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Shen J.,China Agricultural University | Wang Y.,China Agricultural University | Schwarz S.,Institute of Farm Animal Genetics
Journal of Antimicrobial Chemotherapy | Year: 2013

The emergence of the multiresistance gene cfr in staphylococci is of global concern. In addition to conferring resistance to phenicols, lincosamides, pleuromutilins, streptogramin A antibiotics and selected 16-membered macrolides, the cfr gene also confers resistance to the oxazolidinone linezolid. Linezolid is a last-resort antimicrobial agent for the treatment of serious infections in humans caused by resistant Gram-positive bacteria. The cfr gene is often located on plasmids and several cfr-carrying plasmids have been described, which differ in their structure, their size and the presence of additional resistance genes. These plasmids are important vehicles that promote the spread of the cfr gene not only among bacteria of the same species, but also among those of different species and genera. Moreover, the cfr gene has been identified in close proximity to different insertion sequences, which most probably also play an important role in its dissemination. This review summarizes current knowledge on the genetic environment of the multiresistance gene cfr with particular reference to mobile genetic elements and co-located resistance genes that may support its emergence. © The Author 2013. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.


Roberts M.C.,University of Washington | Schwarz S.,Institute of Farm Animal Genetics
Journal of Environmental Quality | Year: 2016

Recent reports have speculated on the future impact that antibiotic-resistant bacteria will have on food production, human health, and global economics. This review examines microbial resistance to tetracyclines and phenicols, antibiotics that are widely used in global food production. The mechanisms of resistance, mode of spread between agriculturally and humanimpacted environments and ecosystems, distribution among bacteria, and the genes most likely to be associated with agricultural and environmental settings are included. Forty-six different tetracycline resistance (tet) genes have been identified in 126 genera, with tet(M) having the broadest taxonomic distribution among all bacteria and tet(B) having the broadest coverage among the Gram-negative genera. Phenicol resistance genes are organized into 37 groups and have been identified in 70 bacterial genera. The review provides the latest information on tetracycline and phenicol resistance genes, including their association with mobile genetic elements in bacteria of environmental, medical, and veterinary relevance. Knowing what specific antibiotic-resistance genes (ARGs) are found in specific bacterial species and/or genera is critical when using a selective suite of ARGs for detection or surveillance studies. As detection methods move to molecular techniques, our knowledge about which type of bacteria carry which resistance gene(s) will become more important to ensure that the whole spectrum of bacteria are included in future surveillance studies. This review provides information needed to integrate the biology, taxonomy, and ecology of tetracycline- and phenicol-resistant bacteria and their resistance genes so that informative surveillance strategies can be developed and the correct genes selected. © American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.


Hall R.M.,University of Sydney | Schwarz S.,Institute of Farm Animal Genetics
Journal of Antimicrobial Chemotherapy | Year: 2016

In the genomic era, studying the epidemiology of individual antibiotic resistance genes and resistance gene discovery are open to all. However, the identification and naming of resistance genes is not currently understandable by all owing to a plethora of competing nomenclature systems, many of which do not comply with the basic rules of bacterial gene nomenclature. Change is needed urgently. Here, we make a case for the resistance research community to begin this process by agreeing on an answer to the question of when a new gene number should be assigned. This cut-off is of necessity arbitrary and we suggest a threshold value of ≥2% difference in the sequences of the DNA, predicted protein or both as a realistic boundary for assigning a new gene number. This proposal can be a starting point for agreement or debate followed by renumbering of the affected gene families. © The Author 2015. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.


Urrego R.,University of Antioquia | Urrego R.,CES University | Rodriguez-Osorio N.,University of Antioquia | Niemann H.,Institute of Farm Animal Genetics
Epigenetics | Year: 2014

The use of Assisted Reproductive Technologies (ARTs) in modern cattle breeding is an important tool for improving the production of dairy and beef cattle. A frequently employed ART in the cattle industry is in vitro production of embryos. However, bovine in vitro produced embryos differ greatly from their in vivo produced counterparts in many facets, including developmental competence. The lower developmental capacity of these embryos could be due to the stress to which the gametes and/or embryos are exposed during in vitro embryo production, specifically ovarian hormonal stimulation, follicular aspiration, oocyte in vitro maturation in hormone supplemented medium, sperm handling, gamete cryopreservation, and culture of embryos. The negative effects of some ARTs on embryo development could, at least partially, be explained by disruption of the physiological epigenetic profile of the gametes and/or embryos. Here, we review the current literature with regard to the putative link between ARTs used in bovine reproduction and epigenetic disorders and changes in the expression profile of embryonic genes. Information on the relationship between reproductive biotechnologies and epigenetic disorders and aberrant gene expression in bovine embryos is limited and novel approaches are needed to explore ways in which ARTs can be improved to avoid epigenetic disorders. © 2014 Landes Bioscience.


Nowak-Imialek M.,Institute of Farm Animal Genetics | Niemann H.,Institute of Farm Animal Genetics
Reproduction, Fertility and Development | Year: 2013

Pluripotent cells, such as embryonic stem (ES) cells, embryonic germ cells and embryonic carcinoma cells are a unique type of cell because they remain undifferentiated indefinitely in in vitro culture, show self-renewal and possess the ability to differentiate into derivatives of the three germ layers. These capabilities make them a unique in vitro model for studying development, differentiation and for targeted modification of the genome. True pluripotent ESCs have only been described in the laboratory mouse and rat. However, rodent physiology and anatomy differ substantially from that of humans, detracting from the value of the rodent model for studies of human diseases and the development of cellular therapies in regenerative medicine. Recently, progress in the isolation of pluripotent cells in farm animals has been made and new technologies for reprogramming of somatic cells into a pluripotent state have been developed. Prior to clinical application of therapeutic cells differentiated from pluripotent stem cells in human patients, their survival and the absence of tumourigenic potential must be assessed in suitable preclinical large animal models. The establishment of pluripotent cell lines in farm animals may provide new opportunities for the production of transgenic animals, would facilitate development and validation of large animal models for evaluating ESC-based therapies and would thus contribute to the improvement of human and animal health. This review summarises the recent progress in the derivation of pluripotent and reprogrammed cells from farm animals. We refer to our recent review on this area, to which this article is complementary. © 2013 IETS.


