scholarly journals Effective Heat Inactivation of Mycobacterium avium subsp. paratuberculosis in Raw Milk Contaminated with Naturally Infected Feces

2007 ◽  
Vol 73 (13) ◽  
pp. 4185-4190 ◽  
Author(s):  
Jan L. W. Rademaker ◽  
Marc M. M. Vissers ◽  
Meike C. te Giffel
Keyword(s):  
Mycobacterium Avium ◽  
Clinical Symptoms ◽  
Raw Milk ◽  
Pilot Scale ◽  
Holding Time ◽  
Heat Inactivation ◽  
Inactivation Kinetics ◽  
Data Points ◽  
Mycobacterium Avium Subsp Paratuberculosis ◽  
High Concentrations

ABSTRACT The effectiveness of high-temperature, short holding time (HTST) pasteurization and homogenization with respect to inactivation of Mycobacterium avium subsp. paratuberculosis was evaluated quantitatively. This allowed a detailed determination of inactivation kinetics. High concentrations of feces from cows with clinical symptoms of Johne's disease were used to contaminate raw milk in order to realistically mimic possible incidents most closely. Final M. avium subsp. paratuberculosis concentrations varying from 102 to 3.5 × 105 cells per ml raw milk were used. Heat treatments including industrial HTST were simulated on a pilot scale with 22 different time-temperature combinations, including 60 to 90°C at holding (mean residence) times of 6 to 15 s. Following 72°C and a holding time of 6 s, 70°C for 10 and 15 s, or under more stringent conditions, no viable M. avium subsp. paratuberculosis cells were recovered, resulting in >4.2- to >7.1-fold reductions, depending on the original inoculum concentrations. Inactivation kinetic modeling of 69 quantitative data points yielded an Ea of 305,635 J/mol and an lnk 0 of 107.2, corresponding to a D value of 1.2 s at 72°C and a Z value of 7.7°C. Homogenization did not significantly affect the inactivation. The conclusion can be drawn that HTST pasteurization conditions equal to 15 s at ≥72°C result in a more-than-sevenfold reduction of M. avium subsp. paratuberculosis.

scholarly journals Efficacy of Various Pasteurization Time-Temperature Conditions in Combination with Homogenization on Inactivation of Mycobacterium avium subsp. paratuberculosis in Milk

2005 ◽  
Vol 71 (6) ◽  
pp. 2853-2861 ◽  
Author(s):  
Irene R. Grant ◽  
Alan G. Williams ◽  
Michael T. Rowe ◽  
D. Donald Muir
Keyword(s):  
Mycobacterium Avium ◽  
Egg Yolk ◽  
Raw Milk ◽  
Pilot Scale ◽  
Temperature Conditions ◽  
High Temperature Short Time ◽  
Mycobacterium Avium Subsp Paratuberculosis ◽  
Clump Size ◽  
Short Time ◽  
The Impact

ABSTRACT The effect of various pasteurization time-temperature conditions with and without homogenization on the viability of Mycobacterium avium subsp. paratuberculosis was investigated using a pilot-scale commercial high-temperature, short-time (HTST) pasteurizer and raw milk spiked with 101 to 105 M. avium subsp. paratuberculosis cells/ml. Viable M. avium subsp. paratuberculosis was cultured from 27 (3.3%) of 816 pasteurized milk samples overall, 5 on Herrold's egg yolk medium and 22 by BACTEC culture. Therefore, in 96.7% of samples, M. avium subsp. paratuberculosis had been completely inactivated by HTST pasteurization, alone or in combination with homogenization. Heat treatments incorporating homogenization at 2,500 lb/in2, applied upstream (as a separate process) or in hold (at the start of a holding section), resulted in significantly fewer culture-positive samples than pasteurization treatments without homogenization (P < 0.001 for those in hold and P < 0.05 for those upstream). Where colony counts were obtained, the number of surviving M. avium subsp. paratuberculosis cells was estimated to be 10 to 20 CFU/150 ml, and the reduction in numbers achieved by HTST pasteurization with or without homogenization was estimated to be 4.0 to 5.2 log10. The impact of homogenization on clump size distribution in M. avium subsp. paratuberculosis broth suspensions was subsequently assessed using a Mastersizer X spectrometer. These experiments demonstrated that large clumps of M. avium subsp. paratuberculosis cells were reduced to single-cell or “miniclump” status by homogenization at 2,500 lb/in2. Consequently, when HTST pasteurization was being applied to homogenized milk, the M. avium subsp. paratuberculosis cells would have been present as predominantly declumped cells, which may possibly explain the greater inactivation achieved by the combination of pasteurization and homogenization.

