Survival of Borrelia burgdorferi in Whole Milk, Low Fat Milk, and Skim Milk at 34°C and in Skim Milk at 5°C

1991 ◽  
Vol 54 (7) ◽  
pp. 532-536 ◽  
Author(s):  
GERALDINE M. FARRELL ◽  
AHMED E. YOUSEF ◽  
ELMER H. MARTH
Keyword(s):  
Borrelia Burgdorferi ◽  
Milk Protein ◽  
Skim Milk ◽  
Storage Period ◽  
Most Probable Number ◽  
Low Fat ◽  
Probable Number ◽  
Whole Milk ◽  
The Mean ◽  
D Values

Autoclaved whole milk, low-fat milk, protein-fortified skim milk and regular skim milk were inoculated to contain ca. 105 to 106 Borrelia burgdorferi strains 35210, 35211, or EBNI/ml and stored at 34°C for 16 d. Similarly inoculated skim milk also was held at 5°C for 46 d. Numbers of survivors were estimated by the Most Probable Number (MPN) technique. In all instances, numbers of B. burgdorferi decreased over the storage period. At 34°C, no strain of B. burgdorferi was detected after day 12. The mean D-values, at 34°C, for strains 35210, 35211, and EBNI were 2.2, 2.4, and 2.2 d, respectively. The mean D-values, at 34°C, for all strains in whole milk, low-fat milk, protein-fortified skim milk, and regular skim milk were 2.4, 2.3, 1.9, and 2.4 d, respectively. At 5°C, spirochete numbers in regular skim milk decreased, but all three strains remained at a detectable level for 46 d. The mean D-values, at 5°C, for strains 35210, 35211, and EBNI were 12, 15, and 12 d, respectively.

Thermal Inactivation of Borrelia burgdorferi, the Cause of Lyme Disease

1990 ◽  
Vol 53 (4) ◽  
pp. 296-299 ◽  
Author(s):  
SI K. LEE ◽  
AHMED E. YOUSEF ◽  
ELMER H. MARTH
Keyword(s):  
Borrelia Burgdorferi ◽  
Thermal Inactivation ◽  
Treatment Time ◽  
Treatment Temperature ◽  
Most Probable Number ◽  
Lag Phase ◽  
Probable Number ◽  
Heat Treated ◽  
Thermal Death ◽  
D Values

Borrelia burgdorferi strain EBNI was cultivated in BSK-II medium at 34°C, then cultures at different physiological states were heat-treated at temperatures in the range of 50 to 70°C. Numbers of survivors were estimated by the Most Probable Number technique. Log MPN was plotted against treatment time, and resulting survivor curves were linear. Estimated D-values for cultures incubated at 34°C for 7 d before heat-treatment were 5.5, 4.3, 2.7, .47, and .14 min at 50, 55, 60, 65, and 70°C, respectively. Spirochetes in the lag phase had greater resistance to heat than those in the stationary phase, with the latter being more resistant to heat than spirochetes in the same phase of growth but refrigerated at 4°C for 3 d. D-values for B. burgdorferi are generally less at 50°C, and greater at 70°C than those reported for other nonsporeforming pathogens. When log10 MPN was plotted against treatment temperature, two linear segments for each thermal death curve were obtained. Our data show the spirochete had higher z-values than most nonsporeforming pathogens. The pH of the medium, in the range of 5.0 to 7.6, did not affect resistance of B. burgdorferi to heat.

Use of Iron Milk Medium for Enumeration of Clostridium perfringens

1982 ◽  
Vol 65 (5) ◽  
pp. 1129-1133 ◽  
Author(s):  
William D St John ◽  
Jack R Matches ◽  
Marleen M Wekell
Keyword(s):  
Clostridium Perfringens ◽  
Incubation Time ◽  
Incubation Temperature ◽  
Egg Yolk ◽  
Most Probable Number ◽  
Biochemical Tests ◽  
Probable Number ◽  
Large Numbers ◽  
Whole Milk ◽  
Short Incubation Time

