Canadian journal of microbiology最新文献

Africa's vast geographic and climatic diversity makes it a critical region for the ecology and spread of avian influenza viruses, particularly due to its role as a wintering ground for Palearctic migratory waterbirds. The continent has experienced multiple waves of clade 2.3.4.4b A/H5Nx high pathogenicity avian influenza (HPAI), which has caused widespread outbreaks in poultry and wild birds since 2017. From 2023 to mid-2025, clade 2.3.4.4b A/H5N1 outbreaks were reported across West and Southern Africa, with severe impacts on poultry production and conservation of endangered wild bird species. Concurrently, South Africa and Mozambique battled an unprecedented A/H7N6 HPAI epizootic in 2023, leading to the culling or loss of over 6.8 million chickens. Additionally, the A/H9N2 subtype, particularly G5.5 sublineage strains, continues to circulate in North, West, and East Africa, with reassortant viruses with A/H5Nx viruses reported in Egypt. Underreporting and limited surveillance hamper accurate epidemiological assessment. Despite these challenges, advancements in noninvasive environmental sampling offer promising tools for early detection. Strengthening regional cooperation and surveillance is essential for mitigating future outbreaks and protecting both animal and public health.

Coinfection and secondary infection by fungi in patients with viral pulmonary infection, especially SARS-CoV-2, are important factors that worsen the prognosis and are associated to increased death rates. This work aims to report the prevalence of Candida isolates in bronchoalveolar and nasopharyngeal samples from suspected COVID-19 patients in the first-second pandemic waves and their antifungal resistance profile. From 2321 patients, 29.04% were diagnosed with SARS-CoV-2 infection. The yeast isolation rate of 6.97% (47/674) from positive SARS-CoV-2 was statistically higher than 4.43% (73/1647) from negative SARS-CoV-2 patients (p = 0.0177). Among yeasts, the most prevalent species was Candida albicans (63/120), with four being azole-resistant isolates (6.35%); however, other emerging and less susceptible species were also isolated, such as Candida guilliermondii (11), Candida glabrata (5), Candida lusitaniae (4), Candida krusei (1), and Candida norvegensis (1). Here, we highlighted Candida prevalence in respiratory tract, emphasizing the relevance for surveillance in SARS-CoV-2/COVID patients for improvement of management as well as patient outcomes.

Community-associated Clostridioides difficile infections (CA-CDI) remain a concern in Canada, comprising a quarter of cases previously reported through the Canadian Nosocomial Infection Surveillance Program. Previous Canadian studies have reported toxigenic C. difficile isolated from Canadian retail meat, suggesting that it may be a source of exposure for CA-CDI in Canada. In this study, 3/219 (1.4%) of retail pork and 0/99 (0%) of retail beef samples tested positive for toxigenic C. difficile, which were molecularly characterized by PCR ribotyping and whole-genome sequencing. All three isolates were obtained from pork and belonged to sequence types (STs)/ribotypes (RTs) that have previously been isolated from human clinical CA-CDI cases in Canada: ST1/RT027, ST8/RT002, and ST10/RT015. Retail meat isolates were susceptible to the antimicrobials tested, save one isolate with intermediate resistance to clindamycin. Genomic comparison to Canadian human clinical CA-CDI isolates with the same corresponding ST/RT types showed two of the three pork isolates clustered with CA-CDI isolates via core-genome multilocus sequencing typing, with single nucleotide variant (SNV) analysis showing further genomic relatedness of 2-11 SNVs. Retail meat may therefore be a low source of CA-CDI exposure in Canada, with the potential for foodborne transmission of select clones.

Streptococcus suis and Glaesserella parasuis are commensal organisms that can shift from a benign to pathogenic state and cause severe disease in swine. We hypothesized that a change in host temperature and/or interactions with G. parasuis could impact S. suis growth dynamics. We compared phenotypic properties of a clinical S. suis serovar 9 strain (SS9C) with clinical serovar 2 and healthy serovar 9 isolates grown at 37 and 41 °C. We further investigated how co-culturing with G. parasuis affected biofilm formation of SS9C. Crystal violet staining indicated that SS9C produced significantly more biofilm than the other strains when grown at 37 °C; this difference was amplified at 41 °C. However, cell counts did not increase at the higher temperature. Biofilms of SS9C at 37 and 41 °C were unaffected by DNase I digestion, while other strains were both susceptible at 41 °C. All biofilms were susceptible to proteinase K and α-amylase digestion at both temperatures. We showed that growth at 41 °C increased biofilm formation and shifted the phenotype of SS9C; however, neither increased temperature nor co-culture with G. parasuis increased planktonic or sessile cell counts. Our study suggests that increased temperature in the host may be an important factor in understanding S. suis disease development.

