scholarly journals Qualitative vs quantitative microbiology

2004 ◽  
Vol 25 (3) ◽  
pp. 20
Author(s):  
Narelle Fegan
Keyword(s):  
Escherichia Coli ◽  
Escherichia Coli O157 ◽  
Qualitative Information ◽  
E Coli ◽  
Food Borne Pathogens ◽  
Food Borne ◽  
Almost All

Escherichia coli O157 and Salmonella are food-borne pathogens of importance to the Australian beef and dairy industries. Cattle are a significant reservoir for both of these pathogens and beef has been the source of food-borne outbreaks of both E. coli O157 and Salmonella. The presence of pathogens in cattle can lead to contamination of carcasses during slaughter and products produced from these contaminated carcasses pose a risk to consumers. However, the magnitude of the risk is not clear. Until recently, almost all of the information published on E. coli O157 and Salmonella in cattle has consisted of only qualitative information i.e. the prevalence of these organisms in cattle. In order to estimate risk, it is important to understand not only how many cattle shed E. coli O157 and Salmonella but also the number of pathogens shed.

Note: Behaviour of Escherichia Coli O157: H7, Listeria Monocytogenes 4b and Yersinia Enterocolitica O3 in Pasteurised and Non-pasteurised Kefir Fermented for One or Two Days

2003 ◽  
Vol 9 (5) ◽  
pp. 365-369 ◽  
Author(s):  
M. Gulmez ◽  
A. Guven
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Yersinia Enterocolitica ◽  
Cold Storage ◽  
Susceptible Strain ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Food Borne Pathogens ◽  
Food Borne

The behaviour of three selected food-borne pathogens, E. coli O157: H7, L. monocytogenes 4b and Y. enterocolitica O3, added to fermented and pasteurised kefir was monitored. Populations of the three strains increased in one-day-fermented kefir, but only E. coli O157: H7 increased in two-days-fermented kefir during fermentation. None of the strains grew during cold storage (4 1 C), although E. coli O157: H7 and L. monocytogenes 4b survived up to 21 days in all samples cold. Y. enterocolitica O3 was the most susceptible strain that was present in one-day-fermented kefir for at least 14 days. Twodaysfermented kefir samples were more acidic thanthose of one-day-fermented samples, but none of the samples was safe enough to create an environment to eliminate the pathogens.

Introduction to the Food Safety Concerns of Verotoxin-Producing Escherichia coli

2003 ◽  
Vol 228 (4) ◽  
pp. 331-332 ◽  
Author(s):  
Hussein S. Hussein ◽  
Stanley T. Omaye
Keyword(s):  
Escherichia Coli ◽  
Food Safety ◽  
Safety Concern ◽  
Critical Evaluation ◽  
The United States ◽  
Global Perspective ◽  
E Coli ◽  
The Past ◽  
Food Borne Pathogens ◽  
Food Borne

Verotoxin-producing Escherichia coli (VTEC) have emerged in the past two decades as food-borne pathogens that can cause major outbreaks of human illnesses worldwide. The number of outbreaks has increased in recent years due to changes in food production and processing systems, eating habits, microbial adaptation, and methods of VTEC transmission. The human illnesses range from mild diarrhea to hemolytic uremic syndrome (HUS) that can lead to death. The VTEC outbreaks have been attributed to O157:H7 and non-O157:H7 serotypes of E. coli. These E. coli serotypes include motile (e.g., O26:H11 and O104:H21) and nonmotile (e.g., O111:H–,0145:H–, and O157:H–) strains. In the United States, E. coli O157:H7 has been the major cause of VTEC outbreaks. Worldwide, however, non-O157:H7 VTEC (e.g., members of the 026, O103, O111, O118, O145, and O166 serogroups) have caused approximately 30% of the HUS cases in the past decade. Because large numbers of the VTEC outbreaks have been attributed to consumption of ruminant products (e.g., ground beef), cattle and sheep are considered reservoirs of these food-borne pathogens. Because of the food safety concern of VTEC, a global perspective on this problem is addressed (Exp Biol Med Vol. 228, No. 4). The first objective was to evaluate the known non-O157:H7 VTEC strains and the limitations associated with their detection and characterization. The second objective was to identify the VTEC serotypes associated with outbreaks of human illnesses and to provide critical evaluation of their virulence. The third objective was to determine the rumen effect on survival of E. coli O157:H7 as a VTEC model. The fourth objective was to explore the role of intimins in promoting attaching and effacing lesions in humans. Finally, the ability of VTEC to cause persistent infections in cattle was evaluated.

