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  • 1
    Online Resource
    Online Resource
    RpoN Modulates Carbapenem Tolerance in Pseudomonas aeruginosa through Pseudomonas Quinolone Signal and PqsE
    American Society for Microbiology ; 2016
    In:  Antimicrobial Agents and Chemotherapy Vol. 60, No. 10 ( 2016-10), p. 5752-5764
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 60, No. 10 ( 2016-10), p. 5752-5764
    Abstract: The ability of Pseudomonas aeruginosa to rapidly modulate its response to antibiotic stress and persist in the presence of antibiotics is closely associated with the process of cell-to-cell signaling. The alternative sigma factor RpoN (σ 54 ) is involved in the regulation of quorum sensing (QS) and plays an important role in the survival of stationary-phase cells in the presence of carbapenems. Here, we demonstrate that a Δ rpoN mutant grown in nutrient-rich medium has increased expression of pqsA , pqsH , and pqsR throughout growth, resulting in the increased production of the Pseudomonas quinolone signal (PQS). The link between pqsA and its role in carbapenem tolerance was studied using a Δ rpoN Δ pqsA mutant, in which the carbapenem-tolerant phenotype of the Δ rpoN mutant was abolished. In addition, we demonstrate that another mechanism leading to carbapenem tolerance in the Δ rpoN mutant is mediated through pqsE . Exogenously supplied PQS abolished the biapenem-sensitive phenotype of the Δ rpoN Δ pqsA mutant, and overexpression of pqsE failed to alter the susceptibility of the Δ rpoN Δ pqsA mutant to biapenem. The mutations in the Δ rpoN Δ rhlR mutant and the Δ rpoN Δ pqsH mutant led to susceptibility to biapenem. Comparison of the changes in the expression of the genes involved in QS in wild-type PAO1 with their expression in the Δ rpoN mutant and the Δ rpoN mutant-derived strains demonstrated the regulatory effect of RpoN on the transcript levels of rhlR , vqsR , and rpoS . The findings of this study demonstrate that RpoN negatively regulates the expression of PQS in nutrient-rich medium and provide evidence that RpoN interacts with pqsA , pqsE , pqsH , and rhlR in response to antibiotic stress.
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.00260-16
    RVK:
    XA 24552
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2016
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
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  • 2
    Online Resource
    Online Resource
    Novel Pseudomonas aeruginosa Gene That Suppresses Tolerance to Carbapenems
    American Society for Microbiology ; 2003
    In:  Antimicrobial Agents and Chemotherapy Vol. 47, No. 9 ( 2003-09), p. 2997-3001
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 47, No. 9 ( 2003-09), p. 2997-3001
    Abstract: A biapenem-tolerant mutant of Pseudomonas aeruginosa was isolated by Tn 1737 KH insertion. The survival of the mutant 3 h after the addition of biapenem was about 1,000 times greater than that of the wild type. The mutant was also tolerant to other biapenems, such as imipenem, panipenem, and meropenem.
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.47.9.2997-3001.2003
    RVK:
    XA 24552
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2003
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
    Location Call Number Limitation Availability
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  • 3
    Online Resource
    Online Resource
    rpoN Gene of Pseudomonas aeruginosa Alters Its Susceptibility to Quinolones and Carbapenems
    American Society for Microbiology ; 2007
    In:  Antimicrobial Agents and Chemotherapy Vol. 51, No. 4 ( 2007-04), p. 1455-1462
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 51, No. 4 ( 2007-04), p. 1455-1462
    Abstract: The alternative sigma factor σ 54 has been implicated in diverse functions within the cells. In this study, we have constructed an rpoN mutant of Pseudomonas aeruginosa and investigated its importance as a target for antimicrobial agents, such as quinolones and carbapenems. The stationary-phase cells of the rpoN mutant displayed a survival rate approximately 15 times higher than that of the wild-type cells in the presence of quinolones and carbapenems. The stationary phase led to substantial production of pyoverdine by the P. aeruginosa rpoN mutant. Pyoverdine synthesis correlated with decreased susceptibility to antimicrobial agents. Quantitative real-time PCR revealed that stationary-phase cells of the rpoN mutant grown without an antimicrobial agent had approximately 4- to 140- and 2- to 14-fold-higher levels of transcripts of the pvdS and vqsR genes, respectively, than the wild-type strain. In the presence of an antimicrobial agent, levels of pvdS and vqsR transcripts were elevated 400- and 5-fold, respectively, in comparison to the wild-type levels. Flow cytometry assays using a green fluorescent protein reporter demonstrated increased expression of the vqsR gene in the rpoN mutant throughout growth. A pvdS mutant of P. aeruginosa , deficient in pyoverdine production, was shown to be susceptible to biapenem. These findings suggest that rpoN is involved in tolerance to antimicrobial agents in P. aeruginosa and that its tolerant effect is partly dependent on increased pyoverdine production and vqsR gene expression.
