Thermal inactivation of antimicrobial-resistant Gram-positive cocci in chicken meat: D and Z value determinations

Thermal inactivation of the H5N1 high pathogenicity avian influenza (HPAI) virus strain A/chicken/Korea/ES/2003 (Korea/03) was quantitatively measured in thigh and breast meat harvested from infected chickens. The Korea/03 titers were recorded as the mean embryo infectious dose (EID50) and were 108.0 EID50/g in uncooked thigh samples and 107.5 EID50/g in uncooked breast samples. Survival curves were constructed for Korea/03 in chicken thigh and breast meat at 1°C intervals for temperatures of 57 to 61°C. Although some curves had a slightly biphasic shape, a linear model provided a fair-to-good fit at all temperatures, with R2 values of 0.85 to 0.93. Stepwise linear regression revealed that meat type did not contribute significantly to the regression model and generated a single linear regression equation for z-value calculations and D-value predictions for Korea/03 in both meat types. The z-value and the upper limit of the 95% confidence interval for the z-value were 4.64 and 5.32°C, respectively. From the lowest temperature to the highest, the predicted D-values and the upper limits of their 95% prediction intervals (conservative D-values) for 57 to 61°C were 241.2 and 321.1 s, 146.8 and 195.4 s, 89.3 and 118.9 s, 54.4 and 72.4 s, and 33.1 and 44.0 s. D-values and conservative D-values predicted for higher temperatures were 0.28 and 0.50 s for 70°C and 0.041 and 0.073 s for 73.9°C. Calculations with the conservative D-values predicted that cooking chicken meat according to current U.S. Department of Agriculture Food Safety and Inspection Service time-temperature guidelines will inactivate Korea/03 in a heavily contaminated meat sample, such as those tested in this study, with a large margin of safety.

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Bacteremia due to gram-positive cocci in patients with neoplastic disease

The American Journal of Medicine ◽

10.1016/0002-9343(79)91169-0 ◽

1979 ◽

Vol 66 (4) ◽

pp. 596-602 ◽

Cited By ~ 35

Author(s):

Lary J. Kilton ◽

Byron E. Fossieck ◽

Martin H. Cohen ◽

Richard H. Parker

Keyword(s):

Neoplastic Disease ◽

Gram Positive ◽

Gram Positive Cocci

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In vitro activity of telavancin and comparators against selected groups of Gram-positive cocci

International Journal of Antimicrobial Agents ◽

10.1016/j.ijantimicag.2012.10.016 ◽

2013 ◽

Vol 41 (3) ◽

pp. 213-217 ◽

Cited By ~ 10

Author(s):

Russell Hope ◽

Aiysha Chaudhry ◽

Rachael Adkin ◽

David M. Livermore

Keyword(s):

Vitro Activity ◽

In Vitro Activity ◽

Gram Positive ◽

Gram Positive Cocci

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Structural and Functional Conversion of Molecular Chaperone ClpB from the Gram-Positive Halophilic Lactic Acid Bacterium Tetragenococcus halophilus Mediated by ATP and Stress

Journal of Bacteriology ◽

10.1128/jb.00404-06 ◽

2006 ◽

Vol 188 (23) ◽

pp. 8070-8078 ◽

Cited By ~ 17

Author(s):

Shinya Sugimoto ◽

Hiroyuki Yoshida ◽

Yoshimitsu Mizunoe ◽

Keigo Tsuruno ◽

Jiro Nakayama ◽

...

Keyword(s):

Lactic Acid ◽

Lactic Acid Bacterium ◽

Molecular Chaperone ◽

Thermal Inactivation ◽

Gel Filtration ◽

Ring Structure ◽

Stress Conditions ◽

Gel Filtration Chromatography ◽

Gram Positive ◽

Tetragenococcus Halophilus

ABSTRACT In this study, we report the purification, initial structural characterization, and functional analysis of the molecular chaperone ClpB from the gram-positive, halophilic lactic acid bacterium Tetragenococcus halophilus. A recombinant T. halophilus ClpB (ClpB Tha ) was overexpressed in Escherichia coli and purified by affinity chromatography, hydroxyapatite chromatography, and gel filtration chromatography. As demonstrated by gel filtration chromatography, chemical cross-linking with glutaraldehyde, and electron microscopy, ClpB Tha forms a homohexameric single-ring structure in the presence of ATP under nonstress conditions. However, under stress conditions, such as high-temperature (>45°C) and high-salt concentrations (>1 M KCl), it dissociated into dimers and monomers, regardless of the presence of ATP. The hexameric ClpB Tha reactivated heat-aggregated proteins dependent upon the DnaK system from T. halophilus (KJE Tha ) and ATP. Interestingly, the mixture of dimer and monomer ClpB Tha , which was formed under stress conditions, protected substrate proteins from thermal inactivation and aggregation in a manner similar to those of general molecular chaperones. From these results, we hypothesize that ClpB Tha forms dimers and monomers to function as a holding chaperone under stress conditions, whereas it forms a hexamer ring to function as a disaggregating chaperone in cooperation with KJE Tha and ATP under poststress conditions.

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