After isolating Staphylococcus aureus from a diabetic patient showing methicillin resistance, which additional antibiotic should be tested for susceptibility?

Testing for susceptibility to vancomycin after isolating methicillin-resistant Staphylococcus aureus (MRSA) is essential because vancomycin is often considered the antibiotic of choice for treating infections caused by MRSA. While MRSA strains remain responsive to vancomycin in many cases, some isolates have shown reduced susceptibility or complete resistance, which can complicate treatment. Therefore, determining the sensitivity of the isolated strain to vancomycin is crucial for effective treatment management.

In contrast, other antibiotics in the options may not be as effective or relevant for treating MRSA infections. For example, erythromycin is generally not effective against MRSA, and gentamicin and kanamycin might not penetrate adequately into the target tissues affected by MRSA. Therefore, the focus on vancomycin susceptibility testing allows healthcare providers to select the most appropriate antibiotic therapy for the patient.