Development and perspectives of rapid detection technology in food and environment

Food safety become a hot issue currently with globalization of food trade and food supply chains. Chemical pollution, microbial contamination and adulteration in food have attracted more attention worldwide. Contamination with antibiotics, estrogens and heavy metals in water environment and soil environment have also turn into an enormous threat to food safety. Traditional small-scale, long-term detection technologies have been unable to meet the current needs. In the monitoring process, rapid, convenient, accurate analysis and detection technologies have become the future development trend. We critically synthesizing the current knowledge of various rapid detection technology, and briefly touched upon the problem which still exist in research process. The review showed that the application of novel materials promotes the development of rapid detection technology, high-throughput and portability would be popular study directions in the future. Of course, the ultimate aim of the research is how to industrialization these technologies and apply to the market.

Metabolic Traits of Bovine Shiga Toxin-Producing Escherichia Coli (STEC) Strains with Different Colonization Properties

Cattle harbor Shiga toxin-producing Escherichia coli (STEC) in their intestinal tract, thereby providing these microorganisms with an ecological niche, but without this colonization leading to any clinical signs. In a preceding study, genotypic characterization of bovine STEC isolates unveiled that their ability to colonize cattle persistently (STEC^per) or only sporadically (STEC^spo) is more closely associated with the overall composition of the accessory rather than the core genome. However, the colonization pattern could not be unequivocally linked to the possession of classical virulence genes. This study aimed at assessing, therefore, if the presence of certain phenotypic traits in the strains determines their colonization pattern and if these can be traced back to distinctive genetic features. STEC^spo strains produced significantly more biofilm than STEC^per when incubated at lower temperatures. Key substrates, the metabolism of which showed a significant association with colonization type, were glyoxylic acid and L-rhamnose, which were utilized by STEC^spo, but not or only by some STEC^per. Genomic sequences of the respective glc and rha operons contained mutations and frameshifts in uptake and/or regulatory genes, particularly in STEC^per. These findings suggest that STEC^spo conserved features leveraging survival in the environment, whereas the acquisition of a persistent colonization phenotype in the cattle reservoir was accompanied by the loss of metabolic properties and genomic mutations in the underlying genetic pathways.

Microarray-based detection of resistance and virulence factors in commensal Escherichia coli from livestock and farmers in Egypt

The objective of our study was to provide a molecular analysis using DNA-microarray based assays of commensal E. coli populations from apparently healthy livestock and their attendants to assess the virulence potential as well as multidrug resistance (MDR) genotypes. We randomly collected 132 fecal samples from seemingly healthy smallholder´s food producing animals [buffalo (n = 32) and cattle (n = 50)] as well as from contacting farmers (n = 50). Bacterial isolation and identification were performed using standard protocols, while E. coli isolates were characterized using a DNA microarray system targeting 60 different virulence and 47 antibiotic resistance genes of clinical importance and allowing assignment to most common H and O types. From the fecal samples examined, 47 E. coli isolates were obtained. The array predicted serotypes for 14 out of the 47 E. coli isolates. Six E. coli isolates were identified as STEC since Shiga toxin genes were detected. In summary, 36 different virulence genes were identified; of which, hemL, lpfA and iss were most prevalent. Thirty-four E. coli isolates were found to carry at least one antimicrobial resistance gene. Of these, 20 did exhibit genes allowing strain classification as MDR. More than half of the isolates contained antimicrobial resistance genes associated with beta lactam resistance 27/47 (57.5 %). The 13 remaining isolates did not contain any resistance gene tested with the array. Our study demonstrated the presence of antimicrobial resistance genes and virulence genotypes among commensal E. coli of human and animal sources.