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Journal of Applied Microbiology Nov 2008The aim of this study was to investigate the invasion and intracellular survival of different Hafnia alvei strains in HeLa cells.
AIMS
The aim of this study was to investigate the invasion and intracellular survival of different Hafnia alvei strains in HeLa cells.
METHODS AND RESULTS
We performed different experiments on the bacterial invasion of different strains of H. alvei into the HeLa cell line using gentamicin protection assays and immunofluorescence. We also report the time course of cell internalization and the effects of inhibitors on the invasion of H. alvei. Levels of invasion varied depending on the conditions (strain, time and inoculum size) used.
CONCLUSIONS
This study revealed that H. alvei strains were able to enter and persist in a human epithelial cell line.
SIGNIFICANCE AND IMPACT OF THE STUDY
Our in vitro findings highlight the possibility that some H. alvei strains may exploit nonprofessional phagocytes or nonphagocytic cells to spread in vivo, which may be important for the persistence and establishment of an asymptomatic carrier state.
Topics: Bacterial Adhesion; Cell Line; Cytochalasin D; Epithelial Cells; Fluorescent Antibody Technique; Gentamicins; Hafnia alvei; Humans; Nucleic Acid Synthesis Inhibitors
PubMed: 18795976
DOI: 10.1111/j.1365-2672.2008.03884.x -
Vaccines Jul 2022Antimicrobial resistance has become a significant health issue because of the misuse of antibiotics in our daily lives, resulting in high rates of morbidity and...
Antimicrobial resistance has become a significant health issue because of the misuse of antibiotics in our daily lives, resulting in high rates of morbidity and mortality. is a rod-shaped, Gram-negative and facultative anaerobic bacteria. The medical community has emphasized 's possible association with gastroenteritis. As of now, there is no licensed vaccine for , and as such, computer aided vaccine design approaches could be an ideal approach to highlight the potential vaccine epitopes against this bacteria. By using bacterial pan-genome analysis (BPGA), we were able to study the entire proteomes of with the aim of developing a vaccine. Based on the analysis, 20,370 proteins were identified as core proteins, which were further used in identifying potential vaccine targets based on several vaccine candidacy parameters. The prioritized vaccine targets against the bacteria are; type 1 fimbrial protein, flagellar hook length control protein (FliK), flagellar hook associated protein (FlgK), curli production assembly/transport protein (CsgF), fimbria/pilus outer membrane usher protein, fimbria/pilus outer membrane usher protein, molecular chaperone, flagellar filament capping protein (FliD), TonB-dependent hemoglobin /transferrin/lactoferrin family receptor, Porin (OmpA), flagellar basal body rod protein (FlgF) and flagellar hook-basal body complex protein (FliE). During the epitope prediction phase, different antigenic, immunogenic, non-Allergenic, and non-Toxic epitopes were predicted for the above-mentioned proteins. The selected epitopes were combined to generate a multi-epitope vaccine construct and a cholera toxin B subunit (adjuvant) was added to enhance the vaccine's antigenicity. Downward analyses of vaccines were performed using a vaccine three-dimensional model. Docking studies have confirmed that the vaccine strongly binds with MHC-I, MHC-II, and TLR-4 immune cell receptors. Additionally, molecular dynamics simulations confirmed that the vaccine epitopes were exposed to nature and to the host immune system and interpreted strong intermolecular binding between the vaccine and receptors. Based on the results of the study, the model vaccine construct seems to have the capacity to produce protective immune responses in the host, making it an attractive candidate for further in vitro and in vivo studies.
PubMed: 35891291
DOI: 10.3390/vaccines10071127 -
Journal of Clinical Microbiology Sep 2011A collection of 68 Hafnia strains previously identified to the species level by 16S rRNA gene sequencing were investigated for simple phenotypic properties that could...
A collection of 68 Hafnia strains previously identified to the species level by 16S rRNA gene sequencing were investigated for simple phenotypic properties that could aid in their recognition in the clinical laboratory. Four tests, including malonate utilization, fermentation of salicin and d-arabinose, and expression of β-glucosidase activity, correctly assigned each strain to either Hafnia alvei or H. paralvei. Antibiotic susceptibility profiles were generated for 35 H. alvei and H. paralvei isolates using Etest strips for 24 antibiotics. All strains were susceptible to aminoglycosides, quinolones, carbapenems, and monobactams. Most of the Hafnia isolates had a colistin MIC of ≥2 μg/ml. Sequencing of an internal ampC gene fragment allowed genotypic differentiation of the two Hafnia species. Approximately 70% of the hafniae tested additionally produced a cytolytic toxin active on Vero cells which may play a role in gastroenteritis.
