Survival of osmotic and acid stress by Listeria monocytogenes strains of clinical or meat origin

Dykes, Gary A.; Moorhead, S.M.

doi:10.1016/s0168-1605(99)00205-6

Cited by 62 publications

(45 citation statements)

References 20 publications

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“…Furthermore, the initial dose of ingested bacteria and factors that diminished the dose in the human tract could be implicated. Resistance of the carriage strains to several sources of stress (i.e., the low-pH environment of the stomach, the antimicrobial environment of the mucosal surfaces, and the presence of bile and enzymes in the gastric fluids) has to be evaluated since significantly different behaviors have been already described for strains of clinical or meat origin (9,10,13).…”

Section: Discussionmentioning

confidence: 99%

Expression of Truncated Internalin A Is Involved in Impaired Internalization of Some Listeria monocytogenes Isolates Carried Asymptomatically by Humans

et al. 2003

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Fourteen human carriage Listeria monocytogenes isolates were compared to sporadic and epidemic-associated human strains in order to ascertain the pathogenic behavior of these unrecognized asymptomatic strains. Experimental infection of 14-day-old chick embryos revealed that the majority of the carriage strains were attenuated for virulence. Of the 10 attenuated carriage strains, 5 were affected in their invasion capacities in vitro. Western blot analysis with antibody directed against InlA, the surface protein implicated in the internalization in host cells, allowed correlation between the ability of the carriage strains to enter Caco-2 cells and InlA expression. Indeed, these five carriage strains produced truncated forms of InlA. Four of the five truncated forms of InlA had an apparent molecular mass of 47 kDa. In order to assess the existence of a genetic lineage, partial sequences of inlA gene of these four strains were compared and revealed that they had a high degree of sequence conservation at the gene (99.86%) and amino acid (100%) levels. Comparison of their nucleotide sequences with that of the corresponding segment of inlA from EGD-e and Scott A strains, taken as epidemic references, showed more divergence. Taken together, these observations suggest the presence of specific traits that characterize L. monocytogenes strains isolated during asymptomatic carriage. Some of these traits could provide some explanations about the determinants that make them unable to cause systemic human infection.

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Section: Discussionmentioning

confidence: 99%

Expression of Truncated Internalin A Is Involved in Impaired Internalization of Some Listeria monocytogenes Isolates Carried Asymptomatically by Humans

et al. 2003

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“…This high level could be the reason why the infections in the liver and spleen were almost identical in this study, regardless of the PFGE studies. Also the (6,21) and could have an influence on the level of invading bacteria. Future investigations will show whether invasion of these isolates is influenced by stress both in vitro and in vivo.…”

Section: Discussionmentioning

confidence: 99%

In Vitro and In Vivo Invasiveness of Different Pulsed-Field Gel Electrophoresis Types of Listeria monocytogenes

Larsen¹,

Nørrung

Sommer

et al. 2002

Appl Environ Microbiol

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The virulence of different pulsed-field gel electrophoresis (PFGE) types of Listeria monocytogenes was examined by monitoring their ability to invade Caco-2 cells. Strains belonging to seven different PFGE types originating from both foods and humans were included. No significant differences in invasiveness were detected between strains isolated from humans and those isolated from food. Strains belonging to PFGE type 1 expressed a significantly lower ability to invade cells compared to strains belonging to other PFGE types. Although strains of PFGE type 2 also seemed to invade at a low level, this was not significant in the present study. PFGE types 1 and 2 as well as type 14 are more frequently found in food than the four other PFGE types examined and moreover have a relatively low prevalence in humans compared to their prevalence in food. Thus, the hypothesis that some PFGE types are less virulent than others is supported by this study showing that certain PFGE types of L. monocytogenes commonly found in food are less invasive than others to Caco-2 cells. In contrast to the differences in invasion, identical intracellular growth rates between the different PFGE types were observed. In vivo studies of the actual ability of the strains to invade the liver and spleen of cimetidinetreated rats following an oral dose of 10 9 L. monocytogenes cells were performed for isolates of PFGE types 1, 2, 5, and 15. After 2 days, equal amounts of bacteria were observed in the liver and spleen of the rats for any of the PFGE types tested.Listeria monocytogenes is an intracellular pathogen of humans and animals that expresses differences in virulence within individual strains (7, 27). Among the 13 serotypes known for this species, most isolates from human cases of listeriosis seem to belong to only three serotypes (1/2a, 1/2b, and 4b). While serotyping has limited application in epidemiological studies, more discriminatory molecular typing methods, such as multilocus enzyme electrophoresis (12, 16), pulsed-field gel electrophoresis (PFGE) (18,20), random amplification of polymorphic DNA (3, 4), ribotyping (23), and phage typing (14), have successfully been used to differentiate among isolates of L. monocytogenes.PFGE has been shown to be highly discriminative for strains of L. monocytogenes (10, 11, 15), either alone or in combination with other methods. PFGE typing of 123 isolates of L. monocytogenes from ready-to-eat foods and 39 isolates from human clinical cases of infection showed a significant difference in the distribution of PFGE types among food isolates compared to human isolates (18), with some types having a higher prevalence among food isolates and vice versa.Individual isolates of L. monocytogenes are known to vary in virulence (7,9). Most earlier studies that have described the association between various subtypes and the virulence of the strains have focused on multiplication inside the host rather than invasion into the intestinal mucosa. The results are not clear, however. By this approach, Nørrung and Anderse...

