Hamza Mbareche

Samuel Lunenfeld Research Institute

Background Single nucleotide polymorphisms (SNPs) in the Interleukin 23 receptor (IL23R) gene have been implicated in CD pathogenesis and shown in animal models to be involved in regulation of intestinal epithelial barrier function via the production of IL17A. Additionally, previous studies suggest that IL23R may impact gut microbial composition po...

Background Previous studies have shown that offspring of Crohn’s disease (CD) patients have a 6-8 fold risk of incident CD than the general population. Also, newborns of women with CD (vs healthy women) have altered stool microbiome composition and elevated fecal calprotectin (FCP). The "peri-natal period" (pregnancy and first year postpartum) is c...

In the past few years, significant efforts have been made to investigate the transmission of COVID-19. This paper provides a review of the COVID-19 airborne transmission modeling and mitigation strategies. The simulation models here are classified into airborne transmission infectious risk models and numerical approaches for spatiotemporal airborne...

Introduction The Omicron variant of the SARS-CoV-2 virus is described as more contagious than previous variants. We sought to assess risk to healthcare workers (HCWs) caring for patients with COVID-19 in surgical/obstetrical settings, and the perception of risk amongst this group. Methods From January to April, 2022, reverse transcription polymera...

INTRODUCTION Lung microbiota plays a central role in health and disease development. Recently, recurrent viral infections in preschool age children were associated with lung microbiota carriage of Streptococcus pneumonia (SP). In addition, immune development and inflammatory responses have sexual dimorphism, but it is still controversial whether th...

During wastewater treatment, bioaerosols are generated and, can either remain in suspension for several hours or settle on surfaces and workers may be exposed. The presence of pathogens in the air could contribute to an increased frequency of gastrointestinal or respiratory illness amongst workers. Due to harsh winter conditions in Eastern Canada,...

The Association of Medical Microbiology and Infectious Disease Canada Conference–AMMI 2022, Vancouver, British Columbia, Canada.

Background: The exposure risks to front-line health care workers caring for patients with SARS-CoV-2 infection undergoing surgery or obstetric delivery are unclear, and an understanding of sample types that may harbour virus is important for evaluating risk. We sought to determine whether SARS-CoV-2 viral RNA from patients with SARS-CoV-2 infectio...

Wastewater treatment is one of the major biotechnological processes used to treat municipal and industrial sewage. All the steps involved in the removal of contaminants from wastewaters to treat municipal and industrial sewage represent a reservoir of a dynamic microbial communities with specific key players in the different process types. Aerosoli...

Background We determined the burden of SARS-CoV-2 in air and on surfaces in rooms of patients hospitalized with COVID-19 and investigated patient characteristics associated with SARS-CoV-2 environmental contamination. Methods Nasopharyngeal swabs, surface, and air samples were collected from the rooms of 78 inpatients with COVID-19 at six acute car...

Background We determined the burden of SARS-CoV-2 in air and on surfaces in rooms of patients hospitalized with COVID-19 and investigated patient characteristics associated with SARS-CoV-2 environmental contamination. Methods Nasopharyngeal swabs, surface, and air samples were collected from the rooms of 78 inpatients with COVID-19 at six acute ca...

Background: The exposure risks to front-line health care workers who are in close proximity for prolonged periods of time, caring for COVID-19 patients undergoing surgery or obstetrical delivery is unclear. Understanding of sample types that may harbour virus is important for evaluating risk. Objectives To determine if SARS-CoV-2 viral RNA from pat...

Public bus system worldwide transports daily more than 34 million people; therefore, air quality inside buses is an important urban air pollution issue. Airborne microbiological composition and abundance was examined inside five different fuel type buses (diesel (EURO IV and EURO V), hybrid diesel (HD), compressed natural gas (CNG), hybrid natural...

Student Research Conference

COVID-19 patients with respiratory distress require additional oxygen support. Some of the respiratory support devices used in intensive care units could increase the dispersion of infectious viral particles placing healthcare workers at increased risk of infection. The goal was to compare viral aerosol dispersion from invasive and non-invasive res...

