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  • Frontiers Media SA  (23)
  • Bao, Qiyu  (23)
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  • Frontiers Media SA  (23)
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  • 1
    In: Frontiers in Microbiology, Frontiers Media SA, Vol. 13 ( 2022-12-1)
    Abstract: In this study, we identified and characterized a novel chromosomally-encoded class B metallo-β-lactamase (MBL) gene designated bla WUS-1 in a carbapenem-resistant isolate Myroides albus P34 isolated from sewage discharged from an animal farm. Comparative analysis of the deduced amino acid sequence revealed that WUS-1 shares the highest amino acid similarities with the function-characterized MBLs MUS-1 (AAN63647.1; 70.73%) and TUS-1 (AAN63648.1; 70.32%). The recombinant carrying bla WUS-1 exhibited increased MICs levels against a number of β-lactam antimicrobials such as carbenicillin, ampicillin and imipenem, and β-lactamase inhibitors (clavulanic acid and tazobactam). The metallo-β-lactamase WUS-1 could also hydrolyze these antimicrobials and the hydrolytic activities could be inhibited by EDTA. Genetic context analysis of bla WUS-1 revealed that no mobile genetic element was found in its surrounding region. The plasmid pMA84474 of Myroides albus P34 harbored 6 resistance genes ( bla OXA-347 , aadS , bla MYO-1 , ereD , sul2 and ermF ) within an approximately 17 kb multidrug resistance (MDR) region. These genes, however, were all related to mobile genetic elements.
    Type of Medium: Online Resource
    ISSN: 1664-302X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
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  • 2
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    Frontiers Media SA ; 2023
    In:  Frontiers in Microbiology Vol. 14 ( 2023-8-28)
    In: Frontiers in Microbiology, Frontiers Media SA, Vol. 14 ( 2023-8-28)
    Abstract: Aminoglycosides, as important clinical antimicrobials, are used as second-line drugs for treating multidrug-resistant tuberculosis or combined with β-lactam drugs for treating severe infections such as sepsis. Aminoglycoside-modifying enzyme (AME) is the most important mechanism of aminoglycoside resistance and deserves more attention. Methods The bacterium Kluyvera intermedia DW18 was isolated from the sewage of an animal farm using the conventional method. The agar dilution method was used to determine the minimum inhibitory concentrations (MICs) of antimicrobials. A novel resistance gene was cloned, and the enzyme was expressed. The kinetic parameters were measured by a SpectraMax M5 multifunctional microplate reader. Bioinformatic analysis was performed to reveal the genetic context of the aph(3′)-Id gene and its phylogenetic relationship with other AMEs. Results A novel aminoglycoside 3′- O -phosphotransferase gene designated aph(3′)-Id was identified in K. intermedia DW18 and shared the highest amino acid identity of 77.49% with the functionally characterized aminoglycoside 3′- O -phosphotransferase APH(3′)-Ia. The recombinant plasmid carrying the novel resistance gene (pMD19- aph(3′)-Id / E. coli DH5α) showed 1,024-, 512-, 128- and 16-fold increased MIC levels for kanamycin, ribostamycin, paromomycin and neomycin, respectively, compared with the reference strain DH5α. APH(3′)-Id showed the highest catalytic efficiency for ribostamycin [ k cat /K m of (4.96 ± 1.63) × 10 5 M −1 /s −1 ], followed by paromomycin [ k cat /K m of (2.18 ± 0.21) × 10 5 M −1 /s −1 ], neomycin [ k cat /K m of (1.73 ± 0.20) × 10 5 M −1 /s −1 ], and kanamycin [ k cat /K m of (1.10 ± 0.18) × 10 5 M −1 /s −1 ]. Three conserved functional domains of the aminoglycoside phosphotransferase family and ten amino acid residues responsible for the phosphorylation of kanamycin were found in the amino acid sequence of APH(3′)-Id. No mobile genetic element (MGE) was discovered surrounding the aph(3′)-Id gene. Conclusion In this work, a novel aminoglycoside 3’- O -phosphotransferase gene designated aph(3′)-Id encoded in the chromosome of the environmental isolate Kluyvera intermedia DW18 was identified and characterized. These findings will help clinicians select effective antimicrobials to treat infections caused by pathogens with this kind of resistance gene.
