• Login
    View Item 
    •   UMB Digital Archive
    • School, Graduate
    • Theses and Dissertations All Schools
    • View Item
    •   UMB Digital Archive
    • School, Graduate
    • Theses and Dissertations All Schools
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Browse

    All of UMB Digital ArchiveCommunitiesPublication DateAuthorsTitlesSubjectsThis CollectionPublication DateAuthorsTitlesSubjects

    My Account

    LoginRegister

    Statistics

    Display statistics

    Modulation of microbial growth and antimicrobial activity of aminoglycosides by oxygen tensions in gram-negative bacteria

    • CSV
    • RefMan
    • EndNote
    • BibTex
    • RefWorks
    Find Full text
    Author
    Park, Matthew Kihoon
    Advisor
    Marzella, Louis
    Date
    1991
    Type
    dissertation
    
    Metadata
    Show full item record
    Abstract
    Oxygen tensions alter microbial growth, antimicrobial activity, and host responses to infections. In particular, hyperoxia is bactericidal for microorganisms with deficient antioxidant defenses and influences the activity of several classes of antimicrobial agents. I hypothesized that hyperoxia can augment the bacteriostatic and bactericidal effects of protein synthesis inhibitors by increasing the generation of reactive oxygen species. To test this hypothesis, I have characterized the interactions between hyperoxia and aminoglycosides on the growth of gram-negative bacteria. Growth inhibition was quantitated by determining the postantibiotic effect (PAE; the period of bacterial growth suppression that follows a brief exposure to an antibiotic) under normoxic and hyperoxic conditions. I found that hyperoxia (100% O{dollar}\sb2{dollar}, 101.3 kPa) enhanced the PAE of tobramycin against P. aeruginosa. The delay in growth recovery was associated with reduced rates of protein synthesis. Hyperbaric oxygen (100% O{dollar}\sb2{dollar}, 274.5 kPa) further suppressed the growth recovery of P. aeruginosa. I next examined the effects of hyperoxia on bacterial growth and killing by aminoglycosides in the family Enterobacteriaceae. While hyperoxia did not influence bacterial growth, hyperoxia markedly influenced the bactericidal activity of aminoglycosides in a strain-specific manner. This finding extends the range of oxygen tensions that are known to influence the bactericidal activity of tobramycin. Finally, I investigated the role of reactive oxygen species in the hyperoxic enhancement of the tobramycin-induced PAE in P. aeruginosa. Hyperoxia is known to increase the intracellular flux of reactive oxygen species. I found that hyperoxia induced antioxidant defenses and that tobramycin blocked this induction. However, antioxidants did not decrease the susceptibility of tobramycin-exposed P. aeruginosa to hyperoxia. I conclude that hyperoxia influences the bacteriostatic and bactericidal activities of aminoglycosides against gram-negative bacteria. These findings have potential implications for the treatment of infections in patients exposed to high fractional inspired oxygen concentrations.
    Description
    University of Maryland, Baltimore. Pathology. Ph.D. 1991
    Keyword
    Microbiology
    Health Sciences, Medicine and Surgery
    Health Sciences, Pathology
    Aminoglycosides
    Gram-Negative Bacteria
    Hyperoxia--microbiology
    Pseudomonas aeruginosa
    Identifier to cite or link to this item
    http://hdl.handle.net/10713/2461
    Collections
    Theses and Dissertations School of Medicine
    Theses and Dissertations All Schools

    entitlement

     
    DSpace software (copyright © 2002 - 2021)  DuraSpace
    Quick Guide | Policies | Contact Us | UMB Health Sciences & Human Services Library
    Open Repository is a service operated by 
    Atmire NV
     

    Export search results

    The export option will allow you to export the current search results of the entered query to a file. Different formats are available for download. To export the items, click on the button corresponding with the preferred download format.

    By default, clicking on the export buttons will result in a download of the allowed maximum amount of items.

    To select a subset of the search results, click "Selective Export" button and make a selection of the items you want to export. The amount of items that can be exported at once is similarly restricted as the full export.

    After making a selection, click one of the export format buttons. The amount of items that will be exported is indicated in the bubble next to export format.