Topics: Bacterial Proteins; Bacteriological Techniques; Biomarkers; Enterobacteriaceae Infections; Hafnia; Humans; Microbial Sensitivity Tests; Molecular Diagnostic Techniques; beta-Lactamases
PubMed: 21795516
DOI: 10.1128/JCM.00866-11 -
Microbiology Spectrum Feb 2022Honeybee gut microbiota plays an important role in host physiology and metabolism. Recent studies have shown that the influence of the resident microorganisms in the...
Honeybee gut microbiota plays an important role in host physiology and metabolism. Recent studies have shown that the influence of the resident microorganisms in the regulation of honeybee immune system is profound, which protects against the pathogen Serratia marcescens. However, only few of the core gut members in the regulation of immune functions have been studied. Here, we explored how different bee gut bacterial species aided in the clearance of the pathogenic Hafnia alvei, which causes bee septicemia with a high mortality rate. We found that both Gilliamella apicola W8136 and Lactobacillus apis W8172 protect honeybees from the opportunistic pathogen, while two other strains from and did not affect the invasion of . Transcriptomic analysis revealed that gut species induced different expression profiles in the gut. Specifically, two regulator genes from the Toll pathway, PGRP-S3 recognizing Gram-positive and Spätzle that bind to the Toll protein for the downstream signal transduction, were elevated by . Correspondingly, multiple genes encoding antibacterial proteins were also stimulated by . Interestingly, we found an increased expression of apidaecin, which also exhibited a high inhibitory effect on . To elucidate the difference of strains in the host's immune regulation, comparative genomic analyses indicate that the S-layer proteins unique to are potentially involved in honeybee Toll signaling and the activation of antibacterial protein production. Honeybees are essential pollinators supporting global agricultural economies and food supplies. Recent honeybee decline has been linked to several factors, while pathogen infection is considered one of the most significant contributing factors. Although a limited number of bacterial pathogens have been identified, Hafnia alvei is one of the pathogens causing septicemia in adult bees. In this study, we showed that two bee gut members, and , can clear H. alvei from invasion. Mono-colonization of specific strains can stimulate the host Toll signaling pathway and the downstream expression of AMPs. Specifically, apidaecin upregulated by the gut symbionts is more effective against the pathogen. Moreover, our genomic analysis suggests that the surface-layer proteins specific to strains are an important driver of Toll signaling, highlighting the variation of bee gut strains in regulating the host immune system.
Topics: Animals; Antimicrobial Cationic Peptides; Bacteria; Bees; Gammaproteobacteria; Gastrointestinal Microbiome; Gastrointestinal Tract; Genomics; Hafnia alvei; Immune System; Immunity, Innate; Lactobacillus; Symbiosis; Tetracycline
PubMed: 34985299
DOI: 10.1128/spectrum.01896-21 -
Microbiology Resource Announcements Mar 2022A bacteriophage that is able to infect Hafnia alvei and can also infect two other hosts, Klebsiella pneumoniae and Salmonella enterica, was isolated from wastewater. The...
A bacteriophage that is able to infect Hafnia alvei and can also infect two other hosts, Klebsiella pneumoniae and Salmonella enterica, was isolated from wastewater. The complete genome sequence was determined by long-read PacBio sequencing. Based on sequence similarity, the bacteriophage is assigned to the viral genus within the family .
PubMed: 35225670
DOI: 10.1128/mra.00049-22 -
BMC Genomics Oct 2019The Hafnia genus is an opportunistic pathogen that has been implicated in both nosocomial and community-acquired infections. Although Hafnia is fairly often isolated...
Comparative genomic analysis of the Hafnia genus reveals an explicit evolutionary relationship between the species alvei and paralvei and provides insights into pathogenicity.
BACKGROUND
The Hafnia genus is an opportunistic pathogen that has been implicated in both nosocomial and community-acquired infections. Although Hafnia is fairly often isolated from clinical material, its taxonomy has remained an unsolved riddle, and the involvement and importance of Hafnia in human disease is also uncertain. Here, we used comparative genomic analysis to define the taxonomy of Hafnia, identify species-specific genes that may be the result of ecological and pathogenic specialization, and reveal virulence-related genetic profiles that may contribute to pathogenesis.