Abstract A simple iron milk medium was used for isolation and enumeration of Clostridium perfringens from soil, sludge, and water samples. The whole milk contained only iron powder as a reducing agent; no other inhibitors were added. The iron milk most probable number (MPN) procedure was compared with 4 plating media: sulfite-polymyxin-sulfadiazine, Shahidi-Ferguson perfringens, tryptose-sulfite- cycloserine (both with and without egg yolk), and tryptone-sulfite-neomycin. The selectivity of the iron milk relies solely on the rapid growth of C. perfringens at 45°C and the stormy fermentation reaction within 18 h. Isolates were confirmed as C. perfringens by standard biochemical tests. The iron milk MPN procedure compared very well with the 4 plating media tested. Selectivity of incubation temperature, short incubation time, and ease of identification by the characteristic stormy fermentation make this method ideal for enumerating C. perfringens from large numbers of samples.

Survey of Postharvest-Processed Oysters in the United States for Levels of Vibrio vulnificus and Vibrio parahaemolyticus

2009 ◽  
Vol 72 (10) ◽  
pp. 2110-2113 ◽  
Author(s):  
ANGELO DePAOLA ◽  
JESSICA L. JONES ◽  
KATHY E. NOE ◽  
ROBIN H. BYARS ◽  
JOHN C. BOWERS
Keyword(s):  
Vibrio Vulnificus ◽  
Gulf Coast ◽  
Virulence Gene ◽  
Selective Advantage ◽  
The United States ◽  
Most Probable Number ◽  
Probable Number ◽  
Mild Heat ◽  
Thermostable Direct Hemolysin ◽  
The Mean

From June through October 2004, the U.S. Food and Drug Administration collected oysters (61 samples) that had been subjected to postharvest processing (PHP) methods, including mild heat treatment, freezing, and high hydrostatic pressure, from processors and retail markets in various states to determine Vibrio vulnificus and V. parahaemolyticus levels. Presence in a 25-g sample and most probable number (MPN) using standard enrichment and selective isolation procedures were utilized. Suspect colonies were isolated and identified using DNA probe colony hybridization. Neither species of vibrio was detected in 25-g portions of most samples regardless of the PHP. The lowest frequency of isolation of either pathogen (<10%) was observed with the mild heat process. Few (12 to 13%) frozen samples collected at the processor but not at retail contained >30 MPN/g of either pathogen. The mean levels of either organism in PHP oysters observed in the present study were 5 to 6 log less than in unprocessed raw Gulf Coast oysters. Of the 70 V. vulnificus isolates examined, only 5 possessed the putative virulence marker, type B 16S rRNA. Neither the thermostable direct hemolysin (tdh) nor the tdh-related hemolysin (trh) virulence gene was detected in any of the 40 V. parahaemolyticus isolates examined in the present study. These data suggest that if there is any selective advantage to pathogenic strains of V. vulnificus and V. parahaemolyticus, these differences are minimal. These results indicate that all PHP treatments greatly reduce exposure of V. vulnificus and V. parahaemolyticus to raw-oyster consumers. Consequently, these PHP oysters pose a much lower risk of illness to consumers due to these pathogens.

Thermal Inactivation of Staphylococcus aureus in Retentates from Ultrafiltered Milk

1989 ◽  
Vol 52 (9) ◽  
pp. 631-637 ◽  
Author(s):  
JEFFREY L. KORNACKI ◽  
ELMER H. MARTH
Keyword(s):  
Staphylococcus Aureus ◽  
Heat Resistance ◽  
Thermal Inactivation ◽  
Thermal Protection ◽  
Skim Milk ◽  
Stationary Growth Phase ◽  
Plate Count ◽  
Mannitol Salt Agar ◽  
Whole Milk ◽  
D Values

