When the Antibiotic Combination “Vosyn” Isn’t Enough for Sepsis

Treatment Recommendations

Some septic patients are at very high risk of Staphylococcus aureus bacteremia. These include patients with a chronic venous catheter/fistula (eg, dialysis patients) and cancer patients with an infected port site. Of S. aureus isolates, some will be methicillin-sensitive S. aureus (MSSA); some, methicillin-resistant S. aureus (MRSA). MSSA is susceptible to oxacillin and nafcillin (anti-staphylococcal β-lactams); MRSA is not.

While vancomycin is active in vitro against both, for MSSA bacteremia, studies demonstrate reduced mortality associated with oxacillin and nafcillin. In one case-control study with patients matched for outcome confounders, mortality was 37 percent with vancomycin compared to 11 percent for β-lactams.² So after blood cultures, ordering nafcillin in addition to vancomycin will give your patient the best chance.

Finally, there’s evidence that for MRSA pneumonia, linezolid leads to superior clinical outcomes when compared to vancomycin. Randomized controlled trials comparing linezolid and vancomycin for pneumonia found that, among the subgroup of patients with MRSA, survival was significantly greater with linezolid, 80 percent versus 63.5 percent.³ Another randomized controlled trial targeting MRSA pneumonia patients confirmed improved clinical response with linezolid.⁴ Risk factors for MRSA etiology of pneumonia include the following: severe illness, imaging suggestive of cavities, abscesses or empyema, and history of MRSA infection. Linezolid is also active against pneumococcus, the most common cause of severe community-acquired pneumonia, and MSSA. Of note, linezolid is not indicated for primary bloodstream infections (eg, endocarditis). In septic patients with pneumonia who are at risk for MRSA, linezolid would be a better empirical choice than vancomycin.

While these recommendations are evidence-based and supported by survival and clinical improvement data, hospital antibiotic stewards will fear emergency physicians overgeneralizing these broadened regimens. It’s always best to engage and seek consensus with your infectious disease specialists.

So, for your next ED patient with sepsis, before reaching for vosyn, take a moment to think about ESBL, MSSA bloodstream, and MRSA pneumonia infections as exceptions. There’s no shame in knowing more.

Dr. Talan is professor of emergency medicine and medicine (infectious diseases) in the departments of emergency medicine at Ronald Reagan UCLA Medical Center, Olive View-UCLA Medical Center, and The David Geffen School of Medicine at UCLA, in Los Angeles.