Certified Healthcare Safety Professional (CHSP) Practice Exam

Which genus of bacteria is responsible for the disease legionellosis?

1. Legionella

2. Clostridium

3. Escherichia

4. Staphylococcus

The correct answer is: Legionella

The genus responsible for the disease legionellosis is Legionella. This genus comprises various species, with Legionella pneumophila being the most significant pathogen associated with the disease. Legionellosis primarily manifests in two forms: legionnaires' disease, which can lead to severe pneumonia, and Pontiac fever, characterized by a milder flu-like illness. Legionella bacteria are typically found in freshwater environments, such as lakes and streams, and can also thrive in man-made water systems, including hot tubs, cooling towers, and plumbing systems. The transmission of legionellosis occurs through inhalation of aerosolized water droplets containing the bacteria, making understanding and monitoring these environments crucial for preventing outbreaks. In contrast, the other genera listed—Clostridium, Escherichia, and Staphylococcus—do not cause legionellosis and are associated with different infections. Clostridium is known for producing toxins that can lead to diseases such as tetanus and botulism, Escherichia includes species like E. coli, which can cause gastrointestinal infections, and Staphylococcus is known for a variety of conditions, including skin infections and food poisoning. Therefore, Legionella is the only genus among the choices that is specifically linked to the condition in