Rapid In-Field Detection of Airborne Pathogens Using Loop-Mediated Isothermal Amplification (LAMP)

Abstract

Multiple human and plant pathogens are dispersed and transmitted as bioaerosols (e.g., Mycobacterium tuberculosis, SARS-CoV-2, Legionella pneumophila, Aspergillus fumigatus, Phytophthora spp., and Fusarium graminearum). Rapid, on-site methods to detect airborne pathogens would greatly enhance our ability to monitor exposure and trigger early mitigation measures across different settings. Analysis of air samples for microorganisms in a regulatory context is often based on culture-based methods, which are slow, lack specificity, and are not suitable for detecting viruses. Molecular methods (based on nucleic acids) could overcome these challenges. For example, loop-mediated isothermal amplification (LAMP) is rapid, sensitive, specific, and may detect microbial pathogens from air samples in under 60 min. However, the low biomass in air samples makes recovering sufficient nucleic acids for detection challenging. To overcome this, we present a simple method for concentrating bioaerosols collected through liquid impingement (one of the most common methods for bioaerosol collection). This method paired with LAMP (or other molecular approaches) offers simple, rapid, and sensitive detection of pathogens. We validated this method using three airborne pathogens (Mycobacterium tuberculosis, Legionella pneumophila, and Aspergillus fumigatus), and we were able to detect fewer than five cells in a 15 mL liquid impinger air sample in under 60 min. This simple method offers rapid pathogen detection without the use of specialist equipment, and it can be used across healthcare, education, environmental monitoring, and military settings.

Keywords: airborne pathogen; bioaerosol; biological aerosols; loop-mediated isothermal amplification (LAMP); rapid detection.

Figure 1

Workflow for rapid detection of airborne pathogens, from the air sample to the result in under 60 min.

Figure 2

(A) Gel electrophoresis image of LAMP products and (B) reaction tubes at 0, 30, and 50 min for LAMP assay for the E. coli malB gene. Yellow color indicates positive LAMP reaction, orange indicates negative reaction. L = ladder (1 KB); the number indicates the number of cells in the reaction. Rhodococcus sp. negative control contained (10⁴ cells reaction⁻¹). NTC = No template control (i.e., PCR-grade water in place of DNA template/cells).