Nutritional Requirements of Enterotoxigenic Strains of Staphylococcus Aureus

Mah, Robert A.

doi:10.21236/ad0624249

Cited by 10 publications

(12 citation statements)

References 2 publications

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“…In a complex medium containing glucose, S. aureus will preferentially catabolize glucose for carbon and energy through the glycolytic and pentose phosphate pathways (4,10,20,29,36). Despite a preference for glucose and a high concentration of glucose in the medium (Ͼ15 mM) ( Fig.…”

Section: Discussionmentioning

confidence: 99%

Staphylococcus aureus Biofilm Metabolism and the Influence of Arginine on Polysaccharide Intercellular Adhesin Synthesis, Biofilm Formation, and Pathogenesis

et al. 2007

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Staphylococcus aureus and Staphylococcus epidermidis are the leading causes of nosocomial infections in the United States and often are associated with biofilms attached to indwelling medical devices. Despite the importance of biofilms, there is very little consensus about the metabolic requirements of S. aureus during biofilm growth. To assess the metabolic requirements of S. aureus growing in a biofilm, we grew USA200 and USA300 clonal types in biofilm flow cells and measured the extraction and accumulation of metabolites. In spite of the genetic differences, both clonal types extracted glucose and accumulated lactate, acetate, formate, and acetoin, suggesting that glucose was catabolized to pyruvate that was then catabolized via the lactate dehydrogenase, pyruvate formate-lyase, and butanediol pathways. Additionally, both clonal types selectively extracted the same six amino acids (serine, proline, arginine, glutamine, glycine, and threonine) from the culture medium. These data and recent speculation about the importance of arginine in biofilm growth and the function of arginine deiminase in USA300 clones led us to genetically inactivate the sole copy of the arginine deiminase operon by deleting the arginine/ornithine antiporter gene (arcD) in the USA200 clonal type and to assess the effect on biofilm development and pathogenesis. Although inactivation of arcD did completely inhibit arginine transport and did reduce polysaccharide intercellular adhesin accumulation, arcD mutants formed biofilms and achieved cell densities in catheter infection studies that were equivalent to those for isogenic wild-type strains.

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Section: Discussionmentioning

confidence: 99%

Staphylococcus aureus Biofilm Metabolism and the Influence of Arginine on Polysaccharide Intercellular Adhesin Synthesis, Biofilm Formation, and Pathogenesis

et al. 2007

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“…However, most studies involving staphylococci and amino acids have focused on the amino acid requirements for growth. Phenotypic studies of S. aureus that have attempted to determine the absolute amino acid requirements necessary for growth have met with diverse results (56,61,146,168,170,220). Those studies concluded that S. aureus frequently possessed multiple amino acid auxotrophies because growth often required between 3 and 12 amino acids, with proline, arginine, valine, and cysteine being most frequently required.…”

Section: Nitrogen-dependent Regulatorsmentioning

confidence: 99%

At the Crossroads of Bacterial Metabolism and Virulence Factor Synthesis in Staphylococci

Somerville

Proctor

2009

Microbiol Mol Biol Rev

329

348

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SUMMARY Bacteria live in environments that are subject to rapid changes in the availability of the nutrients that are necessary to provide energy and biosynthetic intermediates for the synthesis of macromolecules. Consequently, bacterial survival depends on the ability of bacteria to regulate the expression of genes coding for enzymes required for growth in the altered environment. In pathogenic bacteria, adaptation to an altered environment often includes activating the transcription of virulence genes; hence, many virulence genes are regulated by environmental and nutritional signals. Consistent with this observation, the regulation of most, if not all, virulence determinants in staphylococci is mediated by environmental and nutritional signals. Some of these external signals can be directly transduced into a regulatory response by two-component regulators such as SrrAB; however, other external signals require transduction into intracellular signals. Many of the external environmental and nutritional signals that regulate virulence determinant expression can also alter bacterial metabolic status (e.g., iron limitation). Altering the metabolic status results in the transduction of external signals into intracellular metabolic signals that can be “sensed” by regulatory proteins (e.g., CodY, Rex, and GlnR). This review uses information derived primarily using Bacillus subtilis and Escherichia coli to articulate how gram-positive pathogens, with emphasis on Staphylococcus aureus and Staphylococcus epidermidis, regulate virulence determinant expression in response to a changing environment.

