Escherichia coli selective detection

In the bacterial mutation test, the mutagenic potential of a pharmaceutical and its metabolites is evaluated by measuring and quantifying its ability to induce reverse mutations at selected loci of Salmonella typhimurium or Escherichia coli in the presence and absence of metabolic activation. This test system has been shown to detect a diverse group of chemical mutagens.3,4 The technical details of this test have been reported in the literature.5-7... 

Chakrabarty et al. (1989) selected several antihistamines for detection of antibacterial action [15]. According to them, promethazine was the most powerful and significant antimicrobial. The authors observed that in staphylococci, shigellae, and vibrios the MIC of promethazine varied between 100 and 200 xg/ml. Although one strain of Escherichia coli was sensitive at 50 xg/ml, the others were resistant. With respect to Pseudomonas aeruginosa, Proteus vulgaris, and Providencia spp., the MIC of promethazine was always >200 pg/ml (Table 7). 

Ames developed strains of bacteria that had carefully selected lethal mutations. In a test system the bacteria could survive only when its mutation had been corrected by experiencing another mutation caused by the tested material. This correction could be accomplished by causing a point mutation or frameshift mutations . Point mutations are base-pair substitutions, that is, a base change in DNA of at least one DNA base pair. In a reverse mutation test, this change in base pairs may occur at the site of the original mutation, or at a secondary site in the bacterial genome. Frameshift mutations are the addition or deletion of one or more base pairs in the DNA. Since amino acids are encoded by triplets of base pairs in sequence, any addition or deletion of 1 or 2 base pairs will dramatically alter the expressed protein from that point on. The Ames system employs strains of Salmonella typhimurium and Escherichia coli that require amino acids (histidine or tryptophan, respectively) to detect such reverse point and frameshift mutations. The reverse mutation allows the S. typhimurium or E. coli strains to restore the functional capability of the bacteria to be able to synthesize the specific amino acid on their own, independent of amino acid content in the medium. 

The enumeration of Enterobacteriaceae and Escherichia coli in water using SPC has been the subject of several studies. These microorganisms serve as indicators of faecal contamination as part of the monitoring of the quality of raw and partially purified waters. They are also used to demonstrate the compliance of a final product with legal standards. For the selective detection of viable Enterobacteriaceae, Baudart et al. (2002,2005) used a nucleic acid probe targetting the 16S rRNA. In order to enumerate the viable cells and to increase the fluorescence intensity, FISH was combined with a DVC procedure and TSA. Using this approach, as little as one fluorescent target cell could be demonstrated in the presence of lO -lO non-fluorescent other cells. 

De Vos MM, Nelis HJ (2006) An improved method for the selective detection of fungi in hospital water by solid phase cytometry. J Microbiol Meth 67 557-565 D Haese E, Nelis HJ (2000) Effect of antibiotics on viability staining of Escherichia coli in solid phase cytometry. J Appl Microbiol 89 778-784... 

Chandler DP, Brown J, CaU DR, Wunschel S, Grate JW, Holman DA, Olson L, Stottlemyre MS, Bruckner-Lea CJ (2001) Automated immunomagnetic separation and microarray detection of E. coli 0157 H7 from poultry carcass rinse. Int J Food Microbiol 70 143-154 Chapman PA, Siddons CA, Zadik PM, Jewes L (1991) An improved selective medium for the isolation of Escherichia coli 0157. J Med Microbiol 35 107-110 Chapman PA, Wright DJ, Siddons CA (1994) A comparison of immunomagnetic separation and direct culture for the isolation of verocytotoxin-producing Escherichia coli 0157 from bovine faeces. J Med Microbiol 40 424 27... 

Hiramatsu R, Matsumoto M, Miwa Y, Suzuki Y, Saito M, Miyazaki Y (2002) Characterization of Shiga toxin-producing Escherichia coli 026 strains and establishment of selective isolation media for these strains. J Clin Microbiol 40 922-925 Hu Y, Zhang Q, Meitzler JC (1999) Rapid and sensitive detection of Escherichia coli 0157 H7 in bovine faeces by a multiplex PCR. J Appl Microbiol 87 867-876 Huang L, Cooper MA (2006) Real-time label-free acoustic technology for rapid detection of Escherichia coli 0157 H7. Chn Chem 52 2148-2151 Ibekwe AM, Watt PM, Grieve CM, Sharma VK, Lyons SR (2002) Multiplex fluorogenic real-time PCR for detection and quantification of Escherichia coli 0157 H7 in dairy wastewater wetlands. Appl Environ Microbiol 68 4853 862... 

Thomas A, Smith HR, Willshaw GA, Rowe B (1991) Non-radioactively labelled polynucleotide and oligonucleotide DNA probes, for selectively detecting Escherichia coli strains producing Vero cytotoxins VTl, VT2 and VT2 variant. Mol Cell Probes 5 129-135 Thompson JS, Hodge DS, Borczyk AA (1990) Rapid biochemical test to identify verocytotoxin-positive strains of Escherichia coli serotype 0157. J Chn Microbiol 28 2165-2168 Tyagi S, Kramer FR (1996) Molecular beacons Probes that fluoresce upon hybridization. Nat Biotechnol 14 303-308... 

Usually, the detection of pathogenic bacteria, such as Escherichia coli is based on the selective growth of these bacteria in liquid media or on plates. This procedure may require several days [52]. More recently, methods such as pathogen recognition by fluorescently labeled antibodies, DNA probes, or bacteriophages have been developed and proved to be much faster [52],... 

Trinuclear clusters have been detected in over 20 proteins as well as a number of enzymes, among them aconitase, beef heart succinate-ubiquinone oxidoreductase (120), Escherichia coli nitrate reductase (121), E. coli fumarate reductase (122), and succinate dehydrogenase (123). Selected instances of the occurrence of [3Fe-4S] clusters are listed in Table II. Because of the paramagnetic ground states of both oxidation levels, these clusters can be uniquely identified by a number of spectroscopic techniques. Among these, Mossbauer spectroscopy in applied magnetic fields (124, 128, 132, 141-143) and low temperature MCD spectroscopy (127, 138, 144-146) are decisive. While there are small spectroscopic differences among certain [3Fe-4S] centers, the similarities dominate and support the essential structure 3 for all. In a number of the earlier papers on protein... 

---