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Biofilm Production and Susceptibility Among Candida albicans Isolates from Various Clinical Sites

Press, Ellen Grace (2014) Biofilm Production and Susceptibility Among Candida albicans Isolates from Various Clinical Sites. Master's Thesis, University of Pittsburgh. (Unpublished)

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Candida albicans exists as a commensal in healthy adults but is one of the most common causes of fungal infections in the United States. Candida is known to form biofilms (highly organized networks of cells adherent to a surface) on foreign devices and host tissues; infections associated with these structures are associated with increased virulence and drug resistance. However, the in vitro methods of growth and quantification used to assess these characteristics are poorly standardized. In vitro studies suggest minor alterations in growth conditions can drastically affect resultant structures. This project seeks to determine the best methods for biofilm growth and analysis. Utilizing these methods, this study examines whether biofilm production of clinical Candida albicans isolates varies based on conditions of clinical collection, namely the presence or absence of a urinary or bloodstream catheter at time collection and clinical collection site. Additionally, the relationship between extent of biofilm production and antifungal susceptibility will be examined. Eighteen bloodstream (n=10) or urine (n=8) clinical isolates, with (n=9) and without (n=9) a catheter present, will be exposed to urinary catheters and allowed to grow. Resultant biofilm will be quantified using four reported methods: biomass by crystal violet and dry weight, and metabolic activity of free-floating (planktonic) and adherent (sessile) cells, separately. Sessile bioactivity was the most reliable of tested methods, and dry weight was the least. Methods of quantification did not correlate well. Based on reproducibility and correlation, crystal violet and sessile metabolic activity, used together, provide a good indication as to the extent of biofilm production of clinical isolates. Biofilm production did not vary for isolates based on catheter presence or clinical site at time of collection, suggesting biofilm is capable of forming under many clinical conditions. Antifungal susceptibility testing of adherent biofilms showed increased minimum inhibitory concentrations to amphotericin B and fluconazole, with minor increases for caspofungin. There was no difference in drug susceptibility by catheter association or collection site. Biofilm susceptibility is warranted in the clinic; however, quantification methods described here are both labor- and time-consuming. Future studies are needed to develop new methods of quantification.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Press, Ellen Graceelp52@pitt.eduELP52
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee CoChairShields, Ryanshieldsrk@upmc.eduRSHIERES
Committee CoChairPoloyac, Samuelpoloyac@pitt.eduPOLOYAC
Committee MemberEmpey, Kerry Mkme33@pitt.eduKME33
Committee MemberClancy, Cornelius Jcjc76@pitt.eduCJC76
Date: 4 December 2014
Date Type: Publication
Defense Date: 27 October 2014
Approval Date: 4 December 2014
Submission Date: 4 December 2014
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 63
Institution: University of Pittsburgh
Schools and Programs: School of Pharmacy > Pharmaceutical Sciences
Degree: MS - Master of Science
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: Candida, biofilm, susceptibility
Date Deposited: 04 Dec 2014 16:41
Last Modified: 19 Dec 2016 14:42


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