scholarly journals Loss of O157 O Antigenicity of Verotoxin-ProducingEscherichia coli O157:H7 Surviving under Starvation Conditions

2000 ◽  
Vol 66 (12) ◽  
pp. 5540-5543 ◽  
Author(s):  
Yukiko Hara-Kudo ◽  
Michiko Miyahara ◽  
Susumu Kumagai
Keyword(s):  
Escherichia Coli ◽  
E Coli ◽  
Long Period ◽  
Agar Media ◽  
Starvation Conditions

ABSTRACT Verotoxin (VT)-producing Escherichia coli O157:H7 was culturable on agar media after being left in water for 21 months. However, there were a number of colonies which had lost O157 O antigenicity. These colonies produced VTs, which are pathogenic to humans. These observations suggest that the immunologic methods based on O157 O antigenicity are unable to detect and isolate VT-producingE. coli in foods and other environments if the organism has been under starvation conditions for a long period.

Antagonistic activity of Bacillus subtilis strains isolated from various sources

2018 ◽  
Vol 8 (2) ◽  
pp. 354-364
Author(s):  
A. N. Irkitova ◽  
A. V. Grebenshchikova ◽  
A. V. Matsyura
Keyword(s):  
Escherichia Coli ◽  
Bacillus Subtilis ◽  
Wild Strain ◽  
Fish Farming ◽  
Antagonistic Activity ◽  
Antagonistic Effect ◽  
E Coli ◽  
Long Period ◽  
Test Culture ◽  
Agar Media

<p>An important link in solving the problem of healthy food is the intensification of the livestock, poultry and fish farming, which is possible only in the adoption and rigorous implementation of the concept of rational feeding of animals. In the implementation of this concept required is the application of probiotic preparations. Currently, there is an increased interest in spore probiotics. In many ways, this can be explained by the fact that they use no vegetative forms of the bacilli and their spores. This property provides spore probiotics a number of advantages: they are not whimsical, easily could be selected, cultivated, and dried. Moreover, they are resistant to various factors and could remain viable during a long period. One of the most famous spore microorganisms, which are widely used in agriculture, is <em>Bacillus subtilis</em>. Among the requirements imposed to probiotic microorganisms is mandatory – antagonistic activity to pathogenic and conditional-pathogenic microflora. The article presents the results of the analysis of antagonistic activity of collection strains of <em>B. subtilis</em>, and strains isolated from commercial preparations. We studied the antagonistic activity on agar and liquid nutrient medias to trigger different antagonism mechanisms of <em>B. subtilis</em>. On agar media, we applied three diffusion methods: perpendicular bands, agar blocks, agar wells. We also applied the method of co-incubating the test culture (<em>Escherichia coli</em>) and the antagonist (or its supernatant) in the nutrient broth. Our results demonstrated that all our explored strains of <em>B. subtilis</em> have antimicrobial activity against a wild strain of <em>E. coli</em>, but to varying degrees. We identified strains of <em>B. subtilis</em> with the highest antagonistic effect that can be recommended for inclusion in microbial preparations for agriculture.</p><p><em><br /></em><em></em></p>

Relationship of growth conditions to desiccation tolerance of Salmonella enterica, Escherichia coli, and Listeria monocytogenes

2021 ◽  
Author(s):  
Rachel K Streufert ◽  
Susanne E Keller ◽  
Joelle K Salazar
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Desiccation Tolerance ◽  
Salmonella Enterica ◽  
Growth Conditions ◽  
Initial Population ◽  
Desiccation Resistance ◽  
E Coli ◽  
Solid Media ◽  
Agar Media

Growth on solid media as sessile cells is believed to increase the desiccation tolerance of Salmonella enterica . However, the reasons behind increased resistance have not been well explored. In addition, the same effect has not been examined for other foodborne pathogens such as pathogenic Escherichia coli or Listeria monocytogenes . The purpose of this research was two-fold: first, to determine the role of oxygenation during growth on the desiccation resistance of S. enterica , E. coli , and L. monocytogenes , and second, to determine the effect of sessile versus planktonic growth on the desiccation resistance of these pathogens. Three different serotypes each of Salmonella , E. coli , and L. monocytogenes were cultured in trypticase soy broth with 0.6% yeast extract (TSBYE), with (aerobic) shaking or on TSBYE with agar (TSAYE) under either aerobic or anaerobic conditions and harvested in stationary phase. After adding cell suspensions to cellulose filter disks, pathogen survival was determined by enumeration at 0 and after drying for 24 h. Results showed statistical differences in harvested initial populations prior to drying (0 h). For Salmonella , a correlation was found between high initial population and greater survival on desiccation (p = 0.05). In addition, statistical differences (p ≤ 0.05) between survival based on growth type were identified. However, differences found were not the same for the three pathogens, or between their serotypes. In general, Salmonella and E. coli desiccation resistance followed the pattern of aerobic agar media ≥ liquid media ≥ anaerobic agar media. For L. monocytogenes serotypes, resistance to desiccation was not statistically different based on mode of growth. These results indicate growth on solid media under aerobic conditions is not always necessary for optimal desiccation survival but may be beneficial when the desiccation resistance of the test serotype is unknown.

