Development of a Medium for Differentiation between Escherichia coli and Escherichia coli O157:H7

1999 ◽  
Vol 62 (4) ◽  
pp. 313-317 ◽  
Author(s):  
DONG-HYUN KANG ◽  
DANIEL Y. C. FUNG
Keyword(s):  
Escherichia Coli ◽  
Indigo Carmine ◽  
Neutral Red ◽  
Escherichia Coli O157 ◽  
Phenol Red ◽  
Clear Zone ◽  
E Coli ◽  
Popular Medium ◽  
Yellow Color ◽  
Red Color

A new medium (Escherichia coli O157:H7 medium: EOH) was developed for differentiation between E. coli and E. coli O157:H7. The EOH medium was compared with sorbitol MacConkey agar (SMAC), which is the most popular medium to enumerate E. coli O157:H7. Several combinations of 35 dyes were evaluated to develop the new medium. Indigo carmine (0.03 g/liter) and phenol red (0.036 g/liter) were found as the best combination for differentiation between E. coli O157:H7 and E. coli and added to the basal agar medium (SMAC medium excluding neutral red and crystal violet) for EOH medium. On the dark blue EOH medium, E. coli produced a yellow color with clear zone, whereas E. coli O157:H7 produced a red color without clear zone. For differentiation between E. coli and E. coli O157:H7, EOH has much better potential than SMAC. Furthermore, the red color produced by normal E. coli in SMAC may mask the light gray color produced by E. coli O157: H7, whereas the yellow color with clear zone did not mask the red color without clear zone in the EOH medium. The recovery numbers of E. coli O157:H7 from inoculated ground beef, pork, and turkey were not significantly different between SMAC and EOH media (P > 0.05). The recovery rates of heat- and cold-injured E. coli O157:H7 also were not significantly different (P > 0.05).

Thermal inactivation of Escherichia coli O157:H7, Salmonella senftenberg, and Enzymes with Potential as Time-Temperature Indicators in Ground Turkey Thigh Meat

1998 ◽  
Vol 61 (2) ◽  
pp. 171-175 ◽  
Author(s):  
GIRIDARAN J. VEERAMUTHU ◽  
JAMES F. PRICE ◽  
CARL E. DAVIS ◽  
ALDEN M. BOOREN ◽  
DENISE M. SMITH
Keyword(s):  
Escherichia Coli ◽  
Thermal Inactivation ◽  
Heat Processing ◽  
Performance Standard ◽  
Inactivation Kinetics ◽  
Escherichia Coli O157 ◽  
Phenol Red ◽  
E Coli ◽  
Death Time ◽  
Salmonella Senftenberg

The USDA Food Safety and Inspection Service has proposed to amend cooking regulations to require that any thermal process used for poultry products be sufficient to cause a 7 D reduction in salmonellae. Several enzymes have been suggested as potential indicators of heat processing in poultry, yet no relationship between the inactivation rates of these enzymes and salmonellae has been determined. The thermal inactivation kinetics of endogenous muscle proteins, Escherichia coli O157:H7 and Salmonella senftenberg were compared in ground turkey thigh meat in thermal death time studies. Bacteria counts were determined and muscle extracts were assayed for residual enzyme activity or protein concentration. D and z values were calculated using regression analysis. S. senftenberg had higher D values at all temperatures and was more heat resistant than E. coli. The z values of E. coli on Petrifilm Coliform Count plates and phenol red sorbitol agar plates were 6.0 and 5.7°C, respectively. The z values of S. senftenberg were 5.6 and 5.4°C on Petrifilm and agar, respectively. Lactate dehydrogenase (LDH) was the most heat stable protein at 64°C. LDH, glyceraldehyde-3-phosphate dehydrogenase, creatine kinase, triose phosphate isomerase (TPI), acid phosphatase, serum albumin, and immunoglobulin G had z values of 3.8, 4.3, 4.8, 5.8, 6.3, 6.7, and 8.6°C, respectively, in turkey containing 4.3% fat. The z values for TPI decreased to 5.4°C in thigh meat containing 9.8% fat. Temperature dependence of TPI was most similar to that of S. senftenberg, suggesting it might function as an endogenous time-temperature integrator to monitor adequacy of processing when a performance standard based on this pathogen is implemented.

