Burgos Y.,Federal Institute for Risk Assessment BfR
BMC Microbiology | Year: 2010
Background. Alpha ()-hemolysin is a pore forming cytolysin and serves as a virulence factor in intestinal and extraintestinal pathogenic strains of E. coli. It was suggested that the genes encoding -hemolysin (hlyCABD) which can be found on the chromosome and plasmid, were acquired through horizontal gene transfer. Plasmid-encoded α-hly is associated with certain enterotoxigenic (ETEC), shigatoxigenic (STEC) and enteropathogenic E. coli (EPEC) strains. In uropathogenic E. coli (UPEC), the α-hly genes are located on chromosomal pathogenicity islands. Previous work suggested that plasmid and chromosomally encoded α-hly may have evolved independently. This was explored in our study. Results. We have investigated 11 α-hly plasmids from animal and human ETEC, STEC and EPEC strains. The size of α-hly plasmids ranges from 48-157 kb and eight plasmids are conjugative. The regulatory gene (hlyR) located upstream of the hlyCABD gene operon and an IS911 element located downstream of hlyD are conserved. Chromosomally-encoded α-hly operons lack the hlyR and IS911 elements. The DNA sequence of hlyC and hlyA divided the plasmid- and chromosomally-encoded -hemolysins into two clusters. The plasmid-encoded α-hly genes could be further divided into three groups based on the insertion of IS1 and IS2 in the regulatory region upstream of the α-hly operon. Transcription of the hlyA gene was higher than the housekeeping icdA gene in all strains (rq 4.8 to 143.2). Nucleotide sequence analysis of a chromosomally located α-hly determinant in Enterobacter cloacae strain indicates that it originates from an E. coli α-hly plasmid. Conclusion. Our data indicate that plasmids encoding α-hly in E. coli descended from a common ancestor independent of the plasmid size and the origin of the strains. Conjugative plasmids could contribute to the spread of the α-hly determinant to Enterobacter cloacae. The presence of IS-elements flanking the plasmid-encoded α-hly indicate that they might be mobile genetic elements. © 2010 Burgos and Beutin; licensee BioMed Central Ltd.
Woodford N.,Public Health England |
Woodford N.,Queen Mary, University of London |
Wareham D.W.,Queen Mary, University of London |
Guerra B.,Federal Institute for Risk Assessment BfR |
Teale C.,Animal Health and Veterinary Laboratories Agency
Journal of Antimicrobial Chemotherapy | Year: 2014
Acquired carbapenemases pose one of the most pressing public health threats relating to antibiotic resistance. In most countries, the number of carbapenemase-producing bacteria from human clinical specimens is rising, and the epidemiological status of these multiresistant bacteria is progressively worsening. Furthermore, there is a growing number of reports of carbapenemases found either in bacteria isolated from non-human sources or in Salmonella enterica subsp. enterica, a zoonotic species. However, carbapenemases are not yet systematically sought in bacteria from non-human sources, reports of them are largely observational, and there is limited investigation of carbapenemase-positive bacteria in animals and possible links with people who may have acted as potential sources. Active surveillance and monitoring for carbapenem-resistant bacteria in the food chain and other non-human sources is urgently needed, with an enhanced and rigorous follow-up of all positive results. The carbapenems are currently our last good defence against multiresistant Gram-negative bacteria. Our ability to limit the rise and spread of carbapenemase producers, which occur only at basal levels in many countries at present, should serve as a key performance indicator for the success or failure of the efforts that have been called for by international organizations and governments to reduce the impact of antibiotic resistance. © Crown copyright 2013.
