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Updated: Jun 12, 2026
Genotyping of Staphylococcus aureus by Ribosomal Spacer PCR (RS-PCR)
Published on: November 4, 2016
Whole genome analysis of a livestock-associated methicillin-resistant Staphylococcus aureus ST398 isolate from a case
Maarten J Schijffelen1, C H Edwin Boel, Jos A G van Strijp
1Department of Medical Microbiology, University Medical Centre Utrecht, Heidelberglaan 100, 3508 GA, Utrecht, the Netherlands. A.C.Fluit@umcutrecht.nl
Background:
Recently, a new livestock-associated methicillin-resistant Staphylococcus aureus (MRSA) Sequence Type 398 (ST398) isolate has emerged worldwide. Although there have been reports of invasive disease in humans, MRSA ST398 colonization is much more common in livestock and demonstrates especially high prevalence rates in pigs and calves. The aim of this study was to compare the genome sequence of an ST398 MRSA isolate with other S. aureus genomes in order to identify genetic traits that may explain the success of this particular lineage. Therefore, we determined the whole genome sequence of S0385, an MRSA ST398 isolate from a human case of endocarditis.
Results:
The entire genome sequence of S0385 demonstrated considerable accessory genome content differences relative to other S. aureus genomes. Several mobile genetic elements that confer antibiotic resistance were identified, including a novel composite of an type V (5C2&5) Staphylococcal Chromosome Cassette mec (SCCmec) with distinct joining (J) regions. The presence of multiple integrative conjugative elements combined with the absence of a type I restriction and modification system on one of the two nuSa islands, could enhance horizontal gene transfer in this strain. The ST398 MRSA isolate carries a unique pathogenicity island which encodes homologues of two excreted virulence factors; staphylococcal complement inhibitor (SCIN) and von Willebrand factor-binding protein (vWbp). However, several virulence factors such as enterotoxins and phage encoded toxins, including Panton-Valentine leukocidin (PVL), were not identified in this isolate.
Conclusions:
Until now MRSA ST398 isolates did not cause frequent invasive disease in humans, which may be due to the absence of several common virulence factors. However, the proposed enhanced ability of these isolates to acquire mobile elements may lead to the rapid acquisition of determinants which contribute to virulence in human infections.
Insights
Livestock-associated methicillin-resistant Staphylococcus aureus (MRSA) ST398 shows unique genetic traits. Its enhanced ability to acquire mobile elements may increase its virulence in human infections.
Area of Science:
- Microbiology
- Genomics
- Infectious Diseases
Background:
- Livestock-associated methicillin-resistant Staphylococcus aureus (MRSA) ST398 is globally prevalent, with high colonization rates in pigs and calves.
- While invasive disease in humans is reported, ST398 MRSA is more commonly found colonizing livestock.
- Understanding the genetic makeup of ST398 MRSA is crucial for explaining its success and potential impact on human health.
Purpose of the Study:
- To compare the whole genome sequence of an ST398 MRSA isolate (S0385) from a human endocarditis case with other Staphylococcus aureus genomes.
- To identify specific genetic characteristics contributing to the successful adaptation and spread of the ST398 lineage.
Main Methods:
- Whole genome sequencing of the ST398 MRSA isolate S0385.
- Comparative genomic analysis against other Staphylococcus aureus strains.
Main Results:
- The ST398 MRSA genome exhibits significant differences in accessory content compared to other S. aureus.
- Novel mobile genetic elements, including a unique SCCmec type V (5C2&5) and integrative conjugative elements, were identified, potentially enhancing horizontal gene transfer.
- A unique pathogenicity island encoding staphylococcal complement inhibitor (SCIN) and von Willebrand factor-binding protein (vWbp) was found, but common virulence factors like PVL were absent.
Conclusions:
- The lower frequency of invasive disease caused by ST398 MRSA in humans may be linked to the absence of certain common virulence factors.
- The demonstrated capacity for acquiring mobile genetic elements suggests a potential for rapid evolution and increased virulence in human infections.
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