You're absolutely right—while vanA-positive Staphylococcus aureus (VRSA) isolates have been documented globally, the availability of complete vanA operon sequences specifically from S. aureus (as opposed to Enterococcus spp.) in public databases like NCBI remains limited and fragmented.

The vanA operon, typically carried on the transposon Tn1546, is known to be horizontally transferred from Enterococcus faecalis/faecium to S. aureus via conjugative plasmids. In VRSA, this operon is often found integrated into plasmids or chromosomal regions, but full annotated sequences with CDC reference metadata are rare.

🔬 Key Findings and References:

• A recent CDC-confirmed VRSA case from North Carolina (USA600 lineage, CC45) was described in Emerging Infectious Diseases (2025), but the full vanA operon sequence was not deposited in GenBank with CDC reference metadata.

• The classic review by Perichon & Courvalin (2009) outlines the molecular mechanisms of vanA acquisition in VRSA, including transposition events and plasmid recombination, but again lacks full operon sequences from S. aureus strains.

• A 2024 study in the International Journal of Antimicrobial Agents analyzed 15,706 S. aureus genomes and identified 25 strains harboring complete vanA operons. These were found on 17 plasmids and 8 chromosomes, often co-isolated with VRE. The operons were embedded in Tn1546-like elements, and integration sites such as locus L2 were characterized.

📌 Recommendations:

1. Search Strategy: Instead of querying “vanA in VRSA,” try searching for Tn1546 or vanA operon within Staphylococcus aureus genomes in NCBI, EMBL-EBI, or IMG/M databases. Use filters for plasmid vs. chromosomal localization.

2. Sequence Access: The HAL archive Mechanisms of vanA acquisition in VRSA provides detailed genomic contexts and may offer accession numbers or supplementary data for full operon sequences.

3. Contact CDC or Authors: For isolates confirmed by CDC (e.g., USA600 lineage), consider reaching out to authors like Amy Gargis or Maria Karlsson who have published on VRSA genomics. They may provide unpublished sequence data or guidance on accessing restricted datasets.