scholarly journals Effect of Acid Adaptation on the Fate of Listeria monocytogenes in THP-1 Human Macrophages Activated by Gamma Interferon

2002 ◽  
Vol 70 (8) ◽  
pp. 4369-4378 ◽  
Author(s):  
Maria Pia Conte ◽  
Gloria Petrone ◽  
Assunta Maria Di Biase ◽  
Catia Longhi ◽  
Michela Penta ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Cell Invasion ◽  
Acid Resistance ◽  
Intracellular Survival ◽  
Low Ph ◽  
Gamma Interferon ◽  
Acid Adaptation ◽  
Human Macrophages ◽  
Expression Of Genes ◽  
Genes Encoding

ABSTRACT In Listeria monocytogenes the acid tolerance response (ATR) takes place through a programmed molecular response which ensures cell survival under unfavorable conditions. Much evidence links ATR with virulence, but the molecular determinants involved in the reactivity to low pHs and the behavior of acid-exposed bacteria within host cells are still poorly understood. We have investigated the effect of acid adaptation on the fate of L. monocytogenes in human macrophages. Expression of genes encoding determinants for cell invasion and intracellular survival was tested for acid-exposed bacteria, and invasive behavior in the human myelomonocytic cell line THP-1 activated with gamma interferon was assessed. Functional approaches demonstrated that preexposure to an acidic pH enhances the survival of L. monocytogenes in activated human macrophages and that this effect is associated with an altered pattern of expression of genes involved in acid resistance and cell invasion. Significantly decreased transcription of the plcA gene, encoding a phospholipase C involved in vacuolar escape and cell-to-cell spread, was observed in acid-adapted bacteria. This effect was due to a reduction in the quantity of the bicistronic plcA-prfA transcript, concomitant with an increase in the level(s) of the monocistronic prfA mRNA(s). The transcriptional shift from distal to proximal prfA promoters resulted in equal levels of the prfA transcript (and, as a consequence, of the inlA, hly, and actA transcripts) under neutral and acidic conditions. In contrast, the sodC and gad genes, encoding a cytoplasmic superoxide dismutase and the glutamate-based acid resistance system, respectively, were positively regulated at a low pH. Morphological approaches confirmed the increased intracellular survival and growth of acid-adapted L. monocytogenes cells both in vacuoles and in the cytoplasm of interferon gamma-activated THP-1 macrophages. Our data indicate that preexposure to a low pH has a positive impact on subsequent challenge of L. monocytogenes with macrophagic cells.

Transcriptome Analysis of Listeria monocytogenes Grown on a Ready-to-Eat Meat Matrix

2011 ◽  
Vol 74 (7) ◽  
pp. 1104-1111 ◽  
Author(s):  
DONGRYEOUL BAE ◽  
MICHAEL R. CROWLEY ◽  
CHINLING WANG
Keyword(s):  
Listeria Monocytogenes ◽  
Virulence Factors ◽  
Microarray Data ◽  
Meat Products ◽  
Phospholipid Metabolism ◽  
Transcriptional Level ◽  
Cellular Processes ◽  
Reverse Transcription Pcr ◽  
Expression Of Genes ◽  
Genes Encoding

The contamination of ready-to-eat (RTE) meat products with Listeria monocytogenes is a major concern for the food industry. For a better understanding of the adaptation and survival ability of L. monocytogenes grown on turkey deli meat, the transcriptome of L. monocytogenes strain F2365 was determined with a microarray. Microarray data were validated with a quantitative real-time reverse transcription PCR assay. Based on the microarray data, 39 and 45 genes from L. monocytogenes were transcriptionally upregulated and down-regulated, respectively. The genes regulated at the transcriptional level were mainly involved in energy metabolism, fatty acid and phospholipid metabolism, biosynthesis of proteins, transport and binding proteins, DNA metabolism, cellular processes, and regulatory functions. No significant change was noted for the expression of genes encoding known virulence factors such as sigB, prfA, inlA, inlB, plcA, plcB, and hly. These results suggest that L. monocytogenes grown on RTE deli meat changes its transcription of proteins involved in its metabolic pathways to obtain an energy source or to adapt to environmental change without increasing the expression of virulence factors. The global transcriptome profiles provide a better understanding of the growth or adaptation of L. monocytogenes in RTE meat products.