scholarly journals Escherichia coli and Salmonella spp. in meat in Jeddah, Saudi Arabia

2013 ◽  
Vol 7 (11) ◽  
pp. 812-818 ◽  
Author(s):  
Archana Iyer ◽  
Taha Kumosani ◽  
Soonham Yaghmoor ◽  
Elie Barbour ◽  
Esam Azhar ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Gastrointestinal Diseases ◽  
Developed Countries ◽  
Salmonella Spp ◽  
E Coli ◽  
Food Borne Pathogens ◽  
Food Borne ◽  
Microbiological Methods ◽  
Meat Samples ◽  
Butcher Shops

Introduction: Food-borne pathogens are the leading cause of illness and death in developing countries, killing approximately 1.8 million people annually. In developed countries, food-borne pathogens are responsible for millions of cases of infectious gastrointestinal diseases each year, costing billions of dollars. The objective of this study was to screen for two major food-borne pathogens, Escherichia coli and Salmonella spp., from meat samples obtained from different strata of the consumer market in Jeddah. Methodology: A total of 60 meat samples, 20 each from large hypermarkets, groceries and small butcher shops were used in the study. Samples were transported to the laboratory in a cooler. They were macerated in peptone water and then seeded on selective media appropriate for each organism. Colonies were identified using conventional microbiological methods and suspected colonies were confirmed as E. coli and Salmonella spp. by polymerase chain reaction (PCR) using specific primers. Results: The results indicated a high degree of contamination in samples from butcher shops as compared to those from groceries or hypermarkets (high scale supermarkets). Both pathogens E. coli and Salmonella spp. were found in higher rates in the samples from butcher shops. In small butcher shops, E. coli was found at an incidence of 65%, and Salmonella at 45%. Conclusion: The results indicate an urgent need for applying proper food hygienic practices in food outlets, especially in small ones, to reduce the incidence of food-borne diseases. Vigilance by the right agencies must be implemented in order to prevent future food-borne outbreaks.

scholarly journals Modelling Growth and Decline in a Two-Species Model System: Pathogenic Escherichia coli O157:H7 and Psychrotrophic Spoilage Bacteria in Milk

Foods ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 331 ◽  
Author(s):  
Emiliano J. Quinto ◽  
Juan M. Marín ◽  
Irma Caro ◽  
Javier Mateo ◽  
Donald W. Schaffner
Keyword(s):  
Escherichia Coli ◽  
Foodborne Pathogens ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Food Borne ◽  
Pathogenic Escherichia Coli ◽  
Spoilage Bacteria ◽  
Processing And Storage ◽  
And Storage ◽  
Natural Microbiota

Shiga toxin-producing Escherichia coli O157:H7 is a food-borne pathogen and the major cause of hemorrhagic colitis. Pseudomonas is the genus most frequent psychrotrophic spoilage microorganisms present in milk. Two-species bacterial systems with E. coli O157:H7, non-pathogenic E. coli, and P. fluorescens in skimmed milk at 7, 13, 19, or 25 °C were studied. Bacterial interactions were modelled after applying a Bayesian approach. No direct correlation between P. fluorescens’s growth rate and its effect on the maximum population densities of E. coli species was found. The results show the complexity of the interactions between two species in a food model. The use of natural microbiota members to control foodborne pathogens could be useful to improve food safety during the processing and storage of refrigerated foods.

scholarly journals The role of L-arabinose metabolism for Escherichia coli O157:H7 in edible plants

2021 ◽  
Author(s):  
Louise Emma Crozier ◽  
Jacqueline Marshall ◽  
Ashleigh Holmes ◽  
Kathryn Wright ◽  
Yannick Rossez ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Escherichia Coli O157 ◽  
In Planta ◽  
Cell Wall Degrading Enzymes ◽  
Cell Wall Polysaccharides ◽  
E Coli ◽  
Degrading Enzymes ◽  
Food Borne

