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  • Feng, Yanling  (18)
  • 1
    In: Frontiers in Microbiology, Frontiers Media SA, Vol. 13 ( 2022-3-31)
    Abstract: With the increasingly severe problem of bacterial resistance, colistin, as the last line of defense, has attracted attention again. Mobile colistin resistance ( mcr -1) gene is involved in the horizontal transmission of colistin resistance in Gram-negative bacteria (GNB), which is a serious threat to human health. Therefore, rapid detection of mcr -1 gene presence in clinical samples is crucial. In this study, a Recombinase-aided amplification(RAA) method for mcr -1 was successfully constructed, with sensitivity of 20 copies/reaction. In addition, amplification signal could only be detected in the strain containing mcr -1 gene among 14 different bacterial species. The method was then used to test a total of 672 clinical samples from a pediatric hospital in Beijing. Five strains harbored mcr -1 genes were isolated from mcr -1-positive clinical samples and identified as Escherichia coli . Multi-locus sequence typing (MLST) analysis showed that the five E. coli belonged to different ST types. Notably, the mcr -1 gene from the isolates could be transferred conjugately to the recipient strain E. coli J53, with highest transfer efficiency up to 57–58%, suggesting that the mcr -1 gene was located on the plasmid. These findings showed that the RAA assay has potential to be a rapid and sensitive mcr -1 gene screening test for clinical samples, and mcr -1 could be transmitted vertically and horizontally between and within bacterial species in a plasmid-mediated manner.
    Type of Medium: Online Resource
    ISSN: 1664-302X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
    detail.hit.zdb_id: 2587354-4
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  • 2
    In: Journal of Biomedical Science, Springer Science and Business Media LLC, Vol. 30, No. 1 ( 2023-08-31)
    Abstract: Klebsiella aerogenes can cause ventilator-associated pneumonia by forming biofilms, and it is frequently associated with multidrug resistance. Phages are good antibiotic alternatives with unique advantages. There has been a lack of phage therapeutic explorations, kinetic studies, and interaction mechanism research targeting K. aerogenes . Methods Plaque assay, transmission electron microscopy and whole-genome sequencing were used to determine the biology, morphology, and genomic characteristics of the phage. A mouse pneumonia model was constructed by intratracheal/endobronchial delivery of K. aerogenes to assess the therapeutic effect of phage in vivo. Bioinformatics analysis and a prokaryotic protein expression system were used to predict and identify a novel capsule depolymerase. Confocal laser scanning microscopy, Galleria mellonella larvae infection models and other experiments were performed to clarify the function of the capsule depolymerase. Results A novel lytic phage (pK4-26) was isolated from hospital sewage. It was typical of the Podoviridae family and exhibited serotype specificity, high lytic activity, and high environmental adaptability. The whole genome is 40,234 bp in length and contains 49 coding domain sequences. Genomic data show that the phage does not carry antibiotic resistance, virulence, or lysogenic genes. The phage effectively lysed K. aerogenes in vivo, reducing mortality and alleviating pneumonia without promoting obvious side effects. A novel phage-derived depolymerase was predicted and proven to be able to digest the capsule, remove biofilms, reduce bacterial virulence, and sensitize the bacteria to serum killing. Conclusions The phage pK4-26 is a good antibiotic alternative and can effectively relieve pneumonia caused by multidrug-resistant K. aerogenes . It carries a depolymerase that removes biofilms, reduces virulence, and improves intrinsic immune sensitivity.
    Type of Medium: Online Resource
    ISSN: 1423-0127
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2023
    detail.hit.zdb_id: 1482918-6
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  • 3
    Online Resource
    Online Resource
    Frontiers Media SA ; 2022
    In:  Frontiers in Cellular and Infection Microbiology Vol. 12 ( 2022-9-5)
    In: Frontiers in Cellular and Infection Microbiology, Frontiers Media SA, Vol. 12 ( 2022-9-5)
    Abstract: The Burkholderia cepacia complex (BCC) is a group of opportunistic pathogens, including Burkholderia cepacia, Burkholderia multivorans, Burkholderia vietnamiensis and Burkholderia ambifaria , which can cause severe respiratory tract infections and lead to high mortality rates among humans. The early diagnosis and effective treatment of BCC infection are therefore crucial. In this study, a novel and rapid recombinase-aided amplification (RAA) assay targeting the 16S rRNA gene was developed for BCC detection. The protocol for this RAA assay could be completed in 10 min at 39°C, with a sensitivity of 10 copies per reaction and no cross-reactivity with other pathogens. To characterize the effectiveness of the RAA assay, we further collected 269 clinical samples from patients with bacterial pneumonia. The sensitivity and specificity of the RAA assay were 100% and 98.5%, respectively. Seven BCC-infected patients were detected using the RAA assay, and three BCC strains were isolated from the 269 clinical samples. Our data showed that the prevalence of BCC infection was 2.60%, which is higher than the 1.40% reported in previous studies, suggesting that high sensitivity is vital to BCC detection. We also screened a patient with B. vietnamiensis infection using the RAA assay in clinic, allowing for appropriate treatment to be initiated rapidly. Together, these data indicate that the RAA assay targeting the 16S rRNA gene can be applied for the early and rapid detection of BCC pathogens in patients with an uncharacterized infection who are immunocompromised or have underlying diseases, thereby providing guidance for effective treatment.