Comparative Analysis of Acid Resistance between Susceptible and Multi-Antimicrobial-Resistant Salmonella Strains Cultured under Stationary-Phase Acid Tolerance–Inducing and Noninducing Conditions

2003 ◽  
Vol 66 (5) ◽  
pp. 732-740 ◽  
Author(s):  
R. T. BACON ◽  
J. N. SOFOS ◽  
P. A. KENDALL ◽  
K. E. BELK ◽  
G. C. SMITH
Keyword(s):  
Stationary Phase ◽  
Antimicrobial Agents ◽  
Acid Stress ◽  
Acid Tolerance ◽  
Acid Resistance ◽  
Low Ph ◽  
Acid Exposure ◽  
Acid Adaptation ◽  
Acid Shock ◽  
Resistant Strains

This study compared acid resistance levels among five antimicrobial-susceptible strains of Salmonella and five strains that were simultaneously resistant to a minimum of six antimicrobial agents. The induction of a stationary-phase acid tolerance response (ATR) was attempted by both transient low-pH acid shock and acid adaptation. For acid shock induction, strains were grown for 18 h in minimal E medium containing 0.4% glucose (EG medium) and exposed to sublethal acid stress (pH 4.3) for 2 h, and subsequently, both shocked and nonshocked cultures were acid challenged (pH 3.0) for 4 h. Acid adaptation was achieved by growing strains for 18 h in tryptic soy broth containing 1.0% glucose (TSB+G), while nonadapted cultures were grown for 18 h in glucose-free tryptic soy broth (TSB−G). Acid-adapted and nonadapted inocula were acid challenged (pH 2.3) for 4 h. Initial (0 h) mean populations of nonchallenged Salmonella were 8.5 to 8.7, 8.4 to 8.8, and 8.2 to 8.3 log CFU/ml for strains grown in EG medium, TSB−G, and TSB+G, respectively. After 4 h of acid challenge, mean populations were 3.0 to 4.8 and 2.5 to 3.7 log CFU/ml for previously acid-shocked susceptible and resistant strains, respectively, while corresponding counts for nonshocked strains were 4.3 to 5.5 log CFU/ml and 3.9 to 4.9 log CFU/ml. Following 4 h of acid exposure, acid-adapted cultures of susceptible and resistant strains had mean populations of 6.1 to 6.4 log CFU/ml and 6.4 to 6.6 log CFU/ml, respectively, while corresponding counts for nonadapted cultures were 1.9 to 2.1 log CFU/ml and 1.8 to 2.0 log CFU/ml, respectively. A low-pH–inducible ATR was not achieved through transient acid shock, while an ATR was evident following acid adaptation, as adapted populations were 4.2 to 4.8 log units larger than nonadapted populations following acid exposure. Although some strain-dependent variations in acid resistance were observed, results from this study suggest no association between susceptibility to antimicrobial agents and the ability of the Salmonella strains evaluated to survive low-pH stress.

Stationary-Phase Acid Resistance and Injury of Recent Bovine Escherichia coli O157 and non-O157 Biotype I Escherichia coli Isolates†

2004 ◽  
Vol 67 (3) ◽  
pp. 583-590 ◽  
Author(s):  
E. D. BERRY ◽  
G. A. BARKOCY-GALLAGHER ◽  
G. R. SIRAGUSA
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Acid Resistance ◽  
Low Ph ◽  
Acid Adaptation ◽  
E Coli ◽  
Log Reduction ◽  
Natural Isolates ◽  
Acidic Conditions ◽  
Ph Challenge

Stationary-phase acid resistance and the induction of acid resistance were assessed for recent bovine carcass isolates of Escherichia coli, including 39 serotype O157 strains and 20 non-O157 strains. When grown to stationary phase in the absence of glucose and without prior acid exposure, there was a range of responses to a pH challenge of 6 h at pH 2.5. However, populations of 53 of the 59 E. coli isolates examined were reduced by less than 2.00 log CFU/ml, and populations of 24 of these isolates were reduced by less than 1.00 log CFU/ml. In contrast, there was little variation in population reductions when the E. coli were grown with glucose and preadapted to acidic conditions. With few exceptions, acid adaptation improved survival to the acid challenge, with 57 of the 59 isolates exhibiting a log reduction of less than 0.50. Differences in acid resistance or the ability to adapt to acidic conditions between E. coli O157:H7 and non-O157 commensal E. coli were not observed. However, we did find that the E. coli O157 were disposed to greater acid injury after the low pH challenge than the non-O157 E. coli, both for cells that were and were not adapted to acidic conditions before the challenge. The enhancement of low pH survival after acid adaptation that was seen among these recent natural isolates of E. coli O157 further supports the idea that the previous environment of this pathogen should be a consideration when designing microbial safety strategies for foods preserved by low pH and acid.