Cells of Staphylococcus aureus strains 196E, 481, and 425 were thermally stressed at 56°C for 10 min in milk and enumerated on Plate Count Agar (PCA), Mannitol Salt Agar (MSA), and PCA with an overlay of MSA. PCA recovered more S. aureus 196E and 481 than did PCA/MSA, which recovered more than MSA. PCA/MSA recovered slightly more S. aureus 425 than did PCA, which recovered more than MSA. At 58°C, in order of decreasing heat resistance, the four strains of S. aureus originally isolated from food were 425 > 100 and 481 > 196E. Their D-values were 26,14,13, and 3.0 min, respectively. S. aureus 425 was more heat resistant in the stationary than in the log phase when heated at 58°C in whole milk. Heat resistance at 58°C increased overall during the stationary growth phase, but was fairly stable when the culture was from 17 to 25 h or from 41 to 49 h old. S. aureus 425 exhibited no consistent differences in heat resistance in concentrated (4X by volume) and unconcentrated skim or whole milk. Adjustments of protein (3.5–4.0% to 12.6–16%), milkfat (0.28–1.12% to 10%), and lactose (ca. 4.5–5.0% to ca. 14.5–15%) contents of milk and 4X (volume concentration) UF milk retentates afforded no significant thermal protection to S. aureus 425. Diafiltration of 4X skim milk reduced thermal protection of S. aureus 425 in the retentate over that of unconcentrated skim milk of the same lot when tested at 63 and 74°C. S. aureus 425 had greatest D-values (min) in skim milk (0.36 ± 0.05) and permeate (0.30 ± 0.14) followed by permeate from diafiltration (0.28 ± 0.06) when tested at 63°C.

Factors Influencing Survival of Listeria monocytogenes in Milk in a High-Temperature Short-Time Pasteurizer

1992 ◽  
Vol 55 (12) ◽  
pp. 946-951 ◽  
Author(s):  
J. M. FARBER ◽  
E. DALEY ◽  
F. COATES ◽  
D. B. EMMONS ◽  
R. McKELLAR
Keyword(s):  
High Temperature ◽  
Listeria Monocytogenes ◽  
Most Probable Number ◽  
Probable Number ◽  
High Temperature Short Time ◽  
Whole Milk ◽  
Different Temperatures ◽  
Margin Of Safety ◽  
Short Time ◽  
Adequate Margin

Heat resistance experiments were carried out with Listeria monocytogenes which had been grown at three different temperatures (30, 39, and 43°C). Heated whole milk was inoculated with L. monocytogenes and then passed through a high-temperature short-time system at 72, 69, 66, and 63°C for a minimum holding time of 16.2 s. Heated cells were recovered both aerobically and anaerobically using four different methods: direct plating, most probable number, cold enrichment, and warm enrichment. Significant differences in recovery of L. monocytogenes were observed depending on the growth temperature. Cells grown at 43, 39, or 30°C, held 1 d at 4°C, and then heated at 69°C showed an overall decrease in numbers of approximately 2.1, 2.8, and 4.1 logs, respectively. Cells grown at 39°C and then held 3 d at 4°C appeared to be the most heat sensitive. Although cells grown at 43 and 39°C were capable of surviving at the minimum high-temperature short-time temperature (72°C), those grown at 30°C were not. In some instances, anaerobic incubation enhanced the recovery of L. monocytogenes, as compared to cells recovered aerobically, although these differences were not statistically significant. While L. monocytogenes can survive minimum pasteurization treatment (71.7°C/16 s) under certain conditions, common methods of handling, processing, and storing fluid milk will provide an adequate margin of safety.

Recovery of Escherichia coli Biotype I and Enterococcus spp. during Refrigerated Storage of Beef Carcasses Inoculated with a Fecal Slurry

1999 ◽  
Vol 62 (8) ◽  
pp. 944-947 ◽  
Author(s):  
M. CALICIOGLU ◽  
D. R. BUEGE ◽  
S. C. INGHAM ◽  
J. B. LUCHANSKY
Keyword(s):  
Escherichia Coli ◽  
Storage Period ◽  
Most Probable Number ◽  
Probable Number ◽  
E Coli ◽  
Viable Cells ◽  
Beef Carcasses ◽  
Significant Difference ◽  
Enterococcus Spp ◽  
Appreciable Reduction

