Capsule Negative Staphylococcus aureus strains?

So I'm trying to confirm that Congo Red agar plates which were recently made are functioning properly. I tested the S. aureus strains, Becker (cp8+), Reynolds (cp5+) and Wood 46 (cp-), and did get different morphologies on the plates. That being said, my coworker who's used similar plates before doesn't remember if it's the *correct* morphology/phenotype that occurred. So I would like to test another set of strains with the same characteristics. I can find plenty of cp5/8+ strains, but almost no documentation for capsule negative strains.

Outside of performing PCR on a bunch of strains to amplify the genes out, does anyone know of of a capsule negative strain I could use?