Kunal Vaidya

Abstract

Bacterial infection is a rampant problem faced by the medical community. The bacteria gene pool is capable of adapting itself to changing conditions building biofilms to ensure the survival of progeny. This ability reduces the efficiency of antibiotics and protects the bacteria from immune system eradication, prompting the need for a technology capable of early detection of biofilms. The ability to non-invasively image and characterize bacterial biofilms in children during nasopharyngeal (NP) colonization with potential otopathogens and during acute otitis media, (AOM) would represent a significant advance. Identifying the properties of biofilms is a crucial step towards establishing a viable imaging detection plan. In this thesis work two modalities based on different imaging principles were used to study the properties of biofilms and map their progression based on quantitative metrics as a function of time. Systematic time studies were performed on three preparations of an isolated Haemophilus influenzae (NTHi) species, Streptococcus pneumoniae (Sp) and a combination of Haemophilus influenzae and Streptococcus pneumoniae (NTHi+Sp)in an in vitro environment (N=3). A 15 MHz ultrasound acquisition system was built to study the detection of biofilms with ultrasound. Various spectral parameters - peak frequency shift, bandwidth reduction, intercept, mid-band fit, and integrated backscatter coefficient (IBC) - were recorded in a time study of biofilm growth by the bacteria and underlying trends in the progression of these metrics were attributed to the biofilms construction of specific bacteria or the combination of 2 bacteria. The frequency content of the backscattered signal was compared to a theoretical Form Factor model to estimate the effective scatter size which was also used as a characterization metric for biofilm growth. To confirm the ultrasound observations a second imaging modality was applied. Confocal laser-scanning microscopy produces 3D high-resolution time resolved data. Volumetric analyses of confocal microscopy data were used to further define structural properties of biofilms and complement ultrasound-based findings.

Library of Congress Subject Headings

Biofilms--Detection; Imaging systems in biology; Medical microbiology; Pathogenic microorganisms--Detection

Publication Date

3-2014

Document Type

Dissertation

Student Type

Graduate

Degree Name

Imaging Science (Ph.D.)

Department, Program, or Center

Chester F. Carlson Center for Imaging Science (COS)

Advisor

Daniel Phillips

Advisor/Committee Member

Maria Helguera

Comments

Physical copy available from RIT's Wallace Library at QR100.8.B55 V34 2014

Campus

RIT – Main Campus

Plan Codes

IMGS-PHD

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