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.00348-06
    RVK:
    XA 24552
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2007
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
    Location Call Number Limitation Availability
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  • 4
    Online Resource
    Online Resource
    Highly expressed human sialyl Lewisx antigen on cell surface of Streptococcus gallolyticus
    Elsevier BV ; 1996
    In:  The Lancet Vol. 347, No. 9003 ( 1996-03), p. 760-
    Details
    In: The Lancet, Elsevier BV, Vol. 347, No. 9003 ( 1996-03), p. 760-
    Type of Medium: Online Resource
    ISSN: 0140-6736
    URL: Article
    DOI: 10.1016/S0140-6736(96)90109-9
    RVK:
    XA 10000
    Language: English
    Publisher: Elsevier BV
    Publication Date: 1996
    detail.hit.zdb_id: 2067452-1
    detail.hit.zdb_id: 3306-6
    detail.hit.zdb_id: 1476593-7
    SSG: 5,21
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  • 5
    Online Resource
    Online Resource
    Fosfomycin Reduces CD15s-Related Antigen Expression of Streptococcus pyogenes
    American Society for Microbiology ; 1998
    In:  Antimicrobial Agents and Chemotherapy Vol. 42, No. 5 ( 1998-05), p. 1083-1087
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 42, No. 5 ( 1998-05), p. 1083-1087
    Abstract: We have previously shown the immunological mimicry of human sialyl-Lewis x (CD15s) by a surface antigen of Streptococcus pyogenes . This mimicking surface antigen may act as a ligand to the selectin family and may induce antibody production against CD15s on host cells, suggesting a possible role in the pathogenesis of S. pyogenes . In this study, the effects of antibiotics on the CD15s-related antigen expression of S. pyogenes were examined at a concentration below the MIC (sub-MIC). The amounts of CD15s on the surfaces of S. pyogenes cells and on the surfaces of S. pyogenes biofilms were determined by a whole-cell enzyme-linked immunosorbent assay and by laser scanning fluorescence microscopy, respectively, by using an anti-CD15s monoclonal antibody. At the sub-MICs, fosfomycin (1 R ,2 S -1,2-epoxypropyl phosphonic acid), its enantiomer (1 S ,2 R -1,2-epoxypropyl phosphonic acid), and benzylpenicillin significantly inhibited the CD15s expression of all strains studied. The effects of fosfomycin and its enantiomer on biofilms were also observed by scanning electron microscopy. Incubation of S. pyogenes with the sub-MIC of fosfomycin or its enantiomer, which has no antibacterial activity, reduced the amount of CD15s on the biofilm surface and made it smooth. These results suggest that fosfomycin or its enantiomer might be useful for preventing S. pyogenes adherence to human CD15s receptors and the resulting immunological pathogenicity.
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.42.5.1083
    RVK:
    XA 24552
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1998
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
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  • 6
    Online Resource
    Online Resource
    Role of psl Genes in Antibiotic Tolerance of Adherent Pseudomonas aeruginosa
    American Society for Microbiology ; 2017
    In:  Antimicrobial Agents and Chemotherapy Vol. 61, No. 7 ( 2017-07)
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 61, No. 7 ( 2017-07)
    Abstract: Bacteria attached to a surface are generally more tolerant to antibiotics than their planktonic counterparts, even without the formation of a biofilm. The mechanism of antibiotic tolerance in biofilm communities is multifactorial, and the genetic background underlying this antibiotic tolerance has not yet been fully elucidated. Using transposon mutagenesis, we isolated a mutant with reduced tolerance to biapenem (relative to that of the wild type) from adherent cells. Sequencing analysis revealed a mutation in the pslL gene, which is part of the polysaccharide biosynthesis operon. The Pseudomonas aeruginosa PAO1Δ pslBCD mutant demonstrated a 100-fold-lower survival rate during the exposure of planktonic and biofilm cells to biapenem; a similar phenotype was observed in a mouse infection model and in clinical strains. Transcriptional analysis of adherent cells revealed increased expression of both pslA and pelA , which are directly regulated by bis-(3′,5′)-cyclic dimeric GMP (c-di-GMP). Inactivation of wspF resulted in significantly increased tolerance to biapenem due to increased production of c-di-GMP. The loss of pslBCD in the Δ wspF mutant background abolished the biapenem-tolerant phenotype of the Δ wspF mutant, underscoring the importance of psl in biapenem tolerance. Overexpression of PA2133, which can catalyze the degradation of c-di-GMP, led to a significant reduction in biapenem tolerance in adherent cells, indicating that c-di-GMP is essential in mediating the tolerance effect. The effect of pslBCD on antibiotic tolerance was evident, with 50- and 200-fold-lower survival in the presence of ofloxacin and tobramycin, respectively. We speculate that the psl genes, which are activated by surface adherence through elevated intracellular c-di-GMP levels, confer tolerance to antimicrobials.
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.02587-16
    RVK:
    XA 24552
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2017
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
    Location Call Number Limitation Availability
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  • 7
    Online Resource
    Online Resource
    Susceptibilities of Oral and Nasal Isolates of Streptococcus mitis and Streptococcus oralis to Macrolides and PCR Detection of Resistance Genes
    American Society for Microbiology ; 2000
    In:  Antimicrobial Agents and Chemotherapy Vol. 44, No. 4 ( 2000-04), p. 1078-1080
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 44, No. 4 ( 2000-04), p. 1078-1080
    Abstract: The susceptibility of viridans group streptococci to macrolides was determined. Thirteen isolates (17%) were resistant to erythromycin. Five strains carried an erm gene that was highly homologous to that in Tn 917 . Four strains had mefE genes that coded erythromycin efflux ability.
    Type of Medium: Online Resource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.44.4.1078-1080.2000
    RVK:
    XA 24552
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 2000
    detail.hit.zdb_id: 1496156-8
    SSG: 12
    SSG: 15,3
    Location Call Number Limitation Availability
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    Online Resource
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