    Type of Medium: Online Resource
    ISSN: 1664-302X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2023
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  • 3
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    Frontiers Media SA ; 2023
    In:  Frontiers in Microbiology Vol. 14 ( 2023-7-17)
    In: Frontiers in Microbiology, Frontiers Media SA, Vol. 14 ( 2023-7-17)
    Abstract: Pantoea species of the family Erwiniaceae are well-known plant pathogens and animal and human conditional pathogens. Due to the widespread and continuous use of antimicrobials, multidrug-resistant strains continue to emerge, making clinical treatment difficult; therefore, there is an increasing need to clarify the mechanisms of drug resistance. Methods A rabbit anal fecal sample was collected by a swab and the streak plate method was used to isolate single colonies. The standard agar dilution method was used to determine the minimum inhibitory concentrations (MICs) against antimicrobials. The complete genome sequence of the bacterium was obtained using Next-Generation Sequencing platforms. The potential resistance gene was annotated based on the Comprehensive Antibiotic Resistance Database (CARD) and verified by molecular cloning. The β-lactamase PSZ-1 was expressed via the pCold I expression vector and its enzyme kinetic parameters were analyzed. The genetic environment and evolutionary process of the novel resistance gene-related sequences were analyzed by bioinformatic methods. Results The isolate Pantoea endophytica X85 showed some degree of resistance to penicillins as well as cephalosporins. A novel AmpC resistance gene, designated bla PSZ-1 in this research, was identified to be encoded in the plasmid (pPEX85) of P. endophytica X85. Bla PSZ-1 showed resistance to penicillins and several first-, second-and third-generation cephalosporins as well as aztreonam, but it did not show resistance to the fourth-generation cephalosporins or carbapenems tested. Enzyme kinetic assays revealed that it could hydrolyze amoxicillin, penicillin G, cephalothin, and cefazolin, and its hydrolytic activity could be strongly inhibited by the inhibitor avibactam, which was generally consistent with antimicrobial susceptibility testing results. No hydrolytic activity was observed for third-generation cephalosporins or aztreonam. Conclusion In this study, a novel AmpC β-lactamase gene, designated bla PSZ-1, was characterized and it was encoded in the plasmid of the bacterium P. endophytica X85. It shows resistance to penicillins and several cephalosporins. The discovery of novel drug resistance mechanisms can help guide the scientific use of drugs in animal husbandry and clinical practice, effectively avoiding the abuse of antimicrobials and thus preventing the further development and spread of bacterial resistance.
    Type of Medium: Online Resource
    ISSN: 1664-302X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2023
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  • 4
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    Frontiers Media SA ; 2023
    In:  Frontiers in Microbiology Vol. 14 ( 2023-9-21)
    In: Frontiers in Microbiology, Frontiers Media SA, Vol. 14 ( 2023-9-21)
    Abstract: Achromobacter is a genus of gram-negative bacteria that can act as opportunistic pathogens. Recent studies have revealed that some species of Achromobacter show inherent resistance to β-lactams, but the resistance mechanisms of Achromobacter mucicolens have rarely been reported. Method The bacterium was isolated using standard laboratory procedures. The agar dilution method was used to determine the minimum inhibitory concentrations (MICs). Genome sequencing was performed using the PacBio RS II and Illumina HiSeq 2500 platforms, and the Comprehensive Antibiotic Resistance Database (CARD) was used to annotate the drug resistance genes. The localization of the novel β-lactamase AMZ-1 was determined, and its characteristics were determined via molecular cloning and enzyme kinetic analysis. The phylogenetic relationship and comparative genomic analysis of the resistance gene-related sequences were also analyzed. Result Achromobacter mucicolens Y3, isolated from a goose on a farm in Wenzhou, showed resistance to multiple antibiotics, including penicillins and cephalosporins. Bla AMZ–1 showed resistance to amoxicillin, penicillin G, ampicillin, cephalothin and cefoxitin, and the resistance activity could be inhibited by β-lactamase inhibitors. Enzyme kinetic analysis results showed that AMZ-1 has hydrolytic activity against a wide range of substrates, including cephalothin, amoxicillin, penicillin G, and cefoxitin but not ampicillin. The hydrolytic activity of AMZ-1 was greatly inhibited by avibactam but much more weakly inhibited by tazobactam. Mobile genetic elements could not be found around the bla AMZ–1 -like genes, which are conserved on the chromosomes of bacteria of the genus Achromobacter . Conclusion In this study, a novel AmpC gene, bla AMZ–1 , from the animal-origin bacterium A. mucicolens Y3 was identified and characterized. It conferred resistance to some penicillins and first- and second-generation cephalosporins. The identification of this novel resistance gene will be beneficial for the selection of effective antimicrobials to treat associated infections.
