Development of a model to study the interaction of Staphylococcus epidermidis with phagocytic cells on the surface of bone and prosthetic joint material

Robertson, Sheona Anne (2000) Development of a model to study the interaction of Staphylococcus epidermidis with phagocytic cells on the surface of bone and prosthetic joint material. PhD thesis, University of Glasgow.

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Abstract

The genus Staphylococcus contains common pathogens of both humans and animals. In this study the phagocytic ingestion of two strains of Staphylococcus epidermidis adherent to the surface of a biomaterial was investigated. The two strains used were M7 and RP62A, and although both can adhere, strain M7 cannot accumulate onto a substrate. The biomaterial chosen for the study was polymethyl methacrylate, a polymer commonly used in the manufacture of orthopaedic implants. Phagocytic ingestion of the bacteria from the biomaterial was then compared to phagocytosis from bone and polystyrene. Factors affecting phagocytosis such as: slime production, hydrophobicity and the differences in phagocytic capacity of the polymorphonuclear leukocytes, by comparing neutrophils from different patient populations, was investigated. The phagocytic capacities of different cells were compared. These cells were neutrophils, monocytes and J774 cells- a murine macrophage-like cell line. This study showed that both strains of bacteria were able to adhere to the substrates tested in equal amounts. Differences arose when one strain, (RP62A) was then able to accumulate and produce slime whereas M7 could not. Accumulation was noted by the absence of any slime production by strain M7. Both strains of bacteria were found to be hydrophilic in nature. This was determined using two methods, MATH and HIC, both of which correlate well. When phagocytosis of the two strains was compared, no significant difference was found between strains. Strain M7 was slightly easier ingested by neutrophils than RP62A. When neutrophil phagocytosis was compared to phagocytosis by monocytes and J774 cells the order of increasing phagocytic capacity was monocytes > J774 cells > neutrophils. The nature of the substrate can also affect the ingestion of adhered bacteria. Both strains were found to be hydrophilic in nature. Unfortunately the hydrophobicity of the substrates was not determined but strain to strain differences in the ingestion of adhered bacteria was observed. M7 was phagocytosed with no significant difference between any of the substrates. However, with RP62A there was no significant difference between bone and prosthetic joint material, but a highly significant difference was observed between bone and polyethylene. The phagocytic capacity of patient groups to ingest adhered bacteria was also investigated. Two patient groups, those with Diabetes Mellitus and those with Rheumatoid Arthritis were studied. They were chosen as both were groups of patients who have Known immunodeficiencies and may require joint replacement therapy due to the nature of their disease. There was no significant difference in the phagocytic capacity of the neutrophils from patients with Rheumatoid Arthritis or with Diabetes Mellitus compared to the control group. When the groups themselves were further investigated only a gender difference in patients with diabetes mellitus was found. A significant difference between male and female neutrophils to ingest strain RP62A was highlighted. No such difference was observed in patients with Rheumatoid Arthritis. Thus is it not the phagocytic capacity of the neutrophils from these patient populations that pre-disposes them to infection after joint arthroplasty. (Abstract shortened by ProQuest.).

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: C G Gemmell
Keywords: Microbiology
Date of Award: 2000
Depositing User: Enlighten Team
Unique ID: glathesis:2000-72008
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 24 May 2019 15:11
Last Modified: 24 May 2019 15:11
URI: http://theses.gla.ac.uk/id/eprint/72008

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