Date of Award

Fall 12-3-2019

Degree Type


Degree Name

MS Microbiology




TinChun Chu, Ph.D.

Committee Member

Jane L. Ko, Ph.D.

Committee Member

Daniel B. Nichols, Ph.D.

Committee Member

Angela V. Klaus, Ph.D.

Committee Member

Heping Zhou, Ph.D.


Legionella, Passaic County, Detection


Legionella spp. are gram-negative bacteria that are found in a wide range of freshwater environments such as lakes, streams, soil, and manmade water systems. The Legionella genera contains 58 species of bacteria and of them approximately half have been linked to human disease. Infection due to Legionella spp. is known as Legionellosis, which consists of Legionnaires’ disease and Pontiac fever. Legionnaires’ disease cases have been increasing in recent years and the CDC report 7,500 cases in 2017. Infection from Legionella occurs through inhalation of aerosolized water droplets and leads to infection of alveolar macrophages. Legionella pneumophila is responsible for 90% of the cases of Legionnaires’ disease. Currently, L. pneumophila is often detected through culturing. The culture-based assay is a time-consuming process that can take several days and may lead in inconclusive results due to viable but nonculturable cells or low concentrations of cells. This study focused on the development of a new protocol in detecting Legionella spp. and L. pneumophila within biofilms and water samples. Polymerase chain reaction (PCR) based assays were performed for the detection of Legionella spp. and L. pneumophila within 183 samples collected. Of the 183 samples tested, 33 (18%) samples were positive for L. pneumophila and 47 (25.6%) were positive for Legionella spp. Quantitative PCR based assays were then performed on the positive samples to quantify the concentrations of L. pneumophila and L. pneumophila serogroup 1. Amplification was seen for one of the PCR positive samples, suggesting that the samples that were positive were below the limit of quantitation for qPCR. Following molecular detection, positive samples were sequenced and bioinformatic analysis indicated that the environmental samples were closely related to L. pneumophila serogroups 1, 3, 4, and 6.

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