Canadian journal of microbiology最新文献

{"title":"What in Earth? Analyses of Canadian soil populations of <i>Aspergillus fumigatus</i>.","authors":"Greg Korfanty, Arshia Kazerouni, Mykaelah Dixon, Micheala Trajkovski, Paola Gomez, Jianping Xu","doi":"10.1139/cjm-2024-0083","DOIUrl":"10.1139/cjm-2024-0083","url":null,"abstract":"<p><p><i>Aspergillus fumigatus</i> is a globally distributed mold and a major cause of opportunistic infections in humans. Because most infections are from environmental exposure, it is critical to understand environmental populations of <i>A. fumigatus</i>. Soil is a major ecological niche for <i>A. fumigatus</i>. Here, we analyzed 748 soil isolates from 21 locations in six provinces and one territory in Canada. All isolates were genotyped using nine microsatellite markers. Due to small sample size and/or close proximities for some local samples, these isolates were grouped into 16 local geographic and ecological populations. Our results indicated high allelic and genotypic diversities within most local and provincial populations. Interestingly, low but statistically significant genetic differentiations were found among geographic populations within Canada, with relatively similar proportions of strains and genotypes belonging to two large genetic clusters. In Hamilton, Ontario, and Vancouver, BC, where two and three ecological populations were analyzed, respectively, we found limited genetic difference among them. Most local and provincial populations showed evidence of both clonality and recombination, with no population showing random recombination. Of the 748 soil isolates analyzed here, two were resistant to triazole antifungals. We discuss the implications of our results to the evolution and epidemiology of <i>A. fumigatus</i>.</p>","PeriodicalId":9381,"journal":{"name":"Canadian journal of microbiology","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142458630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanisms and implications of phenotypic switching in bacterial pathogens.","authors":"Alexander Stephen Byrne, Nathalie Bissonnette, Kapil Tahlan","doi":"10.1139/cjm-2024-0116","DOIUrl":"10.1139/cjm-2024-0116","url":null,"abstract":"<p><p>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.</p>","PeriodicalId":9381,"journal":{"name":"Canadian journal of microbiology","volume":" ","pages":""},"PeriodicalIF":16.4,"publicationDate":"2024-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142370976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chemical-mediated virulence: the effects of host chemicals on microbial virulence and potential new antivirulence strategies.","authors":"Peri B Moulding, Omar M El-Halfawy","doi":"10.1139/cjm-2024-0017","DOIUrl":"10.1139/cjm-2024-0017","url":null,"abstract":"<p><p>The rising antimicrobial resistance rates and declining antimicrobial discovery necessitate alternative strategies to combat multidrug-resistant pathogens. Targeting microbial virulence is an emerging area of interest. Traditionally, virulence factors were largely restricted to bacteria-derived toxins, adhesins, capsules, quorum sensing systems, secretion systems, factors required to sense, respond to, acquire, or synthesize, and utilize trace elements (such as iron and other metals) and micronutrients (such as vitamins), and other factors bacteria use to establish infection, form biofilms, or damage the host tissues and regulatory elements thereof. However, this traditional definition overlooks bacterial virulence that may be induced or influenced by host-produced metabolites or other chemicals that bacteria may encounter at the infection site. This review will discuss virulence from a non-traditional perspective, shedding light on chemical-mediated host-pathogen interactions and outlining currently available mechanistic insight into increased bacterial virulence in response to host factors. This review aims to define a possibly underestimated theme of chemically mediated host-pathogen interactions and encourage future validation and characterization of the contribution of host chemicals to microbial virulence in vivo. From this perspective, we discuss proposed antivirulence compounds and suggest new potential targets for antimicrobials that prevent chemical-mediated virulence. We also explore proposed host-targeting therapeutics reducing the level of host chemicals that induce microbial virulence, serving as virulence attenuators. Understanding the host chemical-mediated virulence may enable new antimicrobial solutions to fight multidrug-resistant pathogens.