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1.
Food Microbiol ; 87: 103351, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31948609

RESUMO

The objective of this work was to investigate the effect of stress conditions frequently encountered in food-associated environments on virulence-associated characteristics of eight strains of Listeria monocytogenes. Strains were grown at low (11 °C, cold stress) and optimal (37 °C) temperatures and in high NaCl concentrations (6% NaCl, 11 °C; cold-osmotic stress) and tested for their ability to invade the human intestinal epithelial Caco-2 cells. Results demonstrate that the correlation between exposure to cold stress and increased invasion phenotype is strain-dependent as strains investigated exhibited different behaviours, i.e. exposure to cold stress conditions resulted in a significant increase of invasion levels in five out of the eight strains tested, when compared to growth under optimal conditions. On the other hand, when these cold-adapted cells were subsequently submitted to high salt concentrations and low temperature, their enhanced ability to invade Caco-2 was lost. Surprisingly, saturated fatty acids (SFA) and branched chain fatty acids (BCFA) decreased when L. monocytogenes were exposed to stress conditions as opposed to what has been observed in other studies, therefore highlighting that further studies will need to deepen in the understanding of the lipid metabolism of these strains. The effect of stress conditions on the survival of three selected L. monocytogenes strains through an in vitro gastrointestinal (GI) tract digestion model was further investigated. The exposure to cold-osmotic stress increased the survival of one strain through the GI tract.


Assuntos
Listeria monocytogenes/fisiologia , Listeriose/microbiologia , Adaptação Fisiológica , Células CACO-2 , Temperatura Baixa , Contagem de Colônia Microbiana , Humanos , Listeria monocytogenes/química , Listeria monocytogenes/crescimento & desenvolvimento , Listeria monocytogenes/patogenicidade , Pressão Osmótica , Cloreto de Sódio/metabolismo , Estresse Fisiológico , Virulência
2.
Infect Immun ; 88(2)2020 01 22.
Artigo em Inglês | MEDLINE | ID: mdl-31740529

RESUMO

Listeria monocytogenes is a foodborne bacterium that causes gastroenteritis, meningitis, or abortion. Listeria induces its internalization (entry) into some human cells through interaction of the bacterial surface protein InlB with its host receptor, the Met tyrosine kinase. InlB and Met promote entry through stimulation of localized actin polymerization and exocytosis. How actin cytoskeletal changes and exocytosis are controlled during entry is not well understood. Here, we demonstrate important roles for the host GTPase Arf1 and its effectors AP1 and PICK1 in actin polymerization and exocytosis during InlB-dependent uptake. Depletion of Arf1 by RNA interference (RNAi) or inhibition of Arf1 activity using a dominant-negative allele impaired InlB-dependent internalization, indicating an important role for Arf1 in this process. InlB stimulated an increase in the GTP-bound form of Arf1, demonstrating that this bacterial protein activates Arf1. RNAi and immunolocalization studies indicated that Arf1 controls exocytosis and actin polymerization during entry by recruiting the effectors AP1 and PICK1 to the plasma membrane. In turn, AP1 and PICK1 promoted plasma membrane translocation of both Filamin A (FlnA) and Exo70, two host proteins previously found to mediate exocytosis during InlB-dependent internalization (M. Bhalla, H. Van Ngo, G. C. Gyanwali, and K. Ireton, Infect Immun 87:e00689-18, 2018, https://doi.org/10.1128/IAI.00689-18). PICK1 mediated recruitment of Exo70 but not FlnA. Collectively, these results indicate that Arf1, AP1, and PICK1 stimulate exocytosis by redistributing FlnA and Exo70 to the plasma membrane. We propose that Arf1, AP1, and PICK1 are key coordinators of actin polymerization and exocytosis during infection of host cells by Listeria.


Assuntos
Fator 1 de Ribosilação do ADP/metabolismo , Actinas/metabolismo , Proteínas de Transporte/metabolismo , Exocitose/fisiologia , GTP Fosfo-Hidrolases/metabolismo , Listeria monocytogenes/patogenicidade , Proteínas Nucleares/metabolismo , Fator de Transcrição AP-1/metabolismo , Proteínas de Bactérias/metabolismo , Linhagem Celular Tumoral , Membrana Celular/metabolismo , Células HeLa , Interações Hospedeiro-Patógeno/fisiologia , Humanos , Listeriose/metabolismo , Listeriose/microbiologia , Polimerização , Interferência de RNA/fisiologia , Transdução de Sinais/fisiologia
3.
Food Microbiol ; 85: 103280, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31500706

RESUMO

Listeria monocytogenes causes severe diseases in humans, including febrile gastroenteritis and systemic infections that has a high mortality despite antibiotic treatment. This pathogen may cause massive outbreaks associated to the consumption of contaminated food products, which highlight its importance in public health. In the last decade, L. monocytogenes has emerged as a foodborne pathogen of major importance in Chile. A previous work showed that in Chile during 2008 and 2009, L. monocytogenes serotypes 1/2a, 1/2b and 4b were the most frequently identified in food and clinical strains. Here we report the molecular characterization of L. monocytogenes strains isolated from 2008 to 2017 in the country. Our results indicate that serotypes 1/2a, 1/2b and 4b continue to be the most commonly found in food products. In addition, we identify persistent and widespread PFGE subtypes. This study reports ten years of epidemiological surveillance ofL. monocytogenes in Chile.


