Bacteriophages: A possible solution to combat enteropathogenic Escherichia coli infections in neonatal goats

Due to awareness and benefits of goat rearing in developing economies, goats' significance is increasing. Unfortunately, these ruminants are threatened via multiple bacterial pathogens such as enteropathogenic Escherichia coli (EPEC). In goat kids and lambs, EPEC causes gastrointestinal disease leading to substantial economic losses for farmers and may also pose a threat to public health via the spread of zoonotic diseases. Management of infection is primarily based on antibiotics, but the need for new therapeutic measures as an alternative to antibiotics is becoming vital because of the advent of antimicrobial resistance (AMR). The prevalence of EPEC was established using bfpA gene, uspA gene and Stx1 gene, followed by phylogenetic analysis using Stx1 gene. The lytic activity of the isolated putative coliphages was tested on multi-drug resistant strains of EPEC. It was observed that a PCR based approach is more effective and rapid as compared to phenotypic tests of Escherichia coli virulence. It was also established that the isolated bacteriophages exhibited potent antibacterial efficacy in vitro, with some of the isolates (16%) detected as T4 and T4-like phages based on gp23 gene. Hence, bacteriophages as therapeutic agents may be explored as an alternative to antibiotics in managing public, livestock and environmental health in this era of AMR.     

Cell-detaching Escherichia coli (CDEC) strains from children with diarrhea: Identification of a protein with toxigenic activity

Twenty-four strains of cell-detaching Escherichia coli (CDEC) isolated from stool specimens in different cities in Brazil were examined for virulence properties. Aerobactin production and multiple antibiotic resistance were observed in most of the isolates. In hybridization studies, the alphahly, pap, and cnf sequences, common properties of this category of E. coli, were found in a minority of isolates. Half of the CDEC isolates had enteroaggregative DNA sequences (pet, astA, aggA), six strains carried the shet1 gene, nine strains carried the daaC sequence, and one strain carried the stp gene. Thirteen strains induced fluid accumulation in the rabbit intestinal loop assay. Supernatant filtrate of one of those strains, which did not hybridize with any of the toxin probes tested, induced destructive lesions in the rabbit ileal loop and enterotoxic activity in the Ussing chamber. A 12-kDa protein purified by 60% ammonium sulfate precipitation of the supernatant filtrate demonstrated a toxigenic effect that was inhibited by the anti-12-kDa protein antiserum.     

Production of stable isotope enriched antimicrobial peptides in Escherichia coli: An application to the production of a 15N-enriched fragment of lactoferrin

A method is described for the production of recombinant isotopically enriched peptides in E. coli. Peptides are produced in high yield as fusion proteins with ketosteroid isomerase which form insoluble inclusion bodies. This insoluble form allows easy purification, stabilizes the peptide against degradation and prevents bactericidal activity of the peptide. Cyanogen bromide cleavage released peptide which was conjugated with alkylamines to form lipopeptide. An important advantage of this system is that it allows production of peptides that are toxic to bacteria, which we have demonstrated on a dodecapeptide based on residues 21–31 of human bactericidal protein lactoferrin.     

Lack of expression of bundle-forming pili in some clinical isolates of enteropathogenic Escherichia coli (EPEC) is due to a conserved large deletion in the bfp operon

Enteropathogenic Escherichia coli (EPEC) produces a plasmid-encoded type IV pilus, called the bundle-forming pilus (BFP), involved in the formation of the localized adhesion onto epithelial cells. In this study, we demonstrate that clinical isolates of serotypes O128ab:H2 and O119:H2 contain a ca. 13-kb deletion in the bfp operon, resulting in a lack of expression of these pili. An IS sequence with homology to the IS66 of Agrobacterium tumefaciens replaced the deleted bfp genes. These results suggest that the bfp operon was deleted through a transpositional event and that other adherence factors may mediate attachment of these bacteria to the host cells.     

Nonregenerative stimulation of hepatocyte proliferation in the rat: variable effects in relation to spontaneous liver growth; a possible link with metabolic induction

Three procedures were used to stimulate hepatocyte proliferation in the rat without reducing liver mass, resulting in a supplementary growth which differs from the regenerative growth observed after loss of liver mass by hepatectomy or toxic necrosis. They were: (a) the ingestion of cyproterone, a cytochrome P450 inducing drug (b) the injection of an irritant which provokes glycogenesis and synthesis of acute-phase proteins (c) the injection of albumin-bound bilirubin leading to elimination of glucuronated bilirubin in bile.
This ensuing supplementary growth was studied in the rat under several conditions of hepatic proliferation:

The highest level of stimulation occurred when the liver growth and the hepatocyte proliferation were already high. This suggests that these stimulants are not complete mitogenic stimuli and need cofactors which are present during the spontaneous growth or, alternatively, that the effect of stimulants is opposed by an inhibitory mechanism present in the adult rat.     

Nucleic acid hybridisation with a probe specific for 3 aminoglycoside acetyltransferase type IV: A survey of resistance to apramycin and gentamicin in animal strains of Escherichia coli

Abstract Resistance to apramycin due to production of a 3-aminoglycoside acetyltransferase type IV (AAC(3)IV) has recently been detected among Gram-negative bacteria isolated in France from bovine clinical samples. 24 apramycin-resistant Escherichia coli strains isolated over the country, and epidemiologically unrelated, were studied by colony hybridization using an intragenic probe specific for AAC(3)IV. The results obtained indicated that the structural gene for the acetyltransferase was present in all the isolates tested and in the corresponding apramycin-resistant transconjugants. This observation demonstrates that resistance to apramycin by acetylation of the antibiotic has spread very rapidly in bovine Gram-negative bacteria.     

Complementary biophysical tools to investigate lipid specificity in the interaction between bioactive molecules and the plasma membrane: A review

Plasma membranes are complex entities common to all living cells. The basic principle of their organization appears very simple, but they are actually of high complexity and represent very dynamic structures. The interactions between bioactive molecules and lipids are important for numerous processes, from drug bioavailability to viral fusion. The cell membrane is a carefully balanced environment and any change inflicted upon its structure by a bioactive molecule must be considered in conjunction with the overall effect that this may have on the function and integrity of the membrane. Conceptually, understanding the molecular mechanisms by which bioactive molecules interact with cell membranes is of fundamental importance.