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MBio Jun 2024Transposon sequencing (Tn-seq) is a powerful genome-wide technique to assess bacterial fitness under varying growth conditions. However, screening via Tn-seq is...
UNLABELLED
Transposon sequencing (Tn-seq) is a powerful genome-wide technique to assess bacterial fitness under varying growth conditions. However, screening via Tn-seq is challenging. Dose limitations and host restrictions create bottlenecks that diminish the transposon mutant pool being screened. Here, we have developed a murine model with a disruption in that renders the resulting RECON mouse resistant to high-dose infection. We leveraged this model to perform a Tn-seq screen of the human pathogen . We identified 135 genes which were required for growth in mice including novel genes not previously identified for host survival. We identified organ-specific requirements for survival and investigated the role of the folate enzyme FolD in liver pathogenesis. A mutant lacking was impaired for growth in murine livers by 2.5-log compared to wild type and failed to spread cell-to-cell in fibroblasts. In contrast, a mutant in which encodes a transcription factor that represses an operon involved in D-allose catabolism, was attenuated in both livers and spleens of mice by 4-log and 3-log, respectively, but showed modest phenotypes in models. We confirmed that dysregulation of the D-allose catabolism operon is responsible for the growth defect, as deletion of the operon in the ∆ background rescued virulence. By undertaking an unbiased, genome-wide screen in mice, we have identified novel fitness determinants for host infection, which highlights the utility of the RECON mouse model for future screening efforts.
IMPORTANCE
is the gram-positive bacterium responsible for the food-borne disease listeriosis. Although infections with are limiting in healthy hosts, vulnerable populations, including pregnant and elderly people, can experience high rates of mortality. Thus, understanding the breadth of genetic requirements for survival will present new opportunities for treatment and prevention of listeriosis. We developed a murine model of infection using a RECON mouse that is restrictive to systemic infection. We utilized this model to screen for genes required via transposon sequencing. We identified the liver-specific gene and a repressor, , that only exhibits an growth defect. AlsR controls the expression of the D-allose operon which is a marker in diagnostic techniques to identify pathogenic . A better understanding of the role of the D-allose operon in human disease may further inform diagnostic and prevention measures.
PubMed: 38940553
DOI: 10.1128/mbio.01332-24 -
The rapidly progressing and fatal outcome of rhombencephalitis by listeriosis in a 61-year-old male.Annals of Agricultural and... Jun 2024Listeria monocytogenes is a Gram-positive facultative anaerobic bacterium that is ubiquitous in the environment and can cause severe infections in immunocompromised...
Listeria monocytogenes is a Gram-positive facultative anaerobic bacterium that is ubiquitous in the environment and can cause severe infections in immunocompromised individuals, pregnant women, and newborns. Listeriosis can manifest as meningitis, encephalitis, or sepsis, and its diagnosis requires a high index of suspicion. The case is reported of a rare presentation of rhombencephalitis by listeriosis in a 61-year-old male who initially suffered from subacute gastric disturbances and fever. Neurological consultation showed abnormal functions of cranial nerves and meningeal signs were observed. MRI revealed a poorly demarcated focus of approximately 45 × 16 × 15mm, indicating possible inflammatory processes, necessitating a lumbar puncture. Assessment of the CSF indicated infection with the bacterium- Listeria Monocytogenes, with the final diagnosis of Listeriosis encephalitis. Despite antibiotic therapy of Ceftazidine and Ampicillin, the patient's condition deteriorated, followed by death.
Topics: Humans; Male; Listeriosis; Middle Aged; Fatal Outcome; Listeria monocytogenes; Encephalitis; Anti-Bacterial Agents; Rhombencephalon
PubMed: 38940119
DOI: 10.26444/aaem/178178 -
Microorganisms Jun 2024is a ubiquitous bacterial pathogen that threatens the food chain and human health. In this study, whole-genome sequencing (WGS) was used for the genomic...