Assuntos
Monitoramento Epidemiológico , Microbiologia de Alimentos , Doenças Transmitidas por Alimentos/epidemiologia , Listeria monocytogenes/genética , Listeriose/epidemiologia , Chile/epidemiologia , Contagem de Colônia Microbiana , DNA Bacteriano/genética , Surtos de Doenças , Doenças Transmitidas por Alimentos/microbiologia , Gastroenterite/epidemiologia , Gastroenterite/microbiologia , Variação Genética , Humanos , Listeria monocytogenes/patogenicidade , Produtos da Carne/microbiologia , Epidemiologia Molecular , Saúde Pública , Sorogrupo , Sorotipagem , Fatores de Virulência/genética
4.
Enzyme Microb Technol ; 133: 109440, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31874690

RESUMO

The present study investigated the influence of low-shear modeled microgravity (LSMMG) conditions on Listeria monocytogenes stress response (heat, cold, and acid), membrane fatty acid composition, and virulence potential as well as stress-/virulence-associated gene expression. The results showed that LSMMG-cultivated cells had lower survival rate and lower D-values under heat and acid stress conditions compared to cells grown under normal gravity (NG). Interestingly, the cold resistance was elevated in cells cultivated under LSMMG conditions when compared to NG conditions. A higher amount of anteiso-branched chain fatty acids and lower ratio of iso/anteiso were observed in LSMMG cultured cells, which would contribute to increased membrane fluidity. Under LSMMG conditions, upregulated expression of cold stress-related genes (cspA, cspB, and cspD) was noticed but no change in expression was observed for heat (dnaK, groES, clpC, clpP, and clpE) and acid stress-related genes (sigB). The LSMMG-grown cells showed inferior virulence capacity in terms of infection, cell cycle arrest, and apoptosis induction in Caco-2 cells compared to those grown under NG conditions. Approximately 3.65, 2.13, 4.02, and 2.65-fold downregulation of prfA, hly, inlA, and bsh genes, respectively, in LSMMG-cultured cells might be the reason for reduced virulence. In conclusion, these findings suggest that growth under LSMMG conditions stimulates alterations in L. monocytogenes stress/virulence response, perhaps due to changes in lipid composition and related genes expression.


Assuntos
Listeria monocytogenes/genética , Listeria monocytogenes/patogenicidade , Lipídeos de Membrana/análise , Estresse Fisiológico , Ausência de Peso , Proteínas de Bactérias/genética , Células CACO-2 , Temperatura Baixa , Regulação Bacteriana da Expressão Gênica , Temperatura Alta , Humanos , Virulência
5.
BMC Genomics ; 20(1): 1014, 2019 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-31870294

RESUMO

BACKGROUND: Listeria monocytogenes consists of four lineages that occupy a wide variety of ecological niches. Sequence type (ST) 87 (serotype 1/2b), belonging to lineage I, is one of the most common STs isolated from food products, food associated environments and sporadic listeriosis in China. Here, we performed a comparative genomic analysis of the L. monocytogenes ST87 clone by sequencing 71 strains representing a diverse range of sources, different geographical locations and isolation years. RESULTS: The core genome and pan genome of ST87 contained 2667 genes and 3687 genes respectively. Phylogenetic analysis based on core genome SNPs divided the 71 strains into 10 clades. The clinical strains were distributed among multiple clades. Four clades contained strains from multiple geographic regions and showed high genetic diversity. The major gene content variation of ST87 genomes was due to putative prophages, with eleven hotspots of the genome that harbor prophages. All strains carry an intact CRISRP/Cas system. Two major CRISPR spacer profiles were found which were not clustered phylogenetically. A large plasmid of about 90 Kb, which carried heavy metal resistance genes, was found in 32.4% (23/71) of the strains. All ST87 strains harbored the Listeria pathogenicity island (LIPI)-4 and a unique 10-open read frame (ORF) genomic island containing a novel restriction-modification system. CONCLUSION: Whole genome sequence analysis of L. monocytogenes ST87 enabled a clearer understanding of the population structure and the evolutionary history of ST87 L. monocytogenes in China. The novel genetic elements identified may contribute to its virulence and adaptation to different environmental niches. Our findings will be useful for the development of effective strategies for the prevention and treatment of listeriosis caused by this prevalent clone.


