Environmental Health Microbiology

professor jianhua guo and a/professor gilda carvalhoProf Jianhua Guo and A/Prof Gilda Carvalho co-lead the Environmental Health Microbiology team at QAEHS. They contribute to assessing and determining the potential benefits or harm that micro-organisms in the environment may pose to harm human health or our activities.

Environmental health microbiology is a branch of public health concerned with the environmental occurrence of disease-causing microbes, such as viruses and bacteria. Understanding how and where these microbes are present creates health-supportive environments for individuals and communities. This interdisciplinary research aids policy makers or health protection organisations to develop policy, strategy and technology that will effectively protect public health.

Meet the Environmental Health Microbiology research team.

Antimicrobial resistance (AMR) is a looming threat to public health world-wide. AMR occurs when bacteria, parasites, fungi and viruses evolve over time and no longer respond to medicines, making infections harder to treat and increasing the risk of disease spread, severe illness and death. Resistant bacteria can be found in clinical settings and throughout the natural environment. When antibiotics and antimicrobial compounds are consumed by humans or animals, they do not completely break down during metabolism and are excreted into the environment - whether that be via wastewater treatment plants, animal manure, aquaculture reservoirs, and water bodies.

Through methods such as wastewater-based epidemiology, we aim to understand the prevalence of antibiotic resistance in communities, as well as to reveal the role of non-antibiotic pharmaceuticals in the spread of antibiotic resistance. Control of antimicrobial resistance in water is critical. Disinfection in water and wastewater treatment plants (WWTPs) is a vital barrier against antibiotic resistant bacteria (ARB) as recent research highlights WWTPs as a hotspot for the transmission of antibiotic resistance and in the emergence of resistant pathogens.

Previous studies mainly focus on the fates of antibiotic resistance in liquid (i.e., wastewater) and solid (i.e., biosolids) phases. However, little is known about the occurrence, abundance and diversity of ARB and antibiotic resistance genes (ARGs) in bioaerosols from indoor and outdoor zones in WWTPs. Through aeration and mechanical agitation in WWTPs, waterborne pathogens, ARB and even ARGs may be released into the air and form airborne bacteria, which could pose potential health risks for workers of WWTPs and for neighbours in close proximity.

Supporting positive health, environmental and social outcomes is vital for sustaining productive livelihoods in communities facing water scarcity or water-contamination. Through wastewater surveillance and monitoring of drinking water systems, we can better address public health issues across the developed and developing world.

In developed countries, opportunistic pathogens (OP), such as Legionella spp. and nontuberculous mycobacteria (NTM), are major causes of waterborne disease outbreaks. These pathogens are particularly concerning as they contribute to infections acquired in hospitals and health care facilities posing a risk to vulnerable patients.

Plumbing networks within buildings have several characteristics that favour microbial growth, both in the water and as drinking water biofilms lining the interior surfaces of pipes. Drinking water biofilms have been identified as sources of infection within these systems, as they foster a complex ecology, persistence, and increased pathogenicity of waterborne opportunistic pathogens.

In plumbing networks, these opportunistic pathogens may be transmitted through contaminated aerosols and direct contact (such as through skin and abrasions) released by drinking water outlets to downstream users and susceptible individuals, leading to severe health implications. Due to challenges with accessibility, labour and cost with sampling biofilms in plumbing networks, many studies have focused on evaluating biofilms in simulated setups, and sampling for water samples.

There is currently limited understanding of the microbial ecology occurring in real premise plumbing networks, as well as the occurrence and conditions that contribute to the prevalence of OPs.