Survey of ground, surface, and potable waters for the presence of Legionella species by EnviroAmpR PCR Legionella Kit, culture, and immunofluorescent staining

A total of 116 samples from numerous aquatic sources including water from faucets, showerheads, dental units, fire sprinklers, and surface waters were examined for the presence of Legionella by the EnviroAmpR Legionella PCR Kit, culture on BCYEα, or direct fluorescent antibody (DFA) staining. In addition, 58 ground water samples collected across the U.S. were also examined for the presence of Legionella species by PCR and by culture on BCYEα and BCYEα-GVPC. Of the 58 ground water samples tested by polymerase chain reaction (PCR) assay, 93% were positive by PCR, while only 7% were culture positive. Analysis of the remaining samples indicated that 52.7% of the samples were positive by PCR, 50.0% were positive by DFA, while 8.3% were culture positive. Although Legionella species were frequently detected by PCR in all water types examined, concentrations were typically less than 103 cells per ml. Legionalla species were detected much more frequently than was Legionella pneumophila in all aquatic samples. DFA results correlated well to PCR results but culture results were often negative for Legionella due to overgrowth, competition, or inhibition by background organisms. Results of this type of survey confirm the ubiquity of Legionella in aquatic environments, even ground waters. This study represents the first in depth survey of ground water across the United States.