Assuntos
Genômica , Listeria monocytogenes/genética , Sequenciamento Completo do Genoma/métodos , China , Genoma Bacteriano/genética , Listeria monocytogenes/patogenicidade , Listeria monocytogenes/virologia , Família Multigênica/genética , Filogenia , Plasmídeos/genética , Polimorfismo de Nucleotídeo Único , Prófagos/fisiologia , Virulência/genética
6.
mBio ; 10(6)2019 12 17.
Artigo em Inglês | MEDLINE | ID: mdl-31848289

RESUMO

Listeria monocytogenes can cause a life-threatening illness when the foodborne pathogen spreads beyond the intestinal tract to distant organs. Many aspects of the intestinal phase of L. monocytogenes pathogenesis remain unknown. Here, we present a foodborne infection model using C57BL/6 mice that have been pretreated with streptomycin. In this model, as few as 100 L. monocytogenes CFU were required to cause self-limiting enterocolitis, and systemic dissemination followed previously reported routes. Using this model, we report that listeriolysin O (LLO) and actin assembly-inducing protein (ActA), two critical virulence determinants, were necessary for intestinal pathology and systemic spread but were dispensable for intestinal growth. Sequence tag-based analysis of microbial populations (STAMP) was used to investigate the within-host population dynamics of wild-type and LLO-deficient strains. The wild-type bacterial population experienced severe bottlenecks over the course of infection, and by 5 days, the intestinal population was highly enriched for bacteria originating from the gallbladder. In contrast, LLO-deficient strains did not efficiently disseminate and gain access to the gallbladder, and the intestinal population remained diverse. These findings suggest that systemic spread and establishment of a bacterial reservoir in the gallbladder imparts an intraspecies advantage in intestinal occupancy. Since intestinal L. monocytogenes is ultimately released into the environment, within-host population bottlenecks may provide purifying selection of virulence genes.IMPORTANCE Listeria monocytogenes maintains capabilities for free-living growth in the environment and for intracellular replication in a wide range of hosts, including livestock and humans. Here, we characterized an enterocolitis model of foodborne L. monocytogenes infection. This work highlights a multiorgan trafficking circuit and reveals a fitness advantage for bacteria that successfully complete this cycle. Because virulence factors play critical roles in systemic dissemination and multiple bottlenecks occur as the bacterial population colonizes different tissue sites, this multiorgan trafficking circuit likely provides purifying selection of virulence genes. This study also serves as a foundation for future work using the L. monocytogenes-induced enterocolitis model to investigate the biology of L. monocytogenes in the intestinal environment.


Assuntos
Listeria monocytogenes/fisiologia , Listeriose/microbiologia , Fatores de Virulência/genética , Animais , Modelos Animais de Doenças , Humanos , Mucosa Intestinal/metabolismo , Mucosa Intestinal/microbiologia , Mucosa Intestinal/patologia , Listeria monocytogenes/efeitos dos fármacos , Listeria monocytogenes/patogenicidade , Listeriose/tratamento farmacológico , Listeriose/transmissão , Camundongos , Testes de Sensibilidade Microbiana , Especificidade de Órgãos , Estreptomicina/farmacologia , Estreptomicina/uso terapêutico , Virulência/genética
7.
Infect Immun ; 88(1)2019 12 17.
Artigo em Inglês | MEDLINE | ID: mdl-31685546

RESUMO

Listeria monocytogenes, a Gram-positive, facultative intracellular pathogen, survives and replicates in the cytosol of host cells. Synthesis of 1,4-dihydroxy-2-naphthoate (DHNA), an intermediate of menaquinone biosynthesis, is essential for cytosolic survival of L. monocytogenes independent from its role in respiration. Here, we demonstrate that DHNA is essential for virulence in a murine model of listeriosis due to both respiration-dependent and -independent functions. In addition, DHNA can be both secreted and utilized as an extracellular shared metabolite to promote cytosolic survival inside host macrophages. To understand the role(s) of DHNA in L. monocytogenes intracellular survival and virulence, we isolated DHNA-deficient (ΔmenD strain) suppressor mutants that formed plaques in monolayers of fibroblasts. Five ΔmenD suppressor (mds) mutants additionally rescued at least 50% of the cytosolic survival defect of the parent ΔmenD mutant. Whole-genome sequencing revealed that four of the five suppressor mutants had independent missense mutations in a putative transcriptional regulator, ytoI (lmo1576). Clean deletion and complementation in trans confirmed that loss of ytoI could restore plaquing and cytosolic survival of DHNA-deficient L. monocytogenes RNA-seq transcriptome analysis revealed five genes (lmo0944, lmo1575, lmo1577, lmo2005, and lmo2006) expressed at a higher level in the ΔytoI strain than in the wild-type strain, whereas two genes (lmo1917 and lmo2103) demonstrated lower expression in the ΔytoI mutant. Intriguingly, the majority of these genes are involved in controlling pyruvate flux. Metabolic analysis confirmed that acetoin, acetate, and lactate flux were altered in a ΔytoI mutant, suggesting a critical role for regulating these metabolic programs. In conclusion, we have demonstrated that, similar to findings in select other bacteria, DHNA can act as a shared resource, and it is essential for cytosolic survival and virulence of L. monocytogenes Furthermore, we have identified a novel transcriptional regulator in L. monocytogenes and determined that its metabolic regulation is implicated in cytosolic survival of L. monocytogenes.


