Effects of Ascorbic Acid, Glutathione, Thiocyanate, and Iodide on Antimicrobial Activity of Acidified Nitrite

Fite, Alemu; Dykhuizen, R S; Litterick, Audrey; Golden, Michael; Leifert, Carlo

doi:10.1128/aac.48.2.655-658.2004

Cited by 20 publications

(11 citation statements)

References 22 publications

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“…A link between these conditions and the consumption of vegetablederived nitrate has not yet been demonstrated. Further, there is mounting evidence suggesting that nitrate consumed with ascorbic acid and glutathione, contained in fruits and vegetables, has the beneficial effect of increasing the activity of stomach acid against food-borne pathogens (Dykhuizen et al 1996;McKnight et al 1999;Fite et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Nitrate and nitrite in Australian leafy vegetables

Parks

Huett

Campbell

et al. 2008

Aust. J. Agric. Res.

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A market survey of Australian leafy vegetables and a winter and spring experiment with Swiss chard were conducted to examine nitrate and nitrite levels in leaves. The relationship between growth response to nitrogen (N) supply and light level and accumulation of N in leaves was of particular interest. The survey that included 7 types of lettuce and endive (Asteraceae), 6 leafy Asian vegetables (Brassicaceae), and Swiss chard and spinach (Amaranthaceae) showed that fresh leafy vegetables available during a 6-month period on the Australian market can range in nitrate-N from 12 to 1400 mg/kg fresh weight and nitrite-N from 0 to 37.5 mg/kg. Some samples exceeded the limits for nitrate and nitrite based on international food safety standards. The response of Swiss chard to N supply and light was investigated. The accumulation of nitrate in Swiss chard was primarily influenced by increasing N supply and not by light level. Light conditions for all treatments in both the winter and spring experiments exceeded the critical level (~200 mmol/m 2 .s) required to increase leaf nitrate. Growth and leaf nitrate concentration were higher for spring, associated with average minimum to maximum temperatures of 18-398C, compared with 14-288C for winter. Treatment effects on nitrite-N in Swiss chard could not be determined because nitrite was only detected in one-third of plants. The importance of N supply in affecting nitrate accumulation in vegetables is highlighted by the Swiss chard experiments. It confirmed that nitrate accumulation occurs at optimal to supra-optimal nitrate supply, emphasising for growers the undesirable effect of excessive fertiliser use.

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Section: Introductionmentioning

confidence: 99%

Nitrate and nitrite in Australian leafy vegetables

Parks

Huett

Campbell

et al. 2008

Aust. J. Agric. Res.

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“…In humans, dietary nitrates are concentrated in saliva, increasing concentrations up to 10 times that in plasma (6). Salivary nitrate is rapidly reduced to nitrite by bacterial nitrate reductase in the mouth (6)(7)(8). The concentration of nitrite in human saliva typically ranges from 0.05 to 1 mol/ml, depending on dietary intake of nitrate (7)(8).…”

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confidence: 99%

“…These findings suggest that gastric acid may provide an important defense against these organisms; however, relatively little information is available regarding the ability of acidic conditions to kill nosocomial pathogens. In addition, it has recently been demonstrated that salivary nitrites that are converted to reactive nitrogen compounds under acidic conditions may enhance the killing of pathogens in the stomach (6)(7)(8). Acidified nitrite is a sporicidal disinfectant that efficiently kills C. difficile spores (18), but it is not known whether the concentrations in the stomach provide sporicidal activity.…”

mentioning

confidence: 99%

“…Salivary nitrate is rapidly reduced to nitrite by bacterial nitrate reductase in the mouth (6)(7)(8). The concentration of nitrite in human saliva typically ranges from 0.05 to 1 mol/ml, depending on dietary intake of nitrate (7)(8). Under acidic conditions in the stomach, nitrite is converted to various reactive nitrogen compounds, including nitrous acid, peroxynitrite, nitrogen dioxide, and nitric oxide, that have been proposed to be responsible for killing bacteria in the stomach (6-7).…”

mentioning

confidence: 99%

“…The concentration of nitrite in human saliva typically ranges from 0.05 to 1 mol/ml, while concentrations as high as 10 mol/ml have been reported (6)(7)(8). Samples were incubated for 1 h prior to the removal of aliquots for quantitative cultures.…”