Heat and Acid Tolerance Responses of Listeria monocytogenes as Affected by Sequential Exposure to Hurdles during Growth

2009 ◽  
Vol 72 (7) ◽  
pp. 1412-1418 ◽  
Author(s):  
PANAGIOTIS N. SKANDAMIS ◽  
JARRET D. STOPFORTH ◽  
YOHAN YOON ◽  
PATRICIA A. KENDALL ◽  
JOHN N. SOFOS
Keyword(s):  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Yeast Extract ◽  
Acid Tolerance ◽  
Acid Resistance ◽  
Low Ph ◽  
Acid Ph ◽  
Applied Stresses

This study aimed to evaluate the effects of the level and sequence of hurdles, applied during growth, on the subsequent heat and acid tolerances of a 10-strain composite of Listeria monocytogenes. Individual strains were grown in glucose-free tryptic soy broth with 0.6% yeast extract (TSBYE–G). Then cultures were mixed and inoculated in fresh TSBYE–G (0.5% NaCl, pH 7.42; control), TSBYE–G that was supplemented with 3% NaCl (3.5% NaCl in total), or TSBYE–G with pH adjusted to 6.01 or 5.04 with lactic acid and incubated at 30°C for 24 h. Furthermore, the culture composite was exposed to the following five combinations of double sequential hurdles (12 h in each at 30°C): NaCl then pH 6.01, NaCl then pH 5.04, pH 7.42 then NaCl, pH 5.04 then NaCl, and pH 6.01 then NaCl. The heat and acid tolerances of the culture were assessed at 57°C (for 2 h) and at pH 3.5 (for 7 h), respectively, in TSBYE–G. No significant (P ≥ 0.05) differences in thermotolerance were observed among cultures exposed to various stresses. In contrast, the acid resistance followed the order: pH 6.01 = NaCl > NaCl then pH 5.04 > pH 6.01 then NaCl = pH 5.04 > pH 5.04 then NaCl > pH 7.42 then NaCl > control. The results suggest that exposure of L. monocytogenes to NaCl and low pH during growth may not affect its heat (57°C) tolerance, but it may increase its acid (pH 3.5) resistance, depending on the sequence and intensity of the applied stresses.

Ciprofloxacin interferes with Salmonella Typhimurium intracellular survival and host virulence through repression of Salmonella pathogenicity island-2 (SPI-2) genes expression

2020 ◽  
Vol 78 (1) ◽  
Author(s):  
Momen Askoura ◽  
Wael Abdel Halim Hegazy
Keyword(s):  
Intracellular Survival ◽  
Inhibitory Effect ◽  
Expression Of Genes ◽  
Type Three Secretion System ◽  
Genes Expression ◽  
Gentamicin Protection Assay ◽  
Infection Models ◽  
Genes Encoding ◽  
Resistance Patterns ◽  
Host Infection

ABSTRACT Current study aims to characterize the influence of sub-minimum inhibitory concentration (sub-MIC) of ciprofloxacin on Salmonella intracellular survival and host virulence. Herein, Salmonella resistance patterns to various antibiotics were in agreement with those reported in previous studies. Moreover, intracellular survival of both ciprofloxacin-sensitive and -resistant Salmonella was markedly reduced upon treatment with sub-MIC of ciprofloxacin as determined by gentamicin protection assay. These findings were further confirmed using immunostaining indicating an inhibitory effect of sub-MIC of ciprofloxacin on Salmonella intracellular survival. RT-qPCR revealed that expression of genes encoding Salmonella type three secretion system (TTSS) decreased upon bacterial exposure to sub-MIC of ciprofloxacin. Furthermore, bacterial exposure to sub-MIC of ciprofloxacin significantly reduced expression of both sifA and sifB, which are important for Salmonella filaments formation within the host. Treatment of Salmonella with sub-MIC of ciprofloxacin reduced bacterial capacity to kill mice infection models. A lower mortality rate was observed in mice injected with Salmonella treated with sub-MIC of ciprofloxacin as compared with mice inoculated with untreated bacteria. Collectively, current findings indicate that, in addition to its bactericidal potential, sub-MIC of ciprofloxacin could inhibit Salmonella intracellular survival, virulence genes expression as well as host pathogenesis, providing another mechanism for ciprofloxacin in limiting Salmonella host infection.

scholarly journals Characterization of the ArsRS Regulon of Helicobacter pylori, Involved in Acid Adaptation

2006 ◽  
Vol 188 (10) ◽  
pp. 3449-3462 ◽  
Author(s):  
Michael Pflock ◽  
Nadja Finsterer ◽  
Biju Joseph ◽  
Hans Mollenkopf ◽  
Thomas F. Meyer ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Response Regulator ◽  
Transcriptional Profiling ◽  
Acid Resistance ◽  
Two Component System ◽  
Gene Encoding ◽  
Acid Adaptation ◽  
Genes Encoding ◽  
H Pylori ◽  
A Site