Low-density macroarray targeting non-locus of enterocyte effacement effectors (nle genes) and major virulence factors of Shiga toxin-producing Escherichia coli (STEC): A new approach for molecular risk assessment of STEC isolates
Bugarel M.,AFSSA French Food Safety Agency |
Beutin L.,Federal Institute for Risk Assessment BfR |
Fach P.,AFSSA French Food Safety Agency
Applied and Environmental Microbiology | Year: 2010
Rapid and specific detection of Shiga toxin-producing Escherichia coli (STEC) strains with a high level of virulence for humans has become a priority for public health authorities. This study reports on the development of a low-density macroarray for simultaneously testing the genes stx1, stx2, eae, and ehxA and six different nie genes issued from genomic islands OI-122 (ent, nleB, and nleE) and OI-71 (nleF, nleH1-2, and nleA). Various strains of E. coli isolated from the environment, food, animals, and healthy children have been compared with clinical isolates of various seropathotypes. The eae gene was detected in all enteropathogenic E. coli (EPEC) strains as well as in enterohemorrhagic E. coli (EHEC) strains, except in EHEC 091:1121 and EHEC O113:H21. The gene ehxA was more prevalent in EHEC (90%) than in STEC (42.66%) strains, in which it was unequally distributed. The nie genes were detected only in some EPEC and EHEC strains but with various distributions, showing that nie genes are strain and/or serotype specific, probably reflecting adaptation of the strains to different hosts or environmental niches. One characteristic nie gene distribution in EHEC O157: [H7], 0111:[H8], O26:[H11], 0103:H25, 0118:[H16], O121:[H19], 05:H-, 055:H7, 0123:H11, 0172:H25, and O165:1125 was ent/espL2, nleB, nleE, nleF, nleH1-2, nleA. (Brackets indicate genotyping of tne flic or rfb genes.) A second nie pattern (ent/espL2, nleB, nleE, nleH1-2) was characteristic of EHEC O103:H2,0145:[H28], 045:H2, and O15:H2. The presence of eae, ent/espL2, nleB, nleE, and nleH1-2 genes is a clear signature of STEC strains with high virulence for humans. Copyright © 2010, American Society for Microbiology. All Rights Reserved.
Reemtsma T.,Federal Institute for Risk Assessment BfR |
Reemtsma T.,Helmholtz Center for Environmental Research |
Alder L.,Federal Institute for Risk Assessment BfR |
Banasiak U.,Federal Institute for Risk Assessment BfR
Journal of Chromatography A | Year: 2013
Based on the information available on 293 pesticides (herbicides, insecticides, fungicides, biocides, growth regulators) 210 pesticide metabolites were selected for inclusion into a multimethod for the analysis of ground and surface water. With the final method 150 pesticide metabolites can be analysed from groundwater and surface water by direct injection-liquid chromatography-electrospray ionization-tandem mass spectrometry with multiple-reaction monitoring. For most of these metabolites this is the first method published. For all metabolites linear calibration in drinking water was possible, with a lower limit of calibration of 0.1. μg/L achieved for 142 analytes and of 0.01. μg/L for 113 of the analytes. Matrix effects in ground and surface water compared to those in the drinking water were moderate (±20%) for 87% of the analytes. For critical sample/analyte combinations standard addition has to be used for correct quantification. This method allows for an extensive study of the occurrence of previously unknown or undetectable pesticide metabolites in groundwaters and surface waters. © 2012 Elsevier B.V.
Guerra B.,Federal Institute for Risk Assessment BfR |
Fischer J.,Federal Institute for Risk Assessment BfR |
Helmuth R.,Federal Institute for Risk Assessment BfR
Veterinary Microbiology | Year: 2014
Worldwide, the emergence and global spread of microorganisms with acquired carbapenemases is of great concern. The reservoirs for such organisms are increasing, not only in hospitals, but also in the community and environment. A new and important development is the presence of such organisms in livestock, companion animals and wildlife. During the last three years, carbapenemase-producing Escherichia coli, Salmonella spp. (VIM-1 producers) and Acinetobacter spp. (producing OXA-23 and NDM-1) in livestock animals (poultry, cattle and swine) and their environment have been reported. In addition, the isolation of NDM-1-producing E. coli, OXA-48 in E. coli and Klebsiella pneumoniae or OXA-23 in Acinetobacter spp. from companion animals (cats, dogs or horses) has also been observed. Other reports have described the presence of NDM-1-producing Salmonella isolated from wild birds, as well as OXA-23-like-producing Acinetobacter baumannii in ectoparasites. However, until now carbapenemase producers from foods have not been detected. For humans in contrast carbapenem-producing Salmonella isolates are increasingly reported. The real prevalence of carbapenemase-encoding genes in zoonotic bacteria or commensals from animals is unknown. Consequently, there is a need for intensified surveillance on the occurrence of carbapenemase-producing bacteria in the food chain and other animal sources in order to assist in the formulation of measures to prevent their potential spread. © 2014 Elsevier B.V.