Assuntos
Listeria monocytogenes/metabolismo , Listeriose/microbiologia , Proteínas Mutantes/metabolismo , Naftóis/metabolismo , Supressão Genética , Fatores de Transcrição/metabolismo , Animais , Citosol/química , Modelos Animais de Doenças , Listeria monocytogenes/genética , Listeria monocytogenes/crescimento & desenvolvimento , Listeria monocytogenes/patogenicidade , Camundongos , Viabilidade Microbiana , Proteínas Mutantes/genética , Fatores de Transcrição/genética , Virulência , Vitamina K 2/análise , Sequenciamento Completo do Genoma
8.
Nat Commun ; 10(1): 4283, 2019 09 30.
Artigo em Inglês | MEDLINE | ID: mdl-31570766

RESUMO

The foodborne pathogen Listeria monocytogenes (Lm) is a highly heterogeneous species and currently comprises of 4 evolutionarily distinct lineages. Here, we characterize isolates from severe ovine listeriosis outbreaks that represent a hybrid sub-lineage of the major lineage II (HSL-II) and serotype 4h. HSL-II isolates are highly virulent and exhibit higher organ colonization capacities than well-characterized hypervirulent strains of Lm in an orogastric mouse infection model. The isolates harbour both the Lm Pathogenicity Island (LIPI)-1 and a truncated LIPI-2 locus, encoding sphingomyelinase (SmcL), a virulence factor required for invasion and bacterial translocation from the gut, and other non-contiguous chromosomal segments from another pathogenic species, L. ivanovii. HSL-II isolates exhibit a unique wall teichoic acid (WTA) structure essential for resistance to antimicrobial peptides, bacterial invasion and virulence. The discovery of isolates harbouring pan-species virulence genes of the genus Listeria warrants global efforts to identify further hypervirulent lineages of Lm.


Assuntos
Listeria monocytogenes/genética , Listeriose/microbiologia , Animais , Células CACO-2 , Genoma Bacteriano , Genômica , Cabras/microbiologia , Humanos , Listeria monocytogenes/isolamento & purificação , Listeria monocytogenes/patogenicidade , Camundongos , Filogenia , Suínos/microbiologia , Virulência
9.
J Med Microbiol ; 68(11): 1677-1685, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31524579

RESUMO

Purpose. Listeria monocytogenes is a foodborne pathogen that causes central nervous system (CNS) and maternal-neonatal (MN) infections, bacteremia (BAC), and gastroenteritis in humans and ruminants. Specific clonal complexes (CC) have been associated with severe listeriosis cases, however, less is known about differences among subgroup virulence patterns. This study aimed to assess variation in virulence across different CC and clinical outcomes.Methodology. Galleria mellonella larvae were used to compare virulence phenotypes of 34 L. monocytogenes strains representing isolates from CC1, CC6 (from lineage I), and CC7, CC9, CC14, CC37 and CC204 (from lineage II) classified by clinical outcome: BAC, CNS and MN infection. Larvae survival, LD50, cytotoxicity, health index scores and bacterial concentrations post-infection were evaluated as quantifiable indicators of virulence.Results. Isolates belonging to CC14 and MN-associated infections are hypervirulent in G. mellonella as they led to lower G. mellonella survival rates and health index scores, as well as reduced cytotoxic effects when compared to other CC and clinical outcomes included here. CC14 isolates also showed increased bacterial concentrations at 8 and 24 h post-infection, indicating ability to survive the initial immune response and proliferate within G. mellonella larvae.Conclusion. Subgroups of L. monocytogenes possess different virulence phenotypes that may be associated with niche-specificity. While hypervirulent clones have been identified so far in lineage I, our data demonstrate that hypervirulent clones are not restricted to lineage I, as CC14 belongs to lineage II. Identification of subgroups with a higher ability to cause disease may facilitate surveillance and management of listeriosis.


