[Show abstract][Hide abstract] ABSTRACT: THE LANCET • Vol 359 • May 25, 2002 • www.thelancet.com 1819 Summary Background A new type of meticillin-resistant Staphylococcus aureus (MRSA), designated community-acquired MRSA, is becoming increasingly noticeable in the community, some strains of which cause fatal infections in otherwise healthy individuals. By contrast with hospital-acquired MRSA, community-acquired MRSA is more susceptible to non -lactam antibiotics. We investigated the high virulence potential of certain strains of this bacterium. Methods We ascertained the whole genome sequence of MW2, a strain of community-acquired MRSA, by shotgun cloning and sequencing. MW2 caused fatal septicaemia and septic arthritis in a 16-month-old girl in North Dakota, USA, in 1998. The genome of this strain was compared with those of hospital-acquired MRSA strains, including N315 and Mu50. Findings Meticillin resistance gene (mecA) in MW2 was carried by a novel allelic form (type IVa) of staphylococcal cassette chromosome mec (SCCmec), by contrast with type II in N315 and Mu50. Type IVa SCCmec did not carry any of the multiple antibiotic resistance genes reported in type II SCCmec. By contrast, 19 additional virulence genes were recorded in the MW2 genome. All but two of these virulence genes were noted in four of the seven genomic islands of MW2. Interpretation MW2 carried a range of virulence and resistance genes that was distinct from those displayed on the chromosomes of extant S aureus strains. Most genes were carried by specific allelic forms of genomic islands in the MW2 chromosome. The combination of allelic forms of genomic islands is the genetic basis that determines the pathogenicity of medically important phenotypes of S aureus, including those of community-acquired MRSA strains.
[Show abstract][Hide abstract] ABSTRACT: 1225 Summary Background Staphylococcus aureus is one of the major causes of community-acquired and hospital-acquired infections. It produces numerous toxins including superantigens that cause unique disease entities such as toxic-shock syndrome and staphylococcal scarlet fever, and has acquired resistance to practically all antibiotics. Whole genome analysis is a necessary step towards future development of countermeasures against this organism. Methods Whole genome sequences of two related S aureus strains (N315 and Mu50) were determined by shot-gun random sequencing. N315 is a meticillin-resistant S aureus (MRSA) strain isolated in 1982, and Mu50 is an MRSA strain with vancomycin resistance isolated in 1997. The open reading frames were identified by use of GAMBLER and GLIMMER programs, and annotation of each was done with a BLAST homology search, motif analysis, and protein localisation prediction.
[Show abstract][Hide abstract] ABSTRACT: The complete sequence of the genome of a hyper-thermophilic archaebacterium, Pyrococcus horikoshii OT3, has been determined by assembling the sequences of the physical map-based contigs of fosmid clones and of long polymerase
chain reaction (PCR) products which were used for gap-filling. The entire length of the genome was 1,738,505 bp. The authenticity
of the entire genome sequence was supported by restriction analysis of long PCR products, which were directly amplified from
the genomic DNA. As the potential protein-coding regions, a total of 2061 open reading frames (ORFs) were assigned, and by
similarity search against public databases, 406 (19.7%) were related to genes with putative function and 453 (22.0%) to the
sequences registered but with unknown function. The remaining 1202 ORFs (58.3%) did not show any significant similarity to
the sequences in the databases. Sequence comparison among the assigned ORFs in the genome provided evidence that a considerable
number of ORFs were generated by sequence duplication. By similarity search, 11 ORFs were assumed to contain the intein elements.
The RNA genes identified were a single 16S-23S rRNA operon, two 5S rRNA genes and 46 tRNA genes including two with the intron
structure. All the assigned ORFs and RNA coding regions occupied 91.25% of the whole genome. The data presented in this paper
are available on the internet at http://www.nite.go.jp.