</p>","PeriodicalId":9381,"journal":{"name":"Canadian journal of microbiology","volume":" ","pages":"405-425"},"PeriodicalIF":1.8,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141436327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Identification of key drivers of antimicrobial resistance in <i>Enterococcus</i> using machine learning.","authors":"Jee In Kim, Alexander Manuele, Finlay Maguire, Rahat Zaheer, Tim A McAllister, Robert G Beiko","doi":"10.1139/cjm-2024-0049","DOIUrl":"10.1139/cjm-2024-0049","url":null,"abstract":"<p><p>With antimicrobial resistance (AMR) rapidly evolving in pathogens, quick and accurate identification of genetic determinants of phenotypic resistance is essential for improving surveillance, stewardship, and clinical mitigation. Machine learning (ML) models show promise for AMR prediction in diagnostics but require a deep understanding of internal processes to use effectively. Our study utilised AMR gene, pangenomic, and predicted plasmid features from 647 <i>Enterococcus faecium</i> and <i>Enterococcus</i> <i>faecalis</i> genomes across the One Health continuum, along with corresponding resistance phenotypes, to develop interpretive ML classifiers. Vancomycin resistance could be predicted with 99% accuracy with AMR gene features, 98% with pangenome features, and 96% with plasmid clusters. Top pangenome features overlapped with the resistance genes of the <i>vanA</i> operon, which are often laterally transmitted via plasmids. Doxycycline resistance prediction achieved approximately 92% accuracy with pangenome features, with the top feature being elements of Tn<i>916</i> conjugative transposon, a <i>tet</i>(M) carrier. Erythromycin resistance prediction models achieved about 90% accuracy, but top features were negatively correlated with resistance due to the confounding effect of population structure. This work demonstrates the importance of reviewing ML models' features to discern biological relevance even when achieving high-performance metrics. Our workflow offers the potential to propose hypotheses for experimental testing, enhancing the understanding of AMR mechanisms, which are crucial for combating the AMR crisis.</p>","PeriodicalId":9381,"journal":{"name":"Canadian journal of microbiology","volume":" ","pages":"446-460"},"PeriodicalIF":1.8,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141854900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Totarol exhibits antibacterial effects through antibiofilm and combined interaction against vancomycin-resistant <i>Enterococcus faecalis</i>.","authors":"Ga-Eun Hyeon, Yong-Bin Eom","doi":"10.1139/cjm-2024-0014","DOIUrl":"10.1139/cjm-2024-0014","url":null,"abstract":"<p><p>The rise of vancomycin-resistant enterococci (VRE) due to antibiotic overuse poses a significant threat to long-term care patients and those with impaired immune systems. Therefore, it is imperative to seek alternatives to overcome multidrug resistance. This study aimed to evaluate totarol, a natural compound derived from <i>Podocarpus totara</i>, for its antibacterial activity against vancomycin-resistant <i>Enterococcus faecalis</i> (VREF). Totarol exhibited potent antibacterial activity at a very low concentration of 0.25 µg/mL and demonstrated antibiofilm effects through biofilm inhibitory concentration and biofilm eradication concentration assays. Confocal laser scanning microscopy confirmed that totarol inhibited not only biofilm mass but also bacterial cell viability. The combinatorial use of sublethal concentrations of totarol and vancomycin showed antibacterial activity, as observed in the time-kill assay. Quantitative polymerase chain reaction assays revealed a concentration-dependent downregulation of key virulence genes (<i>vanA, ace, asa, efaA</i>, and <i>esp</i>) in VREF when exposed to totarol. In summary, totarol emerges as a promising adjuvant with vancomycin for inhibiting VREF, addressing vancomycin resistance and biofilm formation-critical challenges associated with VRE infection. Since this was an in vitro study, the role of totarol in the clinical implications of VREF treatment remains to be demonstrated.</p>","PeriodicalId":9381,"journal":{"name":"Canadian journal of microbiology","volume":" ","pages":"426-432"},"PeriodicalIF":1.8,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141757291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of herbaceous litter thickness on bacterial community structure and physicochemical properties of aeolian sand.","authors":"Jieru Kong, Huili Liu, Ruixia Wang, Jun Wang, Pin Zhai, Ruoshi Ma, Peng Kang, Bingru Liu","doi":"10.1139/cjm-2023-0219","DOIUrl":"10.1139/cjm-2023-0219","url":null,"abstract":"<p><p>The change and mechanism of soil and soil bacterial diversity during the change of herbaceous litter thickness in desert areas is crucial to understand. In the study, the dominant herbaceous litter mixture in Baijitan National Nature Reserve was selected as the research material, and an experiment was established