Effect of incubation of Escherichia coli cells with halophyte extracts on their subsequent survival in seawater

1992 ◽  
Vol 38 (8) ◽  
pp. 838-842 ◽  
Author(s):  
G. N. Flatau ◽  
R. L. Clement ◽  
M. J. Gauthier ◽  
D. C. Puel
Keyword(s):  
Escherichia Coli ◽  
Key Words ◽  
Enteric Bacteria ◽  
Marine Organisms ◽  
Taxonomic Position ◽  
Organic Osmolytes ◽  
Aqueous Extracts ◽  
High Osmolarity ◽  
Escherichia Coli Cells ◽  
Key Words Escherichia Coli

Organic osmolytes are utilized by enteric bacteria for their survival when entering a high-osmolarity medium such as seawater. As these are commonly synthetized by marine organisms (fauna and flora), the purpose of this work was to investigate the effects of aqueous extracts from some marine phytoplanktonic species, alga, and phanerogam on the survival of Escherichia coli cells in seawater. Some of the tested halophyte extracts greatly enhanced survival, whereas others were inhibitory. The efficiency of the extracts could not be correlated to the taxonomic position of the halophyte or to the presence of Dragendorff-positive compounds known to be osmoprotective. Key words: Escherichia coli, survival, seawater, halophytes, osmoprotection.

The effect of fasting and diet on fecal shedding of Escherichia coli O157:H7 by cattle

2000 ◽  
Vol 80 (4) ◽  
pp. 741-744 ◽  
Author(s):  
S. J. Buchko ◽  
R. A. Holley ◽  
W. O. Olson ◽  
V. P. J. Gannon ◽  
D. M. Veira
Keyword(s):  
Escherichia Coli ◽  
Key Words ◽  
Escherichia Coli O157 ◽  
Fecal Shedding ◽  
E Coli ◽  
Feed Withdrawal ◽  
Alfalfa Silage ◽  
Key Words Escherichia Coli

Cattle naturally infected with Escherichia coli O157:H7 were used to assess the effects of diet and feed withdrawal on the fecal shedding of E. coli O157:H7. Animals were fed an 80% concentrate diet (80% barley and 20% alfalfa silage), fasted for 48 h, fed a 100% forage diet (alfalfa silage), fasted for 48 h, and subsequently re-fed 100% forage (alfalfa silage). There were no differences in the numbers of animals positive for the shedding of E. coli O157:H7 when fed an 80% barley diet or an all-forage diet (P > 0.05) or during the fasting periods following each diet (P > 0.05). Upon re-feeding an all-forage diet following a 48-h fast, animals positive for E. coli O157:H7 shedding increased (P < 0.05), with 42.5% of the animals shedding the pathogen after 5 d. Re-feeding 100% forage following fasting appeared to have increased the number of animals shedding E. coli O157:H7 in their feces, which may have been influenced by diet in addition to fasting. Key words: Escherichia coli O157:H7, fasting, diet, cattle, fecal shedding

Detection of Escherichia coli cytotoxins by enzyme-linked immunosorbent assays

1991 ◽  
Vol 37 (8) ◽  
pp. 650-653 ◽  
Author(s):  
Joan I. Speirs ◽  
Mumtaz Akhtar
Keyword(s):  
Escherichia Coli ◽  
Monoclonal Antibody ◽  
Monoclonal Antibodies ◽  
Vero Cell ◽  
Key Words ◽  
E Coli ◽  
Treated Cell ◽  
Cell Extracts ◽  
Immunosorbent Assays ◽  
Key Words Escherichia Coli

Sandwich enzyme-linked immunosorbent assays (ELISAs) were developed to detect Escherichia coli cytotoxins. Wells were coated with monoclonal antibodies from hybridomas 13C4 and (or) 11E10, and biotin conjugates of these antibodies were used for detecting verotoxin 1 and Shiga-like toxin II, respectively. Sensitivities were about 100 and 200 cytotoxic doses, respectively. Verotoxin 2 was detected by ELISA with monoclonal antibody 11E10, but at a sensitivity of only about 4000 cytotoxic doses. ELISA results of polymyxin-treated cell extracts from cultures of 67 E. coli strains were in agreement with Vero cell assay as regards the presence and type of toxin. Key words: Escherichia coli, cytotoxin, ELISA.

