Characterization of an Osteomyelitis Case Caused by Dalbavancin, Ceftaroline and Vancomycin Non-Susceptible Methicillin-Resistant Staphylococcus Aureus

This study reports a case of osteomyelitis due to methicillin-resistant Staphylococcus aureus (MRSA) that is also non-susceptible to vancomycin, dalbavancin, ceftaroline and ceftobiprole, among other antibiotics. The resistance to ceftaroline, ceftobiprole and dalbavancin emerged in the absence of exposure to these antibiotics and the MRSA strain pertained to ST247. The mecA gene was detected within the SSCmec Type I (1B) gene cassette, but it lacked the E447K mutation that is known to produce resistance to ceftobiprole and ceftaroline. However, mutations in other genes related to resistance to these antibiotics and other antimicrobial agents were found.