Date on Master's Thesis/Doctoral Dissertation

8-2013

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Biology

Committee Chair

Remold, Susanna K.

Author's Keywords

Biogeography; Pseudomonas; Burkholderia; Cystic Fibrosis

Subject

Biogeography--Kentucky--Louisville; Pseudomonas; Cystic fibrosis

Abstract

15 households in the Louisville Metro area were sampled, 7 had a patient with cystic fibrosis (CF), and 8 did not. Houses were sampled between 3 and 8 times each, and samples were collected from 123 different sites within and around the homes. These sites were categorized into the variable environment type based on ecological similarity of sites. Between 75 and 168 samples were collected from each home per visit. Recovery was examined for biogeographical patterns by environment type and season at multiple taxonomic levels. Approximately 10% of samples taken yielded Pseudomonas, and of these 61% were P. putida group, 23% P. fluorescens group, and 15% P. aeruginosa group. Environment type and season influenced patterns of Pseudomonas species recovery at all taxonomic levels (genus, species groups, and species), and house of recovery influenced recovery for all species groups but P. aeruginosa. Soils and drains were the environment types with the highest recovery. Soils had the highest recovery rates for P. fluorescens group and P. putida group, while drains had the highest recovery rates for P. aeruginosa group. This indicates that household Pseudomonas distribution is influenced by dispersal limitation as well as adaption to the environment. Recovery from the opportunistic pathogen, P. aeruginosa, was examined in greater detail with the aim of determining hotspots of recovery in the home. Drains were identified as hotspots for P. aeruginosa recovery were identified and no differences in recovery from drains were found in houses with CF patients compared to those without CF patients. No P. aeruginosa was recovered from animals, and only a single isolate was recovered from each soils and equipment used to treat CF. Indicating that P. aeruginosa is a drain specialist regardless of patient presence. The human home was investigated as a potential source of Burkholderia spp. by looking at recovery from various types of environments. Overall, the recovery rate of Burkholderia sp. was very low (0.22%). Isolates that were recovered were primarily from soil environments and drains. Isolates evenly clustered within two phylogenetic clades: the plant-associated beneficial environmental group described by Suárez-Moreno et al. (2012) and the B. cepacia complex.

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