Comparison of Methods for Detection and Isolation of Cold- and Freeze-Stressed Escherichia coli O157:H7 in Raw Ground Beef†

2007 ◽  
Vol 70 (7) ◽  
pp. 1663-1669 ◽  
Author(s):  
PINA M. FRATAMICO ◽  
LORI K. BAGI
Keyword(s):  
Escherichia Coli ◽  
Ground Beef ◽  
Escherichia Coli O157 ◽  
Pcr Assay ◽  
Initial Inoculum ◽  
E Coli ◽  
Multiplex Pcr Assay ◽  
Treatment Type ◽  
Agar Media ◽  
Main Effects

A comparison was made of the relative efficiencies of three enrichment media, RapidChek Escherichia coli O157:H7 enrichment broth (REB), R&F broth (RFB), and modified E. coli broth containing novobiocin (mEC+n), and four selective plating media for detection of cold- and freeze-stressed E. coli O157:H7 in raw ground beef. Ground beef (25 g) was inoculated with E. coli O157:H7 at ≤0.5 and ≤2 CFU/g, and samples were then enriched immediately or were stored at 4°C for 72 h or at −20°C for 2 weeks and then enriched. After 8 or 20 h of enrichment, the cultures were plated onto R&F E. coli O157: H7 chromogenic plating medium, cefixime-tellurite sorbitol MacConkey agar, CHROMagar O157, and Rainbow agar O157 and tested using the RapidChek E. coli O157 lateral flow immunoassay and a multiplex PCR assay targeting the E. coli O157: H7 eae, stx1, and stx2 genes. Recovery of E. coli O157:H7 on the four agar media was 4.0 to 7.9 log CFU/ml with the REB enrichment, 1.4 to 7.4 log CFU/ml with RFB, 1.7 to 6.7 log CFU/ml with mEC+n incubated at 42°C, and 1.3 to 3.3 log CFU/ml from mEC+n incubated at 35°C. The percentages of positive ground beef samples containing nonstressed, cold-stressed, and freeze-stressed E. coli O157:H7 as obtained by plating, the immunoassay, and the PCR assay were 97, 88, and 97%, respectively, with REB, 92, 81, and 78%, respectively, with RFB, 97, 58, and 53%, respectively, with mEC+n incubated at 42°C, and 22, 31, and 25%, respectively, with mEC+n incubated at 35°C. Logistic regression analyses of the data indicated significant main effects of treatment, type of medium, enrichment time, inoculum concentration, and detection method. In particular, a positive result was 1.1 times more likely to occur after 20 h of enrichment than after 8 h, 25 times more likely with RFB and REB than with mEC+nat35°C, 3.7 times more likely with an initial inoculum of ≤2.0 CFU/g than with ≤0.5 CFU/g, 2.5 to 3 times more likely using freeze-stressed or nonstressed bacteria than with cold-stressed bacteria, and 2.5 times more likely by plating than by the immunoassay or the PCR assay. REB had better overall performance for enrichment of cold- and freeze-stressed E. coli O157:H7 present in ground beef than did the other media examined.

Ascorbic Acid Enhances Destruction of Escherichia coli O157:H7 during Home-Type Drying of Apple Slices

2001 ◽  
Vol 64 (8) ◽  
pp. 1244-1248 ◽  
Author(s):  
JENNIFER A. BURNHAM ◽  
PATRICIA A. KENDALL ◽  
JOHN N. SOFOS
Keyword(s):  
Escherichia Coli ◽  
Ascorbic Acid ◽  
Acid Solution ◽  
Escherichia Coli O157 ◽  
Bacterial Populations ◽  
Ascorbic Acid Solution ◽  
Initial Inoculum ◽  
E Coli ◽  
Apple Slices ◽  
Agar Media

