-resistant (hv+AMR) characteristic. Besides, the phylogenetic structure revealed the clone divergence of CG25, and this is the first report with sufficient CG25 genomes to identify the divergence. The outcomes of the hv+AMR CG25 cluster 1 affected patients were poorer (P < 0.05). Moreover, two episodes of strain transmissions were associated with CG25 cluster 1. Other transmissions were associated with ST20 and ST307. Genomic epidemiology identified clone divergence of CG11 and CG25. The hv+AMR subclones pose greater threats on a global scale. Nosocomial transmissions of the high-risk clones raised our concerns about the evolution and transmission of emerging clones among newborns and critically ill patients. IMPORTANCE The convergence of AMR and acquired virulence posing higher risks to the public is a focusing point. With sufficient genomes and genotypes, we successfully identify the convergence in two subclones, the previously reported CG11-KL64, and the newly reported CG25 cluster 1. The novel finding of the CG25 divergence was not only revealed by the phylogenetic tree but also confirmed by the clinical outcome data and the accessory genome patterns. Moreover, the transmission subclones circulated in two clinically important wards highlights the deficiency of infection control program using conventional methods. Without the assistance of whole-genome sequencing, the transmissions of high-risk clones could not be identified.

Preliminary Investigation of Iron Acquisition in Hypervirulent Klebsiella pneumoniae Mediated by Outer Membrane Vesicles.

OBJECTIVE: To investigate the role of outer membrane vesicles (OMVs) and related proteins in iron acquisition of hypervirulent Klebsiella pneumoniae (HVKP) and classic Klebsiella pneumoniae (cKP). METHODS: The OMVs of HVKP and cKP under iron-deficient and iron-sufficient media were extracted and purified by ultracentrifugation. Transmission electron microscopy (TEM) was used to identify OMVs. The quantitative proteomics were performed based on mass spectrometry. RESULTS: Four OMVs samples secreted by HVKP and cKP under iron-deficient and iron-sufficient environment were isolated and collected (HVKP OMVs under iron-deficient environment (A1), HVKP OMVs under iron-sufficient environment (A2), cKP OMVs under iron-deficient environment (B1), cKP OMVs under iron-sufficient environment (B2)). The amount of OMVs released by HVKP in iron-deficient medium was significantly larger than that in iron-sufficient medium (P < 0.05). HVKP secreted more OMVs than cKP in iron-deficient medium (P < 0.05). A total of 1074 kinds of proteins were identified in four samples. A comparison between the iron-deficient vs iron-sufficient environment showed that 61 proteins in HVKP OMVs were identified with a significant change in abundance under iron-deficient environment. Among them, 17 proteins were related to iron acquisition and transportation systems. While in cKP OMVs, 62 proteins significantly changed under iron-deficient environment in which 5 proteins were related to iron acquisition and transportation systems. Upon comparison of the HVKP vs cKP OMVs under iron deficiency, 81 proteins were detected with a significant change in which 8 proteins were related to iron acquisition and transportation systems. CONCLUSION: Above all, the results of this study suggest a potential role for OMVs in iron acquisition of HVKP and provide evidence of potential connections between OMVs and strong iron-acquisition ability of HVKP during iron limitation.

Interferon-γ release assays for tuberculous meningitis diagnosis: a meta-analysis.

INTRODUCTION: Tuberculous meningitis (TBM) is still a great challenge to global public health. As conventional diagnostic methods for TBM are unsatisfactory, interferon-γ release assays (IGRAs) have been introduced for TBM diagnosis tentatively. However, the role of IGRAs for diagnosing TBM remains unclear. Thus, we systematically evaluated the diagnostic performance of cerebrospinal fluid (CSF) and peripheral blood (PB) IGRAs in TBM to fill this blank. MATERIAL AND METHODS: Relevant studies were systematically searched in both foreign and Chinese databases up to March 2018. Studies in which TBM diagnosis was based on microbiological or clinical criteria were included. The quality of the included studies was assessed through the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. Main outcome measures, including sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR) and diagnostic odds ratio (DOR), were pooled statistically using random effects models. The potential heterogeneity was explored by threshold effect analysis, subgroup analyses and meta-regression. Funnel plots and Egger's test were used to test the potential publication bias. Statistical analyses were performed using Stata and Meta-DiSc software. RESULTS: Twenty-six out of 656 publications were eligible for meta-analysis, including 1892 participants in total. The pooled estimates of PB IGRAs for TBM diagnosis are as follows: sensitivity: 0.81 (95% CI: 0.78-0.84); specificity: 0.76 (95% CI: 0.73-0.78); PLR: 4.23 (95% CI: 2.95-6.07); NLR: 0.24 (95% CI: 0.19-0.32) and DOR: 21.06 (11.91-37.24). The corresponding estimates for CSF IGRAs were obtained: sensitivity: 0.81 (95% CI: 0.76-0.85); specificity: 0.89 (95% CI: 0.86-0.92); PLR: 7.87 (95% CI: 4.98-12.46); NLR: 0.19 (95% CI: 0.13-0.29); and DOR: 47.74 (25.02-91.12). CONCLUSIONS: The diagnostic performance of IGRAs is suboptimal. In terms of cost, turn-around time and accessibility, these assays are unsuitable for use as biomarkers for TBM diagnosis.

Fructose-coated Ångstrom silver prevents sepsis by killing bacteria and attenuating bacterial toxin-induced injuries.

Serious infection caused by multi-drug-resistant bacteria is a major threat to human health. Bacteria can invade the host tissue and produce various toxins to damage or kill host cells, which may induce life-threatening sepsis. Here, we aimed to explore whether fructose-coated Ångstrom-scale silver particles (F-AgÅPs), which were prepared by our self-developed evaporation-condensation system and optimized coating approach, could kill bacteria and sequester bacterial toxins to attenuate fatal bacterial infections. Methods: A series of in vitro assays were conducted to test the anti-bacterial efficacy of F-AgÅPs, and to investigate whether F-AgÅPs could protect against multi-drug resistant Staphylococcus aureus (S. aureus)- and Escherichia coli (E. coli)-induced cell death, and suppress their toxins (S. aureus hemolysin and E. coli lipopolysaccharide)-induced cell injury or inflammation. The mouse models of cecal ligation and puncture (CLP)- or E. coli bloodstream infection-induced lethal sepsis were established to assess whether the intravenous administration of F-AgÅPs could decrease bacterial burden, inhibit inflammation, and improve the survival rates of mice. The levels of silver in urine and feces of mice were examined to evaluate the excretion of F-AgÅPs. Results: F-AgÅPs efficiently killed various bacteria that can cause lethal infections and also competed with host cells to bind with S. aureus α-hemolysin, thus blocking its cytotoxic activity. F-AgÅPs inhibited E. coli lipopolysaccharide-induced endothelial injury and macrophage inflammation, but not by directly binding to lipopolysaccharide. F-AgÅPs potently reduced bacterial burden, reversed dysregulated inflammation, and enhanced survival in mice with CLP- or E. coli bloodstream infection-induced sepsis, either alone or combined with antibiotic therapy. After three times injections within 48 h, 79.18% of F-AgÅPs were excreted via feces at the end of the 14-day observation period. Conclusion: This study suggests the prospect of F-AgÅPs as a promising intravenous agent for treating severe bacterial infections.