From Cempra Soars on Drug’s Potential to Treat MRSA, Other Infections:

methicillin-resistant S. aureus (MRSA)
methicillin-resistant S. aureus (MRSA)

Image of methicillin-resistant S. aureus (MRSA) by Flickr user NIAID
Micrograph of Methicillin-Resistant Staphylococcus aureus (MRSA)
via a Creative Commons license
https://creativecommons.org/licenses/by/2.0/