Behavior of Hemorrhagic Escherichia coli O157:H7 During the Manufacture of Cottage Cheese

1992 ◽  
Vol 55 (5) ◽  
pp. 379-381 ◽  
Author(s):  
MARLENE M. AROCHA ◽  
MELINDA MCVEY ◽  
SUSAN D. LODER ◽  
JOHN H. RUPNOW ◽  
LLOYD BULLERMAN
Keyword(s):  
Escherichia Coli ◽  
Glucuronic Acid ◽  
Skim Milk ◽  
Enterohemorrhagic Escherichia Coli ◽  
Cottage Cheese ◽  
Escherichia Coli O157 ◽  
Phenol Red ◽  
E Coli ◽  
Heat Treated ◽  
And Control

The ability of enterohemorrhagic Escherichia coli O157:H7 to grow and survive during the manufacture of Cottage cheese was determined. Pasteurized skim milk artificially contaminated with E. coli O157:H7 was used to make Cottage cheese by the washed curd method. E. coli O157:H7 was enumerated by surface plating samples on MacConkey sorbitol agar with 5-bromo-4-chloro-3-indoxyl-β-D-glucuronic acid cyclohexylammonium salt (MSA-BCIG) and incubating at 42°C for 24 h. The heat treated samples were previously inoculated into a modified EC broth with novobiocin and incubated static at 35°C for 24 h. Sorbitol and β-glucuronidase negative colonies were picked from MSA-BCIG, spread on Levine eosin methylene blue agar plates and phenol red sorbitol agar plates with 4-methylumbelliferyl-β-D-glucuronide (PRS-MUG) added for confirmation. E. coli O157:H7 increased 100-fold in numbers during the manufacturing process, but death occurred during cooking of the curd and whey. The pH and acidity did not halt the growth of this pathogen during the manufacture of the cheese; furthermore, the values of these parameters were the same between the contaminated and control samples.

Evaluation of Various Media for Recovery of Thermally-Injured Escherichia coli O157:H71

1995 ◽  
Vol 58 (4) ◽  
pp. 357-360 ◽  
Author(s):  
NAHED M. AHMED ◽  
DONALD E. CONNER
Keyword(s):  
Escherichia Coli ◽  
Pyruvic Acid ◽  
Effective Medium ◽  
Plate Count ◽  
Escherichia Coli O157 ◽  
Phenol Red ◽  
E Coli ◽  
Plate Count Agar ◽  
Better Than

Efficacies of plating media for recovering heated Escherichia coli O157:H7 were determined and compared. To compare populations of recovered cells, suspensions of cells (three isolates, four replications/isolate) were heated at 50, 55, or 60°C, and then inoculated onto eight media: PCA-PA (plate count agar with 1% pyruvic acid [PA]), MSA (MacConkey sorbitol agar), MSA-Mg (MSA with 0.025% MgSO4), MSA-PA (MSA with 1% PA), MSA-MUG (MSA with 0.005% 4-methylumbelliferyl-β-d-glucuronide (MUG), PRSA-MUG (phenol red sorbitol agar [PSRA] with 0.005% MUG), PRSA-PA (PRSA with 1% PA), and TSA-PA (tryptic soy agar with 1% PA). Recovery was consistently higher (P < 0.05) with PRSA-MUG and PRSA-PA. At 50, 55, and 60°C, mean numbers (log10 CFU/ml) of recovered cells on PRSA-MUG were 4.42, 4.62, and 3.32, respectively, as compared to 2.78, 2.08, and 1.63, respectively, on MSA. PCA-PA and TSA-PA were less effective than PRSA media, but better than MSA media. Thus, PRSA with MUG or PA was an effective medium for recovering heated cells of E. coli O157:H7; whereas MSA failed to detect sublethally injured cells. Furthermore, addition of Mg, PA, or MUG to MSA further compromised this medium.

Heat Inactivation of Escherichia coli O157:H7 in Turkey Meat as Affected by Sodium Chloride, Sodium Lactate, Polyphosphate, and Fat Content†

1997 ◽  
Vol 60 (8) ◽  
pp. 898-902 ◽  
Author(s):  
JOHN S. KOTROLA ◽  
DONALD E. CONNER
Keyword(s):  
Escherichia Coli ◽  
Sodium Lactate ◽  
Heat Inactivation ◽  
Escherichia Coli O157 ◽  
Phenol Red ◽  
E Coli ◽  
Turkey Meat ◽  
Death Time ◽  
Product Formulation ◽  
D Values

