Heat Resistance of Escherichia coli in Cow and Buffalo Milk

1980 ◽  
Vol 43 (5) ◽  
pp. 376-380 ◽  
Author(s):  
R. S. SINGH ◽  
B. RANGANATHAN
Keyword(s):  
Escherichia Coli ◽  
Heat Treatment ◽  
Heat Resistance ◽  
Skim Milk ◽  
Buffalo Milk ◽  
Time Interval ◽  
E Coli ◽  
Heat Resistant ◽  
Whole Milk

Three Escherichia coli cultures (0111:B4, 0127:B8 and NP) were selected to study their heat-resistant characteristics when in cow skim, cow whole and buffalo whole milk. The temperatures of heat-treatment included in this study were 50, 55, 60 and 63 C. The time interval during heat-treatment was 10 min at 50 and 55 C and 5 min at 60 and 63 C. Marked differences in heat-resistance were observed in the three E. coli cultures. The z-values obtained for strain 0111:B4 were 8.3, 9.0 and 10.2 when tested in cow skim milk, cow whole milk and buffalo milk, respectively. The z-values for 0127:B8 and NP were 17.5, 18.0 and 19.2 and 18.8, 19.0 and 20.3, respectively, for the three types of milk.

scholarly journals Heat-resistance of suspect persistent strains of Escherichia coli from cheesemaking plants

2020 ◽  
Vol 38 (No. 5) ◽  
pp. 323-329
Author(s):  
Irena Němečková ◽  
Šárka Havlíková ◽  
Tereza Gelbíčová ◽  
Lucie Pospíšilová ◽  
Eliška Hromádková ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Heat Treatment ◽  
Heat Resistance ◽  
Raw Material ◽  
Resistance Locus ◽  
Manufacturing Environment ◽  
E Coli ◽  
Heat Resistant ◽  
Plant Environment ◽  
Cheese Production

Besides its health and spoilage hazards, Escherichia coli is a process hygiene indicator for cheeses made from milk that has undergone heat treatment. Hence, its ability to persist in cheesemaking plant environment and equipment is important. In total, 120 samples from two producing plants were analysed and 72 E. coli isolates were obtained. The target was to find out whether there is a difference in heat-resistance between persistent and non-persistent E. coli strains. The strains were selected using macrorestriction analysis and recurrent detection in cheesemaking plants hereby: one strain persisting in brine for blue-veined cheeses, two strains persisting in brine for hard cheeses and one non-persistent strain from raw material. Their D(50)-values were 196; 417; 370 and 182 min, respectively, D(59)-values ranged from 20 to 32 min and z-values were 7.5; 6.6; 8.1 and 9.0 °C, respectively. The non-persistent strain was the least resistant to heating to 50 °C but it was not the least resistant generally. All tested strains were highly heat-resistant and carried genes of the heat resistance locus LHR1 and/or LHR2. Our results emphasise the need to screen for the presence of LHR genes and the occurrence of heat-resistant E. coli in cheese production where they could survive sub-pasteurisation temperatures and contaminate the manufacturing environment and finished products.

scholarly journals Heat Resistance in Escherichia coli and its Implications on Ground Beef Cooking Recommendations in Canada

2019 ◽  
Vol 3 (2) ◽  
Author(s):  
X. Yang ◽  
F. Tran ◽  
M. Klasse
Keyword(s):  
Escherichia Coli ◽  
Heat Resistance ◽  
Growth Medium ◽  
Thermal Characteristics ◽  
Ground Beef ◽  
Coli Strain ◽  
E Coli ◽  
Log Reduction ◽  
Heat Resistant ◽  
Resistant Strains