Background The aim of this prospective cohort study was to determine the burden of SARS-CoV-2 in air and on surfaces in rooms of patients hospitalized with COVID-19, and to identify patient characteristics associated with SARS-CoV-2 environmental contamination. Methods Nasopharyngeal swabs, surface, and air samples were collected from the rooms of...

Rationale: Patients with severe COVID-19 require supplemental oxygen and ventilatory support. It is unclear whether some respiratory support devices may increase the dispersion of infectious bioaerosols and thereby place healthcare workers at increased risk of infection with SARS-CoV-2. Objectives: To quantitatively compare viral dispersion from...

This paper presents an in silico analysis to assess the current state of the fungal UNITE database in terms of the two eukaryote nuclear ribosomal regions, Internal Transcribed Spacers 1 and 2 (ITS1 and ITS2), used in describing fungal diversity. Microbial diversity is often evaluated with amplicon-based high-throughput sequencing approaches, which...

High-throughput DNA sequencing (HTS) has changed our understanding of the microbial composition present in a wide range of environments. Applying HTS methods to air samples from different environments allows the identification and quantification (relative abundance) of the microorganisms present and gives a better understanding of human exposure to...

Genome sequencing of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is increasingly important to monitor the transmission and adaptive evolution of the virus. The accessibility of high-throughput methods and polymerase chain reaction (PCR) has facilitated a growing ecosystem of protocols. Two differing protocols are tiling multiplex P...

A presentation about the career path in academia

This paper presents the performance of two eukaryotic genomic ribosomal regions, ITS1 and ITS2, in describing fungal diversity in aerosol samples using amplicon-based High-Throughput Sequencing (HTS). Composting sites, biomethanization facilities, and dairy farms, all affected by the presence of fungi, were visited to collect air samples. The ampli...

Fungal spores are ubiquitous in the air and their diversity and quantity vary depending on growth, the geographical location, environmental conditions, and the presence of sources. The health effects linked to this exposure are likely underestimated due to the presence of undocumented fungi. Culture methods are still widely used to describe fungal...

Le traitement des eaux usées comporte plusieurs étapes susceptibles de générer des bioaérosols auxquels des travailleurs peuvent être exposés. Bien que la littérature à ce sujet soit relativement abondante, les connaissances relatives au risque, à l’exposition et à la fréquence de certaines maladies chez cette population demeurent mal documentées....

Because bioaerosols are related to adverse health effects in exposed humans and indoor environments represent a unique framework of exposure, concerns about indoor bioaerosols have risen over recent years. One of the major issues in indoor bioaerosol research is the lack of standardization in the methodology, from air sampling strategies and sample...

Bioaerosols collected in a liquid-based sampler can be re-aerosolized into the airflow during collection and lost or concentrated in the collection fluid and overestimated during the subsequent analyses. Very little information is available concerning the specific impact on bioaerosol quantification and diversity and wrong evaluation of pathogens o...

A High-throughput sequencing and bioinformatics workshop designed for undergrad students and new beginners. The main focus of the workshop is to help you: Know the difference between sequencing technologies. Recognize the challenges faced in amplicon-based HTS and metagenomic studies. Choose the right method according to the objectives of your p...

Background: Bioaerosols are a major concern for public health and sampling for exposure assessment purposes is challenging. The nasopharyngeal region could be a potent carrier of long-term bioaerosol exposure agents. This study aimed to evaluate the correlation between nasopharyngeal bacterial flora of swine workers and the swine barns bioaerosol b...

This work shed light on a significant issue regarding the loss of fungal spores when recovered from air samples using liquid medium and centrifugation to concentrate air particles before DNA extraction. We provide proof that the loss affects the overall fungal diversity of aerosols and that some taxa are differentially more affected than others. Fu...