Assuntos
Listeria monocytogenes/patogenicidade , Listeriose/microbiologia , Animais , Humanos , Larva/microbiologia , Lepidópteros/microbiologia , Listeria monocytogenes/classificação , Listeria monocytogenes/fisiologia , Fenótipo , Virulência
10.
mSphere ; 4(4)2019 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-31391275

RESUMO

Listeria monocytogenes is frequently found in foods and processing facilities, where it can persist, creating concerns for the food industry. Its ability to survive under a wide range of environmental conditions enhances the potential for cross-contamination of the final food products, leading to possible outbreaks of listeriosis. In this study, whole-genome sequencing (WGS) was applied as a tool to characterize and track 100 L. monocytogenes isolates collected from three food processing environments. These WGS data from environmental and food isolates were analyzed to (i) assess the genomic diversity of L. monocytogenes, (ii) identify possible source(s) of contamination, cross-contamination routes, and persistence, (iii) detect absence/presence of antimicrobial resistance-encoding genes, (iv) assess virulence genotypes, and (v) explore in vivo pathogenicity of selected L. monocytogenes isolates carrying different virulence genotypes. The predominant L. monocytogenes sublineages (SLs) identified were SL101 (21%), SL9 (17%), SL121 (12%), and SL5 (12%). Benzalkonium chloride (BC) tolerance-encoding genes were found in 62% of these isolates, a value that increased to 73% among putative persistent subgroups. The most prevalent gene was emrC followed by bcrABC, qacH-Tn6188, and qacC. The L. monocytogenes major virulence factor inlA was truncated in 31% of the isolates, and only one environmental isolate (L. monocytogenes CFS086) harbored all major virulence factors, including Listeria pathogenicity island 4 (LIPI-4), which has been shown to confer hypervirulence. A zebrafish embryo infection model showed a low (3%) embryo survival rate for all putatively hypervirulent L. monocytogenes isolates assayed. Higher embryo survival rates were observed following infection with unknown virulence potential (20%) and putatively hypovirulent (53 to 83%) L. monocytogenes isolates showing predicted pathogenic phenotypes inferred from virulence genotypes.IMPORTANCE This study extends current understanding of the genetic diversity among L. monocytogenes from various food products and food processing environments. Application of WGS-based strategies facilitated tracking of this pathogen of importance to human health along the production chain while providing insights into the pathogenic potential for some of the L. monocytogenes isolates recovered. These analyses enabled the grouping of selected isolates into three putative virulence categories according to their genotypes along with informing selection for phenotypic assessment of their pathogenicity using the zebrafish embryo infection model. It has also facilitated the identification of those isolates with genes conferring tolerance to commercially used biocides. Findings from this study highlight the potential for the application of WGS as a proactive tool to support food safety controls as applied to L. monocytogenes.


Assuntos
Microbiologia de Alimentos , Genótipo , Listeria monocytogenes/genética , Sequenciamento Completo do Genoma , Animais , Proteínas de Bactérias/genética , Farmacorresistência Bacteriana , Manipulação de Alimentos/instrumentação , Variação Genética , Genoma Bacteriano , Listeria monocytogenes/patogenicidade , Listeriose/microbiologia , Fatores de Virulência/genética , Peixe-Zebra
11.
Microbiol Spectr ; 7(4)2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31418407

RESUMO

Bacterial metabolism represents the biochemical space that bacteria can manipulate to produce energy, reducing equivalents and building blocks for replication. Gram-positive pathogens, such as Listeria monocytogenes, show remarkable flexibility, which allows for exploitation of diverse biological niches from the soil to the intracytosolic space. Although the human host represents a potentially rich source for nutrient acquisition, competition for nutrients with the host and hostile host defenses can constrain bacterial metabolism by various mechanisms, including nutrient sequestration. Here, we review metabolism in the model Gram-positive bacterium, L. monocytogenes, and highlight pathways that enable the replication, survival, and virulence of this bacterial pathogen.


Assuntos
Listeria monocytogenes/metabolismo , Listeria monocytogenes/patogenicidade , Listeriose/microbiologia , Animais , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Regulação Bacteriana da Expressão Gênica , Humanos , Listeria monocytogenes/genética , Virulência
12.
Food Microbiol ; 84: 103234, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31421784

RESUMO

Listeria monocytogenes is a relevant pathogen usually associated with meat and ready-to-eat products. This study aimed to assess the distribution, adhesion, virulence and antibiotic resistance of L. monocytogenes in a pork production chain. Environment, carcass and food samples (n = 894) were obtained from different steps of a pork production chain over a 6-month period (10 samplings), including from farms and the slaughterhouse (reception, slaughtering, processing, storage and end products). L. monocytogenes was detected in samples from the reception (lairage floor, 1/10), slaughtering (drains, 2/20) and cutting room stages (conveyor belts in the final packing stage - 11/20, knife - 1/40, and cutting boards - 1/20). Positive results for conveyor belts were recorded in seven consecutive samplings. L. monocytogenes isolates (n = 87) were characterized as belonging to serogroup IVb and presented positive PCR results for inlA, inlB, inlC, inlJ, hlyA, plcA, actA and iap. Isolates were selected according to the original samples (n = 31) and subjected to Pulsed Field Gel Electrophoresis (PFGE), demonstrating their high clonal identity (98.4-100%). According to PFGE results and their original samples, isolates were selected (n = 16) and subjected to phenotypic assay to assess their adhesion potential and tested for resistance against 15 antibiotics; all tested isolates presented weak adhesion potential and were resistant to ampicillin. The present study demonstrated the persistence of L. monocytogenes in the pork processing facility, indicating the potential risk for cross-contamination with a potential virulent and resistant clone.