Destruction of Escherichia coli O157:H7 was evaluated on inoculated apple slices dehydrated at two temperatures with and without application of predrying treatments. Half-ring slices (0.6 cm thick) of peeled and cored Gala apples were inoculated by immersion for 30 min in a four-strain composite inoculum of E. coli O157:H7. The inoculated slices (8.7 to 9.4 log CFU/g) either received no predrying treatment (control), were soaked for 15 min in a 3.4% ascorbic acid solution, or were steam blanched for 3 min at 88°C immediately prior to drying at 57.2 or 62.8°C for up to 6 h. Samples were plated on tryptic soy (TSA) and sorbitol MacConkey (SMAC) agar media for direct enumeration of surviving bacterial populations. Steam blanching changed initial inoculation levels by +0.3 to −0.7 log CFU/g, while immersion in the ascorbic acid solution reduced the inoculation levels by 1.4 to 1.6 log CFU/g. Dehydration of control samples for 6 h reduced mean bacterial populations by 2.9 log CFU/g (TSA or SMAC) at 57.2°C and by 3.3 (SMAC) and 3.5 (TSA) log CFU/g at 62.8°C. Mean decreases from initial inoculum levels for steam-blanched slices after 6 h of drying were 2.1 (SMAC) and 2.0 (TSA) log CFU/g at 57.2°C, and 3.6 (TSA or SMAC) log CFU/g at 62.8°C. In contrast, initial bacterial populations on ascorbic acid–pretreated apple slices declined by 5.0 (SMAC) and 5.1 (TSA) log CFU/g after 3 h of dehydration at 57.2°C, and by 7.3 (SMAC) and 6.9 (TSA) log CFU/g after 3 h at 62.8°C. Reductions on slices treated with ascorbic acid were in the range of 8.0 to 8.3 log CFU/g after 6 h of drying, irrespective of drying temperature or agar medium used. The results of immersing apple slices in a 3.4% ascorbic acid solution for 15 min prior to drying indicate that a predrying treatment enhances the destruction of E. coli O157:H7 on home-dried apple products.

scholarly journals Evaluation of stx1, stx2, hlyA, and eaeA Virulence Genes in Escherichia coli O157:H7 Isolated from Meat (Beef and Mutton) in Hamedan, Iran, During 2015-2016

2020 ◽  
Vol 8 (2) ◽  
pp. 55-59
Author(s):  
Fatemeh Binandeh ◽  
Mohammadreza Pajohi-Alamoti ◽  
Pezhman Mahmoodi ◽  
Azam Ahangari
Keyword(s):  
Escherichia Coli ◽  
Virulence Genes ◽  
Escherichia Coli O157 ◽  
Isolation And Identification ◽  
E Coli ◽  
Multiplex Pcr Assay ◽  
Agar Media ◽  
Cattle Meat ◽  
Meat Samples ◽  
Encoding Genes

Background and Objectives: Consuming raw or undercooked cattle meat is the most common transmission way of infection with Escherichia coli O157:H7. The present study aimed to identify virulence genes stx1, stx2, hlyA, and eaeA in E. coli isolated from meat samples (beef and mutton) in Hamedan during 2015 and 2016. Materials and Methods: For this purpose, the swabs were randomly taken from 160 meat samples including 80 beef samples and 80 mutton samples from butcher shops. Isolation and identification of E. coli cells were conducted by culturing the swab samples on MacConkey agar and Eosin methylene blue agar media. Then, the identity of the suspected E. coli O157:H7 colonies was investigated by a multiplex PCR assay and eventually, the isolates were evaluated for the presence of stx1, stx2, hlyA, eaeA virulence genes. Results: The results showed that out of 160 cultured samples on the selective media, 60 samples (37.5%) were contaminated with E. coli. O157:H7, O157, and H7 strains were identified using PCR, among which only E. coli O157:H7 possessed all four virulence factor encoding genes. Conclusion: The results of this study showed that beef could be a reservoir for E. coli O157:H7, and it may be involved in the transmission of this pathogen to humans.

scholarly journals Granulomatous colitis in two French bulldogs unresponsive to fluoroquinolone antimicrobials: a case report

2017 ◽  
Vol 62 (No. 5) ◽  
pp. 292-294
Author(s):  
R. Lucena ◽  
M. Novales ◽  
PJ Ginel
Keyword(s):  
Escherichia Coli ◽  
Clinical Remission ◽  
Colonic Mucosa ◽  
Antibiotic Sensitivity ◽  
Microbial Culture ◽  
Granulomatous Colitis ◽  
Sensitivity Testing ◽  
E Coli ◽  
Amoxicillin Clavulanate ◽  
Agar Media

