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Clinical Microbiology Reviews Jun 2019Hypervirulent (hvKp) is an evolving pathotype that is more virulent than classical (cKp). hvKp usually infects individuals from the community, who are often healthy.... (Review)
Review
Hypervirulent (hvKp) is an evolving pathotype that is more virulent than classical (cKp). hvKp usually infects individuals from the community, who are often healthy. Infections are more common in the Asian Pacific Rim but are occurring globally. hvKp infection frequently presents at multiple sites or subsequently metastatically spreads, often requiring source control. hvKp has an increased ability to cause central nervous system infection and endophthalmitis, which require rapid recognition and site-specific treatment. The genetic factors that confer hvKp's hypervirulent phenotype are present on a large virulence plasmid and perhaps integrative conjugal elements. Increased capsule production and aerobactin production are established hvKp-specific virulence factors. Similar to cKp, hvKp strains are becoming increasingly resistant to antimicrobials via acquisition of mobile elements carrying resistance determinants, and new hvKp strains emerge when extensively drug-resistant cKp strains acquire hvKp-specific virulence determinants, resulting in nosocomial infection. Presently, clinical laboratories are unable to differentiate cKp from hvKp, but recently, several biomarkers and quantitative siderophore production have been shown to accurately predict hvKp strains, which could lead to the development of a diagnostic test for use by clinical laboratories for optimal patient care and for use in epidemiologic surveillance and research studies.
Topics: Anti-Bacterial Agents; Bacterial Typing Techniques; Humans; Klebsiella Infections; Klebsiella pneumoniae; Virulence
PubMed: 31092506
DOI: 10.1128/CMR.00001-19 -
Proceedings of the National Academy of... Apr 2022Bacterial pathogen identification, which is critical for human health, has historically relied on culturing organisms from clinical specimens. More recently, the...
Bacterial pathogen identification, which is critical for human health, has historically relied on culturing organisms from clinical specimens. More recently, the application of machine learning (ML) to whole-genome sequences (WGSs) has facilitated pathogen identification. However, relying solely on genetic information to identify emerging or new pathogens is fundamentally constrained, especially if novel virulence factors exist. In addition, even WGSs with ML pipelines are unable to discern phenotypes associated with cryptic genetic loci linked to virulence. Here, we set out to determine if ML using phenotypic hallmarks of pathogenesis could assess potential pathogenic threat without using any sequence-based analysis. This approach successfully classified potential pathogenetic threat associated with previously machine-observed and unobserved bacteria with 99% and 85% accuracy, respectively. This work establishes a phenotype-based pipeline for potential pathogenic threat assessment, which we term PathEngine, and offers strategies for the identification of bacterial pathogens.
Topics: Bacteria; Genome, Bacterial; Machine Learning; Phenotype; Virulence; Virulence Factors; Whole Genome Sequencing
PubMed: 35363569
DOI: 10.1073/pnas.2112886119 -
Frontiers in Cellular and Infection... 2023
Topics: Fungi; Virulence; Plants
PubMed: 37065206
DOI: 10.3389/fcimb.2023.1168148 -
Journal of Gastroenterology Mar 2016Colonization resistance by the commensal microbiota is a key defense against infectious pathogens in the gastrointestinal tract. The microbiota directly competes with... (Review)
Review
Colonization resistance by the commensal microbiota is a key defense against infectious pathogens in the gastrointestinal tract. The microbiota directly competes with incoming pathogens by occupying the colonization niche, depleting nutrients in the gut lumen as well as indirectly inhibiting the growth of pathogens through activation of host immunity. Enteric pathogens have evolved strategies to cope with microbiota-mediated colonization resistance. Pathogens utilize a wide array of virulence factors to outcompete their commensal rivals in the gut. However, since the expression of virulence factors is costly to maintain and reduces bacterial fitness, pathogens need to regulate their virulence properly in order to maximize their fitness. To this end, most pathogens use environmental cues to regulate their virulence gene expression. Thus, a dynamic regulation of virulence factor expression is a key invasion strategy utilized by enteric pathogens. On the other hand, host immunity selectively targets virulent pathogens in order to counter infection in the gut. The host immune system is generally tolerant of harmless microorganisms, such as the commensal microbiota. Moreover, the host relies on its commensal microbiota to contribute, in concert with its immune system, to the elimination of pathogens. Collectively, regulation of virulence determines the fate of enteric pathogens, from the establishment of infection to the eventual elimination. Here, we will review the dynamics of virulence and its role in infection.
