The in vitro response of Acinetobacter baumannii to host signals simulating host cell damage
Cardiff Metropolitan University
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Acinetobacter baumannii has become the recent focus of investigations due to its increasing endemic spread in the nosocomial environment and high morbidity in association with underlying illness. Although the strength of the biofilm produced by different A. baumannii serotypes vary, strong biofilm forming strains have been firmly linked with its ability to grow on abiotic surfaces and resist disinfection and desiccation. The biofilm is responsible for establishing a safe community from which to disperse and cause infection, and recent studies have shown increased planktonic dispersal to be correlated with pathogenicity by upregulation of virulence genes, triggered in other species by host signals simulating illness and cell damage. The aim of the present study was to measure planktonic dispersal as an indicator of Acinetobacter baumannii’s response to interkingdom host signals simulating illness and cell damage: febrile temperature and cell lysate exposure. Methods include the culture of biofilms on microtitre plates, measured at total growth, planktonic dispersal and biomass by optical density, and colony forming unit counts conducted on planktonic samples to confirm culture purity and support spectrophotometer readings. Results of assays investigating the effects of cell lysate on planktonic dispersal at 37°C indicated the most dispersal in the absence of cell lysate, but results at febrile temperatures (39°C and 40°C) revealed a significant pattern of decreasing planktonic dispersal as cell lysate concentration increased. A novel observation was made of the inhibitory effects that increased temperature has on the dispersal of A. baumannii, as significant reduction in biofilm dispersal was seen at higher temperatures with and without cell lysate present. Conclusions summarise that A. baumannii responds to host signals simulating illness and cell damage by retaining biomass and decreasing planktonic dispersal, however the study requires further investigation into the subject by more complex methods, with more separately analysed signal component variables, extended range of cell lysate concentrations, with more time for repeats.
BSc (Hons) Biomedical Science
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