Bioaerosols are recognized as one of the main transmission routes for infectious diseases and are responsible for other various types of health effects through inhalation and potential ingestion. Associating exposure to bioaerosol and health problems is challenging and adequate exposure monitoring is a top priority for aerosol scientists. The multi...

While bioaerosols are a major concern for public health, accurately assessing human exposure is challenging. Highly contaminated environments, such as pig buildings, contain a broad diversity of aerosolized bacteria that may impact human health. The nasopharyngeal region may represent a long-term reservoir of inhaled bioaerosols. The herein study a...

Colloque de l’Association Québécoise des Cadres Scolaires. Saint-Sauveur, Québec, Canada.

Exposure to bioaerosols is connected to the development of respiratory diseases, and fungi play an important part in it. Fungal aerosols were first studied by culture methods. These classical methods induce a bias in fungal diversity: they do not represent all risks faced by exposed persons when they are in the presence of non-viable and/or non-cul...

Rendez-vous de la science de l’IRSST. Montreal, Québec, Canada.

Occupational exposure to harmful bioaerosols in industrial environments is a real threat to the workers. In particular, dairy-farmworkers are exposed to high levels of fungal bioaerosols on a daily basis. Associating bioaerosol exposure and health problems is challenging and adequate exposure monitoring is a top priority for aerosol scientists. Usi...

Bioaerosol studies aim to describe the microbial content and increase understanding of the aerosolization processes linked to diseases. Air samplers are used to collect, identify, and quantify bioaerosols. Studies comparing the performances of air samplers have typically used a culture approach or have targeted a specific microorganism in laborator...

While bioaerosols are a major concern for public health, accurately assessing human exposure is challenging. Highly contaminated environments, such as pig buildings, contain a broad diversity of aerosolized bacteria that may impact human health. The nasopharyngeal region may represent a long-term reservoir of inhaled bioaerosols. The herein study a...

La biométhanisation est un procédé de transformation anaérobie des matières organiques putrescibles (MOP) en biogaz et en digestat destiné à l'épandage en milieu agricole. Ce procédé est en forte croissance en raison de la Politique québécoise de gestion des matières résiduelles qui prévoit le bannissement de l'enfouissement des MOP, et ce, dès 202...

L’exposition aux bioaérosols de différents milieux de travail n’est pas étrangère au développement de maladies respiratoires; les moisissures y tiendraient d’ailleurs un rôle important. De par les activités qui y sont menées, certains milieux de travail génèrent de grandes quantités d’aérosols (incluant des moisissures), qui proviennent de la matiè...

Biomethanization is a new technology used for green-waste valorization where organic waste is biodegraded by microbial communities under anaerobic conditions. The main product of this type of anaerobic digestion is a biogas used as an energy source. Moving and handling organic waste may lead to the emission of high concentrations of bioaerosols. Hi...

L’exposition aux bioaérosols n’est pas étrangère au développement de maladies respiratoires. Les moisissures y tiendraient d’ailleurs un rôle important. Certains environnements génèrent de grandes quantités d’aérosols qui proviennent des différentes sources présentes. Les moisissures dans l’air ont d’abord été étudiée par des méthodes d’analyse par...

Occupational exposure to harmful bioaerosols in industrial environments is a real treat to the workers. In particular, dairy-farm workers are exposed to high levels of fungal bioaerosols on a daily basis. Associating bioaerosol exposure and health problems is challenging and adequate exposure monitoring is a top priority for aerosol scientists. Usi...

L’exposition aux bioaérosols n’est pas étrangère au développement de maladies respiratoires. Les moisissures y tiendraient d’ailleurs un rôle important. De par les activités qui y sont menées, certains environnements génèrent de grandes quantités d’aérosols qui proviennent des différentes sources présentes. La présence de moisissures dans l’air a d...

Bioaerosols are among the less studied particles in the environment. The lack of standardization in sampling procedures, difficulties related to the effect of sampling processes on the integrity of microorganisms, and challenges associated with the application of environmental microbiology analyses and molecular and culture methods frighten many yo...