is a ubiquitous bacterial pathogen that threatens the food chain and human health. In this study, whole-genome sequencing (WGS) was used for the genomic characterization of (n = 24) from beef and beef-based products. Multilocus Sequence Type (MLST) analysis revealed that ST204 of CC204 was the most common sequence type (ST). Other sequence types detected included ST1 and ST876 of CC1, ST5 of CC5, ST9 of CC9, ST88 of CC88, ST2 and ST1430 of CC2, and ST321 of CC321. Genes encoding for virulence factors included complete LIPI-1 (-----) from 54% (13/24) of the isolates of ST204, ST321, ST1430, and ST9 and internalin genes that were present in all the STs. All the STs carried four intrinsic/natural resistance genes, , , , and , conferring resistance to fosfomycin, lincosamide, quinolones, and cationic peptides, respectively. Plasmids pLGUG1 and J1776 were the most detected (54% each), followed by pLI100 (13%) and pLM5578 (7%). The prophage profile, vB_LmoS_188, was overrepresented amongst the isolates, followed by LP_101, LmoS_293_028989, LP_030_2_021539, A006, and LP_HM00113468. genomic island 2 (LGI-2) was found to be present in all the isolates, while genomic island 3 (LGI-3) was present in a subset of isolates (25%). The type VII secretion system was found in 42% of the isolates, and sortase A was present in all genomes. Mobile genetic elements and genomic islands did not harbor any virulence, resistance, or environmental adaptation genes that may benefit . All the STs did not carry genes that confer resistance to first-line antibiotics used for the treatment of listeriosis. The characterization of in our study highlighted the environmental resistance and virulence potential of and the risk posed to the public, as this bacterium is frequently found in food and food processing environments.
PubMed: 38930548
DOI: 10.3390/microorganisms12061166 -
Antibiotics (Basel, Switzerland) May 2024, a foodborne pathogen causing listeriosis, poses substantial societal, economic, and public health challenges due to its resistance, persistence, and biofilm formation...
, a foodborne pathogen causing listeriosis, poses substantial societal, economic, and public health challenges due to its resistance, persistence, and biofilm formation in the food industry. Exploring subinhibitory concentrations of compounds to target virulence inhibition and increase susceptibility to adverse conditions presents a promising strategy to mitigate its impact of and unveils new potential applications. Thus, this study aims to explore the effect of linalool on virulence factors of and potential use in the reduction in its tolerance to stressful conditions. This action was analysed considering the use of two sub-inhibitory concentrations of linalool, 0.312 and 0.625 mg/mL. We found that even with the lowest tested concentrations, a 65% inhibition of violacein production by , 55% inhibition in biofilm formation by and 62% reduction on haemolysis caused by this bacterium were observed. In addition to its impact on virulence factors, linalool diminished the tolerance to osmotic stress (up to 4.3 log reduction after 24 h with 12% NaCl), as well as to high (up to 3.8 log reduction after 15 min at 55 °C) and low temperatures (up to 4.6 log reduction after 84 days with 12% NaCl at 4 °C). Thus, this study paves the way to further investigation into the potential utilization of linalool to mitigate the threat posed by in the field of food safety and public health.
PubMed: 38927141
DOI: 10.3390/antibiotics13060474 -
Pathogens (Basel, Switzerland) May 2024is a human pathogen that has the ability to cause listeriosis, a disease with possible fatal outcomes. The typical route of infection is ingestion of the bacteria with...
High Prevalence of Virulence-Associated Genes and Length Polymorphism in and Genes Identified in Isolates from Meat Products and Meat-Processing Environments in Poland.
is a human pathogen that has the ability to cause listeriosis, a disease with possible fatal outcomes. The typical route of infection is ingestion of the bacteria with contaminated food. In this study, 13 virulence-associated genes were examined with PCR in the genomes of 153 isolates collected from meat products and processing environments in Poland. All isolates possessed genes from LIPI-1-, , , and -as well as four internalins: , , , . Invasion-associated protein , as well as genes and encoding regulatory proteins, were also detected in all isolates. Gene , encoding flagellin, was detected in 113 (74%) isolates. This was the only gene that was not detected in all isolates, as its presence is serotype-dependent. Gene showed polymorphism with longer and shorter variants in PCR amplicons. Two isolates were characterized by truncated genes, lacking 141 bp in their sequence, which was confirmed by gene sequencing. All isolates were positive in hemolysis assays, proving the synthesis of functional PrfA and Hly proteins. Four genotypes of based on polymorphism and two genotypes based on polymorphism were distinguished within the isolates' collection.