The purpose of this research was to determine the survival of Escherichia coli O157:H7 when heated in ground turkey containing various additives and fat levels. D values and z values were determined for low (3%)- and high (11 %)- fat ground turkey with or without one of three additives: 8% NaCl, 4% sodium lactate, or a mixture of 8% NaCl, 4% sodium lactate, and 0.5% polyphosphate. Products inoculated with E. coli O157:H7 strain 204P were mixed, aseptically placed into thermal-death-time (TDT) tubes which were sealed and heated at 52, 55, 57 and 60°C. Survival was determined by enumeration on phenol red sorbitol agar, and D values were calculated by two methods. Mean D52 values ranged from 46.8 to 104.8 min; mean D55 values ranged from 7.7 to 27.2 min; mean D57 values ranged from 2.7 to 13.0 min; and mean D60 values ranged from 0.7 to 4.8 min. The greatest survival, as evidenced by higher (P < 0.001) D values, occurred in turkey containing the mixture of additives. The z values ranged from 6.09 to 4.08°C, and higher z values were obtained in turkey meat containing the additive mixture versus other turkey additive formulations. The additives evaluated enhanced survival of E. coli O157:H7 in cooked turkey meat as compared to turkey meat with no additives. In contrast to earlier reports, added fat did not enhance survival (P > 0.05). Product formulation should be a critical consideration when safe cooking processes are developed for ready-to-eat turkey products.

A Screening Method for the Isolation of Escherichia coli O157:H7 from Ground Beef

1990 ◽  
Vol 53 (3) ◽  
pp. 249-252 ◽  
Author(s):  
ANITA J. G. OKREND ◽  
BONNIE E. ROSE ◽  
BARBARA BENNETT
Keyword(s):  
Escherichia Coli ◽  
Screening Method ◽  
Agar Plate ◽  
Ground Beef ◽  
Escherichia Coli O157 ◽  
Phenol Red ◽  
E Coli ◽  
Screening Programs ◽  
Meat Samples ◽  
Incubation Method

A screening method was developed for the isolation of Escherichia coli O157:H7 from raw ground beef. Suspensions at a 1:10 dilution of beef were made in a modified EC broth with novobiocin (mEC+n; EC broth with 1.12 g/L instead of 1.5 g/L Bile salts #3 and novobiocin at 20 mg/L). The samples were macerated in a Stomacher for 2 min and either shaken at 37°C (100 RPM) for 6 h, or incubated static at 35°C for 24 h. Appropriate dilutions of the cultures were then spread plated on 150×15 mm plates of MacConkey sorbitol agar (MSA). The MSA plates were incubated at 42°C overnight. A set of two plates consisting of a deep (40 ml/plate) phenol red sorbitol agar plate with 4-methylumbelliferyl ß-D-glucuronide (PRS-MUG), and a Levine EMB agar plate with added agar for a final concentration of 3%, were gridded into 12 numbered sections. Sorbitol negative colonies were picked from the MSA plates, spread on the appropriate section of the EMB, and stabbed into the corresponding section on the PRS-MUG plate. Those cultures that were sorbitol negative and MUG negative on PRS-MUG and were typically E. coli on EMB were confirmed biochemically and serologically. By this procedure O157:H7 was isolated from 5 of 10 meat samples inoculated at 0.6 organisms/g, and 10 of 10 samples at the 5/g level using the 6 h shaken method. With the 24 h static incubation method, O157:H7 was isolated from 8 of 10 samples at the 0.6/g level and 10 of 10 at the 5/g level. Thirteen strains of O157:H7 inoculated at levels between 0.4 and 0.6/g were tested and 9 of the 13 were isolated with the 6 h method, and 13 of the 13 with the 24 h method. The method is reliable and simple enough to be used in large screening programs.

Evaluation of Consumer-Style Cooking Methods for Reduction of Escherichia coli O157:H7 in Ground Beef

2003 ◽  
Vol 66 (6) ◽  
pp. 1030-1034 ◽  
Author(s):  
MIN-SUK RHEE ◽  
SUN-YOUNG LEE ◽  
VIRGINIA N. HILLERS ◽  
SANDRA M. McCURDY ◽  
DONG-HYUN KANG
Keyword(s):  
Escherichia Coli ◽  
Thermal Inactivation ◽  
Ground Beef ◽  
Cooking Methods ◽  
Escherichia Coli O157 ◽  
Phenol Red ◽  
Internal Temperature ◽  
E Coli ◽  
The One ◽  
Time Required