    Type of Medium: Online Resource
    ISSN: 1664-302X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2023
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  • 5
    In: Frontiers in Microbiology, Frontiers Media SA, Vol. 13 ( 2022-9-13)
    Abstract: A novel chromosome-encoded aminoglycoside O -nucleotidyltransferase AadA33 was identified in Providencia vermicola strain P13. The AadA33 shares the highest amino acid identity of 51.28% with the function characterized AadA31. Antibiotic susceptibility testing and enzyme kinetics analysis revealed that the function of AadA33 is to mediate spectinomycin and streptomycin resistance. The recombinant strain harboring aadA33 (pUCP20- aadA33 / Escherichia coli DH5α) displayed & gt;256- and 128-fold increases in the minimum inhibitory concentration levels to spectinomycin and streptomycin, respectively, compared with the control strains pUCP20/DH5α. Enzyme kinetic parameters manifested the substrate of AadA33 including spectinomycin and streptomycin, with k cat / K m of 3.28 × 10 4 (M −1 s −1 ) and 3.37 × 10 4 (M −1 s −1 ), respectively. Bioinformatics analysis revealed its structural mechanism of antimicrobial resistance, genetic context, and phylogenetic relationship with other aminoglycoside O -nucleotidyltransferases. This study of AadA33 contributed to understanding the function and resistance mechanism of aminoglycoside O -nucleotidyltransferase.
    Type of Medium: Online Resource
    ISSN: 1664-302X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
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  • 6
    Online Resource
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    Frontiers Media SA ; 2021
    In:  Frontiers in Microbiology Vol. 12 ( 2021-8-31)
    In: Frontiers in Microbiology, Frontiers Media SA, Vol. 12 ( 2021-8-31)
    Abstract: A novel plasmid-encoded aminoglycoside 3''-nucleotidyltransferase ANT(3")-IId, was discovered in Acinetobacter lwoffi strain H7 isolated from a chick on an animal farm in Wenzhou, China. The whole-genome of A. lwoffii H7 consisted of one chromosome and five plasmids (pH7-250, pH7-108, pH7-68, pH7-48, and pH7-11). ant(3")-IId was identified as being encoded on pH7-250, sharing the highest amino acid identity of 50.64% with a function-known resistance gene, ant(3")-IIb (KB849358.1). Susceptibility testing and enzyme kinetic parameter analysis were conducted to determine the function of the aminoglycoside 3"-nucleotidyltransferase. The ant(3")-IId gene conferred resistance to spectinomycin and streptomycin [the minimum inhibitory concentration (MIC) levels of both increased 16-fold compared with the control strain]. Consistent with the MIC data, kinetic analysis revealed a narrow substrate profile including spectinomycin and streptomycin, with K cat / K m ratios of 4.99 and 4.45×10 3 M −1 S −1 , respectively. Sequencing analysis revealed that the ant(3")-IId gene was associated with insertion sequences (IS) element [ΔIS Aba14 -ΔIS Aba14 -hp-orf-orf-orf1- ant(3")-IId ], and ant(3")-IId were identified in plasmids from various Acinetobacter species. This study of the novel aminoglycoside 3"-nucleotidyltranferase ANT(3")-IId helps us further understand the functional and sequence characteristics of aminoglycoside 3"-nucleotidyltranferases, highlights the risk of resistance gene transfer among Acinetobacter species and suggests that attention should be given to the emergence of new aminoglycoside 3"-nucleotidyltranferase genes.