Assessment of two commercial agglutination kits for detecting Escherichia coli heat-labile enterotoxin

1991 ◽  
Vol 37 (11) ◽  
pp. 877-880 ◽  
Author(s):  
J. Speirs ◽  
S. Stavric ◽  
B. Buchanan
Keyword(s):  
Escherichia Coli ◽  
Cell Culture ◽  
Key Words ◽  
Agglutination Test ◽  
Enzyme Linked Immunosorbent Assay ◽  
Gm1 Ganglioside ◽  
Heat Labile ◽  
Toxigenic Strains ◽  
Good Substitute ◽  
Key Words Escherichia Coli

Two commercial agglutination kits, a reserved passive agglutination test (VET-RPLA) and a staphylococcal coagglutination test (Phadebact ETEC-LT Test), were compared with two cell culture assays (Y-1 and Vero) and GM1 ganglioside enzyme-linked immunosorbent assay (GM1-ELISA) for sensitivity in detecting Escherichia coli heat-labile enterotoxin (LT). Of 48 toxigenic strains, 23 were positive by all assays. One strain was negative only by the Phadebact test. Four strains, all LT-II producers, were positive by cell culture only. For LT-I detection, the Phadebact test was the least sensitive but was simple and rapid; VET-RPLA was simple, sensitive, and a good substitute for cell culture or GM1-ELISA. Key words: Escherichia coli, heat-labile enterotoxin, agglutination kits.

Antibiotic resistance indexing of Escherichia coli to identify sources of fecal contamination in water

1990 ◽  
Vol 36 (12) ◽  
pp. 891-894 ◽  
Author(s):  
Charles W. Kaspar ◽  
Janie L. Burgess ◽  
Ivor T. Knight ◽  
R. R. Colwell
Keyword(s):  
Escherichia Coli ◽  
Water Quality ◽  
Antibiotic Resistance ◽  
Key Words ◽  
Fecal Contamination ◽  
Antibiotic Resistant ◽  
E Coli ◽  
Rural Water ◽  
Key Words Escherichia Coli

A total of 202 Escherichia coli isolated from urban and rural water were tested with 11 antibiotics to assess the prevalence of antibiotic resistance from each source. Urban waters harbored higher percentages of resistant E. coli strains than rural waters. Antibiotic-resistant E. coli may offer an index of water quality related to source. Key words: Escherichia coli, antibiotic resistance, indicator.

Survie du Salmonella paratyphi B et du Pseudomonas aeruginosa dans l'eau de mer après incubation ou lavage en présence d'osmolytes

1992 ◽  
Vol 38 (7) ◽  
pp. 690-693 ◽  
Author(s):  
Amina Bakhrouf ◽  
Moncef Jeddi ◽  
Michel J. Gauthier
Keyword(s):  
Pseudomonas Aeruginosa ◽  
B Cells ◽  
Key Words ◽  
Marine Environment ◽  
Glycine Betaine ◽  
Osmotic Shock ◽  
Organic Osmolytes ◽  
High Osmolarity ◽  
Paratyphi B ◽  
Survival Potential

The authors have compared the survival in seawater of Salmonella paratyphi B and Pseudomonas aeruginosa cells grown at low or high osmolarity, in the presence of organic osmolytes: glycine betaine, choline, proline, and glutamate. The four substrates enhanced the survival potential of S. paratyphi B while only glycine betaine protected P. aeruginosa. In addition only S. paratyphi B cells were more resistant after a preliminary growth at high osmolarity. Both bacteria were sensitive to osmotic down-shock, sensitization of S. paratyphi B being inversely proportional (p ≥ 0.01) to the osmolarity of the medium used to wash cells. The transit in wastewater, at low osmolarity, can therefore modify the behavior of these pathogens in the marine environment. Key words: Salmonella paratyphi B, Pseudomonas aeruginosa, survival, seawater, osmotic shock.