Inactivation of Mycobacterium avium subsp. paratuberculosis during Cooking of Hamburger Patties

2013 ◽  
Vol 76 (7) ◽  
pp. 1194-1201 ◽  
Author(s):  
PHILIPP HAMMER ◽  
HANS-GEORG C. WALTE ◽  
SÖ NKE MATZEN ◽  
JANN HENSEL ◽  
CHRISTIAN KIESNER
Keyword(s):  
Mycobacterium Avium ◽  
Egg Yolk ◽  
Mycobacterium Avium Subsp ◽  
Most Probable Number ◽  
Heat Inactivation ◽  
Inactivation Kinetics ◽  
Bacterial Reduction ◽  
Probable Number ◽  
Mycobacterium Avium Subsp Paratuberculosis ◽  
Cooking Times

The role of Mycobacterium avium subsp. paratuberculosis (MAP) in Crohn's disease in humans has been debated for many years. Milk and milk products have been suggested as possible vectors for transmission since the beginning of this debate, whereas recent publications show that slaughtered cattle and their carcasses, meat, and organs can also serve as reservoirs for MAP transmission. The objective of this study was to generate heat-inactivation data for MAP during the cooking of hamburger patties. Hamburger patties of lean ground beef weighing 70 and 50 g were cooked for 6, 5, 4, 3, and 2 min, which were sterilized by irradiation and spiked with three different MAP strains at levels between 102 and 106 CFU/ml. Single-sided cooking with one flip was applied, and the temperatures within the patties were recorded by seven thermocouples. Counting of the surviving bacteria was performed by direct plating onto Herrold's egg yolk medium and a three-vial most-probable-number method by using modified Dubos medium. There was considerable variability in temperature throughout the patties during frying. In addition, the log reduction in MAP numbers showed strong variations. In patties weighing 70 g, considerable bacterial reduction of 4 log or larger could only be achieved after 6 min of cooking. For all other cooking times, the bacterial reduction was less than 2 log. Patties weighing 50 g showed a 5-log or larger reduction after cooking times of 5 and 6 min. To determine the inactivation kinetics, a log-linear regression model was used, showing a constant decrease of MAP numbers over cooking time.

scholarly journals Heat Inactivation of Mycobacterium avium subsp. paratuberculosis in Milk

2005 ◽  
Vol 71 (4) ◽  
pp. 1785-1789 ◽  
Author(s):  
Wendy L. McDonald ◽  
Kimberly J. O'Riley ◽  
Christopher J. Schroen ◽  
Robin J. Condron
Keyword(s):  
Mycobacterium Avium ◽  
Dairy Products ◽  
Raw Milk ◽  
Heat Inactivation ◽  
Time Intervals ◽  
Flow Rates ◽  
Milk Samples ◽  
Whole Milk ◽  
Mycobacterium Avium Subsp Paratuberculosis ◽  
Logarithmic Reduction