ObjectivesRecent reports of an extremely heat resistant but non-pathogenic beef Escherichia coli strain, AW 1.7, raised concerns over the adequacy of cooking ground beef to 71°C in Canada. The objective of this study was to assess the adequacy of the current cooking recommendations for ground beef in relation to heat resistant E. coli.Materials and MethodsIn total, 8 potentially heat resistant E. coli strains (4 generic and 4 E. coli O157:H7) from beef along with E. coli AW1.7 were included in this study. Heat resistance of the strains was first evaluated by decimal reductions at 60°C (D60°C-value), the time required to have a log reduction of the bacterial population at 60°C. The more heat resistant strains of each group (E. coli 62 and 68, and E. coli O157 J3 and C37) were further assessed for their heat resistance when grown in Lennox Broth without salt (LB-NS), LB + 2% NaCl and Meat Juice (MJ). Then, the two most heat resistant E. coli O157 strains (J3 and C37) and E. coli AW 1.7 were each introduced to extra lean ground beef (100 g) in vacuum pouches for determination of their D-values at three temperatures, 54, 57, and 60°C, from which a z-value for each strain was derived. The thermal characteristics of all three strains were fed into a predictive model to determine the process lethality of cooking burgers to 71°C with resting for up to 5 min. Finally, inactivation of the most heat resistant E. coli strain AW1.7, assessed in this study and reported in the literature, in ground beef was validated by grilling burgers containing 6.20 ± 0.24 log CFU/g of the organism to 71°C without or with a resting of 3 or 5 min.ResultsThe D60°C-values for these strains varied from 1.3 to 9.0 min, with J3 and AW1.7 being the least and most heat resistant strains, respectively. The D60°C-values for E. coli 62 and 68 were similar and were not affected by growth medium, while the heat resistance of C37, J3 and AW1.7 varied with the growth medium. When heated in extra lean ground beef (100 g) in vacuum pouches, the mean D54°C, D57°C, and D60°C-values were 44.8, 18.6 and 2.9 min for C37, 13.8, 6.9 and 0.9 min for J3, and 40.5, 9.1 6.1 min for AW1.7. The derived z- and D71°C-values were, respectively, 5.0, 5.1 and 7.3°C; and 0.022, 0.008, and 0.156 min. Burger temperatures continued to rise after being removed from heat when the target temperature was reached, by up to 5°C, and resting of 1 min would result in a destruction of 133, 374, and 14 log C37, J3 and AW1.7, estimated from process lethality. When burgers inoculated with AW1.7 were cooked to 71°C, 14 of the 15 burgers yielded no E. coli, while the 15th had a reduction of 4.5 log. Additional resting of 3 or 5 min resulted in complete elimination of AW 1.7.ConclusionIt has been predicted that 2% of E. coli from beef may carry heat resistant genes. The findings in this study, along with the very low level of total E. coli expected in ground beef in Canada, suggest that cooking ground beef to 71°C should be adequate to ensure the safety of such products.

scholarly journals Are Antimicrobial Interventions Associated with Heat-Resistant Escherichia coli on Meat?

2020 ◽  
Vol 86 (13) ◽  
Author(s):  
Peipei Zhang ◽  
Frances Tran ◽  
Kim Stanford ◽  
Xianqin Yang
Keyword(s):  
Escherichia Coli ◽  
Heat Resistance ◽  
Ecological Niches ◽  
Beef Production ◽  
Production Chain ◽  
Content Type ◽  
E Coli ◽  
Heat Resistant ◽  
Significant Difference ◽  
Antimicrobial Interventions

ABSTRACT Decontamination practices, which often involve thermal treatments, are routinely performed in beef packing plants and have generally improved the safety of meat in North America. We investigated whether Escherichia coli in the beef production chain is becoming more heat resistant due to those treatments. Cattle isolates (n = 750) included seven serogroups (O157, O103, O111, O121, O145, O26, and O45) which were collected between 2002 and 2017. Beef plant isolates (n = 700) from carcasses, fabrication equipment, and beef products were included. Heat resistance was determined in Luria-Bertani broth at 60°C and by PCR screening for the locus of heat resistance (LHR). The decimal reduction for E. coli at 60°C (D60ºC values) ranged from 0 to 7.54 min, with 97.2% of the values being <2 min. The prevalence of E. coli with D60ºC values of >2 min was not significantly different (P > 0.05) among cattle and meat plant isolates. E. coli from equipment before sanitation (median, 1.03 min) was more heat resistant than that after sanitation (median, 0.9 min). No significant difference in D60ºC values was observed among E. coli isolates from different years, from carcasses before and after antimicrobial interventions, or from before and during carcass chilling. Of all isolates, 1.97% harbored LHR, and the LHR-positive isolates had greater median D60ºC values than the LHR-negative isolates (3.25 versus 0.96 min). No increase in heat resistance in E. coli was observed along the beef production chain or with time. IMPORTANCE The implementation of multiple hurdles in the beef production chain has resulted in substantial improvement in the microbial safety of beef in Canada. In this study, we characterized a large number of Escherichia coli isolates (n = 1,450) from various sources/stages of beef processing to determine whether the commonly used antimicrobial interventions would give rise to heat-resistant E. coli on meat, which in turn may require alternatives to the current control of pathogens and/or modifications to the current cooking recommendations for meat. The findings show that the degree and rate of heat resistance in E. coli did not increase along the production chain or with time. This furthers our understanding of man-made ecological niches that are required for the development of heat resistance in E. coli.