Topics: Environment; Gastrointestinal Microbiome; Gastrointestinal Tract; Gene Expression Regulation; Humans; Immunity, Innate; Mechanotransduction, Cellular; Microbial Interactions; Virulence; Virulence Factors
PubMed: 26553054
DOI: 10.1007/s00535-015-1141-5 -
Microbiology and Molecular Biology... Jun 2010Like for all microbes, the goal of every pathogen is to survive and replicate. However, to overcome the formidable defenses of their hosts, pathogens are also endowed... (Review)
Review
Like for all microbes, the goal of every pathogen is to survive and replicate. However, to overcome the formidable defenses of their hosts, pathogens are also endowed with traits commonly associated with virulence, such as surface attachment, cell or tissue invasion, and transmission. Numerous pathogens couple their specific virulence pathways with more general adaptations, like stress resistance, by integrating dedicated regulators with global signaling networks. In particular, many of nature's most dreaded bacteria rely on nucleotide alarmones to cue metabolic disturbances and coordinate survival and virulence programs. Here we discuss how components of the stringent response contribute to the virulence of a wide variety of pathogenic bacteria.
Topics: Animals; Bacteria; Guanosine Tetraphosphate; Humans; Models, Biological; Virulence
PubMed: 20508246
DOI: 10.1128/MMBR.00046-09 -
Mikrobiyoloji Bulteni Jan 2013Salmonella species are facultative intracellular pathogenic bacteria. They can invade macrophages, dendritic and epithelial cells. The responsible virulence genes for... (Review)
Review
Salmonella species are facultative intracellular pathogenic bacteria. They can invade macrophages, dendritic and epithelial cells. The responsible virulence genes for invasion, survival, and extraintestinal spread are located in Salmonella pathogenicity islands (SPIs). SPIs are thought to be acquired by horizontal gene transfer. Some of the SPIs are conserved throughout the Salmonella genus, and some of them are specific for certain serovars. There are differences between Salmonella serotypes in terms of adaptation to host cell, virulence factors and the resulting infection according to SPA presence and characteristics. The most important Salmonella virulence gene clusters are located in 12 pathogenicity islands. Virulence genes that are involved in the intestinal phase of infection are located in SPI-1 and SPI-2 and the remaining SPIs are required for intracellular survival, fimbrial expression, magnesium and iron uptake, multiple antibiotic resistance and the development of systemic infections. In addition SPIs, Sigma ss (RpoS) factors and adaptive acid tolerance response (ATR) are the other two important virulence factors. RpoS and ATR found in virulent Salmonella strains help the bacteria to survive under inappropriate conditions such as gastric acidity, bile salts, inadequate oxygen concentration, lack of nutrients, antimicrobial peptides, mucus and natural microbiota and also to live in phagosomes or phagolysosomes. This review article summarizes the data related to pathogenicity islands in Salmonella serotypes and some factors which play role in the regulation of virulence genes.
Topics: Genomic Islands; Salmonella; Salmonella Infections; Virulence; Virulence Factors
PubMed: 23390917
DOI: 10.5578/mb.4138 -
BioMed Research International 2019Data on () infection and virulence factors in countries across West Africa are scattered. This systematic review seeks to present an update on the status of infection... (Review)
Review
Data on () infection and virulence factors in countries across West Africa are scattered. This systematic review seeks to present an update on the status of infection focusing on prevalence rate, distribution of virulent genes, and their link to clinical outcomes across countries in the western part of Africa. This information is expected to broaden the knowledge base of clinicians and researchers regarding infection and associated virulence factors in West African countries. A comprehensive search of the scientific literature in PubMed and ScienceDirect was conducted using the search terms including " infection in West Africa". Databases were sourced from January 1988 to December 2018. Data on the incidence of infection and related pathological factors were found for some countries, whereas others had no information on it. Smoking, alcohol, exposure to high levels of carcinogens and diet were reported to be involved in the pathogenesis of gastroduodenal diseases and gastric cancer. Besides the environmental factors and genetic characteristics, there are important characteristics of such as the ability to infect, replicate, and persist in a host that have been associated with the pathogenesis of various gastroduodenal diseases. This systematic search has provided information so far available on virulence factors and clinical outcomes in West Africa. Accordingly, this piece has identified gaps in the body of knowledge highlighting the need for more studies to clarify the role of virulence factors and associated clinical outcomes in the burden of this bacterial infection in West Africa, as data from these countries do not give the needed direct relation.
