Canadian journal of microbiology最新文献

Clade 2.3.4.4b Eurasian-origin H5N1 entered North America in late 2021 and spread across the continent. While studies have characterized the antibody response mounted by dabbling ducks following exposure, little data are available for diving ducks. This study sought to identify influenza A virus (IAV) infection and antibodies in Lesser and Greater Scaup captured in Maryland, Illinois, and Rhode Island. In Maryland, IAV seroprevalence increased from the 2021/2022 to 2022/2023 sampling season, with IAV antibody prevalence increasing for juvenile (38% to 80%) and adult (82% to 90%) Lesser Scaup. While adult Lesser Scaup sampled in Illinois in 2021/2022 had IAV antibody prevalence comparable to those sampled in Maryland (76% and 82%, respectively), they had higher antibody prevalence to both H5 (48% and 18%) and N1 (68% and 35%), potentially due to being sampled in March versus December and January. Our data suggest that Lesser Scaup had limited antibodies to highly pathogenic H5 IAV prior to the introduction of clade 2.3.4.4b H5N1 to North America, but relevant antibodies were widely observed in the months and year following. Our more limited data suggest similar trends may have occurred in Greater Scaup as well.

The chicken intestine presents a complex environment for microbial survival due to high interbacterial competition, high bile salt concentrations, a low pH, and microaerophilic conditions. While most probiotics contain members of the Bacillota phylum, members of the Pseudomonadota phylum are known to be more important in competitive exclusion - which may be an important consideration in the formulation of future probiotics. Little is known about commensal Pseudomonadota in healthy chickens, or what benefits members of this phylum may offer the host; most studies on Pseudomonadota focus on aspects of opportunistic pathogenesis and dysbiosis. In this study, we use an in-silico approach to evaluate the pathogenic potential, competition strategies, and potential host benefits of Pseudomonadota isolates from healthy chickens. We analyzed the draft genomes of 29 representative isolates of Pseudomonadota using Bagle4, AntiSMash, SeCreT6, KEGG mapper, and Virsorter2 to identify key interbacterial competition strategies including secondary metabolite biosynthesis, secretion systems, quorum sensing, and prophages. Our results revealed that each isolate exhibits distinct interbacterial competitive strategies, often independent of their taxonomic affiliation. Including Pseudomonadota in future poultry probiotics may be critical to improving colonization resistance in industrially raised poultry.

Potato tuber periderm is armored with suberin, that consists of two domains, an aliphatic domain composed of fatty acid polyesters and an aromatic domain composed of cinnamic acids. Streptomyces scabies 87.22, a predominant causal agent of potato common scab, was compared for adaptation to tuber suberin with Streptomyces acidiscabies ATCC 49003 and Streptomyces turgidiscabies Car8 belonging to emerging pathogenic species. Streptomyces scabies 87.22 showed higher growth in the suberin supplemented medium than the two other strains. When co-cultured in a rich nutrient medium, S. acidiscabies ATCC 49003 produced the antibiotic oxanthromicin, which inhibited growth and mycelium development of the other strains. Exposure of S. scabies 87.22 and S. acidiscabies ATCC 49003 to suberin was accompanied by the secretion of enzymes degrading cellulose, hemicellulose, fatty acids, and glycerol derivatives. Compared to the two other strains, S. scabies 87.22 showed higher esterase activity in suberin-supplemented medium and strong induction of cellulase gene expression. Both S. acidiscabies ATCC 49003 and S. turgidiscabies Car8 exhibited a poor utilization of trans-ferulic and p-coumaric acids, suggesting almost no ability to degrade the aromatic moiety of suberin. This work suggests that S. scabies 87.22 is better adapted to the potato periderm degradation than the emerging pathogens. The elucidation of pathogenic Streptomyces strains interaction may contribute to the improvement of ecologically oriented agronomic strategies for common scab management.

In recent decades, the study of the opportunistic pathogenic fungus, Candida albicans, has been revolutionized by genomics, transforming our understanding of its molecular biology, pathogenicity, and modes of drug resistance. In this review, our effort is to trace the historical development of C. albicans research, from early clinical observations to modern high-throughput genomic techniques. Advances in molecular biology, transcriptomics, and genome editing, including CRISPR-Cas9, have had a significant impact on the genetic tools available for studying this pathogen. The impact of whole-genome sequencing, functional genomics, and single-cell transcriptomics on the study of C. albicans, alongside the role of fungal population genomics in tracking evolutionary adaptations, have resulted in key insights. Here we discuss the ongoing challenge of antifungal resistance and the implications of new technologies in combating invasive candidiasis. As we move into a new era of precision mycology, integrating multi-omics approaches will further enhance our ability to understand and control C. albicans infections.

Antimicrobial resistance (AMR) is a global public health threat, but the role of foods in its dissemination is poorly understood. We examined the incidence of foodborne bacteria carrying AMR genes considered high-priority research targets by the World Health Organization. Frozen, ready-to-eat, avocado, coconut, mango, and peach (n = 161) were tested for bacteria encoding extended-spectrum β-lactamases (ESBLs) and carbapenemases. Over 600 presumptive-positive isolates were recovered and analyzed with a pooled sequencing (Pool-seq) strategy. Coconut samples exhibited the highest bacterial loads and prevalence/diversity of AMR genes. Isolates harbouring the β-lactamase genes bla_ctx-m, bla_tem, and bla_shv, identified in 14 coconut and 2 mango samples, were further characterized by whole-genome sequencing and antimicrobial susceptibility testing. The most common gene was bla_ctx-m-15, detected in 20 unique strains. Two carbapenemase-producing strains were isolated from coconut: Enterobacter roggenkampii encoding bla_ndm-1 and Escherichia coli encoding bla_ndm-5. Subsequent quantitative PCR (qPCR) analysis of enrichments for bla_ctx-m/bla_ndm indicated a potentially higher prevalence of these genes than observed by colony screening. This study presents a practical method for recovering ESBL- and carbapenemase-producing bacteria from foods. Mapping their distribution in food products is crucial to assessing the role of foods in the global spread of AMR and developing effective public health interventions.