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confidence: 99%

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In Vitro Killing of Nosocomial Pathogens by Acid and Acidified Nitrite

Rao

Jump

Pultz

et al. 2006

Antimicrob Agents Chemother

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Exposure to pH 1 or 2 buffers or acidic gastric contents resulted in the killing of vancomycin-resistant Enterococcus sp., Klebsiella pneumoniae, Staphylococcus aureus, and Candida glabrata but not Clostridium difficile spores. Nitrite enhanced killing under acidic conditions, but significant killing of C. difficile spores required nitrite concentrations above usual physiological levels.Gastric acid may provide an important host defense by killing ingested pathogens (5). For example, normal gastric acidity kills more than 99.9% of several gram-negative bacilli within 30 min (9), and vegetative cells of Clostridium difficile are killed within 5 to 30 min upon exposure to pH 2 to 3 buffers (17). Many studies have demonstrated an association between medications that inhibit production of stomach acid (e.g., proton pump inhibitors and H 2 blockers) and nosocomial pathogens, including C. difficile, Candida albicans, methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus spp. (VRE), and extended-spectrum-␤-lactamase-producing enterobacteriaceae (1-3, 12, 16). These findings suggest that gastric acid may provide an important defense against these organisms; however, relatively little information is available regarding the ability of acidic conditions to kill nosocomial pathogens. In addition, it has recently been demonstrated that salivary nitrites that are converted to reactive nitrogen compounds under acidic conditions may enhance the killing of pathogens in the stomach (6-8). Acidified nitrite is a sporicidal disinfectant that efficiently kills C. difficile spores (18), but it is not known whether the concentrations in the stomach provide sporicidal activity. Therefore, we examined the ability of acidic buffers, with or without the addition of physiological concentrations of nitrite, to kill C. difficile spores and several strains of Klebsiella pneumoniae, VRE, MRSA, and Candida glabrata. We also examined the killing of the pathogens by acidic gastric contents obtained from patients not receiving acid-suppressive medications.For K. pneumoniae, VRE, and MRSA, five isolates from distinct pulsed-field gel electrophoresis groups were studied. The K. pneumoniae isolates were bloodstream isolates that produce extended-spectrum ␤-lactamases (11). The VRE isolates were clinical E. faecium isolates from Cleveland, and the MRSA isolates were cultured from the stool of patients (4, 10). For C. glabrata, three isolates were studied and have been described previously (15). For C. difficile, three isolates were studied, including one clinical isolate from Cleveland and ATTC strains 9689 and 43593.Initial experiments were performed to examine the effect of exposure to acid; C. difficile spores were not included in this analysis because preliminary experiments indicated that pH 1 buffer did not kill the spores. The pathogens were grown overnight in brain heart infusion broth and washed three times in phosphate-buffered saline (PBS). A final concentration of 10 9 CFU/ml of the pathogens was suspended i...

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Sodium Iodide Symporter (NIS) in Gastric Mucosa

Josefsson

Ekblad²

2009

Comprehensive Handbook of Iodine

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Effects of Ascorbic Acid, Glutathione, Thiocyanate, and Iodide on Antimicrobial Activity of Acidified Nitrite

Cited by 20 publications

References 22 publications

Nitrate and nitrite in Australian leafy vegetables

Nitrate and nitrite in Australian leafy vegetables

In Vitro Killing of Nosocomial Pathogens by Acid and Acidified Nitrite

Sodium Iodide Symporter (NIS) in Gastric Mucosa

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