Effect of Heat Shock and Growth Atmosphere on the Heat Resistance of Escherichia coli 0157:H7

1992 ◽  
Vol 55 (3) ◽  
pp. 171-175 ◽  
Author(s):  
ELSA A. MURANO ◽  
MERLE D. PIERSON
Keyword(s):  
Escherichia Coli ◽  
Heat Treatment ◽  
Heat Shock ◽  
Heat Resistance ◽  
Anaerobic Growth ◽  
Optimum Conditions ◽  
E Coli ◽  
Growth Atmosphere ◽  
Sigma Subunit ◽  
Shock Proteins

Log phase cells of Escherichia coli 0157:H7 were grown aerobically at 30°C and heat shocked at various time/temperature combinations to determine the optimum conditions that would result in the highest number of survivors to a subsequent 55°C heat treatment. Heat shocking at 42°C for 5 min resulted in the largest increase in D55 value over nonheat-shocked controls of all heat-shock time/temperature combinations tested. Growth atmosphere significantly contributed to the heat resistance of both heat-shocked and nonheat-shocked cells, with anaerobically grown cells having D55 values higher than those of cells grown aerobically. Therefore, both heat shocking and anaerobic growth contributed to an increase in the number of survivors of E. coli 0157:H7 cells when compared with nonheat-shocked cells grown aerobically. Aerobically grown, heat-shocked cells, and anaerobically grown cells, both heat-shocked and nonheat-shocked, contained a 71,000 dalton protein not present in aerobically grown, nonheat-shocked controls. This protein was found to be immunologically similar to a sigma32 subunit of RNA polymerase, as evidenced by Western Blot using monoclonal antibodies specific for the sigma subunit. In addition to heat, anaerobic growth appeared to be a form of stress, since it resulted in the synthesis of heat-shock proteins and in an increased survival of cells to a heat treatment.

scholarly journals Escherichia coli O157:H7 SURVIVAL IN TRADITIONAL AND LOW LACTOSE YOGURT DURING FERMENTATION AND COOLING PERIODS

2017 ◽  
Vol 18 (0) ◽  
Author(s):  
Camila Sampaio Cutrim ◽  
Raphael Ferreira de Barros ◽  
Robson Maia Franco ◽  
Marco Antonio Sloboda Cortez
Keyword(s):  
Escherichia Coli ◽  
The Other ◽  
Lactose Hydrolysis ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Gas Formation ◽  
Whole Milk ◽  
Milk Contamination ◽  
Different Types ◽  
Fermentation Period

Abstract The purpose of this study was to evaluate the behavior of E. coli O157:H7 during lactose hydrolysis and fermentation of traditional and low lactose yogurt. It also aimed to verify E. coli O157:H7 survival after 12 h of storage at 4 ºC ±1 ºC. Two different types of yogurts were prepared, two with whole milk and two with pre-hydrolyzed whole milk; in both groups one yogurt was inoculated with E. coli O157:H7 and the other one was not inoculated. The survival of E. coli and pH of yogurt were determined during fermentation and after 12-h refrigeration. The results showed that E. coli O157:H7 was able to grow during the fermentation period (from 4.34 log CFU.mL-1 to 6.13 log CFU.mL-1 in traditional yogurt and 4.34 log CFU.mL-1 to 6.16 log CFU.mL-1 in low lactose yogurt). The samples with E. coli O157:H7 showed gas formation and syneresis. Thus, E. coli O157:H7 was able to survive and grow during fermentation of traditional and low lactose yogurts affecting the manufacture technology. Moreover, milk contamination by E. coli before LAB addition reduces the growth of L. bulgaricus and S. thermophilus especially when associated with reduction of lactose content.