    Type of Medium: Online Resource
    ISSN: 2235-2988
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
    detail.hit.zdb_id: 2619676-1
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  • 4
    In: Microbiology Spectrum, American Society for Microbiology, Vol. 11, No. 3 ( 2023-06-15)
    Abstract: It has been known that high alcohol-producing Klebsiella pneumoniae (HiAlc Kpn ) is one of causative agents of nonalcoholic fatty liver disease (NAFLD). However, how HiAlc Kpn promotes liver injury remains unclear. Recent findings suggest that DNA methylation might associate with the pathogenesis of NAFLD. Herein, the role of DNA methylation in HiAlc Kpn -induced liver injury was investigated. Murine models of NAFLD were established in C57BL/6N wild-type mice by gavaging HiAlc Kpn for 8 weeks. The liver injury was assessed based on the liver histopathology and biochemical indicators. In addition, DNA methylation in hepatic tissue was assessed by using dot bolt of 5-mC. RNA sequencing analysis and whole-genome bisulfite sequencing (WGBS) analysis were also performed. HiAlc Kpn significantly increased the activity of aspartate transaminase (AST), alanine transaminase (ALT), triglycerides (TGs), and glutathione (GSH), while hypomethylation was associated with liver injury in the experimental mice induced by HiAlc Kpn . The GO and KEGG pathway enrichment analysis of the transcriptome revealed that HiAlc Kpn induced fat metabolic disorders and DNA damage. The conjoint analysis of methylome and transcriptome showed that hypomethylation regulated related gene expression in signal pathways of lipid formation and circadian rhythm, including Rorα and Arntl1 genes, which may be the dominant cause of NAFLD induced by HiAlc Kpn . Data suggest that DNA hypomethylation might play an important role in liver injury of NAFLD induced by HiAlc Kpn . Which possibly provides a new sight for understanding the mechanisms of NAFLD and selecting the potential therapeutic targets. IMPORTANCE High alcohol-producing Klebsiella pneumoniae (HiAlc Kpn ) is one of causative agents of nonalcoholic fatty liver disease (NAFLD) and could induce liver damage. DNA methylation, as a common epigenetic form following contact with an etiologic agent and pathogenesis, can affect chromosome stability and transcription. We conjointly analyzed DNA methylation and transcriptome levels in the established murine models to explore the potential mechanisms for further understanding the role of DNA methylation in the liver damage of HiAlc Kpn -induced NAFLD. The analysis of the DNA methylation landscape contributes to our understanding of the entire disease process, which might be crucial in developing treatment strategies.
    Type of Medium: Online Resource
    ISSN: 2165-0497
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2023
    detail.hit.zdb_id: 2807133-5
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  • 5
    In: Microbiology Spectrum, American Society for Microbiology, Vol. 11, No. 4 ( 2023-08-17)
    Abstract: This study aimed to develop a rapid and sensitive droplet digital PCR (ddPCR) assay for the specific detection of Klebsiella pneumoniae in fecal samples, and to evaluate its application in the clinic by comparison with real-time PCR assay and conventional microbial culture. Specific primers and a probe targeting the K. pneumoniae hemolysin ( khe ) gene were designed. Thirteen other pathogens were used to evaluate the specificity of the primers and probe. A recombinant plasmid containing the khe gene was constructed and used to assess the sensitivity, repeatability, and reproducibility of the ddPCR. Clinical fecal samples ( n  = 103) were collected and tested by the ddPCR, real-time PCR, and conventional microbial culture methods. The detection limit of ddPCR for K. pneumoniae was 1.1 copies/μL, about a 10-fold increase in sensitivity compared with real-time PCR. The ddPCR was negative for the 13 pathogens other than K. pneumoniae , confirming its high specificity. Clinical fecal samples gave a higher rate of positivity in the K. pneumoniae ddPCR assay than in analysis by real-time PCR or conventional culture. ddPCR also showed less inhibition by the inhibitor in fecal sample than real-time PCR. Thus, we established a sensitive and effective ddPCR-based assay method for K. pneumoniae . It could be a useful tool for K. pneumoniae detection in feces and may serve as a reliable method to identify causal pathogens and help guide treatment decisions. IMPORTANCE Klebsiella pneumoniae can cause a range of illnesses and has a high colonization rate in the human gut, making it crucial to develop an efficient method for detecting K. pneumoniae in fecal samples.