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“…Bacteria exit from the exponential phase of growth upon the depletion of readily catabolizable carbon compounds and/or the accumulation of toxic compounds. During growth in vitro, S. aureus preferentially degrades glucose to pyruvate (9,18,22,28) by way of the pentose phosphate and glycolytic pathways (4). The catabolic fate of pyruvate is determined by the growth conditions.…”

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Staphylococcus aureus Aconitase Inactivation Unexpectedly Inhibits Post-Exponential-Phase Growth and Enhances Stationary-Phase Survival

Somerville¹,

Chaussee²,

Morgan³

et al. 2002

Infect Immun

183

232

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Staphylococcus aureus preferentially catabolizes glucose, generating pyruvate, which is subsequently oxidized to acetate under aerobic growth conditions. Catabolite repression of the tricarboxylic acid (TCA) cycle results in the accumulation of acetate. TCA cycle derepression coincides with exit from the exponential growth phase, the onset of acetate catabolism, and the maximal expression of secreted virulence factors. These data suggest that carbon and energy for post-exponential-phase growth and virulence factor production are derived from the catabolism of acetate mediated by the TCA cycle. To test this hypothesis, the aconitase gene was genetically inactivated in a human isolate of S. aureus, and the effects on physiology, morphology, virulence factor production, virulence for mice, and stationary-phase survival were examined. TCA cycle inactivation prevented the post-exponential growth phase catabolism of acetate, resulting in premature entry into the stationary phase. This phenotype was accompanied by a significant reduction in the production of several virulence factors and alteration in host-pathogen interaction. Unexpectedly, aconitase inactivation enhanced stationaryphase survival relative to the wild-type strain. Aconitase is an iron-sulfur cluster-containing enzyme that is highly susceptible to oxidative inactivation. We speculate that reversible loss of the iron-sulfur cluster in wild-type organisms is a survival strategy used to circumvent oxidative stress induced during host-pathogen interactions. Taken together, these data demonstrate the importance of the TCA cycle in the life cycle of this medically important pathogen.Staphylococcus aureus is a gram-positive pathogen that causes a wide variety of diseases in humans and animals, ranging from local soft-tissue infections to life-threatening septicemia. S. aureus causes disease by producing many extracellular virulence factors, including several proteases, lipases, hemolysins, superantigens, and cell wall-associated adherence proteins. As with many pathogens, maximal expression of S. aureus virulence factors occurs during the post-exponential phase of growth (33). Bacteria exit from the exponential phase of growth upon the depletion of readily catabolizable carbon compounds and/or the accumulation of toxic compounds. During growth in vitro, S. aureus preferentially degrades glucose to pyruvate (9, 18, 22, 28) by way of the pentose phosphate and glycolytic pathways (4). The catabolic fate of pyruvate is determined by the growth conditions. Under anaerobic growth conditions, pyruvate is primarily reduced to lactic acid (22, 24), while it is oxidized to acetate and CO 2 under aerobic growth conditions (16). The ability to oxidize acetate in the exponential phase of growth is severely impaired, and acetate accumulates in the culture medium until the glucose has been depleted (9, 18). Thus, maximal expression of virulence factors coincides with the depletion of glucose, entry into the post-exponential phase of growth, and the catabolism of acetate. Tak...

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Nutritional Requirements of Enterotoxigenic Strains of Staphylococcus Aureus

Cited by 10 publications

References 2 publications

Staphylococcus aureus Biofilm Metabolism and the Influence of Arginine on Polysaccharide Intercellular Adhesin Synthesis, Biofilm Formation, and Pathogenesis

Staphylococcus aureus Biofilm Metabolism and the Influence of Arginine on Polysaccharide Intercellular Adhesin Synthesis, Biofilm Formation, and Pathogenesis

At the Crossroads of Bacterial Metabolism and Virulence Factor Synthesis in Staphylococci

Staphylococcus aureus Aconitase Inactivation Unexpectedly Inhibits Post-Exponential-Phase Growth and Enhances Stationary-Phase Survival

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