Impact of Interventions on the Survival of Salmonella enterica I 4,[5],12:I:- in Pork

2021 ◽  
Author(s):  
Braden Wiser ◽  
S.E. Niebuhr ◽  
James Dickson
Keyword(s):  
Escherichia Coli ◽  
Heat Resistance ◽  
Mixed Culture ◽  
Refrigerated Storage ◽  
Unique Challenge ◽  
E Coli ◽  
Pork Industry ◽  
Pathogenic Escherichia Coli ◽  
Ground Pork ◽  
Salmonella Serovars

A mixed culture of different isolates of Salmonella serovar I 4,[5], 12:i:- was compared to a mixed culture of reference Salmonella serovars as well as non-pathogenic Escherichia coli surrogates.. The two groups of Salmonella were compared for their resistance to commonly used pork carcass interventions, survival in ground pork and thermal resistance in ground pork. There were no observed differences between the response of the two different groups of Salmonella serovars and the non-pathogenic E. coli surrogates within intervention type.  There were no observed differences in the recovery and survival of the two different groups of Salmonella serovars in pork which had been treated with interventions, ground and stored at 5 o C for two weeks. Finally, there were no observed differences in heat resistance between the two different groups of Salmonella serovars in ground pork which had been treated with interventions, ground and stored at 5 o C for two weeks. However, there were observed differences in heat resistance in both groups of Salmonella serovars associated with refrigerated storage. The heat resistance of both groups of Salmonella serovars decreased after refrigerated storage. The results of these experiments demonstrate that there were no observed differences between the responses of Salmonella serovar I 4,[5], 12:i:- when compared to the reference Salmonella serovars to commonly used interventions in the pork industry, and therefore do not present a unique challenge to the pork industry.

scholarly journals Functional Analysis of Genes Comprising the Locus of Heat Resistance in Escherichia coli

2017 ◽  
Vol 83 (20) ◽  
Author(s):  
Ryan Mercer ◽  
Oanh Nguyen ◽  
Qixing Ou ◽  
Lynn McMullen ◽  
Michael G. Gänzle
Keyword(s):  
Escherichia Coli ◽  
Heat Shock ◽  
Heat Shock Proteins ◽  
Heat Resistance ◽  
Growth Phase ◽  
Genomic Island ◽  
Enteric Bacteria ◽  
Content Type ◽  
E Coli ◽  
Shock Proteins

ABSTRACT The locus of heat resistance (LHR) is a 15- to 19-kb genomic island conferring exceptional heat resistance to organisms in the family Enterobacteriaceae, including pathogenic strains of Salmonella enterica and Escherichia coli. The complement of LHR-comprising genes that is necessary for heat resistance and the stress-induced or growth-phase-induced expression of LHR-comprising genes are unknown. This study determined the contribution of the seven LHR-comprising genes yfdX1 GI, yfdX2, hdeD GI, orf11, trx GI, kefB, and psiE GI by comparing the heat resistances of E. coli strains harboring plasmid-encoded derivatives of the different LHRs in these genes. (Genes carry a subscript “GI” [genomic island] if an ortholog of the same gene is present in genomes of E. coli.) LHR-encoded heat shock proteins sHSP20, ClpKGI, and sHSPGI are not sufficient for the heat resistance phenotype; YfdX1, YfdX2, and HdeD are necessary to complement the LHR heat shock proteins and to impart a high level of resistance. Deletion of trx GI, kefB, and psiE GI from plasmid-encoded copies of the LHR did not significantly affect heat resistance. The effect of the growth phase and the NaCl concentration on expression from the putative LHR promoter p2 was determined by quantitative reverse transcription-PCR and by a plasmid-encoded p2:GFP promoter fusion. The expression levels of exponential- and stationary-phase E. coli cells were not significantly different, but the addition of 1% NaCl significantly increased LHR expression. Remarkably, LHR expression in E. coli was dependent on a chromosomal copy of evgA. In conclusion, this study improved our understanding of the genes required for exceptional heat resistance in E. coli and factors that increase their expression in food. IMPORTANCE The locus of heat resistance (LHR) is a genomic island conferring exceptional heat resistance to several foodborne pathogens. The exceptional level of heat resistance provided by the LHR questions the control of pathogens by current food processing and preparation techniques. The function of LHR-comprising genes and their regulation, however, remain largely unknown. This study defines a core complement of LHR-encoded proteins that are necessary for heat resistance and demonstrates that regulation of the LHR in E. coli requires a chromosomal copy of the gene encoding EvgA. This study provides insight into the function of a transmissible genomic island that allows otherwise heat-sensitive enteric bacteria, including pathogens, to lead a thermoduric lifestyle and thus contributes to the detection and control of heat-resistant enteric bacteria in food.