ABSTRACT The effectiveness of pasteurization and the concentration of Mycobacterium avium subsp. paratuberculosis in raw milk have been identified in quantitative risk analysis as the most critical factors influencing the potential presence of viable Mycobacterium paratuberculosis in dairy products. A quantitative assessment of the lethality of pasteurization was undertaken using an industrial pasteurizer designed for research purposes with a validated Reynolds number of 62,112 and flow rates of 3,000 liters/h. M. paratuberculosis was artificially added to raw whole milk, which was then homogenized, pasteurized, and cultured, using a sensitive technique capable of detecting one organism per 10 ml of milk. Twenty batches of milk containing 103 to 104 organisms/ml were processed with combinations of three temperatures of 72, 75, and 78°C and three time intervals of 15, 20, and 25 s. Thirty 50-ml milk samples from each processed batch were cultured, and the logarithmic reduction in M. paratuberculosis organisms was determined. In 17 of the 20 runs, no viable M. paratuberculosis organisms were detected, which represented >6-log10 reductions during pasteurization. These experiments were conducted with very heavily artificially contaminated milk to facilitate the measurement of the logarithmic reduction. In three of the 20 runs of milk, pasteurized at 72°C for 15 s, 75°C for 25 s, and 78°C for 15 s, a few viable organisms (0.002 to 0.004 CFU/ml) were detected. Pasteurization at all temperatures and holding times was found to be very effective in killing M. paratuberculosis, resulting in a reduction of >6 log10 in 85% of runs and >4 log10 in 14% of runs.

scholarly journals Effect of Turbulent-Flow Pasteurization on Survival of Mycobacterium avium subsp.paratuberculosis Added to Raw Milk

2001 ◽  
Vol 67 (9) ◽  
pp. 3964-3969 ◽  
Author(s):  
Lindsay E. Pearce ◽  
H. Tuan Truong ◽  
Robert A. Crawford ◽  
Gary F. Yates ◽  
Sonia Cavaignac ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Turbulent Flow ◽  
Mycobacterium Avium ◽  
Culture Method ◽  
Egg Yolk ◽  
Raw Milk ◽  
Pilot Scale ◽  
Heat Sensitivity ◽  
Decimal Reduction Time ◽  
The Mean

ABSTRACT A pilot-scale pasteurizer operating under validated turbulent flow (Reynolds number, 11,050) was used to study the heat sensitivity ofMycobacterium avium subsp.paratuberculosis added to raw milk. The ATCC 19698 type strain, ATCC 43015 (Linda, human isolate), and three bovine isolates were heated in raw whole milk for 15 s at 63, 66, 69, and 72°C in duplicate trials. No strains survived at 72°C for 15 s; and only one strain survived at 69°C. Means of pooled Dvalues (decimal reduction times) at 63 and 66°C were 15.0 ± 2.8 s (95% confidence interval) and 5.9 ± 0.7 s (95% confidence interval), respectively. The mean extrapolatedD 72°C was <2.03 s. This was equivalent to a >7 log10 kill at 72°C for 15 s (95% confidence interval). The mean Z value (degrees required for the decimal reduction time to traverse one log cycle) was 8.6°C. These five strains showed similar survival whether recovery was on Herrold's egg yolk medium containing mycobactin or by a radiometric culture method (BACTEC). Milk was inoculated with fresh fecal material from a high-level fecal shedder with clinical Johne's disease. After heating at 72°C for 15 s, the minimum M. avium subsp.paratuberculosis kill was >4 log10. Properly maintained and operated equipment should ensure the absence of viable M. avium subsp. paratuberculosisin retail milk and other pasteurized dairy products. An additional safeguard is the widespread commercial practice of pasteurizing 1.5 to 2° above 72°C.

scholarly journals Rapid Assessment of the Viability of Mycobacterium avium subsp. paratuberculosis Cells after Heat Treatment, Using an Optimized Phage Amplification Assay

2010 ◽  
Vol 76 (6) ◽  
pp. 1777-1782 ◽  
Author(s):  
Antonio Foddai ◽  
Christopher T. Elliott ◽  
Irene R. Grant
Keyword(s):  
Mycobacterium Avium ◽  
Thermal Inactivation ◽  
Rapid Assessment ◽  
Egg Yolk ◽  
Inactivation Kinetics ◽  
Complete Inactivation ◽  
Conventional Culture ◽  
Amplification Assay ◽  
Mycobacterium Avium Subsp Paratuberculosis ◽  
Thermal Cycler