RESULTS
One complete genome sequence and 19 draft genome sequences for Hafnia strains were generated and combined with 27 publicly available genomes. We provided high-resolution typing methods by constructing phylogeny and population structure based on single-copy core genes in combination with whole genome average nucleotide identity to identify two distant Hafnia species (alvei and paralvei) and one mislabeled strain. The open pan-genome and the presence of numerous mobile genetic elements reveal that Hafnia has undergone massive gene rearrangements. Presence of species-specific core genomes associated with metabolism and transport suggests the putative niche differentiation between alvei and paralvei. We also identified possession of diverse virulence-related profiles in both Hafnia species., including the macromolecular secretion system, virulence, and antimicrobial resistance. In the macromolecular system, T1SS, Flagellum 1, Tad pilus and T6SS-1 were conserved in Hafnia, whereas T4SS, T5SS, and other T6SSs exhibited the evolution of diversity. The virulence factors in Hafnia are related to adherence, toxin, iron uptake, stress adaptation, and efflux pump. The identified resistance genes are associated with aminoglycoside, beta-lactam, bacitracin, cationic antimicrobial peptide, fluoroquinolone, and rifampin. These virulence-related profiles identified at the genomic level provide insights into Hafnia pathogenesis and the differentiation between alvei and paralvei.
CONCLUSIONS
Our research using core genome phylogeny and comparative genomics analysis of a larger collection of strains provides a comprehensive view of the taxonomy and species-specific traits between Hafnia species. Deciphering the genome of Hafnia strains possessing a reservoir of macromolecular secretion systems, virulence factors, and resistance genes related to pathogenicity may provide insights into addressing its numerous infections and devising strategies to combat the pathogen.
Topics: Bacterial Secretion Systems; Comparative Genomic Hybridization; Drug Resistance, Bacterial; Genome, Bacterial; Genotype; Hafnia; Phylogeny; Species Specificity; Virulence; Virulence Factors
PubMed: 31646960
DOI: 10.1186/s12864-019-6123-1 -
Gut Pathogens 2014Hafnia alvei is an opportunistic pathogen involved in various types of nosocomical infections. The species has been found to inhabit food and mammalian guts. However,...
BACKGROUND
Hafnia alvei is an opportunistic pathogen involved in various types of nosocomical infections. The species has been found to inhabit food and mammalian guts. However, its status as an enteropathogen, and whether the food-inhabiting strains could be a source of gastrointestinal infection remains obscure. In this report we present a draft genome of H. alvei strain FB1 isolated from fish paste meatball, a food popular among Malaysian and Chinese populations. The data was generated on the Illumina MiSeq platform.
RESULTS
A comparative study was carried out on FB1 against two other previously sequenced H. alvei genomes. Several gene clusters putatively involved in survival and pathogenesis of H. alvei FB1 in food and gut environment were characterised in this study. These include the widespread colonisation island (WCI), the tad locus that is known to play an essential role in biofilm formation, a eut operon that might contribute to advantage in nutrient acquisition in gut environment, and genes responsible for siderophore production This features enable the bacteria to successful colonise in the host gut environment.
CONCLUSION
With the whole genome data of H. alvei FB1 presented in this study, we hope to provide an insight into future studies on this candidate of enteropathogen by looking into the possible mechanisms employed to survive stresses and gain advantage in competitions, which eventually leads to successful colonisation and pathogenesis. This is to serve as the basis for more effective clinical diagnosis and treatment.
PubMed: 25075225
DOI: 10.1186/1757-4749-6-29 -
Journal of Food Protection May 2017Quorum sensing (QS) is an intercellular signaling and gene regulatory mechanism that is implicated in food spoilage caused by bacteria. Thus, blocking QS may suppress...
Quorum sensing (QS) is an intercellular signaling and gene regulatory mechanism that is implicated in food spoilage caused by bacteria. Thus, blocking QS may suppress QS-controlled phenotypes of these bacteria that are responsible for food spoilage. Biofilm formation is closely related to bacterial infection, and it is also a major mechanism responsible for the increased resistance of biofilm-associated bacteria to antimicrobial drugs. Food spoilage and biofilm formation caused by food-related bacteria have posed a significant problem for the food industry. Thus, adopting an antibiofilm approach would provide an alternative to an antibiotic strategy. Dihydrocoumarin is a compound that is derived from coumarin, a known natural QS inhibitor that has been used as an additive in food. Hafnia alvei is a spoilage bacterium; H. alvei H4 was isolated from ready-to-eat sea cucumber. Considering that QS and biofilm are often closely linked, this research aimed to detect the effect of dihydrocoumarin on the production of violacein by Chromobacterium violaceum 026 and to evaluate the inhibitory effect of dihydrocoumarin on the formation of biofilm by H. alvei H4 by using violacein and crystal violet assays. C. violaceum 026 treated with dihydrocoumarin showed as much as 70.1% reduction in QS-mediated production of violacein compared with untreated cells, while exhibiting no significant change in growth. H. alvei H4 treated with dihydrocoumarin displayed 75.8% reduction in swimming motility, and as much as 89.4% reduction in biofilm formation compared with the nontreated cells, with the reduction in both cases being dependent on the concentration of dihydrocoumarin. Scanning electron microscopy showed that dihydrocoumarin could effectively destroy the biofilm structure of H. alvei H4 and decrease biofilm density. These findings indicate that dihydrocoumarin can be developed into a new QS inhibitor or antibiofilm agent for controlling food spoilage and potentially investigated to increase food safety.