    Type of Medium: Online Resource
    ISSN: 2165-0497
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2023
    detail.hit.zdb_id: 2807133-5
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  • 6
    In: Nature Communications, Springer Science and Business Media LLC, Vol. 14, No. 1 ( 2023-06-03)
    Abstract: Our previous studies have shown that high alcohol-producing Klebsiella pneumoniae (HiAlc Kpn ) in the intestinal microbiome could be one of the causes of non-alcoholic fatty liver disease (NAFLD). Considering antimicrobial resistance of K. pneumoniae and dysbacteriosis caused by antibiotics, phage therapy might have potential in treatment of HiAlc Kpn -induced NAFLD, because of the specificity targeting the bacteria. Here, we clarified the effectiveness of phage therapy in male mice with HiAlc Kpn -induced steatohepatitis. Comprehensive investigations including transcriptomes and metabolomes revealed that treatment with HiAlc Kpn -specific phage was able to alleviate steatohepatitis caused by HiAlc Kpn , including hepatic dysfunction and expression of cytokines and lipogenic genes. In contrast, such treatment did not cause significantly pathological changes, either in functions of liver and kidney, or in components of gut microbiota. In addition to reducing alcohol attack, phage therapy also regulated inflammation, and lipid and carbohydrate metabolism. Our data suggest that phage therapy targeting gut microbiota is an alternative to antibiotics, with potential efficacy and safety, at least in HiAlc Kpn -caused NAFLD.
    Type of Medium: Online Resource
    ISSN: 2041-1723
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2023
    detail.hit.zdb_id: 2553671-0
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  • 7
    In: Microbiology Spectrum, American Society for Microbiology, Vol. 10, No. 5 ( 2022-10-26)
    Abstract: Pneumonia caused by multidrug-resistant (MDR) Klebsiella pneumoniae of sequence types ST11 and ST383 have highlighted the necessity for new therapies against these prevalent pathogens. Bacteriophages (phages) may be used as alternatives or complements to antibiotics for treating MDR bacteria because they show potential efficacy in mouse models and even individual clinical cases, and they also cause fewer side effects, such as microbiota-imbalance-induced diseases. In the present study, we screened two phages, pKp11 and pKp383, that targeted ST11 and ST383 MDR K. pneumoniae isolates collected from patients with pneumonia, and they exhibited a broad host range, high lytic activity, and high environmental adaptability. Both phages pKp11 and pKp383 provided an effective treatment for the early stage of pneumonia in a murine infection model without promoting obvious side effects, and cocktails consisting of the two phages were more effective for reducing bacterial loads, inflammation, and pathogenic injuries. Our findings support the application of phages as new medications for refractory ST11 and ST383 K. pneumoniae infections and emphasize the potential of enhancing phage therapy modalities through phage screening. These data provided important resources for assessing and optimizing phage therapies for MDR ST11 and ST383 infection treatment. However, substantial amounts of further work are needed before phage therapy can be translated to human therapeutics. IMPORTANCE K. pneumoniae is recognized as the most common pathogen of hospital- and community-acquired pneumonia across the world. The strains of ST11 and ST383 are frequently reported in patients with pneumonia. However, the efficacy of antibiotics toward K. pneumoniae is decreasing dramatically. As a new approach to combat MDR bacteria, phages have exhibited positive clinical effects and efficacy as synergetic or alternative strategies to antibiotics. Thus, we screened two phages that targeted ST11 and ST383 MDR K. pneumoniae , and they exhibited a broad host range, high lytic activity, and high environmental adaptability. Both phages provided an effective treatment for the early stage of pneumonia in mice, and cocktails consisting of the two phages were more effective in reducing bacterial loads, inflammation, and pathogenic injuries. Although these data suggest that phages are effective alternatives or complements to antibiotics, more research is needed before they can be translated into therapeutics for humans.
