Characterization of nisin F and its role in the control of respiratory tract and skin infections

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dc.contributor.advisorDicks, Leon Milner Theodoreen_ZA
dc.contributor.authorDe Kwaadsteniet, Micheleen_ZA
dc.contributor.otherUniversity of Stellenbosch. Faculty of Science. Dept. of Microbiology.
dc.date.accessioned2009-03-11T08:22:06Zen_ZA
dc.date.accessioned2010-06-01T08:17:23Z
dc.date.available2009-03-11T08:22:06Zen_ZA
dc.date.available2010-06-01T08:17:23Z
dc.date.issued2009-03en_ZA
dc.descriptionThesis (PhD (Microbiology))--University of Stellenbosch, 2009.en_ZA
dc.description.abstractMultidrug resistant strains of Staphylococcus aureus is presenting an increasing threat, especially immune compromised individuals. Many of these strains have developed resistance to newly approved drugs such as quinupristin-dalfopristin, linezolid and daptomycin. The search for alternative treatment, including bacteriocins (ribosomally synthesized antimicrobial peptides) of lactic acid bacteria is increasing . Lactococcus lactis subsp. lactis F10, isolated from freshwater catfish, produced a new nisin variant active against clinical strains of S. aureus. The operon encoding nisin F is located on a plasmid and the structural gene has been sequenced. The lantibiotic is closely related to nisin Z, except at position 30 where valine replaced isoleucine. The antimicrobial activity of nisin F against S. aureus was tested in the respiratory tract of Wistar rats. Non-immunosuppressed and immunosuppressed rats were intranasally infected with S. aureus K and then treated with either nisin F or sterile physiological saline. Nisin F protected immunosuppressed rats against S. aureus, as symptoms of an infection were only detected in the trachea and lungs of immunosuppressed rats treated with saline. The safety of intranasally administered nisin F was also evaluated and proved to have no adverse side effects. The potential of nisin F as an antimicrobial agent to treat subcutaneous skin infections was evaluated by infecting C57BL/6 mice with a bioluminescent strain of S. aureus (Xen 36). Immunosuppressed mice were treated with either nisin F or sterile physiological saline 24 h and 48 h after infection with subcutaneously injected S. aureus Xen 36. Histology and bioluminescence flux measurements revealed that nisin F was ineffective in the treatment of deep dermal staphylococcal infections. Non-infected and infected mice treated with nisin F had an influx of polymorphonuclear cells in the deep stroma of the skin tissue. This suggested that nisin F, when injected subcutaneously, may have modulated the immune system. Nisin F proved an effective antimicrobial agent against S. aureus-related infections in the respiratory tract, but not against subcutaneous infections. The outcome of nisin F treatment thus depends on the route of administration and site of infection.en_ZA
dc.identifier.urihttp://hdl.handle.net/10019.1/1285
dc.language.isoenen_ZA
dc.publisherStellenbosch : University of Stellenbosch
dc.rights.holderUniversity of Stellenbosch
dc.subjectDissertations -- Microbiologyen
dc.subjectTheses -- Microbiologyen
dc.subject.lcshNisinen_ZA
dc.subject.lcshRespiratory infections -- Treatmenten_ZA
dc.subject.lcshDrug resistance in microorganismsen_ZA
dc.subject.lcshAntibiotics -- Therapeutic useen_ZA
dc.subject.lcshSkin -- Infections -- Treatmenten_ZA
dc.subject.lcshStaphylococcus aureusen_ZA
dc.subject.lcshBacteriocinsen_ZA
dc.titleCharacterization of nisin F and its role in the control of respiratory tract and skin infectionsen_ZA
dc.typeThesisen_ZA
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