    Type of Medium: Online Resource
    ISSN: 1664-302X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2021
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  • 7
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    Frontiers Media SA ; 2022
    In:  Frontiers in Microbiology Vol. 13 ( 2022-11-1)
    In: Frontiers in Microbiology, Frontiers Media SA, Vol. 13 ( 2022-11-1)
    Abstract: In this study, we characterized a novel chromosome-encoded aminoglycoside nucleotidyltransferase (ANT), AadA36, from the Providencia stuartii strain P14 isolated from the sputum specimen of a burn patient at a hospital in Wenzhou, China. Among the functionally characterized ANTs, AadA36 shared the highest amino acid sequence identity of 51.91% with AadA14. The whole genome of P. stuartii P14 consisted of one chromosome and two plasmids (designated pP14-166 and pP14-114). A total of 19 genes with ≥80% similarity with functionally characterized antimicrobial resistance genes (ARGs) were identified in the whole genome, including aminoglycosides [ aac(2′)-Ia , aph(6)-Id , aph(3″)-Ib , aac(6′)-Ib , ant(3″)-IIa , aph(3′)-Ia ], β-lactams ( bla CMY-2 and bla OXA-10 ) and so on. Antimicrobial susceptibility testing showed that the aadA36 gene conferred specific resistance to spectinomycin and streptomycin, and the minimum inhibitory concentration (MIC) of these antimicrobials increased 128- and 64-fold compared with the control strain. The kinetic parameters of AadA36 were consistent with the MIC data of spectinomycin and streptomycin, with k cat / K m ratios of (1.07 ± 2.23) × 10 4  M −1 s −1 and (8.96 ± 1.01) × 10 3 M −1 s −1 , respectively. The identification of a novel aminoglycoside resistance gene will help us further understand the complexity of the resistance mechanisms and provide deep insights into the dissemination of resistance genes in the microbial population.
    Type of Medium: Online Resource
    ISSN: 1664-302X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
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  • 8
    In: Frontiers in Microbiology, Frontiers Media SA, Vol. 13 ( 2022-11-23)
    Abstract: Lelliottia amnigena , a bacterium usually isolated from natural environments, may cause human infections and has been suggested to be naturally resistant to second- and third-generation cephalosporins. Methods In this study, we determined the whole-genome sequence of an isolate, L. Amnigena P13, isolated from animal farm sewage. On the basis of genome sequence analysis, susceptibility testing, molecular cloning, and enzyme kinetic parameter analysis, we identified a novel chromosome-encoded AmpC β-lactamase, LAQ-1. Results and Discussion bla LAQ-1 is resistant to penicillin G, ampicillin, and several first- to fourth-generation cephalosporins, such as cefazolin, cefoxitin and cefepime. The MIC levels of some β-lactams, such as cefoxitin, cefepime, aztreonam and cefazolin, for the recombinant clone (pUCP24- bla LAQ-1 /DH5α) increased by approximately 4- to 64-fold compared with those of the control strain (pUCP24/DH5α). The kinetic properties of LAQ-1, with the highest catalytic activity observed toward piperacillin, were basically the same as those of typical class C β-lactamases, and avibactam had a strong inhibitory effect on its hydrolytic activity. The genetic background of bla LAQ-1 was relatively conserved, and no mobile genetic element (MGE) was found around it. The plasmid pP13-67 of L. amnigena P13 harbored 12 resistance genes [ qnrS1, aph(6)-Id, aadA2, sul1, sul2, bla TEM-1 , qacEΔ1, dfrA12 , tetA and floR ] related to different mobile genetic elements within an ~22 kb multidrug resistance region. The multidrug resistance region shared the highest nucleotide sequence similarities with those of the chromosomes or plasmids of different bacterial species, indicating the possibility of horizontal transfer of these resistance genes among different bacterial species.