Antimicrobial resistant strains of pathogenic Escherichia coli are a burden on the healthcare system, causing longer hospital stays and increased treatment costs compared to nonresistant strains. With whole genome sequencing almost ubiquitous in the analyses of outbreak and surveillance samples, in silico methods for feature identification can be faster and cheaper than traditional wet-lab methods. In this study, machine learning (ML) classification methods were used to predict antimicrobial resistance (AMR) and identify novel genomic markers of resistance. A total of 4300 E. coli whole genome sequences with laboratory-derived susceptible, intermediate, or resistant (SIR) data for 34 antimicrobials were collected. Three models-gradient boosted decision trees, support vector machines (SVMs), and artificial neural networks (ANNs)-were trained using genome subsequences (k-mers) of length 11 to classify unknown isolates as SIR for each antimicrobial. The models achieved high average accuracies (93.6%, 92.7%, and 92.8%, respectively) for our dataset, outperforming database methods including AMRFinderPlus (63.9%) and ResFinder (75.7%). Tested on two smaller independent datasets, the models' average accuracies were 81.6% (XGB), 79.9% (SVM), and 81.2% (ANN), while ResFinder's average accuracy was 94.7%. An advantage of ML models over database methods is that they can identify novel markers of resistance, which is a key advantage for surveillance and research. As more genomic and AMR data become publicly available, these models are expected to further improve in performance and utility.

The use of probiotics is an alternative approach to mitigate the proliferation of antimicrobial resistance in aquaculture. In our study, we examined the effects of Lactobacillus rhamnosus GG (ATCC 53103, LGG) delivered in-feed on the weight, length, skin mucus, and faecal microbiomes of Atlantic salmon. We also challenged the salmon with Aeromonas salmonicida 2004-05MF26 (Asal2004) and assessed the mortality. Our results showed no significant change (P > 0.05) in weight or length of Atlantic salmon or their resilience to Asal2004 infection after LGG feeding. Infection changed significantly the skin mucus and faecal microbiomes: Clostridium sensu stricto increased from 3.14% to 9.20% in skin mucus and 1.39% to 3.74% in faeces (P < 0.05). Aeromonas increased from 0.02% to 0.60% in faeces (P < 0.05). Photobacterium increased from not detected (0%) to 52.16% (P < 0.01) and Aliivibrio decreased from 67.21% to 0.71% in faeces (P < 0.01). After infection, Lactococcus (9.93%) and Lactobacillus (2.11%) in skin mucus of the LGG group were significantly higher (P < 0.05) than in the skin mucus from the rest of the groups (4.14% and 1.08%, respectively). In conclusion, LGG feeding did not further increase the resilience of vaccinated Atlantic salmon. Asal2004 infection had much greater impact on skin mucus and faecal microbiomes than LGG feeding.

Conjugation is a complex phenomenon involving multiple plasmid, bacterial, and environmental factors. Here we describe an IncI1 plasmid encoding multidrug antibiotic resistance to aminoglycosides, sulfonamides, and third-generation cephalosporins. This plasmid is widespread geographically among animal, human, and environmental sectors. We present data on the transmissibility of this plasmid from Salmonella enterica ser. Kentucky into 40 strains of S. enterica (10 strains each from serovars Enteritidis, Heidelberg, Infantis, and Typhimurium). Thirty seven out of 40 strains were able to take up the plasmid. Rates of conjugation were variable between strains ranging from 10^-8 to 10^-4. Overall, serovars Enteritidis and Typhimurium demonstrated the highest rates of conjugation, followed by Heidelberg, and then Infantis. No relationships were observed between the recipient cell surface and rate of conjugation. Recipient cell numbers correlated positively with conjugation rate and strains with high conjugation rates had marginally but significantly higher growth parameters compared to strains that took up the plasmid at lower frequencies. Environmental conditions known to impact cell growth, such as temperature, nutrient availability, and the presence of antibiotics, had a modulating effect on conjugation. Collectively, these results will further understanding of plasmid transmission dynamics in Salmonella, which is a critical first step towards the development of mitigation strategies.

Rapidly developing microbial resistance to existing antimicrobials poses a growing threat to public health and global food security. Current chemical-based treatments target cells by inhibiting growth or metabolic function, but their effectiveness is diminishing. To address the growing antimicrobial resistance crisis, there is an urgent need for innovative therapies. Conjugative plasmids, a natural mechanism of horizontal gene transfer in bacteria, have been repurposed to deliver toxic genetic cargo to recipient cells, showing promise as next-generation antimicrobial agents. However, the ecological risks posed by unintended gene transfer require robust biocontainment strategies. In this study, we developed inducible conjugative plasmids to solve these challenges. Utilizing an arabinose-inducible promoter, we evaluated 13 plasmids with single essential gene deletions, identifying trbC and trbF as strong candidates for stringent regulation. These plasmids demonstrated inducibility in both cis and trans configurations, with induction resulting in up to a 5-log increase in conjugation efficiency compared to uninduced conditions. Although challenges such as reduced conjugation efficiency and promoter leakiness persist, this work establishes a foundation for the controlled transfer of plasmids, paving the way for safer and more effective antimicrobial technologies.