Two cases of granulomatous colitis in two French bulldogs were found to be unresponsive to fluoroquinolones. The granulomatous colitis diagnosis was made on the basis of PAS-positive histiocytes in the lamina propria of the colonic mucosa in biopsy samples taken at colonoscopy. Remission of granulomatous colitis has been reported using fluoroquinolones leading to the idea that invasive Escherichia coli strains in the colonic mucosa are involved. Oral enrofloxacin (Baytril 150 mg, Bayer, Spain) at 10 mg/kg per day for eight weeks was prescribed to both dogs in this study. A first course of therapy resolved the problem in dog No. 1, which, however, was followed by relapse three months later without enrofloxacin response. No clinical remission was seen in dog No. 2 and 4.4 mg/kg marbofloxacin (Marbocyl P 20 mg, Vetoquinol, Spain) per day for 10 weeks was administered but without any response. From both dogs, biopsy samples from the colonic mucosa were taken during colonoscopy. Samples were homogenised for microbial culture in different agar media to identify invasive microbes. Escherichia coli were largely isolated and antibiotic sensitivity testing (MIC of E. coli to selected antimicrobials, CLSI 2013) was carried out. In both cases, E. coli was resistant to fluoroquinolones. In dog No. 1 E. coli was susceptible to amoxicillin-clavulanate, cefazolin, amikacin and gentamicin whereas in dog No. 2 it was susceptible to doxycycline and amoxicillin-clavulanate. Clinical remission was achieved in dog No. 1 with amoxicillin-clavulanate (Synulox 250 mg, Pfizer, Spain) therapy for eight weeks. No response was found in dog No. 2 with any of the antimicrobials alone or combined with metronidazole.

Interaction in vitro entre l'association ampicilline–colistine et Escherichia coli resistant à l'ampicilline

1983 ◽  
Vol 29 (12) ◽  
pp. 1650-1652
Author(s):  
M. Coste ◽  
L. Escoula
Keyword(s):  
Escherichia Coli ◽  
Proteus Mirabilis ◽  
Lower Layer ◽  
Superficial Layer ◽  
Beta Lactamases ◽  
E Coli ◽  
Agar Media ◽  
Potential Interactions

In this work, the authors studied in vitro potential interactions between bacteria and antibiotics. Colistin and ampicillin were introduced to ampicillin-resistant Escherichia coli and ampicillin activity was measured. Two layers of agar media were used. The lower layer contained E. coli and colistin. The superficial layer was sown with indicating bacteria (ampicillin-sensitive Proteus mirabilis). Ampicillin activity was evaluated on the upper layer with impregnated disks. By this technique, it was ascertained that ampicillin degradation increased with colistin concentration. In this case, colistin may favour interactions of intracellular beta-lactamases on ampicillin.

scholarly journals The Lysine Decarboxylase CadA Protects Escherichia coli Starved of Phosphate against Fermentation Acids

2007 ◽  
Vol 189 (6) ◽  
pp. 2249-2261 ◽  
Author(s):  
Patrice L. Moreau
Keyword(s):  
Escherichia Coli ◽  
Cell Death ◽  
Organic Acids ◽  
Acid Resistance ◽  
Ph Homeostasis ◽  
E Coli ◽  
Weak Organic Acids ◽  
Resistance System ◽  
Aerobic And Anaerobic ◽  
Starvation Conditions

ABSTRACT Conflicting results have been reported for the rate and extent of cell death during a prolonged stationary phase. It is shown here that the viability of wild-type cells (MG1655) could decrease ≥108-fold between days 1 and 14 and between days 1 and 6 of incubation under aerobic and anaerobic phosphate (Pi) starvation conditions, respectively, whereas the cell viability decreased moderately under ammonium and glucose starvation conditions. Several lines of evidence indicated that the loss of viability of Pi-starved cells resulted primarily from the catabolism of glucose into organic acids through pyruvate oxidase (PoxB) and pyruvate-formate lyase (PflB) under aerobic and anaerobic conditions, respectively. Weak organic acids that are excreted into the medium can reenter the cell and dissociate into protons and anions, thereby triggering cell death. However, Pi-starved cells were efficiently protected by the activity of the inducible GadABC glutamate-dependent acid resistance system. Glutamate decarboxylation consumes one proton, which contributes to the internal pH homeostasis, and removes one intracellular negative charge, which might compensate for the accumulated weak acid anions. Unexpectedly, the tolerance of Pi-starved cells to fermentation acids was markedly increased as a result of the activity of the inducible CadBA lysine-dependent acid resistance system that consumes one proton and produces the diamine cadaverine. CadA plays a key role in the defense of Salmonella at pH 3 but was thought to be ineffective in Escherichia coli since the protection of E. coli challenged at pH 2.5 by lysine is much weaker than the protection by glutamate. CadA activity was favored in Pi-starved cells probably because weak organic acids slowly reenter cells fermenting glucose. Since the environmental conditions that trigger the death of Pi-starved cells are strikingly similar to the conditions that are thought to prevail in the human colon (i.e., a combination of low levels of Pi and oxygen and high levels of carbohydrates, inducing the microbiota to excrete high levels of organic acids), it is tempting to speculate that E. coli can survive in the gut because of the activity of the GadABC and CadBA glutamate- and lysine-dependent acid resistance systems.