Assuntos
Matadouros , Aderência Bacteriana , Microbiologia de Alimentos , Listeria monocytogenes/efeitos dos fármacos , Listeria monocytogenes/patogenicidade , /microbiologia , Animais , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Brasil , Farmacorresistência Bacteriana Múltipla , Fazendas , Listeria monocytogenes/genética , Suínos , Virulência
13.
Molecules ; 24(15)2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31375003

RESUMO

Antibiotic resistance is one of the main public health concerns of this century. This resistance is also associated with oxidative stress, which could contribute to the selection of resistant bacterial strains. Bearing this in mind, and considering that flavonoid compounds are well known for displaying both activities, we investigated a series of hydroxy-3-arylcoumarins with structural features of flavonoids for their antibacterial activity against different bacterial strains. Active compounds showed selectivity against the studied Gram-positive bacteria compared to Gram-negative bacteria. 5,7-Dihydroxy-3-phenylcoumarin (compound 8) displayed the best antibacterial activity against Staphylococcus aureus and Bacillus cereus with minimum inhibitory concentrations (MICs) of 11 g/mL, followed by Staphylococcus aureus (MRSA strain) and Listeria monocytogenes with MICs of 22 and 44 g/mL, respectively. Moreover, molecular docking studies performed on the most active compounds against Staphylococcus aureus tyrosyl-tRNA synthetase and topoisomerase II DNA gyrase revealed the potential binding mode of the ligands to the site of the appropriate targets. Preliminary structure-activity relationship studies showed that the antibacterial activity can be modulated by the presence of the 3-phenyl ring and by the position of the hydroxyl groups at the coumarin scaffold.


Assuntos
Antibacterianos/química , Infecções Bacterianas/tratamento farmacológico , Cumarínicos/química , Relação Estrutura-Atividade , Antibacterianos/farmacologia , Bacillus cereus/efeitos dos fármacos , Bacillus cereus/patogenicidade , Infecções Bacterianas/microbiologia , Cumarínicos/farmacologia , DNA Girase/química , DNA Girase/genética , Humanos , Listeria monocytogenes/efeitos dos fármacos , Listeria monocytogenes/patogenicidade , Simulação de Acoplamento Molecular , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/patogenicidade
14.
Rev Med Liege ; 74(7-8): 410-413, 2019 Jul.
Artigo em Francês | MEDLINE | ID: mdl-31373456

RESUMO

The occurrence of non-viral meningitis remains a heavy diagnosis carrying undeniable pejorative aspects that may vary according to several factors such as the age and the presence or absence of an immunodeficiency. In some cases, uncommon germs can also lead to a bad prognosis such as Listeria monocytogenes that can be responsible of an extremely severe septic state. We report the case of a girl with Listeria meningitis, whose evolution was unfortunately quickly negative.


Assuntos
Listeria monocytogenes , Listeriose , Meningite por Listeria , Sepse , Antibacterianos/uso terapêutico , Criança , Evolução Fatal , Feminino , Humanos , Imunocompetência , Listeria monocytogenes/patogenicidade , Listeriose/diagnóstico , Listeriose/tratamento farmacológico , Listeriose/microbiologia , Sepse/diagnóstico , Sepse/tratamento farmacológico , Sepse/microbiologia
15.
Int J Mol Sci ; 20(17)2019 Aug 24.
Artigo em Inglês | MEDLINE | ID: mdl-31450632

RESUMO

The pathogenic Gram-positive bacterium Listeria monocytogenes has been evolving into a few phylogenetic lineages. Phylogenetically defined substitutions were described in the L. monocytogenes virulence factor InlB, which mediates active invasion into mammalian cells via interactions with surface receptors c-Met and gC1q-R. InlB internalin domain (idInlB) is central to interactions with c-Met. Here we compared activity of purified recombinant idInlB isoforms characteristic for L. monocytogenes phylogenetic lineage I and II. Size exclusion chromatography and intrinsic fluorescence were used to characterize idInlBs. Western blotting was used to study activation of c-Met-dependent MAPK- and PI3K/Akt-pathways. Solid-phase microplate binding and competition assay was used to quantify interactions with gCq1-R. Isogenic recombinant L. monocytogenes strains were used to elucidate the input of idInlB isoforms in HEp-2 cell invasion. Physicochemical parameters of idInlB isoforms were similar but not identical. Kinetics of Erk1/2 and Akt phosphorylation in response to purified idInlBs was lineage specific. Lineage I but not lineage II idInlB specifically bound gC1q-R. Antibody against gC1q-R amino acids 221-249 inhibited invasion of L. monocytogenes carrying lineage I but not lineage II idInlB. Taken together, obtained results suggested that phylogenetically defined substitutions in idInlB provide functional distinctions and might be involved in phylogenetically determined differences in virulence potential.


