Abstract
Legionella is a genus of bacteria commonly found in freshwater and moist soil environments such as water towers, potable water systems, compost, and soil mix. Legionella bacteria are the causative agent of Legionnaires’ disease (LD), a severe form of community-transmitted pneumonia with a potentially fatal outcome. LD is a major cause of hospital admissions in New Zealand and around the world. Proper management and treatment of this disease depend on rapid identification of the pathogen. However, current testing methodologies rely on collection of sputum samples from severely ill (and often intubated) patients leading to inconsistent testing. The clinical presentation of LD cannot be clinically or radiographically distinguished from other types of pneumonia, which often results in empirical treatment of symptoms with broad-spectrum antibiotics. This begets poorer patient outcomes and overuse of antimicrobial agents, thus feeding into the evolution of antimicrobial resistance.
During my Honours project I developed and validated a CRISPR-Cas12a diagnostic assay designed to detect Legionella cell-free DNA circulating in the bloodstream. This could provide hospitals and clinics around New Zealand with a tool for the fast, sensitive, and less invasive diagnosis of Legionnaires’ disease, leading to more appropriate prescription of antibiotic medication and better patient outcomes. The availability of an accessible diagnostic test would fuel a better understanding of the epidemiology of this disease, as well as provide a diagnostic platform for other infectious diseases where sample collection is challenging.