Three beef front quarters/carcasses were inoculated with a slurry of cattle manure. During storage at 4°C, two sponge samples from each of three sites (i.e., 100 cm2 from each of two fat surfaces and 100 cm2 from a lean surface) were taken from each of the three carcasses on days 0, 1, 3, 7, and 10 after inoculation. The initial numbers of Escherichia coli averaged 2.0 log10 CFU/cm2 (1.21 to 2.47 log10 CFU/cm2) using the Petrifilm method and 2.09 log10 most probable number (MPN)/cm2 (0.88 to 2.96 log10 MPN/cm2) using the MPN method. The initial numbers of enterococci averaged 3.34 log10 CFU/cm2 (3.07 to 3.79 log10 CFU/cm2) using kanamycin esculin azide agar. In general, an appreciable reduction in the numbers of E. coli occurred during the first 24 h of storage; for the Petrifilm method an average reduction of 1.37 log10 CFU/cm2 (0.69 to 1.71 log10 CFU/cm2) was observed, and for the MPN method an average reduction of 1.52 log10 MPN/cm2 (0.47 to 2.08 log10 MPN/cm2) was observed. E. coli were not detected (<−0.12 log10 CFU/cm2) using Petrifilm on day 7 of the storage period on two (initial counts of 1.21 and 2.29 log10 CFU/cm2) of the three carcasses. However, viable E. coli cells were recovered from these two carcasses after a 24-h enrichment at 37°C in EC broth. Viable E. coli cells were detected at levels of −0.10 log10 CFU/cm2 on the third carcass (initial count of 2.47 log10 CFU/cm2) after 7 days at 4°C. No significant difference in recovery of viable cells was observed between the MPN and Petrifilm methods on days 0, 1, and 3 (P > 0.05). However, viable E. coli cells were recovered from all three carcasses by the MPN method on day 7 at an average of −0.29 log10 MPN/cm2 (−0.6 to −0.1 log10 MPN/cm2). On day 10, viable cells were recovered by the MPN method from two of the three carcasses at −0.63 and −0.48 log10 MPN/cm2 but were not recovered from the remaining carcass (<−0.8 log10 MPN/cm2). Similar to E. coli, the greatest reduction (average of 1.26 log10 CFU/cm2, range = 1.06 to 1.45 log10 CFU/cm2) in the numbers of enterococci occurred during the first 24 h of storage. Because of higher initial numbers and a slightly slower rate of decrease, the numbers of Enterococcus spp. were significantly higher (P < 0.017) than the numbers of E. coli Biotype I after 3, 7, and 10 days of storage. These results suggest that enterococci may be useful as an indicator of fecal contamination of beef carcasses.

Dry Rehydratable Film for Enumeration of Total Coliforms and Escherichia coli in Foods: Collaborative Study

1991 ◽  
Vol 74 (4) ◽  
pp. 635-648 ◽  
Author(s):  
Michael S Curiale ◽  
Therese Sons ◽  
Dawn Mclver ◽  
J Sue McAllister ◽  
Barbara Halsey ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Collaborative Study ◽  
Most Probable Number ◽  
Probable Number ◽  
Total Coliforms ◽  
Repeatability And Reproducibility ◽  
The Mean ◽  
Better Than ◽  
Dry Film

Abstract Rehydratable dry-film plating methods for total coliforms and Escherichia coll In foods have been compared to the AOAC most probable number methods. Fourteen laboratories participated In the collaborative study. Three coliform and £. coll levels In 6 samples of 4 product types (flour, nuts, cheese, and beef with gravy) and in 3 samples of 2 product types (mushrooms and raw turkey) were tested In duplicate by the participants. The mean log counts for the 3 methods were comparable. In general, the repeatability and reproducibility variances of the plating methods were as good as or better than that of the MPN method. The method has been adopted official first action by AOAC.