Composting is used all over the world to transform different types of organic matter through the actions of complex microbial communities. Moving and handling composting material may lead to the emission of high concentrations of bioaerosols. High exposure levels are associated with adverse health effects among compost industry workers. Fungal spor...

Cours MCB-2000 Isolement et culture des microorganismes

Les bioaérosols représentent un important problème de santé publique, car ils sont des éléments fondamentaux de l’air. Particulièrement, les spores fongiques en suspension y constituent une des composantes les plus importantes en termes de nombre et d’effets sur la santé. En plus de la rhinite et de l’asthme, l’exposition aux champignons est associ...

Bioaerosols are commonly defined as biological particles suspended in the air. The concentration of bioaerosols found in the air of composting plants depend upon the source nature and composition, season, physical and mechanical factors such as wind and temperature. The aerosolization potential of particular microorganisms could significantly diffe...

Les bioaérosols représentent un important problème de santé publique, car ils sont des éléments fondamentaux de l’air. Particulièrement, les spores fongiques en suspension y constituent une des composantes les plus importantes en termes de nombre et d’effets sur la santé. Ils sont ubiquitaires dans l’environnement et considérés comme un facteur de...

This study sought to fill the gap in information about the type and the concentration of bioaerosols present in the air of biomethanization facilities (BF). Evaluation of bioaerosol composition and concentration was achieved in two biomethanization facilities located in Eastern Canada, during summer and winter. In order to have a thorough understan...

Composting is a natural dynamic biological process used to valorise putrescible organic matter. The composting process can involve vigorous movements of waste material piles, which release high concentrations of bioaerosols into the surrounding environment. There is a lack of knowledge concerning the dispersal of airborne microorganisms emitted by...

Aerosols of biological origin are a major concern for public health as they are a fundamental constituent of the air. Particularly, airborne fungal spores are one of its most important component as they are ubiquitous in indoor and outdoor environments and are considered a risk factor for respiratory diseases development. High fungal exposure has b...

Les bioaérosols représentent une source importante de contamination de l’air intérieur et extérieurs et la composition microbiologique de l’air est un sujet d’actualité depuis les dernières années. Parmi les microorganismes composant les bioaérosols, les Fungi semblent jouer un rôle important sur les effets nocifs pour la santé. Bien que dans certa...

Le compostage d’animaux morts présente des avantages de gestion et économiques important comparé aux autres modes de gestion de carcasses d’animaux. En effet, le compostage est considéré comme autonome et pouvant être réalisable à l’année. De plus, cela ne demande pas de grandes infrastructures et les entreprises peuvent procéder elles-mêmes à la m...

For the last decade, the microbial composition of aerosols has been a major public preoccupation as bioaerosols are a dominant source of indoor and outdoor air contamination. As a part of bioaerosols, fungi seems to play an important role in different health problems. Even though their association is still not well-defined and understood, the human...

La composition microbiologique de l’air est une préoccupation publique depuis les dernières années. Les bioaérosols représentent une source importante de contamination de l’air intérieur et extérieur. Parmi les microorganismes composant les bioaérosols, les Fungi semblent jouer un rôle important sur les effets nocifs pour la santé. Bien que dans ce...

Bioaerosols are generally characterized as biological particles suspended in the air. Mechanical, physical and seasonal factors affect the concentration of bioaerosols released from composting plants and thus, the exposure of workers. The morphological and biochemical differences between different microorganisms may affect their potential to be aer...

Composting whereby organic matter is stabilized due to aerobic microbial activity. The composting process involves vigorous movement of material waste, which releases a lot of bioaerosols into the environment. There is a lack of knowledge concerning the dispersal of airborne microorganisms emitted by composting plants (CP) as well as the potential...

Le compostage est un procédé permettant de gérer les déchets biodégradables et représente une des techniques les plus prometteuses dans la gestion des résidus biologiques pour les prochaines années. Le produit final obtenu à la suite du compostage peut être utilisé comme engrais afin de fertiliser les terres agricoles et la qualité de l’engrais dép...