Genomic and phenotypic analysis of heat and sanitizer resistance in Escherichia coli from beef in relation to the locus of heat resistance

2021 ◽  
Author(s):  
Xianqin Yang ◽  
Frances Tran ◽  
Peipei Zhang ◽  
Hui Wang
Keyword(s):  
Escherichia Coli ◽  
Heat Resistance ◽  
Phylogenetic Relationships ◽  
Core Genome ◽  
Elevated Temperatures ◽  
Resistant Bacteria ◽  
Phenotypic Analysis ◽  
Decimal Reduction Time ◽  
E Coli ◽  
Clade 1

The locus of heat resistance (LHR) can confer heat resistance to Escherichia coli to various extents. This study investigated the phylogenetic relationships, and genomic and phenotypic characteristics of E. coli with or without LHR recovered from beef by direct plating or from enrichment broth at 42°C. LHR-positive E. coli isolates (n=24) were whole genome-sequenced by short- and long-reads. LHR-negative isolates (n=18) from equivalent sources as LHR-positive isolates were short-read sequenced. All isolates were assessed for decimal reduction time at 60°C ( D 60°C ) and susceptibility to E-SAN and Perox-E. Selected isolates were evaluated for growth at 42°C. The LHR-positive and negative isolates were well separated on the core genome tree, with 22/24 of the positive isolates clustering into three clades. Isolates within clade 1 and 2, despite their different D 60°C values, were clonal, as determined by subtyping (MLST, core genome MLST, and serotyping). Isolates within each clade are of one serotype. The LHR-negative isolates were genetically diverse. The LHR-positive isolates had a larger (p<0.001) median genome size by 0.3 Mbp (5.0 vs 4.7 Mbp), and overrepresentation of genes in plasmid maintenance, stress response and cryptic prophages, but underrepresentation of genes involved in epithelial attachment and virulence. All LHR-positive isolates harbored a chromosomal copy of LHR, and all clade 2 isolates had an additional partial copy of LHR on conjugative plasmids. The growth rates at 42°C were 0.71±0.02 and 0.65±0.02 logOD h −1 for LHR-positive and negative isolates. No meaningful difference in sanitizer susceptibility was noted between LHR-positive and negative isolates. Importance Resistant bacteria are serious food safety and public health concerns. Heat resistance conferred by the LHR varies largely among different strains. The findings in this study show that genomic background and composition of LHR, in addition to the presence of LHR, play an important role in the degree of heat resistance in E. coli , and that strains with certain genetic background are more likely to acquire and maintain the LHR. Also, caution should be exercised when recovering E. coli at elevated temperatures as the presence of LHR may confer growth advantages to some strains. Interestingly, the LHR harboring strains seem to have evolved further from their primary animal host to adapt to their secondary habitat, as reflected by fewer genes in virulence and epithelial attachment. The phylogenetic relationships among the isolates point towards multiple mechanisms for acquiring LHR, likely prior to their deposition on meat.