by adjusting the litter depth. The results showed that the measured values of soil physicochemical factors (total nitrogen, total protein, total potassium, available phosphorus, available potassium, pH, and soil water content) increased with the increase of herbaceous litter mixture thickness in 0-5 cm soil layer. Actinobacteria, Proteobacteria, Acidobacteria, Chloroflexi, and Gemmatimonadetes were the dominant bacterial phyla under different thicknesses of herbaceous litter in 0-5 and 5-10 cm soil layers. <i>Balneimonas, Rubrobacter</i>, and <i>Geodermatophilus</i> were the dominant bacterial genera under different thicknesses of herbaceous litter in 0-5 and 5-10 cm soil layers. There was no obvious change in the α-diversity index of bacterial community the same soil layer, but the α-diversity index in the 0-5 cm soil layer was lower compared to the 5-10 cm soil layer. The results of this study revealed that the change of herbaceous litter thickness had no significant effect on soil bacterial community structure in desert areas.</p>","PeriodicalId":9381,"journal":{"name":"Canadian journal of microbiology","volume":" ","pages":"433-445"},"PeriodicalIF":1.8,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142280565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Longitudinal screening of retail milk from Canadian provinces reveals no detections of influenza A virus RNA (April-July 2024): leveraging a newly established pan-Canadian network for responding to emerging viruses.","authors":"Hannah L Wallace, Jordan Wight, Mariana Baz, Barbara Dowding, Louis Flamand, Tom Hobman, François Jean, Jeffrey B Joy, Andrew S Lang, Sonya MacParland, Craig McCormick, Ryan Noyce, Rodney S Russell, Selena M Sagan, Jumari Snyman, Gabriela J Rzeszutek, Mustafa S Jafri, Isaac Bogoch, Jason Kindrachuk, Angela L Rasmussen","doi":"10.1139/cjm-2024-0120","DOIUrl":"10.1139/cjm-2024-0120","url":null,"abstract":"<p><p>Highly pathogenic avian influenza (HPAI) H5N1 has caused the deaths of more than 100 million birds since 2021, and human cases since 1997 have been associated with significant morbidity and mortality. Given recent detections of HPAI H5N1 in dairy cattle and H5N1 RNA detections in pasteurized retail milk in the United States, we established the pan-Canadian Milk Network in April 2024. Through our network of collaborators from across Canada, retail milk was procured longitudinally, approximately every 2 weeks, and sent to a central laboratory to test for the presence of influenza A virus RNA. Between 29 April and 17 July 2024, we tested 109 retail milk samples from all 10 Canadian provinces (NL, NS, PEI, NB, QC, ON, MB, SK, AB, and BC). All samples tested negative for influenza A virus RNA. This nationwide initiative was established for rapid retail milk screening as per the earliest reports of similar undertakings in the United States. Our independent testing results have aligned with reporting from federal retail milk testing initiatives. Despite no known HPAI infections of dairy cattle in Canada to date, H5N1 poses a significant threat to the health of both humans and other animals. By performing routine surveillance of retail milk on a national scale, we have shown that academic networks and initiatives can rapidly establish nationwide emerging infectious disease surveillance that is cost-effective, standardized, scalable, and easily accessible. Our network can serve as an early detection system to help inform containment and mitigation activities if positive samples are identified and can be readily reactivated should HPAI H5N1 or other emerging zoonotic viruses be identified in agricultural or livestock settings, including Canadian dairy cattle.</p>","PeriodicalId":9381,"journal":{"name":"Canadian journal of microbiology","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142342147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Constraint on boric acid resistance and tolerance evolvability in <i>Candida albicans</i>.","authors":"Yana Syvolos, Ola E Salama, Aleeza C Gerstein","doi":"10.1139/cjm-2023-0225","DOIUrl":"10.1139/cjm-2023-0225","url":null,"abstract":"<p><p>Boric acid is a broad-spectrum antimicrobial used to treat vulvovaginal candidiasis when patients relapse on the primary azole drug fluconazole. <i>Candida albicans</i> is the most common cause of vulvovaginal candidiasis, colloquially referred to as a \"vaginal yeast infection\". Little is known about the propensity of <i>C. albicans</i> to develop BA resistance or tolerance (the ability of a subpopulation to grow slowly in high levels of drug). We evolved 96 replicates from eight diverse <i>C. albicans</i> strains to increasing BA concentrations to test the evolvability of BA resistance and tolerance. Replicate growth was individually assessed daily, with replicates passaged when they had reached an optical density consistent with exponential growth. Many replicates went extinct quickly. Although some replicates could grow in much higher levels of BA than the ancestral strains, evolved populations isolated from the highest terminal BA levels (after 11 weeks of passages) surprisingly showed only modest growth improvements and only at low levels of BA. No large increases in resistance or tolerance were observed in the evolved replicates. Overall, our findings illustrate that there may be evolutionary constraints limiting the emergence of BA resistance and tolerance, which could explain why it remains an effective treatment for recurrent yeast infections.