Effects of Growth at Low Water Activity on the Thermal Tolerance of Staphylococcus aureus

Shebuski, Joseph R.; Vilhelmsson, Oddur; Miller, Karen J.

doi:10.4315/0362-028x-63.9.1277

Cited by 23 publications

(19 citation statements)

References 42 publications

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“…Staphylococcus aureus can grow in a large spectrum of foods, is the most osmotolerant foodbome pathogen, and is highly resistant to acidic stress (14). S. aureus can cause gastrointestinal symptoms such as vomiting and diarrhea through production of staphylococcal enterotoxins (SEs).…”

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confidence: 99%

Virulence and Resistance Gene Profiles of Staphylococcus aureus Strains Isolated from Ready-to-Eat Foods

Baumgärtner

Niederhauser

Johler

2014

Journal of Food Protection

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Staphylococcal food poisoning represents the most prevalent foodborne intoxication worldwide. Oral intake of staphylococcal enterotoxins from food can result in emesis and diarrhea and can be fatal in children and the elderly. Few data have been available on the characteristics and sources of Staphylococcus aureus strains isolated from ready-to-eat (RTE) foods. In this study, we used a DNA microarray to determine virulence and antimicrobial resistance gene profiles of S. aureus from RTE foods. A total of 267 S. aureus strains isolated from 244 RTE foods were investigated. The isolates originated from precooked foods (41% of isolates), meat and fish products (17%), cheese (13%), delicatessen salads (8%), sandwiches and canapés (8%), confectionery and bakery products (6%), and various other RTE foods (7%). Eleven samples (5%), of which 9 were raw milk cheeses, contained > 10(5) CFU/g, which is considered a health risk. Four S. aureus strains were associated with intoxications; three cases were linked to consumption of cheese and one case was linked to consumption of potato salad. DNA microarray results revealed that one-third of the tested strains had at least one major enterotoxin gene (sea through see). We also detected the toxic shock syndrome gene (18% of isolates) and various genes conferring antimicrobial resistance, including genes involved in resistance to beta-lactams (blaZ, 72% of isolates), methicillin (mecA, 1% of isolates), and vancomycin (vanB, 1% of isolates). S. aureus strains were most frequently assigned to clonal complex (CC) 30 (17% of isolates), CC8 (12%), CC15 (11%), and CC45 (10%), which are commonly detected in humans colonized or infected with S. aureus. Although a large proportion of the tested food items contained milk, we did not detect CC705, the most prevalent clonal complex among S. aureus isolates from bovine mastitis milk. Our results suggest that S. aureus isolates from RTE foods do not commonly originate from animals but more likely come from food handlers who contaminate foods.

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confidence: 99%

Virulence and Resistance Gene Profiles of Staphylococcus aureus Strains Isolated from Ready-to-Eat Foods

Baumgärtner

Niederhauser

Johler

2014

Journal of Food Protection

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“…Trehalose (6) and dimethylsulphoniopropionate (79) also alleviate oxidative stress. Glycine-betaine, a widely used osmoprotectant (89), promotes chill tolerance in Listeria monocytogenes (77), yet it reduces the ability of other organisms to tolerate high temperatures (31,32,74). The membrane-permeant solute urea is present in the urine of humans and animals at levels that can inhibit bacterial growth (up to 0.5 M for human urine) (5).…”

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confidence: 99%

Osmoregulatory Systems ofEscherichia coli:Identification of Betaine-Carnitine-Choline Transporter Family MemberBetU and Distributions ofbetUandtrkGamongPathogenic and NonpathogenicIsolates

