Date of Award

Spring 2012

Degree Name

Bachelor of Science



First Advisor

Dr. Lisa-Anne Foster


The human body is colonized with commensal microbes that attach to the skin and mucosal membranes and function to protect the host as part of the innate immune response. These indigenous microbiota are able to prevent infections by blocking attachment sites and outcompeting invading pathogens for necessary nutrients. Disturbance of the host-microbe symbiotic balance may increase a host’s susceptibility to disease. In addition, proper colonization of the normal flora has been implicated in playing a vital role in shaping the immune response. It has been hypothesized that reduced exposure to infectious microorganisms early in life can disrupt the development of normal immune regulation. This “hygiene hypothesis” states that the increased prevalence of allergic diseases in developed countries can be attributed to a more hygienic, westernized lifestyle that is characterized by a decrease in microbial challenges. Therefore, the allergic disease asthma, which is characterized by a heightened inflammatory response, could be the result of disturbed microbial colonization, hindrance of immune maturation, and subsequent disregulation of the allergic response. It would be expected that asthmatic individuals would exhibit a less diverse and less abundant population of normal flora as compared to non-asthmatic individuals. This preliminary study investigated the bacterial communities found in the upper respiratory tracts of asthmatic and non-asthmatic subjects. Terminal restriction fragment length polymorphism (tRFLP) was used to examine the composition of bacteria in oropharyngeal samples collected from student volunteers at Trinity College. The tRFLP profiles of asthmatic and non-asthmatic subjects produced conflicting results, and it cannot be concluded if there is a difference in the diversity or abundance of bacterial communities in the upper respiratory tracts of both populations.


Senior thesis completed at Trinity College for the degree of Bachelor of Science in Biology.