Shelf life study of handmade and industrially processed Minas frescal cheese

2019 ◽  
Vol 49 (6) ◽  
pp. 1207-1218
Author(s):  
Thamiris Evangelista Silva ◽  
Priscila Alonso dos Santos ◽  
Thamara Evangelista Silva ◽  
Kamilla Soares Silva ◽  
André Luiz Borges Machado ◽  
...  
Keyword(s):  
Microbiological Quality ◽  
Oxygen Demand ◽  
Storage Period ◽  
State Inspection ◽  
Most Probable Number ◽  
Probable Number ◽  
Content Type ◽  
Life Study ◽  
Thermotolerant Coliforms ◽  
Milk Pasteurisation

Purpose The purpose of this study is to characterize and compare the results of the inspection mark of handmade and industrially processed Minas frescal cheese. It is one of the most commonly made and consumed cheeses in Brazil, and its production processes range from handmade cheeses produced in small household production sites to cheeses manufactured in large dairy factories subject to federal inspection. Design/methodology/approach The samples were stored for 10 days at 4°C in a biochemical oxygen demand chamber. Cheeses were analyzed using physicochemical analyzes, yield and syneresis indices and microbiological analyses. Findings The cheese A met the criterion of regulatory classification for very high humidity (65.32 g/100 g), while cheese B did not meet the criterion (54.38 g/100 g). Cheeses A (19.01 g/100 g) and B (24 g/100 g) showed average fat contents that did not comply with current legislation. The most probable number per g of thermotolerant coliforms was outside the acceptable range (>24 × 102 MPN/g), and Salmonella spp. were present in the tested samples. The highest yield was observed for handmade cheese (an average of 5.35 L of milk to produce 1 kg of cheese), which had the highest syneresis during the storage period (p = 0.004), reaching 14.26% on the 10th day of storage. Originality/value Municipal and state inspection certificates do not ensure the microbiological quality of Minas frescal cheese, indicating flaws in the good manufacturing practices and/or in the milk pasteurisation stage.

Whole Milk, Low-Fat Milk, or Skim Milk: Which Is to Be Recommended?

PEDIATRICS ◽  
1973 ◽  
Vol 52 (5) ◽  
pp. 752-752
Author(s):  
Gary Gorlick
Keyword(s):  
Skim Milk ◽  
Caloric Content ◽  
Age Group ◽  
Pediatric Age ◽  
Low Fat ◽  
Preventative Measure ◽  
Pediatric Age Group ◽  
Whole Milk ◽  
Skimmed Milk

In the pediatric age group, which milk is most recommended by the Academy: skimmed milk or low-fat milk? The former I note is recommended as a possible preventative measure toward retarding or preventing atherosclerosis; yet the latter is higher in calcium and in caloric content. The Chairman of the A.A.P. Committee on Nutrition answers as follows: The Committee on Nutrition is preparing a broad statement on the use of milk, which will, when completed, provide you information on the questions raised.

scholarly journals Arcobacter cryaerophilusand thermophilic campylobacters in a sewage treatment plant in Italy: two secondary treatments compared

1993 ◽  
Vol 110 (3) ◽  
pp. 633-639 ◽  
Author(s):  
S Stampi ◽  
O Varoli ◽  
F Zanetti ◽  
G De Luca
Keyword(s):  
Activated Sludge ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Most Probable Number ◽  
Tertiary Treatment ◽  
Probable Number ◽  
Urban Sewage ◽  
Thermophilic Campylobacter ◽  
The Mean

SUMMARYMicroaerophilic organisms were monitored in sewage effluent undergoing two secondary treatments: air and oxygen-activated sludge. The mean numbers ofArcobacter cryaerophilusand thermophilic campylobacters detected in incoming sewage were 5639/100 ml and 1720/100 ml respectively.Secondary treatment in air tanks reduced the population ofA. cryaerophilusby 97.1% and of thermophilic campylobacters by 99.08%, whereas treatment in oxygen tanks reduced the bacteria 97.8% and 99.63% respectively, showing that oxygen-activated sludge treatment was more effective. Subsequent tertiary treatment with 2 p.p.m. chlorine dioxide evidenced the removal ofA. cryaerophilusto 99.9% and eliminated thermophilic campylobacters.Campylobacter jejuniandC. coliconstituted 54.1% and 45.9% of 74 thermophilic campylobacter strains isolated. In air-activated sludge effluentC. jejuniwas found more often, thus appearing more sensitive to oxygen.The most probable number assay used for detection of campylobacters, blood medium for enrichment and blood-free medium for plating, also appeared to be fit forA. cryaerophilus, the high density of which in urban sewage may be due to inflows from slaughterhouses.

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