title: Genome-wide high-throughput screening to investigate essential genes involved in methicillin-resistant Staphylococcus aureus Sequence Type 398 survival.
abstract: Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) Sequence Type 398 (ST398) is an opportunistic pathogen that is able to colonize and cause disease in several animal species including humans. To better understand the adaptation, evolution, transmission and pathogenic capacity, further investigations into the importance of the different genes harboured by LA-MRSA ST398 are required. In this study we generated a genome-wide transposon mutant library in an LA-MRSA ST398 isolate to evaluate genes important for bacterial survival in laboratory and host-specific environments. The transposon mutant library consisted of approximately 1 million mutants with around 140,000 unique insertion sites and an average number of unique inserts per gene of 44.8. We identified LA-MRSA ST398 essential genes comparable to other high-throughput S. aureus essential gene studies. As ST398 is the most common MRSA isolated from pigs, the transposon mutant library was screened in whole porcine blood. Twenty-four genes were specifically identified as important for bacterial survival in porcine blood. Mutations in 23 of these genes resulted in attenuated bacterial fitness. Seven of the 23 genes were of unknown function, whereas 16 genes were annotated with functions predominantly related to carbon metabolism, pH shock and a variety of regulations and only indirectly to virulence factors. Mutations in one gene of unknown function resulted in a hypercompetitive mutant. Further evaluation of these genes is required to determine their specific relevance in blood survival.
authors.affiliation: National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark.
authors.forename: Mette T
authors.initials: MT
authors.lastname: Christiansen
authors.affiliation: National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark.
authors.forename: Rolf S
authors.initials: RS
authors.lastname: Kaas
authors.affiliation: Department of Veterinary Medicine, University of Cambridge, Cambridge, England, United Kingdom.
authors.forename: Roy R
authors.initials: RR
authors.lastname: Chaudhuri
authors.affiliation: Department of Veterinary Medicine, University of Cambridge, Cambridge, England, United Kingdom.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Holmes
authors.affiliation: National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Hasman
authors.affiliation: National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark.
authors.forename: Frank M
authors.initials: FM
authors.lastname: Aarestrup
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D004251:DNA Transposable Elements; D015723:Gene Library; D020043:Genes, Essential; D016678:Genome; D005838:Genotype; D057166:High-Throughput Screening Assays; D006801:Humans; D006863:Hydrogen-Ion Concentration; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000235:genetics*; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013203:Staphylococcal Infections / Q000382:microbiology*; D013552:Swine; D037521:Virulence Factors
chemical_list: D000900:Anti-Bacterial Agents; D004251:DNA Transposable Elements; D037521:Virulence Factors