Arabinose is a major plant aldopentose in the form of arabinans complexed in cell wall polysaccharides or glycoproteins (AGP), but comparatively rare as a monosaccharide. L-arabinose is an important bacterial metabolite, accessed by pectolytic microorganisms such as Pectobacterium atrosepticum via pectin and hemicellulose degrading enzymes. However, not all plant-associated microbes encode cell wall degrading enzymes, yet can metabolise L-arabinose, raising questions about their use of and access to the glycan in plants. Therefore, we examined L-arabinose metabolism in the food-borne pathogen Escherichia coli O157:H7 (isolate Sakai) during its colonisation of plants. L-arabinose metabolism (araBA) and transport (araF) genes were activated at 18 C in vitro by L-arabinose and expressed over prolonged periods in planta. Although deletion of araBAD did not impact the colonisation ability of E. coli O157:H7 (Sakai) on plants, araA was induced on exposure to spinach cell wall polysaccharides. Furthermore, debranched and arabinan oligosaccharides induced ara metabolism gene expression in vitro, and stimulated modest proliferation, while immobilised pectin did not. Thus, E. coli O157:H7 (Sakai) can utilise pectin/AGP-derived L-arabinose as a metabolite, but differs fundamentally in ara gene organisation, transport and regulation from the related pectinolytic species P. atrosepticum, reflective of distinct plant-associated lifestyles.

scholarly journals Identification and Characterization of Spontaneous Deletions within the Sp11-Sp12 Prophage Region of Escherichia coli O157:H7 Sakai

2013 ◽  
Vol 79 (6) ◽  
pp. 1934-1941 ◽  
Author(s):  
Chun Chen ◽  
Carrie R. Lewis ◽  
Kakolie Goswami ◽  
Elisabeth L. Roberts ◽  
Chitrita DebRoy ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Type Iii Secretion ◽  
Genomic Region ◽  
Escherichia Coli O157 ◽  
Content Type ◽  
E Coli ◽  
Food Borne ◽  
Genes Encoding ◽  
Identification And Characterization

ABSTRACTProphages make up 12% of the enterohemorrhagicEscherichia coligenome and play prominent roles in the evolution and virulence of this food-borne pathogen. Acquisition and loss of and rearrangements within prophage regions are the primary causes of differences in pulsed-field gel electrophoresis (PFGE) patterns among strains ofE. coliO157:H7. Sp11 and Sp12 are two tandemly integrated and putatively defective prophages carried byE. coliO157:H7 strain Sakai. In this study, we identified 3 classes of deletions that occur within the Sp11-Sp12 region, at a frequency of ca. 7.74 × 10−4. One deletion resulted in a precise excision of Sp11, and the other two spanned the junction of Sp11 and Sp12. All deletions resulted in shifts in the XbaI fragment pattern observed by PFGE. We sequenced the inducible prophage pool of Sakai but did not identify any mature phage particles corresponding to either Sp11 or Sp12. Deletions containingpchBandpsrC, which are Sp11-carried genes encoding proteins known or suspected to regulate type III secretion, did not affect the secretion levels of the EspA or EspB effector. Alignment of the Sp11-Sp12 DNA sequence with its corresponding regions in otherE. coliO157:H7 and O55:H7 strains suggested that homologous recombination rather than integrase-mediated excision is the mechanism behind these deletions. Therefore, this study provides a mechanism behind the previously observed genetic instability of this genomic region ofE. coliO157:H7.

Methods Used for Detection and Recovery of Escherichia coli O157:H7 Associated with a Food-Borne Disease Outbreak†

1995 ◽  
Vol 58 (6) ◽  
pp. 597-603 ◽  
Author(s):  
J. L.JOHNSON ◽  
B. E. ROSE ◽  
A. K. SHARAR ◽  
G. M. RANSOM ◽  
C. P. LATTUADA ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Environmental Samples ◽  
Disease Outbreak ◽  
Screening Methods ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Food Borne ◽  
Quantitative Analyses ◽  
Inspection Service ◽  
Positive Results

The current Food Safety and Inspection Service method for detection and recovery of Escherichia coli O157:H7, (including modified EC broth with novobiocin (mEC+n) and a direct blot ELISA). was used to analyze beef and environmental samples during an investigation of a food-borne disease outbreak attributed to consumption of undercooked hamburger patties. Double-modified trypticase soy broth (dmTSB) and a commercially available dipstick immunoassay were also used to improve detection/recovery of E. coli O157:H7. A total of 1,115 beef and environmental samples was screened with the direct blot ELISA and the dipstick immunoassay; 178 presumptive-positive samples (by either or both of the screening methods) were subjected to recovery/isolation procedures. Toxigenic E. coli O157:H7 was recovered from 45 samples: 40 hamburger-patty samples produced on the epidemiologically identified date, 3 hamburger-patty samples produced on another date, and 2 beef briskets. The organism was not recovered from environmental samples. Limited quantitative analyses indicated that contaminated hamburger patties contained fewer than 4.3 CFU of E. coli O157:H7 per g. Atypical, toxigenic ornithine decarboxylase–negative E. coli O157:H7 and nontoxigenic sorbitol-positive E. coli O157:H29 were also recovered. Both enrichment broths gave strong positive reactions with the two immunoassay screening methods, but E. coli O157:H7 was recovered more often from mEC+n broth than from dmTSB. Both screening methods gave positive results for 44 of the 45 beef samples found to contain E. coli O157:H7. False-positive results were frequently observed with both screening methods.