    Type of Medium: Online Resource
    ISSN: 1664-302X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
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  • 9
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    Frontiers Media SA ; 2021
    In:  Frontiers in Microbiology Vol. 12 ( 2021-12-17)
    In: Frontiers in Microbiology, Frontiers Media SA, Vol. 12 ( 2021-12-17)
    Abstract: In this work, we characterized a novel chromosome-encoded AmpC β-lactamase gene, bla PRC–1 , in an isolate of a newly classified Pseudomonas species designated Pseudomonas wenzhouensis A20, which was isolated from sewage discharged from an animal farm in Wenzhou, China. Susceptibility testing, molecular cloning, and enzyme kinetic parameter analysis were performed to determine the function and enzymatic properties of the β-lactamase. Sequencing and comparative genomic analysis were conducted to clarify the phylogenetic relationship and genetic context of the bla PRC–1 gene. PRC-1 is a 379-amino acid AmpC β-lactamase with a molecular weight of 41.48 kDa and a predicted pI of 6.44, sharing the highest amino acid identity (57.7%) with the functionally characterized AmpC β-lactamase PDC-211 (ARX71249). bla PRC–1 confers resistance to many β-lactam antibiotics, including penicillins (penicillin G, amoxicillin, and amoxicillin-clavulanic acid) and cephalosporins (cefazolin, ceftriaxone, and cefotaxime). The kinetic properties of PRC-1 were compatible with those of a typical class C β-lactamase showing hydrolytic activities against β-lactam antibiotics, and the hydrolytic activity was strongly inhibited by avibactam. The genetic context of bla PRC–1 was relatively conserved, and no mobile genetic element was predicted in its surrounding region. Identification of a novel β-lactamase gene in an unusual environmental bacterium reveals that there might be numerous unknown resistance mechanisms in bacterial populations, which may pose potential risks to human health due to universal horizontal gene transfer between microorganisms. It is therefore of great value to carry out extensive research on the mechanism of antibiotic resistance.
    Type of Medium: Online Resource
    ISSN: 1664-302X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2021
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  • 10
    Online Resource
    Online Resource
    Frontiers Media SA ; 2021
    In:  Frontiers in Microbiology Vol. 12 ( 2021-11-19)
    In: Frontiers in Microbiology, Frontiers Media SA, Vol. 12 ( 2021-11-19)
    Abstract: Multidrug-resistant bacteria from different sources have been steadily emerging, and an increasing number of resistance mechanisms are being uncovered. In this work, we characterized a novel resistance gene named aac(2′)-If from an isolate of a novel Providencia species, Providencia wenzhouensis R33 (CCTCC AB 2021339). Susceptibility testing and enzyme kinetic parameter analysis were conducted to determine the function of the aminoglycoside 2′- N -acetyltransferase. Whole-genome sequencing and comparative genomic analysis were performed to elucidate the molecular characteristics of the genome and the genetic context of the resistance gene-related sequences. Among the functionally characterized resistance genes, AAC(2′)-If shares the highest amino acid sequence identity of 70.79% with AAC(2′)-Ia. AAC(2′)-If confers resistance to several aminoglycoside antibiotics, showing the highest resistance activity against ribostamycin and neomycin. The recombinant strain harboring aac(2′)-If (pUCP20- aac(2′)-If /DH5α) showed 256- and 128-fold increases in the minimum inhibitory concentration (MIC) levels to ribostamycin and neomycin, respectively, compared with those of the control strains (DH5α and pUCP20/DH5α). The results of the kinetic analysis of AAC(2′)-If were consistent with the MIC results of the cloned aac(2′)-If with the highest catalytic efficiency for ribostamycin ( k cat /K m ratio = [3.72 ± 0.52] × 10 4 M –1 ⋅ s –1 ). Whole-genome sequencing demonstrated that the aac(2′)-If gene was located on the chromosome with a relatively unique genetic environment. Identification of a novel aminoglycoside resistance gene in a strain of a novel Providencia species will help us find ways to elucidate the complexity of resistance mechanisms in the microbial population.
    Type of Medium: Online Resource
    ISSN: 1664-302X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2021
    detail.hit.zdb_id: 2587354-4
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