Henderson

et al. 2004

J Bacteriol

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Multiple transporters mediate osmoregulatory solute accumulation in Escherichia coli K-12. The larger genomes of naturally occurring strains such as pyelonephritis isolates CFT073 and HU734 may encode additional osmoregulatory systems. CFT073 is more osmotolerant than HU734 in the absence of organic osmoprotectants, yet both strains grew in high osmolality medium at low K ؉ (micromolar concentrations) and retained locus trkH, which encodes an osmoregulatory K ؉ transporter. Both lacked the trkH homologue trkG. Transporters ProP and ProU account for all glycine-betaine uptake activity in E. coli K-12 and CFT073, but not in HU734, yet elimination of ProP and ProU impairs the growth of HU734, but not CFT073, in high osmolality human urine. No known osmoprotectant stimulated the growth of CFT073 in high osmolality minimal medium, but putative transporters YhjE, YiaMNO, and YehWXYZ may mediate uptake of additional osmoprotectants. Gene betU was isolated from HU734 by functional complementation and shown to encode a betaine uptake system that belongs to the betaine-choline-carnitine transporter family. The incidence of trkG and betU within the ECOR collection, representatives of the E. coli pathotypes (PATH), and additional strains associated with urinary tract infection (UTI) were determined. Gene trkG was present in 66% of the ECOR collection but only in 16% of the PATH and UTI collections. Gene betU was more frequently detected in ECOR groups B2 and D (50% of isolates) than in groups A, B1, and E (20%), but it was similar in overall incidence in the ECOR collection and in the combined UTI and PATH collections (32 and 34%, respectively). Genes trkG and betU may have been acquired by lateral gene transfer, since trkG is part of the rac prophage and betU is flanked by putative insertion sequences. Thus, BetU and TrkG contribute, with other systems, to the osmoregulatory capacity of the species E. coli, but they are not characteristic of a particular phylogenetic group or pathotype.

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“…The protective effects of reduced a w on the resistance of bacteria to heat has been observed in numerous broth studies, where a w was adjusted using various solutes, including sucrose, sodium chloride and glycerol (Sumner et al. 1991; Shebuski et al. 2000; Mattick et al.…”

Section: Discussionmentioning

confidence: 93%

Effects of reduction in beef surface water activity on the survival ofSalmonellaTyphimurium DT104 during heating

McCann

McDowell

Sheridan

2009

Journal of Applied Microbiology

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Aim: To investigate the influence of reducing beef surface water activity (aw) on the survival of Salmonella Typhimurium DT104 during heating. Methods and Results: Beef discs were surface inoculated with S. Typhimurium DT104 and either untreated or dried to achieve surface aw values of 0·95, 0·85 and 0·70. The samples were vacuum packed, heat‐treated at 60°C and removed at predetermined times. The inactivation curves were influenced by aw and treatment time. Biphasic inactivation curves were observed for S. Typhimurium DT104 heat‐treated on beef samples with altered aw values, which were characterized by an initial decline in cell numbers at commencement of heating followed by a much slower rate of inactivation during the remaining treatment period. Point estimates of the heating time required to achieve a 1 log reduction on beef surfaces with aw of 0·99, 0·95, 0·85 and 0·70 were 0·5, 1·55, 11·25 and 17·79 min, respectively. Conclusions: A decrease in beef surface aw can substantially enhance the survival of S. Typhimurium DT104 after heating. Significance and Impact of the Study: Caution needs to be taken using dry air as a decontamination method as this may rapidly decrease product surface and pathogen aw values resulting in enhanced survival.

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Effects of Growth at Low Water Activity on the Thermal Tolerance of Staphylococcus aureus

Cited by 23 publications

References 42 publications

Virulence and Resistance Gene Profiles of Staphylococcus aureus Strains Isolated from Ready-to-Eat Foods

Virulence and Resistance Gene Profiles of Staphylococcus aureus Strains Isolated from Ready-to-Eat Foods

Osmoregulatory Systems ofEscherichia coli:Identification of Betaine-Carnitine-Choline Transporter Family MemberBetU and Distributions ofbetUandtrkGamongPathogenic and NonpathogenicIsolates

Effects of reduction in beef surface water activity on the survival ofSalmonellaTyphimurium DT104 during heating

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