PubMed: 28402186
DOI: 10.4315/0362-028X.JFP-16-460 -
Journal of Clinical Microbiology Dec 1996Hafnia alvei is an emerging human pathogen associated with sporadic cases and outbreaks of diarrhea. Bangladeshi isolates of H. alvei possess the Escherichia coli...
Hafnia alvei is an emerging human pathogen associated with sporadic cases and outbreaks of diarrhea. Bangladeshi isolates of H. alvei possess the Escherichia coli attaching and effacing (eaeA) gene and demonstrate an attaching and effacing phenotype. In the present study we examined 11 Canadian H. alvei isolates and strain 19,982 from Bangladesh to determine if the formation of attaching and effacing lesions is a property shared among multiple isolates. Attaching and effacing lesions were detected by induction of tyrosine kinase protein phosphorylation and cytoskeletal rearrangements in infected tissue culture epithelial cells with immunofluorescence microscopy and by the examination of infected cells with transmission electron microscopy. The presence of the eaeA gene was examined by PCR and colony blot hybridization. Profiles of outer membrane protein extracts, chromosomal macrorestriction fragments, and plasmids were also examined. Accumulation of host phosphotyrosine proteins and rearrangement of the cytoskeletal protein alpha-actinin were both observed in HEp-2 cells infected with H. alvei 19,982. In contrast, none of the other 11 clinical H. alvei isolates demonstrated either of these responses, nor did they form attaching and effacing lesions under electron microscopy. Consistent with the absence of the attaching and effacing phenotype, these clinical isolates did not possess the eaeA gene. The outer membrane protein profiles of all the Canadian isolates were identical but differed from that of H. alvei 19,982. Pulsed-field gel electrophoresis and plasmid profile analyses of the clinical H. alvei isolates differed substantially from those of the Bangladeshi strain. These results indicate that there is heterogeneity among H. alvei strains with respect to signal transduction, attaching and effacing adhesion, outer membrane constituents, and genotype. Epidemiological studies on enteropathogenic H. alvei thus need to go beyond simple species designations and require specific identification of the virulent clones.
Topics: Actinin; Amino Acid Sequence; Bacterial Adhesion; Bacterial Outer Membrane Proteins; Bangladesh; Base Sequence; Canada; DNA Primers; Diarrhea; Electrophoresis, Gel, Pulsed-Field; Enterobacteriaceae; Enterobacteriaceae Infections; Escherichia coli; Genes, Bacterial; Genotype; Humans; Microscopy, Electron; Phenotype; Phosphotyrosine; Plasmids; Polymerase Chain Reaction; Virulence
PubMed: 8940433
DOI: 10.1128/jcm.34.12.2973-2979.1996 -
Saudi Journal of Biological Sciences May 2020I isolated bacteria from blue cheese in order to find bacterial strains secreting l-methioninase enzyme, and optimized the conditions for the most efficient enzyme...
I isolated bacteria from blue cheese in order to find bacterial strains secreting l-methioninase enzyme, and optimized the conditions for the most efficient enzyme secretion. The efficient isolate, identified according to the 16S rRNA gene sequence analysis, was belonging to Enterobacteriaceae. I confirmed that the strain harbored the methionase gene, (1194 bp). The environmental (pH, temperature) and nutritional (carbon and nitrogen sources and Mg concentration) factors influencing the l-methioninase production of were optimized. The highest yield of l-methioninase enzyme was reached after 48 h of incubation when the acidity of the growing medium was adjusted to pH 7.5 and the temperature was 35 °C. The following concentrations of the supplements increased the l-methioninase yield in the medium: galactose (2.0 g L), MgSO (0.25 g L), l-methionine as an inducer (2.0 g L), and l-asparagine as an additional N source (1.5 g L). I introduce a bacterial strain of that is previously unreported to secrete l-methioninase enzyme and show that a carbon source is a mandatory supplement whereas l-methionine is not a mandatory supplement for l-methioninase enzyme production of .
PubMed: 32346328
DOI: 10.1016/j.sjbs.2020.02.008