Assuntos
Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Proteínas de Transporte/metabolismo , Listeria monocytogenes/classificação , Listeria monocytogenes/fisiologia , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Proteínas Mitocondriais/metabolismo , Filogenia , Transdução de Sinais , Sequência de Aminoácidos , Proteínas de Bactérias/química , Linhagem Celular , Humanos , Listeria monocytogenes/patogenicidade , Proteínas de Membrana/química , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Isoformas de Proteínas , Fatores de Virulência
16.
Microbiol Spectr ; 7(4)2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31441398

RESUMO

Whereas obligate human and animal bacterial pathogens may be able to depend upon the warmth and relative stability of their chosen replication niche, environmental bacteria such as Listeria monocytogenes that harbor the ability to replicate both within animal cells and in the outside environment must maintain the capability to manage life under a variety of disparate conditions. Bacterial life in the outside environment requires adaptation to wide ranges of temperature, available nutrients, and physical stresses such as changes in pH and osmolarity as well as desiccation. Following ingestion by a susceptible animal host, the bacterium must adapt to similar changes during transit through the gastrointestinal tract and overcome a variety of barriers associated with host innate immune responses. Rapid alteration of patterns of gene expression and protein synthesis represent one strategy for quickly adapting to a dynamic host landscape. Here, we provide an overview of the impressive variety of strategies employed by the soil-dwelling, foodborne, mammalian pathogen L. monocytogenes to straddle diverse environments and optimize bacterial fitness both inside and outside host cells.


Assuntos
Listeria monocytogenes/patogenicidade , Listeriose/microbiologia , Animais , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Regulação Bacteriana da Expressão Gênica , Humanos , Imunidade Inata , Listeria monocytogenes/genética , Listeria monocytogenes/metabolismo , Listeriose/imunologia , Concentração Osmolar , Virulência
17.
J Appl Microbiol ; 127(5): 1349-1361, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31432571

RESUMO

AIMS: An extensive source investigation was conducted on a dairy farm with neurolisteriosis and subclinical mastitis cases to identify infection source and potential transmission routes of Listeria monocytogenes. METHODS AND RESULTS: A total of 36 L. monocytogenes isolates were obtained from animal clinical cases (neurolisteriosis and udder infection) and the farm environment (silage, faeces, water). Isolates were typed using pulsed-field gel electrophoresis (PFGE) and whole-genome sequencing (WGS). Their virulence potential was assessed using the gentamicin protection assay and WGS-based identification of virulence genes. PFGE and WGS revealed a high genetic diversity of L. monocytogenes. An epidemiological link was confirmed for isolates from (i) several subclinical mastitis cases, (ii) silage and subclinical mastitis cases and (iii) different water sources. The neurolisteriosis isolate belonged to clonal complex (CC) 1, but infection source was not identified. A high occurrence (9/47 cows; 19·1%) of subclinical mastitis was observed with isolates belonging to CC2, CC4 and CC11. CONCLUSIONS: The dairy farm environment was contaminated with diverse L. monocytogenes strains, including genotypes associated with human disease. Several isolates harboured genetic determinants associated with increased infectious potential in humans. SIGNIFICANCE AND IMPACT OF THE STUDY: Results suggest that subclinical listerial mastitis should not be neglected as a potential source of milk contamination. The presence of hypervirulent CCs in subclinical mastitis cases calls for the implementation of improved mastitis detection.


Assuntos
Listeria monocytogenes/isolamento & purificação , Listeria monocytogenes/patogenicidade , Mastite Bovina/epidemiologia , Mastite Bovina/microbiologia , Meningite por Listeria/veterinária , Animais , Bovinos , Fazendas , Fezes/microbiologia , Feminino , Genótipo , Listeria monocytogenes/classificação , Listeria monocytogenes/genética , Meningite por Listeria/epidemiologia , Meningite por Listeria/microbiologia , Silagem/microbiologia , Virulência/genética
18.
Future Microbiol ; 14: 801-828, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31271064

RESUMO

Aim: Among the alternative sigma factors of Listeria monocytogenes, σB controls the largest regulon. The aim of this study was to perform a comprehensive review of σB-regulated genes, and the functions they confer. Materials & methods: A systematic search of PubMed and Web of Knowledge was carried out to identify members of the σB regulon based on experimental evidence of σB-dependent transcription and presence of a consensus σB-dependent promoter. Results: The literature review identified σB-dependent transcription units encompassing 304 genes encoding different functions including stress response and virulence. Conclusion: Our review supports the well-known roles of σB in virulence and stress response and provides new insight into novel roles for σB in metabolism and overall resilience of L. monocytogenes.