Topics: Africa, Western; Genes, Bacterial; Helicobacter Infections; Helicobacter pylori; Humans; Prevalence; Treatment Outcome; Virulence
PubMed: 31886245
DOI: 10.1155/2019/7312908 -
Journal of Evolutionary Biology Dec 2015Parasite strategies of host exploitation may be affected by host defence strategies and multiple infections. In particular, within-host competition between multiple...
Parasite strategies of host exploitation may be affected by host defence strategies and multiple infections. In particular, within-host competition between multiple parasite strains has been shown to select for higher virulence. However, little is known on how multiple infections could affect the coevolution between host recovery and parasite virulence. Here, we extend a coevolutionary model introduced by van Baalen (Proc. R. Soc. B, 265, 1998, 317) to account for superinfection. When the susceptibility to superinfection is low, we recover van Baalen's results and show that there are two potential evolutionary endpoints: one with avirulent parasites and poorly defended hosts, and another one with high virulence and high recovery. However, when the susceptibility to superinfection is above a threshold, the only possible evolutionary outcome is one with high virulence and high investment into defence. We also show that within-host competition may select for lower host recovery, as a consequence of selection for more virulent strains. We discuss how different parasite and host strategies (superinfection facilitation, competitive exclusion) as well as demographic and environmental parameters, such as host fecundity or various costs of defence, may affect the interplay between multiple infections and host-parasite coevolution. Our model shows the interplay between coevolutionary dynamics and multiple infections may be affected by crucial mechanistic or ecological details.
Topics: Animals; Biological Evolution; Host-Parasite Interactions; Parasites; Superinfection; Virulence
PubMed: 26353032
DOI: 10.1111/jeb.12753 -
Medicina Oral, Patologia Oral Y Cirugia... Nov 2021There is a debate as to whether some types of oral leucoplakias (OL) are caused by Candida species, and whether they contribute to the malignant transformation,...
BACKGROUND
There is a debate as to whether some types of oral leucoplakias (OL) are caused by Candida species, and whether they contribute to the malignant transformation, associated with a minority of such lesions. As no detailed population analysis of yeast isolates from OL is available, we evaluated the virulence attributes, and genotypes of 35 C. albicans from OL, and compared their genotypes with 18 oral isolates from healthy individuals.
MATERIAL AND METHODS
The virulence traits evaluated were esterase, phospholipase, proteinase, haemolysin and coagulase production, and phenotypic switching activity, and yeast adherence and biofilm formation. DNA from OL and control yeasts were evaluated for A, B or C genotype status.
RESULTS
Phospholipase, proteinase, and coagulase activity and biofilm formation was observed in 80%, 66%, 97 % and 77 % of the isolates, respectively. Phenotypic switching was detected in 8.6%, while heamolytic, and esterase activity and adherence were noted in all isolates.
CONCLUSIONS
The genotype A was predominant amongst both the OL and control groups. Due to the small sample size of our study a larger investigation to define the role of candidal virulent attributes in the pathogenicity of OL is warranted, and the current data should serve as a basis until then.
Topics: Candida; Candida albicans; Genotype; Humans; Leukoplakia, Oral; Virulence
PubMed: 34023840
DOI: 10.4317/medoral.24748 -
Bioscience Trends Jun 2013Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most critical causes of healthcare-related or community-related infections. Resistance to most β-lactam... (Review)
Review
Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most critical causes of healthcare-related or community-related infections. Resistance to most β-lactam antibiotics makes MRSA a big threat to clinical treatment. Utilization of low efficiency antibiotics such as vancomycin and teicoplanin makes new choices for therapies. Recently, much researchhas shed light on relevance between genetic mutations of MRSA and clinical characteristics such as antibiotic resistance, and virulence. These findings could contribute to development of novel antibiotics and vaccines.
Topics: Anti-Bacterial Agents; Biofilms; Methicillin-Resistant Staphylococcus aureus; Mutation; Virulence
PubMed: 23836034
DOI: No ID Found