</p>","PeriodicalId":9381,"journal":{"name":"Canadian journal of microbiology","volume":" ","pages":"384-393"},"PeriodicalIF":1.8,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140956405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The limit to evolutionary rescue depends on ploidy in yeast exposed to nystatin.","authors":"Jasmine Ono, Anastasia Kuzmin, Lesley Miller, Sarah P Otto","doi":"10.1139/cjm-2023-0235","DOIUrl":"10.1139/cjm-2023-0235","url":null,"abstract":"<p><p>The number of copies of each chromosome, or ploidy, of an organism is a major genomic factor affecting adaptation. We set out to determine how ploidy can impact the outcome of evolution, as well as the likelihood of evolutionary rescue, using short-term experiments with yeast (<i>Saccharomyces cerevisiae</i>) in a high concentration of the fungicide nystatin. In similar experiments using haploid yeast, the genetic changes underlying evolutionary rescue were highly repeatable, with all rescued lines containing a single mutation in the ergosterol biosynthetic pathway. All of these beneficial mutations were recessive, which led to the expectation that diploids would find alternative genetic routes to adaptation. To test this, we repeated the experiment using both haploid and diploid strains and found that diploid populations did not evolve resistance. Although diploids are able to adapt at the same rate as haploids to a lower, not fully inhibitory, concentration of nystatin, the present study suggests that diploids are limited in their ability to adapt to an inhibitory concentration of nystatin, while haploids may undergo evolutionary rescue. These results demonstrate that ploidy can tip the balance between adaptation and extinction when organisms face an extreme environmental change.</p>","PeriodicalId":9381,"journal":{"name":"Canadian journal of microbiology","volume":" ","pages":"394-404"},"PeriodicalIF":1.8,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141320630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization and genome analysis of a broad host range lytic phage vB_SenS_TUMS_E19 against <i>Salmonella enterica</i> and its efficiency evaluation in the liquid egg.","authors":"Narges Torkashvand, Haniyeh Kamyab, Ahmad Reza Shahverdi, Mohammad Reza Khoshayand, Mohammad Amir Karimi Tarshizi, Zargham Sepehrizadeh","doi":"10.1139/cjm-2024-0013","DOIUrl":"10.1139/cjm-2024-0013","url":null,"abstract":"<p><p><i>Salmonella enterica</i> serovars are zoonotic bacterial that cause foodborne enteritis. Due to bacteria's antibiotic resistance, using bacteriophages for biocontrol and treatment is a new therapeutic approach. In this study, we isolated, characterized, and analyzed the genome of vB_SenS_TUMS_E19 (E19), a broad host range <i>Salmonella</i> bacteriophage, and evaluated the influence of E19 on liquid eggs infected with <i>Salmonella enterica</i> serovar Enteritidis. Transmission electron microscopy showed that the isolated bacteriophage had a siphovirus morphotype. E19 showed rapid adsorption (92% in 5 min), a short latent period (18 min), a large burst size (156 PFU per cell), and a broad host range against different <i>Salmonella enterica</i> serovars. Whole-genome sequencing analysis indicated that the isolated phage had a 42 813 bp long genome with 49.8% G + C content. Neither tRNA genes nor those associated with antibiotic resistance, virulence factors, or lysogenic formation were detected in the genome. The efficacy of E19 was evaluated in liquid eggs inoculated with <i>S</i>. Enteritidis at 4 and 25 °C, and results showed that it could effectively eradicate <i>S</i>. Enteritidis in just 30 min and prevented its growth up to 72 h. Our findings indicate that E19 can be an alternative to a preservative to control <i>Salmonella</i> in food samples and help prevent and treat salmonellosis.</p>","PeriodicalId":9381,"journal":{"name":"Canadian journal of microbiology","volume":" ","pages":"358-369"},"PeriodicalIF":1.8,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141579039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}