PubMed: 38921742
DOI: 10.3390/pathogens13060444 -
BMJ Case Reports Jun 2024is a relatively uncommon cause of foodborne infection in the general population. Most cases of Listeriosis occur among newborns, pregnant women, the elderly and those...
is a relatively uncommon cause of foodborne infection in the general population. Most cases of Listeriosis occur among newborns, pregnant women, the elderly and those with impairment of cellular immunity. Neonatal Listeria meningitis is rare. We present a case of Listeria meningitis at the age of 15 days in a previously healthy neonate who presented with acute onset of fever, poor feeding and lethargy. Sepsis workup revealed identified in cerebrospinal fluid PCR and culture. The infant's course was complicated by transient syndrome of inappropriate antidiuretic hormone and subsequent hydrocephalus that required a ventriculoperitoneal shunt placement. Though rare, neonatal infections due to Listeria can present with meningitis leading to serious and devastating complications. Our case emphasises the importance of considering Listeria in cases of neonatal meningitis and the value of close follow-up of such cases through early detection and management of acute and long-term complications.
Topics: Humans; Hydrocephalus; Infant, Newborn; Meningitis, Listeria; Listeria monocytogenes; Ventriculoperitoneal Shunt; Female; Male; Anti-Bacterial Agents
PubMed: 38914530
DOI: 10.1136/bcr-2023-258825 -
Journal of Bacteriology Jun 2024is a foodborne bacterial pathogen that causes listeriosis. Positive regulatory factor A (PrfA) is a pleiotropic master activator of virulence genes of that becomes...
is a foodborne bacterial pathogen that causes listeriosis. Positive regulatory factor A (PrfA) is a pleiotropic master activator of virulence genes of that becomes active upon the entry of the bacterium into the cytosol of infected cells. can survive and multiply at low temperatures; this is accomplished through the maintenance of appropriate membrane fluidity via branched-chain fatty acid (BCFA) synthesis. Branched-chain α-keto acid dehydrogenase (BKD), which is composed of four polypeptides encoded by , , , and , is known to play a vital role in BCFA biosynthesis. Here, we constructed BKD-deficient strains by in-frame deletion of , , , and genes. To determine the role in and , mouse model challenges, plaque assay in murine L2 fibroblast, and intracellular replication in J744A.1 macrophage were conducted. BKD-deficient strains exhibited defects in BCFA composition, virulence, and PrfA-regulon function within the host cells. Transcriptomics analysis revealed that the transcript level of the PrfA-regulon was lower in Δ strain than those in the wild-type. This study demonstrates that strains lacking BKD complex components were defective in PrfA-regulon function, and full activation of wild-type may not occur within host cells in the absence of BKD. Further study will investigate the consequences of BKD deletion on PrfA function through altering BCFA catabolism.IMPORTANCE is the causative agent of listeriosis, a disease with a high mortality rate. In this study, we have shown that the deletion of BKD can impact the function of PrfA and the PrfA-regulon. The production of virulence proteins within host cells is necessary for to promote its intracellular survival and is likely dependent on membrane integrity. We thus report a link between membrane integrity and the function of PrfA. This knowledge will increase our understanding of pathogenesis, which may provide insight into the development of antimicrobial agents.
PubMed: 38899896
DOI: 10.1128/jb.00033-24 -
Applied Microbiology and Biotechnology Jun 2024Bacteriocins have the potential to effectively improve food-borne infections or gastrointestinal diseases and hold promise as viable alternatives to antibiotics. This...