The objective of this study was to evaluate the thermal inactivation of Escherichia coli O157:H7 in ground beef cooked to an internal temperature of 71.1°C (160°F) under conditions simulating consumer-style cooking methods. To compare a double-sided grill (DSG) with a single-sided grill (SSG), two different cooking methods were used for the SSG: for the one-turnover (OT-SSG) method, a patty was turned once when the internal temperature reached 40°C, and for the multiturnover (MT-SSG) method, a patty was turned every 30 s. Patties (100 g, n = 9) inoculated with a five-strain mixture of E. coli O157: H7 at a concentration of 107 CFU/g were cooked until all three temperature readings (for two sides and the center) for a patty were 71.1°C. The surviving E. coli O157:H7 cells were enumerated on sorbitol MacConkey (SMAC) agar and on phenol red agar base with 1% sorbitol (SPRAB). The order of the cooking methods with regard to the cooking time required for the patty to reach 71.1°C was as follows: DSG (2.7 min) < MT-SSG (6.6 min) < OT-SSG (10.9 min). The more rapid, higher-temperature cooking method was more effective (P < 0.01) in destroying E. coli O157:H7 in ground beef. E. coli O157:H7 reduction levels were clearly differentiated among treatments as follows: OT-SSG (4.7 log10 CFU/g) < MT-SSG (5.6 log10 CFU/g) < DSG (6.9 log10 CFU/g). Significantly larger numbers of E. coli O157:H7 were observed on SPRAB than on SMAC agar. To confirm the safety of ground beef cooked to 71.1°C, additional patties (100 g, n = 9) inoculated with lower concentrations of E. coli O157:H7 (103 to 104 CFU/g) were tested. The ground beef cooked by the OT-SSG method resulted in two (22%) of nine samples testing positive after enrichment, whereas no E. coli O157:H7 was found for samples cooked by the MT-SSG and DSG methods. Our findings suggest that consumers should be advised to either cook ground beef patties in a grill that cooks the top and the bottom of the patty at the same time or turn patties frequently (every 30 s) when cooking on a grill that cooks on only one side.

Occurrence of Escherichia coli O157:H7 in Hamburgers Produced in Brazil

1999 ◽  
Vol 62 (11) ◽  
pp. 1333-1335 ◽  
Author(s):  
NELIANE F. A. SILVEIRA ◽  
NEUSELY SILVA ◽  
CARMEN CONTRERAS ◽  
LUCIANA MIYAGUSKU ◽  
MARIA de LOURDES F. BACCIN ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Culture Method ◽  
High Rate ◽  
Escherichia Coli O157 ◽  
Phenol Red ◽  
Initial Screening ◽  
The South ◽  
E Coli ◽  
Subsequent Identification

The occurrence of Escherichia coli O157:H7 was evaluated in 886 samples of hamburgers produced by eight manufacturers in the south and southeast of Brazil from January to September of 1997. The pathogen was not detected in any of the samples analyzed, although 17 (1.9%) showed the presence of E. coli strains, which presented agglutination with O157 antiserum. These strains were not confirmed, since a subsequent identification indicated that they were fermentation positive for sorbitol, incapable of agglutination with the antisera of other commercial brands, and nonproducers of verocytotoxins. A high rate of false-presumptive-positive tests was observed with strains of enterobacteria when isolated by the culture method and when using a commercially purchased enzymatic immunoassay. This high rate of false presumptive positives was likely because the initial screening for sorbitol-negative strains was carried out using phenol red sorbitol 4-methylumbelliferyl-β-d-glucuronide agar, which was shown to be inadequate for this purpose.

Antimicrobial Effects of Zataria multiflora and Ocimum basilicum on Escherichia coli O157:H7 During Ripening of Traditional Lighvan Cheese

2020 ◽  
Vol 16 (3) ◽  
pp. 373-380
Author(s):  
Mohammad B. Zendeh ◽  
Vadood Razavilar ◽  
Hamid Mirzaei ◽  
Khosrow Mohammadi
Keyword(s):  
Escherichia Coli ◽  
Essential Oils ◽  
Dairy Products ◽  
Antimicrobial Agents ◽  
Escherichia Coli O157 ◽  
Zataria Multiflora ◽  
Antimicrobial Effects ◽  
E Coli ◽  
Common Causes ◽  
Lighvan Cheese

