Sequence-based typing to identify novel Polymorphisms among Legionella Pneumophila isolates in Western Pennsylvania

Legionella pneumophila is a gram-negative bacterium that can cause two types of human illness, Legionnaires’ disease and Pontiac fever. The goal of this study was to determine the sequence types (STs) for several L. pneumophila isolates collected in western Pennsylvania and compare them to STs from other geographic areas. Investigating ST of L. pneumophila can help to establish control measures and determine sources of outbreaks, both of which are of great public health significance. Environmental and patient samples were collected in Pittsburgh and Erie, Pennsylvania from October 2013 through December 2014. Sequence-based typing (SBT) was conducted to determine the sequence type of L. pneumophila present in the samples. Out of the nine STs that were identified in western Pennsylvania, five were novel. The known STs found in this study were ST 8, 986, 154, and 1941. When compared to similar SBT studies done in Portugal, Canada, England, and Spain, the results of the Pittsburgh study proved to be unique due to the identification of the five novel STs. The known STs found in the study were also not commonly found in investigations in other geographic areas. Overall, the results from the Pittsburgh investigation indicate environmental and patient isolates from western Pennsylvania have a unique ST compared to other isolates of L. pneumophila from around the world