    Type of Medium: Online Resource
    ISSN: 2165-0497
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2022
    detail.hit.zdb_id: 2807133-5
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  • 8
    In: Biochemical and Biophysical Research Communications, Elsevier BV, ( 2023-12), p. 149463-
    Type of Medium: Online Resource
    ISSN: 0006-291X
    RVK:
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2023
    detail.hit.zdb_id: 1461396-7
    SSG: 12
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  • 9
    Online Resource
    Online Resource
    Frontiers Media SA ; 2023
    In:  Frontiers in Microbiology Vol. 14 ( 2023-6-22)
    In: Frontiers in Microbiology, Frontiers Media SA, Vol. 14 ( 2023-6-22)
    Abstract: Mycoplasma pneumoniae is a common causative pathogen of community-acquired pneumonia. An accurate and sensitive detection method is important for evaluating disease severity and treatment efficacy. Digital droplet PCR (ddPCR) is a competent method enabling the absolute quantification of DNA copy number with high precision and sensitivity. We established ddPCR for M. pneumoniae detection, using clinical specimens for validation, and this showed excellent specificity for M. pneumoniae . The limit of detection of ddPCR was 2.9 copies/reaction, while that for real-time PCR was 10.8 copies/reaction. In total, 178 clinical samples were used to evaluate the ddPCR assay, which correctly identified and differentiated 80 positive samples, whereas the real-time PCR tested 79 samples as positive. One sample that tested negative in real-time PCR was positive in ddPCR, with a bacterial load of three copies/test. For samples that tested positive in both methods, the cycle threshold of real-time PCR was highly correlated with the copy number of ddPCR. Bacterial loads in patients with severe M. pneumoniae pneumonia were significantly higher than those in patients with general M. pneumoniae pneumonia. The ddPCR showed that bacterial loads were significantly decreased after macrolide treatment, which could have reflected the treatment efficacy. The proposed ddPCR assay was sensitive and specific for the detection of M. pneumoniae . Quantitative monitoring of bacterial load in clinical samples could help clinicians to evaluate treatment efficacy.
    Type of Medium: Online Resource
    ISSN: 1664-302X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2023
    detail.hit.zdb_id: 2587354-4
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  • 10
    In: Microbiology Spectrum, American Society for Microbiology, Vol. 11, No. 4 ( 2023-08-17)
    Abstract: High-alcohol-producing K. pneumoniae (HiAlc Kpn ) causes nonalcoholic fatty liver disease (NAFLD) by producing excess endogenous alcohol in the gut of patients with NAFLD, using glucose as the main carbon source. The role of glucose in the response of HiAlc Kpn to environmental stresses such as antibiotics remains unclear. In this study, we found that glucose could enhance the resistance of HiAlc Kpn to polymyxins. First, glucose inhibited the expression of crp in HiAlc Kpn and promoted the increase of capsular polysaccharide (CPS), which promoted the drug resistance of HiAlc Kpn . Second, glucose maintained high ATP levels in HiAlc Kpn cells under the pressure of polymyxins, enhancing the resistance of the cells to the killing effect of antibiotics. Notably, the inhibition of CPS formation and the decrease of intracellular ATP levels could both effectively reverse glucose-induced polymyxins resistance. Our work demonstrated the mechanism by which glucose induces polymyxins resistance in HiAlc Kpn , thereby laying the foundation for developing effective treatments for NAFLD caused by HiAlc Kpn . IMPORTANCE HiAlc Kpn can use glucose to produce excess endogenous alcohol for promoting the development of NAFLD. Polymyxins are the last line of antibiotics and are commonly used to treat infections caused by carbapenem-resistant K. pneumoniae . In this study, we found that glucose increased bacterial resistance to polymyxins via increasing CPS and maintaining intracellular ATP; this increases the risk of failure to treat NAFLD caused by multidrug-resistant HiAlc Kpn infection. Further research revealed the important roles of glucose and the global regulator, CRP, in bacterial resistance and found that inhibiting CPS formation and decreasing intracellular ATP levels could effectively reverse glucose-induced polymyxins resistance. Our work reveals that glucose and the regulatory factor CRP can affect the resistance of bacteria to polymyxins, laying a foundation for the treatment of infections caused by multidrug-resistant bacteria.
    Type of Medium: Online Resource
    ISSN: 2165-0497
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2023
    detail.hit.zdb_id: 2807133-5
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