ABSTRACT The human gastric pathogen Helicobacter pylori is extremely well adapted to the highly acidic conditions encountered in the stomach. The pronounced acid resistance of H. pylori relies mainly on the ammonia-producing enzyme urease; however, urease-independent mechanisms are likely to contribute to acid adaptation. Acid-responsive gene regulation is mediated at least in part by the ArsRS two-component system consisting of the essential OmpR-like response regulator ArsR and the nonessential cognate histidine kinase ArsS, whose autophosphorylation is triggered in response to low pH. In this study, by global transcriptional profiling of an ArsS-deficient H. pylori mutant grown at pH 5.0, we define the ArsR∼P-dependent regulon consisting of 109 genes, including the urease gene cluster, the genes encoding the aliphatic amidases AmiE and AmiF, and the rocF gene encoding arginase. We show that ArsR∼P controls the acid-induced transcription of amiE and amiF by binding to extended regions located upstream of the −10 box of the respective promoters. In contrast, transcription of rocF is repressed by ArsR∼P at neutral, acidic, and mildly alkaline pH via high-affinity binding of the response regulator to a site overlapping the promoter of the rocF gene.

scholarly journals Human Short Peptidoglycan Recognition Protein PGLYRP1/Tag-7/PGRP-S Inhibits Listeria monocytogenes Intracellular Survival in Macrophages

2020 ◽  
Vol 10 ◽  
Author(s):  
Darya Slonova ◽  
Alexandra Posvyatenko ◽  
Alexey Kibardin ◽  
Elena Sysolyatina ◽  
Elena Lyssuk ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Proinflammatory Cytokine ◽  
Mammalian Cells ◽  
Intracellular Survival ◽  
Intracellular Pathogen ◽  
Bacterial Cells ◽  
Human Macrophages ◽  
Peptidoglycan Recognition Protein ◽  
Molecular Sensor ◽  
Recognition Protein

PGLYRP1/Tag-7/PGRP-S is one of mammalian peptidoglycan recognition proteins (PGRPs). Here, we demonstrate that human recombinant PGLYRP1/Tag-7/PGRP-S potentiates the response of murine macrophage-like ANA-1 cells and human macrophages to facultative intracellular pathogen Listeria monocytogenes. PGLYRP1/Tag-7/PGRP-S binds to the surface of L. monocytogenes and other bacterial cells but has no effect on their growth in culture. While PGLYRP1/Tag-7/PGRP-S treatment modestly enhanced phagocytosis of bacteria by ANA-1 cells, the intracellular survival of PGLYRP1/Tag-7/PGRP-S treated L. monocytogenes was strongly inhibited 2 h after internalization. PGLYRP1/Tag-7/PGRP-S treatment of bacteria boosted oxidative burst induction and increased the level of proinflammatory cytokine IL-6 produced by ANA-1, however, these effects happened too late to be responsible for decreased intracellular survival of bacteria. Our results thus suggest that PGLYRP1/Tag-7/PGRP-S acts as a molecular sensor for detection of L. monocytogenes infection of mammalian cells that leads to increased killing through a mechanism(s) that remains to be defined.

scholarly journals Presence of GadD1 Glutamate Decarboxylase in Selected Listeria monocytogenes Strains Is Associated with an Ability To Grow at Low pH

2005 ◽  
Vol 71 (6) ◽  
pp. 2832-2839 ◽  
Author(s):  
Paul D. Cotter ◽  
Sheila Ryan ◽  
Cormac G. M. Gahan ◽  
Colin Hill
Keyword(s):  
Listeria Monocytogenes ◽  
Glutamate Decarboxylase ◽  
Low Ph ◽  
Strain Variation ◽  
Ph Stress ◽  
Genes Encoding ◽  
Acidic Conditions ◽  
The Creation ◽  
Isogenic Mutants ◽  
Acid Challenge

ABSTRACT The glutamate decarboxylase (GAD) system is critical to the survival of Listeria monocytogenes LO28 at low-pH stress (<pH 4.0). The GAD system classically involves two proteins, a glutamate decarboxylase enzyme coupled to a glutamate/γ-aminobutyrate antiporter, which results in the consumption of an intracellular proton for each glutamate entering the system. Uniquely among prokaryotes, some strains of L. monocytogenes, including strain LO28, possess genes encoding three decarboxylases (gadD1, gadD2, and gadD3) and two antiporters (gadT1 and gadT2). These are organized in two pairs (gadD1T1 and gadD2T2) and a distinct gadD3. While the creation of a gadD3 mutant has not been possible, analysis of 15 isogenic mutants has confirmed previous observations that GadD2/T2 are primarily responsible for surviving severe acid challenge (pH 2.8). However, we have now established that GadD1 plays a major role in growth at mildly acidic pHs (pH 5.1). When strain variation studies revealed that a large number of L. monocytogenes strains (including all serotype 4 strains) lack the gadD1 gadT1 pair, low-pH growth assays were carried out. It was found that the majority of strains that grew poorly at pH 5.1 lacked these genes. The strain-variable ability to grow in mildly acidic conditions may explain why non-serotype 4 strains of L. monocytogenes predominate in foods.

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