ABSTRACT Thermal inactivation experiments were carried out to assess the utility of a recently optimized phage amplification assay to accurately enumerate viable Mycobacterium avium subsp. paratuberculosis cells in milk. Ultra-heat-treated (UHT) whole milk was spiked with large numbers of M. avium subsp. paratuberculosis organisms (106 to 107 CFU/ml) and dispensed in 100-μl aliquots in thin-walled 200-μl PCR tubes. A Primus 96 advanced thermal cycler (Peqlab, Erlangen, Germany) was used to achieve the following time and temperature treatments: (i) 63°C for 3, 6, and 9 min; (ii) 68°C for 20, 40, and 60 s; and (iii) 72°C for 5, 10, 15, and 25 s. After thermal stress, the number of surviving M. avium subsp. paratuberculosis cells was assessed by both phage amplification assay and culture on Herrold's egg yolk medium (HEYM). A high correlation between PFU/ml and CFU/ml counts was observed for both unheated (r 2 = 0.943) and heated (r 2 = 0.971) M. avium subsp. paratuberculosis cells. D and z values obtained using the two types of counts were not significantly different (P > 0.05). The D 68°C, mean D 63°C, and D 72°C for four M. avium subsp. paratuberculosis strains were 81.8, 9.8, and 4.2 s, respectively, yielding a mean z value of 6.9°C. Complete inactivation of 106 to 107 CFU of M. avium subsp. paratuberculosis/ml milk was not observed for any of the time-temperature combinations studied; 5.2- to 6.6-log10 reductions in numbers were achieved depending on the temperature and time. Nonlinear thermal inactivation kinetics were consistently observed for this bacterium. This study confirms that the optimized phage assay can be employed in place of conventional culture on HEYM to speed up the acquisition of results (48 h instead of a minimum of 6 weeks) for inactivation experiments involving M. avium subsp. paratuberculosis-spiked samples.

scholarly journals Antibacterial Activities of Naturally Occurring Compounds against Mycobacterium avium subsp. paratuberculosis

2008 ◽  
Vol 74 (19) ◽  
pp. 5986-5990 ◽  
Author(s):  
Stella Y. Y. Wong ◽  
Irene R. Grant ◽  
Mendel Friedman ◽  
Christopher T. Elliott ◽  
Chen Situ
Keyword(s):  
Mycobacterium Avium ◽  
Tween 80 ◽  
Raw Milk ◽  
Antibacterial Activities ◽  
Aldehyde Group ◽  
Green Tea Polyphenols ◽  
Cinnamon Oil ◽  
Naturally Occurring ◽  
Mycobacterium Avium Subsp Paratuberculosis ◽  
Oregano Oil

ABSTRACT The antibacterial activities of 18 naturally occurring compounds (including essential oils and some of their isolated constituents, apple and green tea polyphenols, and other plant extracts) against three strains of Mycobacterium avium subsp. paratuberculosis (a bovine isolate [NCTC 8578], a raw-milk isolate [806R], and a human isolate [ATCC 43015]) were evaluated using a macrobroth susceptibility testing method. M. avium subsp. paratuberculosis was grown in 4 ml Middlebrook 7H9 broth containing 10% oleic acid-albumin-dextrose-catalase, 0.05% Tween 80 (or 0.2% glycerol), and 2 μg/ml mycobactin J supplemented with five concentrations of each test compound. The changes in the optical densities of the cultures at 600 nm as a measure of CFU were recorded at intervals over an incubation period of 42 days at 37�C. Six of the compounds were found to inhibit the growth of M. avium subsp. paratuberculosis. The most effective compound was trans-cinnamaldehyde, with a MIC of 25.9 μg/ml, followed by cinnamon oil (26.2 μg/ml), oregano oil (68.2 μg/ml), carvacrol (72.2 μg/ml), 2,5-dihydroxybenzaldehyde (74 μg/ml), and 2-hydroxy-5-methoxybenzaldehyde (90.4 μg/ml). With the exception of carvacrol, a phenolic compound, three of the four most active compounds are aldehydes, suggesting that the structure of the phenolic group or the aldehyde group may be important to the antibacterial activity. No difference in compound activity was observed between the three M. avium subsp. paratuberculosis strains studied. Possible mechanisms of the antimicrobial effects are discussed.

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