Bacteriocins have the potential to effectively improve food-borne infections or gastrointestinal diseases and hold promise as viable alternatives to antibiotics. This study aimed to explore the antibacterial activity of three bacteriocins (nisin, enterocin Gr17, and plantaricin RX-8) and their ability to attenuate intestinal barrier dysfunction and inflammatory responses induced by Listeria monocytogenes, respectively. Bacteriocins have shown excellent antibacterial activity against L. monocytogenes without causing any cytotoxicity. Bacteriocins inhibited the adhesion and invasion of L. monocytogenes on Caco-2 cells, lactate dehydrogenase (LDH), trans-epithelial electrical resistance (TEER), and cell migration showed that bacteriocin improved the permeability of Caco-2 cells. These results were attributed to the promotion of tight junction proteins (TJP) assembly, specifically zonula occludens-1 (ZO-1), occludin, and claudin-1. Furthermore, bacteriocins could alleviate inflammation by inhibiting the mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) pathways and reducing the secretion of interleukin-6 (IL-6), interleukin-1 β (IL-1β) and tumor necrosis factor α (TNF-α). Among three bacteriocins, plantaricin RX-8 showed the best antibacterial activity against L. monocytogenes and the most pronounced protective effect on the intestinal barrier due to its unique structure. Based on our findings, we hypothesized that bacteriocins may inhibit the adhesion and invasion of L. monocytogenes by competing adhesion sites. Moreover, they may further enhance intestinal barrier function by inhibiting the expression of L. monocytogenes virulence factors, increasing the expression of TJP and decreasing the secretion of inflammatory factors. Therefore, bacteriocins will hopefully be an effective alternative to antibiotics, and this study provides valuable insights into food safety concerns. KEY POINTS: • Bacteriocins show excellent antibacterial activity against L. monocytogenes • Bacteriocins improve intestinal barrier damage and inflammatory response • Plantaricin RX-8 has the best protective effect on Caco-2 cells damage.
Topics: Listeria monocytogenes; Bacteriocins; Humans; Caco-2 Cells; Anti-Bacterial Agents; Inflammation; NF-kappa B; Bacterial Adhesion; Tight Junction Proteins; Cytokines; Listeriosis; Cell Movement
PubMed: 38896287
DOI: 10.1007/s00253-024-13228-w -
Foods (Basel, Switzerland) May 2024() is an opportunistic foodborne pathogen that causes listeriosis in humans and animals, reaching up to 30% case mortality. There are only a few reports in Mexico...
() is an opportunistic foodborne pathogen that causes listeriosis in humans and animals, reaching up to 30% case mortality. There are only a few reports in Mexico about the strains found in various foods. The aim of this study was to determine the prevalence of , serogroups, virulence genes, and antimicrobial resistance in different foods from Reynosa, Tamaulipas, Mexico. strains were characterized by microbiological and molecular methods. Susceptibility to 12 antibiotics was determined according to CLSI and EUCAST. A total of 300 samples of seafood, pasteurized and raw milk, cheese, beef, and chicken were collected from supermarkets and retail markets. The presence of was detected in 5.6% of the samples. Most strains belonged to serogroups 4b, 4d, and 4e (68.4%). All strains presented a minimum of four virulence genes; the most common were , , and (92.1%). A high percentage of antimicrobial susceptibility was observed, with resistance only to STX-TMP (78.9%), STR (26.3%), MEM (21.0%), and E (2.6%). These results show that the foods in Reynosa, Tamaulipas, are a reservoir of and represent a potential health risk.
PubMed: 38890883
DOI: 10.3390/foods13111656 -
Scientific Data Jun 2024Listeria monocytogenes (Lm) is a highly pathogenic bacterium that can cause listeriosis, a relatively rare food-borne infectious disease that affects farm, domestic,...
Listeria monocytogenes (Lm) is a highly pathogenic bacterium that can cause listeriosis, a relatively rare food-borne infectious disease that affects farm, domestic, wild animals and humans as well. The infected livestock is the frequent sources of Lm. Vaccination is one of the methods of controlling listeriosis in target farm animals to prevent Lm-associated food contamination. Here we report the complete sequence of the Lm strain AUF attenuated from a fully-virulent Lm strain by ultraviolet irradiation, successfully used since the 1960s as a live whole-cell veterinary vaccine. The de novo assembled genome consists of a circular chromosome of 2,942,932 bp length, including more than 2,800 CDSs, 17 pseudogenes, 5 antibiotic resistance genes, and 56/92 virulence genes. Two wild Lm strains, the EGD and the 10403S that is also used in cancer Immunotherapy, were the closest homologs for the Lm strain AUF. Although all three strains belonged to different sequence types (ST), namely ST12, ST85, and ST1538, they were placed in the same genetic lineage II, CC7.
Topics: Animals; Bacterial Vaccines; Genome, Bacterial; Listeria monocytogenes; Listeriosis; Vaccines, Attenuated
PubMed: 38886393
DOI: 10.1038/s41597-024-03440-8