Chemical and Irradiation Treatments for Killing Escherichia coli O157:H7 on Alfalfa, Radish, and Mung Bean Seeds

2003 ◽  
Vol 66 (5) ◽  
pp. 767-774 ◽  
Author(s):  
M. L. BARI ◽  
E. NAZUKA ◽  
Y. SABINA ◽  
S. TODORIKI ◽  
K. ISSHIKI
Keyword(s):  
Escherichia Coli ◽  
Heat Treatment ◽  
Mung Bean ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Chemical Treatments ◽  
Dry Heat ◽  
Pathogen Populations ◽  
Dry Heat Treatment ◽  
Alfalfa Seeds

In this study, the effectiveness of dry-heat treatment in combination with chemical treatments (electrolyzed oxidizing [EO] water, califresh-S, 200 ppm of active chlorinated water) with and without sonication in eliminating Escherichia coli O157:H7 on laboratory-inoculated alfalfa, radish, and mung bean seeds was compared with that of dry-heat treatment in combination with irradiation treatment. The treatment of mung bean seeds with EO water in combination with sonication followed by a rinse with sterile distilled water resulted in reductions of approximately 4.0 log10 CFU of E. coli O157:H7 per g, whereas reductions of ca. 1.52 and 2.64 log10 CFU/g were obtained for radish and alfalfa seeds. The maximum reduction (3.70 log10 CFU/g) for mung bean seeds was achieved by treatment with califresh-S and chlorinated water (200 ppm) in combination with sonication and a rinse. The combination of dry heat, hot EO water treatment, and sonication was able to eliminate pathogen populations on mung bean seeds but was unable to eliminate the pathogen on radish and alfalfa seeds. Other chemical treatments used were effective in greatly reducing pathogen populations on radish and alfalfa seeds without compromising the quality of the sprouts, but these treatments did not result in the elimination of pathogens from radish and alfalfa seeds. Moreover, a combination of dry-heat and irradiation treatments was effective in eliminating E. coli O157:H7 on laboratory-inoculated alfalfa, radish, and mung bean seeds. An irradiation dose of 2.0 kGy in combination with dry heat eliminated E. coli O157:H7 completely from alfalfa and mung bean seeds, whereas a 2.5-kGy dose of irradiation was required to eliminate the pathogen completely from radish seeds. Dry heat in combination with irradiation doses of up to 2.0 kGy did not unacceptably decrease the germination percentage for alfalfa seeds or the length of alfalfa sprouts but did decrease the lengths of radish and mung bean sprouts.

scholarly journals Culture of Urine Specimens by Use of chromID CPS Elite Medium Can Expedite Escherichia coli Identification and Reduce Hands-On Time in the Clinical Laboratory

2016 ◽  
Vol 54 (11) ◽  
pp. 2767-2773 ◽  
Author(s):  
Melanie L. Yarbrough ◽  
Meghan A. Wallace ◽  
Cynthia Marshall ◽  
Erin Mathias ◽  
Carey-Ann D. Burnham
Keyword(s):  
Escherichia Coli ◽  
Clinical Laboratory ◽  
Time Interval ◽  
Clinical Microbiology Laboratory ◽  
Biochemical Tests ◽  
Content Type ◽  
E Coli ◽  
Hands On ◽  
Clinically Significant ◽  
Urine Specimens

Urine is one of the most common specimen types submitted to the clinical microbiology laboratory; the use of chromogenic agar is one method by which the laboratory might expedite culture results and reduce hands-on time and materials required for urine culture analysis. The objective of our study was to compare chromID CPS Elite (bioMérieux), a chromogenic medium, to conventional primary culture medium for evaluation of urine specimens. Remnant urine specimens (n= 200) were inoculated into conventional media and into chromID CPS Elite agar (chromID). The time to identification and consumables used were documented for both methods. Clinically significant pathogen(s) were recovered from 51 cultures using conventional media, withEscherichia colibeing the most frequently recovered organism (n= 22). The rate of exact uropathogen agreement between conventional and chromogenic media was 82%, while overall categorical agreement was 83.5% The time interval between plating and final organism identification was decreased with chromID agar versus conventional media forE. coli(mean of 24.4 h versus 27.1 h,P< 0.001). Using chromID, clinically significant cultures required less hands-on time per culture (mean of 1 min and 2 s [1:02 min]) compared to conventional media (mean of 1:31 min). In addition, fewer consumables (2.4 versus 3.3 sticks and swabs) and rapid biochemical tests (1.0 versus 1.9) were necessary using chromID versus conventional media. Notably, antimicrobial susceptibility testing demonstrated good overall agreement (97.4%) between the chromID and conventional media for all antibiotics tested. chromID CPS Elite is accurate for uropathogen identification, reduces consumable usage, and may expedite the identification ofE. coliin clinical specimens.

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