Background: Escherichia coli O157:H7 is one of the most common causes of contamination in Lighvan cheese processing. Using from natural antimicrobial essential oils is applied method to decrease the rate of microbial contamination of dairy products. The present investigation was done to study the antimicrobial effects of Z. multiflora and O. basilicum essential oils on survival of E. coli O157:H7 during ripening of traditional Lighvan cheese. Methods: Leaves of the Z. multiflora and O. basilicum plants were subjected to the Clevenger apparatus. Concentrations of 0, 100 and 200 ppm of the Z. multiflora and 0, 50 and 100 ppm of O. basilicum essential oils and also 103 and 105 cfu/ml numbers of E. coli O157:H7 were used. The numbers of the E. coli O157:H7 bacteria were analyzed during the days 0, 30, 60 and 90 of the ripening period. Results: Z. multiflora and O. basilicum essential oils had considerable antimicrobial effects against E. coli O157:H7. Using the essential oils caused decrease in the numbers of E. coli O157:H7 bacteria in 90th days of ripening (P <0.05). Using from Z. multiflora at concentration of 200 ppm can reduce the survival of E. coli O157:H7 in Lighvan cheese. Conclusion: Using Z. multiflora and O. basilicum essential oils as good antimicrobial agents can reduce the risk of foodborne bacteria and especially E. coli O157:H7 in food products.

An Aggregation-Induced Emission Material Labeling Antigen-Based Lateral Flow Immunoassay Strip for Rapid Detection of Escherichia coli O157:H7

2021 ◽  
pp. 247263032098193
Author(s):  
Cheng Liu ◽  
Shuiqin Fang ◽  
Yachen Tian ◽  
Youxue Wu ◽  
Meijiao Wu ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Rapid Detection ◽  
Foodborne Pathogen ◽  
Test Strip ◽  
Lateral Flow ◽  
Detection Sensitivity ◽  
Lateral Flow Immunoassay ◽  
Escherichia Coli O157 ◽  
Aggregation Induced Emission ◽  
E Coli

Escherichia coli O157:H7 ( E. coli O157:H7) is a dangerous foodborne pathogen, mainly found in beef, milk, fruits, and their products, causing harm to human health or even death. Therefore, the detection of E. coli O157:H7 in food is particularly important. In this paper, we report a lateral flow immunoassay strip (LFIS) based on aggregation-induced emission (AIE) material labeling antigen as a fluorescent probe for the rapid detection of E. coli O157:H7. The detection sensitivity of the strip is 105 CFU/mL, which is 10 times higher than that of the colloidal gold test strip. This method has good specificity and stability and can be used to detect about 250 CFU of E. coli O157:H7 successfully in 25 g or 25 mL of beef, jelly, and milk. AIE-LFIS might be valuable in monitoring food pathogens for rapid detection.

Bacteriophages reduce Escherichia coli O157:H7 levels in experimentally inoculated sheep

2009 ◽  
Vol 89 (2) ◽  
pp. 285-293 ◽  
Author(s):  
S J Bach ◽  
R P Johnson ◽  
K. Stanford ◽  
T A McAllister
Keyword(s):  
Escherichia Coli ◽  
Oral Administration ◽  
Coliform Bacteria ◽  
Escherichia Coli O157 ◽  
Fecal Shedding ◽  
Total Coliforms ◽  
E Coli ◽  
Oral Inoculation ◽  
Experimental Treatments ◽  
And Control

Bacteriophage biocontrol has potential as a means of mitigating the prevalence of Escherichia coli O157:H7 in ruminants. The efficacy of oral administration of bacteriophages for reducing fecal shedding of E. coli O157:H7 by sheep was evaluated using 20 Canadian Arcott rams (50.0 ± 3.0) housed in four rooms (n = 5) in a contained facility. The rams had ad libitum access to drinking water and a pelleted barley-based total mixed ration, delivered once daily. Experimental treatments consisted of administration of E. coli O157:H7 (O157), E. coli O157:H7+bacteriophages (O157+phage), bacteriophages (phage), and control (CON). Oral inoculation of the rams with 109 CFU of a mixture of four nalidixic acid-resistant strains of E. coli O157:H7 was performed on day 0. A mixture of 1010 PFU of bacteriophages P5, P8 and P11 was administered on days -2, -1, 0, 6 and 7. Fecal samples collected on 14 occasions over 21 d were analyzed for E. coli O157:H7, total E. coli, total coliforms and bacteriophages. Sheep in treatment O157+phage shed fewer (P < 0.05) E. coli O157:H7 than did sheep in treatment O157. Populations of total coliforms and total E. coli were similar (P < 0.05) among treatments, implying that bacteriophage lysis of non-target E. coli and coliform bacteria in the gastrointestinal tract did not occur. Bacteriophage numbers declined rapidly over 21 d, which likely reduced the chance of collision between bacteria and bacteriophage. Oral administration of bacteriophages reduced shedding of E. coli O157:H7 by sheep, but a delivery system that would protect bacteriophages during passage through the intestine may increase the effectiveness of this strategy as well as allow phage to be administered in the feed.Key words: Escherichia coli O157:H7, bacteriophage, sheep, environment, coliforms

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