Fessler A.T.,Institute of Farm Animal Genetics | Kadlec K.,Institute of Farm Animal Genetics | Schwarz S.,Institute of Farm Animal Genetics
Antimicrobial Agents and Chemotherapy | Year: 2011

A novel apramycin resistance gene, apmA, was detected on the ca.-40-kb resistance plasmid pAFS11 from bovine methicillin-resistant Staphylococcus aureus (MRSA) of sequence type 398 (ST398). The apmA gene coded for a protein of 274 amino acids that was related only distantly to acetyltransferases involved in chloramphenicol or streptogramin A resistance. NsiI deletion of apmA resulted in a 16-to 32-fold decrease in the apramycin MICs. An apmA-specific PCR identified this gene in one additional bovine and four porcine MRSA ST398 isolates. Copyright © 2011 American Society for Microbiology. All Rights Reserved.


Kadlec K.,Institute of Farm Animal Genetics | Schwarz S.,Institute of Farm Animal Genetics
Antimicrobial Agents and Chemotherapy | Year: 2010

The trimethoprim resistance gene dfrK was found to be part of the novel Tn554-related transposon Tn559 integrated in the chromosomal radC gene of a porcine methicillin-susceptible Staphylococcus aureus ST398 strain. While Tn559 and Tn554 had similar arrangements of the transposase genes tnpA, tnpB, and tnpC, the Tn554-associated resistance genes erm(A) and spc were replaced by dfrK in Tn559. Circular forms of Tn559 were detected and suggest the functional activity of this transposon. Copyright © 2010, American Society for Microbiology. All Rights Reserved.


Kadlec K.,Institute of Farm Animal Genetics | Schwarz S.,Institute of Farm Animal Genetics
Antimicrobial Agents and Chemotherapy | Year: 2010

A novel plasmid-borne resistance gene cluster comprising the genes erm(T) for macrolide-lincosamidestreptogramin B resistance, dfrK for trimethoprim resistance, and tet(L) for tetracycline resistance was identified in a porcine methicillin-resistant Staphylococcus aureus sequence type 398 (ST398) strain. This erm(T)-dfrK-tet(L) region was flanked by copies of the novel IS element ISSau10. The erm(T) region resembled that of Streptococcus pyogenes plasmid pRW35. The erm(T) gene of pKKS25 was expressed constitutively due to a 57-bp deletion in the erm(T) translational attenuator. Copyright © 2010, American Society for Microbiology. All Rights Reserved.


Niemann H.,Institute of Farm Animal Genetics | Lucas-Hahn A.,Institute of Farm Animal Genetics
Reproduction in Domestic Animals | Year: 2012

Contents: Somatic cloning is emerging as a new biotechnology by which the opportunities arising from the advances in molecular genetics and genome analysis can be implemented in animal breeding. Significant improvements have been made in SCNT protocols in the past years which now allow to embarking on practical applications. The main areas of application of SCNT are: Reproductive cloning, therapeutic cloning and basic research. A great application potential of SCNT based cloning is the production of genetically modified (transgenic) animals. Somatic cell nuclear transfer based transgenic animal production has significant advances over the previously employed microinjection of foreign DNA into pronuclei of zygotes. This cell based transgenesis is compatible with gene targeting and allows both, the addition of a specific gene and the deletion of an endogenous gene. Efficient transgenic animal production provides numerous opportunities for agriculture and biomedicine. Regulatory agencies around the world have agreed that food derived from cloned animals and their offspring is safe and there is no scientific basis for questioning this. Commercial application of somatic cloning within the EU is via the Novel Food regulation EC No. 258/97. Somatic cloning raises novel questions regarding the ethical and moral status of animals and their welfare which has prompted a controversial discussion in Europe which has not yet been resolved. © 2012 Blackwell Verlag GmbH.


Schink A.-K.,Institute of Farm Animal Genetics | Kadlec K.,Institute of Farm Animal Genetics | Schwarz S.,Institute of Farm Animal Genetics
Applied and Environmental Microbiology | Year: 2011

In this study, 417 Escherichia coli isolates from defined disease conditions of companion and farm animals collected in the BfT-GermVet study were investigated for the presence of extended-spectrum β-lactamase (ESBL) genes. Three ESBL-producing E. coli isolates were identified among the 100 ampicillin-resistant isolates. The E. coli isolates 168 and 246, of canine and porcine origins, respectively, harbored bla CTX-M-1, and the canine isolate 913 harbored bla CTX-M-15, as confirmed by PCR and sequence analysis. The isolates 168 and 246 belonged to the novel multilocus sequence typing (MLST) types ST1576 and ST1153, respectively, while isolate 913 had the MLST type ST410. The ESBL genes were located on structurally related IncN plasmids in isolates 168 and 246 and on an IncF plasmid in isolate 913. The bla CTX-M-1 upstream regions of plasmids pCTX168 and pCTX246 were similar, whereas the downstream regions showed structural differences. The genetic environment of the bla CTX-M-15 gene on plasmid pCTX913 differed distinctly from that of both bla CTX-M-1 genes. Detailed sequence analysis showed that the integration of insertion sequences, as well as interplasmid recombination events, accounted for the structural variability in the bla CTX-M gene regions. © 2011, American Society for Microbiology.

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