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“…This is the case for the betaine uptake system BetU of the uropathogenic E. coli strain HU734, which is absent from the sequenced strain K-12 (19). As well as the potential absence of particular genes from the genome of the sequenced strain, significant strain variation in relation to the activity and/or regulation of specific osmolyte uptake systems has also been reported in Listeria (22,64), thus limiting the information that can be gleaned from the genome sequence of a single strain, at least in the context of a global understanding of the listerial salt stress response.…”

Section: Future Prospectsmentioning

confidence: 99%

A Postgenomic Appraisal of Osmotolerance in Listeria monocytogenes

Sleator

Gahan

Hill

2003

Appl Environ Microbiol

135

105

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A characteristic feature of the intracellular food-borne pathogen Listeria monocytogenes is its ability to survive and even proliferate under a variety of hostile environmental conditions, particularly elevated osmolarity (10% NaCl) (47) and reduced temperature (Ϫ0.1°C) (75). Early physiological analysis revealed that this adaptation results, at least in part, from the accumulation of a restricted range of low-molecular-weight molecules termed osmolytes, or compatible solutes, owing to their compatibility with vital cellular processes at high internal concentrations (reviewed in reference 59). Initially restricted to betaine, carnitine, and proline (or proline-containing peptides), the list of compatible solutes promoting both salt and chill tolerances in Listeria has since been extended to include proline betaine, acetylcarnitine, gamma-butyrobetaine, and 3-dimethylsulfoniopropionate (6).Following the elegant biochemical and physiological analyses of the early 1990s, the listerial salt and chill stress response has recently become the focus of intense genetic analysis. A variety of innovative and imaginative molecular techniques led to the identification and subsequent characterization of some of the major genetic elements governing compatible-solute accumulation in Listeria. The recent publication of the listerial genome allows us for the first time to place the earlier experimentally generated data against the background of the in silico-based complete gene set. This exercise permits an informed overview of the complex interplay of systems controlling and enacting the listerial osmo-and cryostress responses.Beginning with a brief overview of the general principles underlying the biophysics of compatible-solute function, we review the development of our understanding of the mechanisms of compatible-solute accumulation in Listeria and use this information to attempt to construct a simplified model incorporating the known salt and chill stress response mechanisms of this ubiquitous and tenacious food-borne pathogen (Fig. 1.) In addition, we examine potential regulatory mechanisms governing osmolyte acquisition and suggest possible future directions in the field of listerial osmo-and cryotolerance. BACTERIAL OSMOADAPTATIONOsmoadaptation includes both the genetic and physiological manifestations of adaptation to low-water environments (26). In principle, two strategies of osmoadaptation have evolved to cope with life at elevated osmolarity (27): (i) the salt-in-cytoplasm type, restricted mainly to members of the family Halobacteriaceae (for a review, see reference 26), and (ii) the organic-osmolyte type, an adaptation strategy which has as its hallmarks a minimal requirement for genetic change and a high degree of flexibility in allowing organisms to cope with fluctuations in external osmolarity (77). The organic-osmolyte solution is a biphasic response in which increased levels of K ϩ (and its counterion, glutamate) represent the primary response, followed by a dramatic increase in the cytoplasmic concentrations ...

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Survival of osmotic and acid stress by Listeria monocytogenes strains of clinical or meat origin

Cited by 62 publications

References 20 publications

Expression of Truncated Internalin A Is Involved in Impaired Internalization of Some Listeria monocytogenes Isolates Carried Asymptomatically by Humans

Expression of Truncated Internalin A Is Involved in Impaired Internalization of Some Listeria monocytogenes Isolates Carried Asymptomatically by Humans

In Vitro and In Vivo Invasiveness of Different Pulsed-Field Gel Electrophoresis Types of Listeria monocytogenes

A Postgenomic Appraisal of Osmotolerance in Listeria monocytogenes

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