Destruction of Escherichia coli O157:H7 and Salmonella typhimurium in Lebanon Bologna by Interaction of Fermentaron pH, Heating Temperature, and Time

1998 ◽  
Vol 61 (2) ◽  
pp. 152-157 ◽  
Author(s):  
KAMESWAR R. ELLAJOSYULA ◽  
STEPHANIE DOORES ◽  
EDWARD W. MILLS ◽  
RICHARD A. WILSON ◽  
RAMASWAMY C. ANANTHESWARAN ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Salmonella Typhimurium ◽  
Heating Temperature ◽  
Enterohemorrhagic Escherichia Coli ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Food Borne ◽  
Recent Outbreak ◽  
Food Borne Illness ◽  
Effects Of Ph

Fermented meats have caused food-borne illness due to enterohemorrhagic Escherichia coli. Consumption of Lebanon bologna was epidemiologically associated with a recent outbreak of salmonellosis. The present study was conducted to determine the effects of pH (after the fermentation step), final heating temperature, and time on destruction of E. coli O157:H7 and Salmonella typhimurium in Lebanon bologna. Raw Lebanon bologna mix was inoculated with either of the pathogens (ca. 108 CFU/g) and fermented for 12 h at 80°F (26.7°C) and then at 100°F (37.8°C) until the pH reached either 5.2 or 4.7. The mix was then heated to 110,115, or 120°F (43.3, 46.1, or 48.9°C). The bologna was sampled at various times, decimally diluted, and plated on either McConkey sorbitol agar or XLD agar to enumerate E. coli O157:H7 and S. typhimurium, respectively. Fermentation alone reduced populations of both pathogens by <2 log units and heating alone reduced populations of E. coli O157:H7 by < 3 log units. A combination of fermenting to either pH 5.2 or 4.7, followed by heating at 110°F (43.3°C) for 20 h, 115°F (46.1°C) for 10 h, or 120°F (48.9°C) for 3 h reduced populations of both pathogens by >7 log units. Overall, S. typhimurium cells were either equally or significantly less resistant (P < 0.01) than cells of E. coli O157:H7. Significant interactions (P < 0.01) among the three factors for the destruction of E. coli O157:H7 were observed. A process-specific regression equation was developed to predict the destruction of E. coli O157:H7 in Lebanon bologna.

scholarly journals Comparison of the BAX for Screening/E. coli O157:H7 Method with Conventional Methods for Detection of Extremely Low Levels of Escherichia coli O157:H7 in Ground Beef

1998 ◽  
Vol 64 (11) ◽  
pp. 4390-4395 ◽  
Author(s):  
Jennifer L. Johnson ◽  
Cheryl L. Brooke ◽  
Scott J. Fritschel
Keyword(s):  
Escherichia Coli ◽  
Ground Beef ◽  
Escherichia Coli O157 ◽  
Important Food ◽  
E Coli ◽  
Cultural Methods ◽  
Food Borne ◽  
Highly Sensitive ◽  
Low Levels ◽  
Very High

ABSTRACT Escherichia coli O157:H7 is an important food-borne pathogen. Often E. coli O157:H7 is difficult to detect, because it is present sporadically at very low levels together with very high levels of competitor organisms which can be difficult to distinguish phenotypically. Cultural methods are time-consuming and give variable results in the detection of E. coli O157:H7. This study examined the performance of BAX for Screening/E. coli O157:H7, a new rapid method for the detection of E. coli O157:H7, against traditional and improved cultural methods and an immunodiffusion assay. All cultural methods demonstrated inadequacy in detecting the presence of E. coliO157:H7 in inoculated samples. The limitations of these cultural methods further complicate evaluation of screening methodologies. The BAX for Screening/E. coli O157:H7 assay outperformed the other methods, with a detection rate of 96.5%, compared to 39% for the best cultural method and 71.5% for the immunodiffusion method. The BAX for Screening/E. coli O157:H7 assay proved to be a rapid, highly sensitive test for the detection of low levels ofE. coli O157:H7 in ground beef.

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