Assuntos
Proteínas de Bactérias/metabolismo , Regulação Bacteriana da Expressão Gênica , Listeria monocytogenes/genética , Metabolismo , Regulon , Fator sigma/metabolismo , Estresse Fisiológico , Listeria monocytogenes/patogenicidade , Listeria monocytogenes/fisiologia , Virulência
19.
Microbiol Res ; 223-225: 88-98, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31178056

RESUMO

CodY and (p)ppGpp synthetases are two important global regulators of bacteria. In some pathogens, such as Listeria monocytogenes, the GTP pool links these two regulatory systems, and introducing a codY mutant into the ΔrelA strain restored the pathogenicity of the attenuated ΔrelA mutant. In previous studies, we identified the (p)ppGpp synthetases (RelA and RelQ) and CodY of Streptococcus suis. To understand the interrelationships between these two regulators in S. suis, a ΔrelAΔrelQΔcodY mutant was constructed, and its growth, morphology, and pathogenicity were evaluated. Compared with ΔrelAΔrelQ, ΔcodY, its growth was very slow, but its chain length was partly restored to the wild-type length and its capsule became thick and rough. The adherence, invasion ability, and resistance to whole-blood killing in vitro of ΔrelAΔrelQΔcodY and its lethality and colonization ability in mice were clearly reduced, which differs from the effects of these mutations in L. monocytogenes. An analysis of gene expression showed that CodY interacted with the relA promoter in a GTP-independent manner to positively regulate the expression of relA. The introduction of a codY mutant into the ΔrelAΔrelQ strain further reduced the expression of virulence factors, which suggests a novel interaction between the (p)ppGpp synthetases and CodY. This study extends our understanding of the relationship between the (p)ppGpp-mediated stringent response and the regulation of CodY in S. suis.


Assuntos
Regulação Bacteriana da Expressão Gênica , Ligases/metabolismo , Streptococcus suis/citologia , Streptococcus suis/metabolismo , Streptococcus suis/patogenicidade , Fatores de Transcrição/metabolismo , Transcriptoma , Adesinas Bacterianas/genética , Animais , Proteínas de Bactérias/genética , Modelos Animais de Doenças , Feminino , Guanosina Trifosfato/metabolismo , Ligases/genética , Listeria monocytogenes/genética , Listeria monocytogenes/metabolismo , Listeria monocytogenes/patogenicidade , Camundongos , Mutação , Regiões Promotoras Genéticas , Infecções Estreptocócicas/microbiologia , Streptococcus suis/genética , Fatores de Transcrição/genética , Fatores de Virulência/genética , Fatores de Virulência/metabolismo
20.
Nat Commun ; 10(1): 2488, 2019 06 06.
Artigo em Inglês | MEDLINE | ID: mdl-31171794

RESUMO

Listeria monocytogenes (Lm) is a major human and animal foodborne pathogen. Here we show that hypervirulent Lm clones, particularly CC1, are strongly associated with dairy products, whereas hypovirulent clones, CC9 and CC121, are associated with meat products. Clone adaptation to distinct ecological niches and/or different food products contamination routes may account for this uneven distribution. Indeed, hypervirulent clones colonize better the intestinal lumen and invade more intestinal tissues than hypovirulent ones, reflecting their adaption to host environment. Conversely, hypovirulent clones are adapted to food processing environments, with a higher prevalence of stress resistance and benzalkonium chloride tolerance genes and a higher survival and biofilm formation capacity in presence of sub-lethal benzalkonium chloride concentrations. Lm virulence heterogeneity therefore reflects the diversity of the ecological niches in which it evolves. These results also have important public health implications and may help in reducing food contamination and improving food consumption recommendations to at-risk populations.


Assuntos
Laticínios/microbiologia , Doenças Transmitidas por Alimentos/microbiologia , Intestinos/microbiologia , Listeria monocytogenes/patogenicidade , Produtos da Carne/microbiologia , Virulência , Adaptação Fisiológica , Animais , Anti-Infecciosos Locais , Compostos de Benzalcônio , Biofilmes , Células Clonais , Farmacorresistência Bacteriana/genética , Ecossistema , Contaminação de Alimentos , Manipulação de Alimentos , Humanos , Listeria monocytogenes/genética
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