scholarly journals Identification of a Conserved N-Terminal Sequence Involved in Transmembrane Signal Transduction in EnvZ

1999 ◽  
Vol 181 (17) ◽  
pp. 5534-5538 ◽  
Author(s):  
Jill Waukau ◽  
Steven Forst
Keyword(s):  
Escherichia Coli ◽  
Signal Transduction ◽  
Comparative Analysis ◽  
Amino Acid ◽  
Enteric Bacteria ◽  
Terminal Sequence ◽  
Signaling Mechanism ◽  
High Osmolarity ◽  
Conserved Sequence

ABSTRACT To determine whether N-terminal sequences are involved in the transmembrane signaling mechanism of EnvZ, the nucleotide sequences ofenvZ genes from several enteric bacteria were determined. Comparative analysis revealed that the amino acid sequence between Pro41 and Glu53 was highly conserved. To further analyze the role of the conserved sequence, envZ of Escherichia coli was subjected to random PCR mutagenesis and mutant alleles that produced a high-osmolarity phenotype, in which ompFwas repressed, were isolated. The mutations identified clustered within, as well as adjacent to, the Pro41-to-Glu53 sequence. These findings suggest that the conserved Pro41-to-Glu53 sequence is involved in the signal transduction mechanism of EnvZ.

Escherichia coli O157:H7-secreted cytotoxins are toxic to enterocytes and increase Escherichia coli O157:H7 colonization of jejunum and descending colon in cattle

2008 ◽  
Vol 88 (1) ◽  
pp. 41-50 ◽  
Author(s):  
Danica Baines ◽  
Luke Masson ◽  
Tim McAllister
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Key Words ◽  
Potential Role ◽  
Enterohemorrhagic Escherichia Coli ◽  
Target Cells ◽  
Escherichia Coli O157 ◽  
Descending Colon ◽  
Key Words Escherichia Coli

Enterohemorrhagic Escherichia coli (EHEC) O157:H7-secreted cytotoxins are toxic to target cells and enhance colonization of intestinal tissues in disease-susceptible animals. It is unclear what role, if any, EHEC O157:H7-secreted cytotoxins play in the colonization of intestinal tissues of healthy reservoir animals. We previously reported that EHEC O157:H7 colonization sites were associated with focal hemorrhages in the jejunum and descending colon of persistent shedding cattle, suggesting a potential role for cytotoxins in EHEC O157:H7 colonization. We have used a traditional EHEC O157:H7 IVOC adherence assay and a novel lawn assay to examine the role of EHEC O157:H7-secreted cytotoxins in EHEC O157:H7 strain colonization of the jejunum and descending colon of non-persistent and persistent shedding cattle. Four EHEC O157:H7 strains that were previously reported to differentially colonize cattle produced cytotoxins that were differentially active against epithelial cells from the jejunum and descending colon. There was a relationship between EHEC O157:H7-secreted cytotoxin activity and strain adherence for epithelial cells from the jejunum and descending colon of cattle. There was also a greater susceptibility of epithelial cells from the jejunum and descending colon to EHEC O157:H7-secreted cytotoxins of persistent shedding cattle compared with non-persistent shedding cattle. Addition of the most active secreted cytotoxins from EHEC O157:H7 R318N to the IVOC adherence assays significantly increased the adhere nce of the most (R318N) and least (H4420N) virulent EHEC O157:H7 strain to intestinal tissues. The current study supports a role for EHEC O157:H7-secreted cytotoxins in enhancing EHEC O157:H7 colonization of intestinal tissues of cattle. Key words: Escherichia coli O157:H7, cattle, intestine, cytotoxins, colonization

DETECTION OF GAMMA RADIATION EFFECT INDUCED BY COBELT-60 ON ESCHERICHIA COLI CELLS

2010 ◽  
Vol 13 (3) ◽  
pp. 129-133
Author(s):  
Ghusoon Ali Abdul Hasan Al-Sudany ◽  
◽  
Wasan Zuheir Majeed ◽  
Hind Jabbar Abdul Rhman Akram Al-Aubeidi ◽  
◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Gamma Radiation ◽  
Radiation Effect ◽  
Escherichia Coli Cells
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