Method for the Detection of Priority Shiga Toxin–Producing Escherichia coli in Beef Trim

2013 ◽  
Vol 76 (10) ◽  
pp. 1689-1696 ◽  
Author(s):  
GEORGE HUSZCZYNSKI ◽  
MARTINE GAUTHIER ◽  
SAM MOHAJER ◽  
ALEXANDER GILL ◽  
BURTON BLAIS
Keyword(s):  
Escherichia Coli ◽  
Multiplex Pcr ◽  
Shiga Toxin ◽  
Limit Of Detection ◽  
Turnaround Time ◽  
Direct Plating ◽  
E Coli ◽  
Agar Media ◽  
Pcr Techniques ◽  
Positive Results

A method has been developed for the detection in beef trim of priority Shiga toxin–producing E. coli (STEC) strains, defined as E. coli possessing the virulence factors stx1 and/or stx2 and intimin (eae), with O serogroups O26, O45, O103, O111, O121, O145, or O157. The method is based on recovery of the target bacteria by overnight enrichment in a broth optimized for recovery of O157 and non-O157 STEC, followed by screening using multiplex PCR techniques targeting (i) stx1, stx2, and eae (STE PCR) and (ii) gene sequences associated with the seven priority O serogroups (Poly O PCR), and then direct plating of broth samples positive in both STE and Poly O PCR onto Rainbow agar. Colonies on agar media were screened batchwise for STEC by the STE PCR, and presumptive isolates were characterized using a multiplex PCR and cloth-based hybridization array system targeting key virulence and O serogroup-specific markers. Using one representative strain of each priority O serogroup individually inoculated in beef trim samples, the method exhibited a limit of detection approaching 1 to 2 viable STEC cells per 65 g. None of the uninoculated trim samples produced positive results with either of the screening PCR procedures or on analysis of colonies recovered on plating media. STEC-negative samples were readily identified by screening PCR within 24 h, with a turnaround time of fewer than 4 days for confirmation of positives. The inclusivity and exclusivity characteristics of the screening PCR techniques were verified using a total of 65 different priority STEC strains: 24 nonpriority STEC, 15 non-STEC bacteria, and only those strains bearing the targeted characteristics produced screening PCR-positive results.

Enumeration of Escherichia coli O157:H7 in Outbreak-Associated Beef Patties

2016 ◽  
Vol 79 (7) ◽  
pp. 1266-1268 ◽  
Author(s):  
ALEXANDER GILL ◽  
GEORGE HUSZCZYNSKI
Keyword(s):  
Escherichia Coli ◽  
Ground Beef ◽  
Most Probable Number ◽  
Escherichia Coli O157 ◽  
Cross Contamination ◽  
Probable Number ◽  
E Coli ◽  
Beef Patties ◽  
Selective Agar ◽  
Agar Media

ABSTRACT An outbreak of five cases of Escherichia coli O157 infection that occurred in Canada in 2012 was linked to frozen beef patties seasoned with garlic and peppercorn. Unopened retail packs of beef patties from the implicated production lot were recovered and analyzed to enumerate E. coli O157, other E. coli strains, and total coliforms. E. coli O157 was not recovered by direct enumeration on selective agar media. E. coli O157 in the samples was estimated at 3.1 most probable number per 140 g of beef patty, other E. coli was 11 CFU/g, and coliforms were 120 CFU/g. These results indicate that the presence of E. coli O157 in ground beef at levels below 0.1 CFU/g may cause outbreaks. However, the roles of temperature abuse, undercooking, and cross-contamination in amplifying the risk are unknown.

Sign in / Sign up

Export Citation Format

Share Document