Antimicrobial resistance is an environmental, agricultural, and public health problem that is impacting the health of humans and animals. The role of the environment as a source of and transmission pathway for antibiotic resistant bacteria and antibiotic resistance genes is a topic of increasing interest that, to date, has received limited attention. This study aimed to describe the sources and possible pathways contributing to antimicrobial resistance dissemination through bioaerosols, water, and soil in Canada using a scoping review methodology and systems thinking approach. A systems map was created to describe the occurrence and relationships between sources and pathways for antimicrobial resistance dissemination through water, soil, and bioaerosols. The map guided the development of the scoping review protocol, specifically the keywords searched and what data were extracted from the included studies. In total, 103 studies of antimicrobial resistance in water, 67 in soil, and 12 in air were identified. Studies to detect the presence of antimicrobial resistance genes have mainly been conducted at wastewater treatment plants and commercial animal livestock facilities. We also identified elements in the systems map with little or no data available (e.g., retail) that need to be investigated further to have a better understanding of antimicrobial resistance dissemination through different Canadian environments.

Bacteria encounter various stressful conditions within a variety of dynamic environments, which they must overcome for survival. One way they achieve this is by developing phenotypic heterogeneity to introduce diversity within their population. Such distinct subpopulations can arise through endogenous fluctuations in regulatory components, wherein bacteria can express diverse phenotypes and switch between them, sometimes in a heritable and reversible manner. This switching may also lead to antigenic variation, enabling pathogenic bacteria to evade the host immune response. Therefore, phenotypic heterogeneity plays a significant role in microbial pathogenesis, immune evasion, antibiotic resistance, host niche tissue establishment, and environmental persistence. This heterogeneity can result from stochastic and responsive switches, as well as various genetic and epigenetic mechanisms. The development of phenotypic heterogeneity may create clonal populations that differ in their level of virulence, contribute to the formation of biofilms, and allow for antibiotic persistence within select morphological variants. This review delves into the current understanding of the molecular switching mechanisms underlying phenotypic heterogeneity, highlighting their roles in establishing infections caused by select bacterial pathogens.

As it flows through the collection system, maple sap is likely to be contaminated by microorganisms that colonize the tubing, potentially compromising its quality in terms of physicochemical properties, microbial load, and flavor. This study investigates the effect of microbial inoculation, as protective cultures, on the sap collection system to improve maple syrup quality. The research explored how inoculating collection tubing with specific bacterial strains influences the microbial composition, physicochemical properties (pH, Brix, conductivity, sugars, and organic acids content), and sensory attributes of both maple sap and syrup. Three strains selected for their capacity to produce biofilm on plastic tubing and their impact on maple syrup production from inoculated sap, Pseudomonas sp. MSB2019, Janthinobacterium lividum 100-P12-9, and Pseudomonas fluorescens ATCC 17926, were inoculated to independent sap collection system throughout two sugaring seasons. A non-inoculated system was included. Pseudomonas sp. MSB2019 treatment resulted in a distinct bacterial composition in sap and impact the organoleptic properties of syrup by the end of second flow season, particularly the maple and overall flavor intensity scores were higher. While sap yield and primary microbial load remained unaffected, inoculation treatments corresponded to shifts in flavor attributes of the syrup. These findings indicate that inoculating sap collection systems with targeted strains can positively influence maple syrup quality, particularly in enhancing desirable flavor profiles, suggesting promising applications for syrup production.

Many arthropods, including economically important pests of stored grains, host intracellular bacterial symbionts. These symbionts can have diverse impacts on host morphology, stress tolerance, and reproductive success. The ability to rapidly determine the infection status of host insects and the identity of intracellular symbionts, if present, is vital to understanding the biology and ecology of these organisms. We used a microbiome profiling method based on amplicon sequencing to rapidly screen 35 captive insect colonies. This method effectively revealed single and mixed infections by intracellular bacterial symbionts, as well as the presence or absence of a dominant symbiont, when that was the case. Because no a priori decisions are required about probable host-symbiont pairing, this method is able to quickly identify novel associations. This work highlights the frequency of endosymbionts, indicates some unexpected pairings that should be investigated further, such as dominant bacterial taxa that are not among the canonical genera of endosymbionts, and reveals different colonies of the same host insect species that differ in the presence and identity of endosymbiotic bacteria.

M13 bacteriophages form self-assembled nanorods with the ability to self-assemble into complex materials with higher-order structures. These features make them useful templates for material fabrication. Their use in soft materials, bio-nano systems, and biomedical applications is well established. For these bio-interfacial applications, it is crucial that phages remain biocompatible and their production sustainable. Here, we review the bioprocessing of M13 phages and genetic engineering strategies that retain their natural assets in nanomaterials or bulk materials. Specifically, we highlight the extensively studied fermentation process of M13 phages with Escherichia coli (E. coli) and common downstream processing methods suitable for materials manufacturing. The ease of phage production contributes to its wide use for phage display, enabling the creation of large libraries of functional mutants. For materials purposes, genetic engineering often targets the pIII and pVIII proteins, enabling different geometries and fragment sizes. We also review common peptides displayed on phages, including arginine-glycine-aspartic acid (RGD) peptides, used for surface plasmon resonance (SPR) probes, targeted medicine, cell regeneration, or tissue scaffolding. We study glutamate-modified phages for metal binding, biomineralization, and electronics in bulk materials. By considering self-assembly, bioprocessing, and genetic engineering, material engineers can fully harness M13 phages for diverse functional and sustainable devices.