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methicillin-sensitive Staphylococcus aureus (MSSA)

Staphylococcus aureus sensitive to methicillin & oxacillin. Epidemiology: - in the neonatal ICU, MSSA are more common than MRSA infections & result in higher mortality - compared with MRSA carriers, risk of MRSA infection were 14 times lower for uncolonized patients & 125 times lower for MSSA carriers [5] Management: - MSSA sepsis (bacteremia) - 2nd generation penicillin or 1st generation cephalosporin - IV nafcillin, oxacillin, or cefazolin [2] - cefazolin superior to nafcillin or oxacillin [3] - lower 30 & 90 day mortality (37% & 23%, respectively) - lower risk for endocarditis (4% vs 7%) - add rifampin for osteomyelitis if orthopedic hardware cannot be removed [2] - ceftriaxone inferior to nafcillin, oxacillin, or cefazolin in patients with sepsis [6] - vancomycin - use may be associated with reduced susceptibility & increased risk of complications [4] - use not associated with increased mortality [4]

General

Staphylococcus aureus

References

  1. Ericson JE et al Burden of Invasive Staphylococcus aureus Infections in Hospitalized Infants. JAMA Pediatr. Published online October 19, 2015 PMID: 26502073 http://archpedi.jamanetwork.com/article.aspx?articleid=2449666 - Cantey JB, Ronchi A Spreading the Benefits of Infection Prevention in the Neonatal Intensive Care Unit. JAMA Pediatr. Published online October 19, 2015 PMID: 26501886 http://archpedi.jamanetwork.com/article.aspx?articleid=2449664
  2. Medical Knowledge Self Assessment Program (MKSAP) 17, 18, 19. American College of Physicians, Philadelphia 2015, 2018, 2021.
  3. McDanel JS, Roghmann MC, Perencevich EN et al. Comparative effectiveness of cefazolin versus nafcillin or oxacillin for treatment of methicillin-susceptible Staphylococcus aureus infections complicated by bacteremia: A nationwide cohort study. Clin Infect Dis 2017 Mar 31 PMID: 28379314 - Karchmer AW. Definitive treatment for methicillin-sensitive Staphylococcus aureus bacteremia: Data versus a definitive answer? Clin Infect Dis 2017 Mar 31 PMID: 28379366
  4. Sullivan SB, Austin ED, Stump S et al. Reduced vancomycin susceptibility of methicillin-susceptible Staphylococcus aureus has no significant impact on mortality but results in an increase in complicated infection. Antimicrob Agents Chemother 2017 Jul; 61:e00316 PMID: 28507105 http://aac.asm.org/content/61/7/e00316-17
  5. Shrestha NK, Fraser TG, Gordon SM. Methicillin resistance in Staphylococcus aureus infections among patients colonized with methicillin-susceptible Staphylococcus aureus. Clin Microbiol Infect 2018 Apr 10. PMID: 29649598
  6. Yetmar ZA et al. Post-treatment outcomes of ceftriaxone versus antistaphylococcal penicillins or cefazolin for definitive therapy of methicillin-susceptible Staphylococcus aureus bacteremia. Eur J Clin Microbiol Infect Dis 2023 Apr; 42:423. PMID: 36800065 https://link.springer.com/article/10.1007/s10096-023-04575-z - Buis DTP et al. Comparative effectiveness of beta-lactams for empirical treatment of methicillin- susceptible Staphylococcus aureus bacteraemia: A prospective cohort study. J Antimicrob Chemother 2023 Mar 10; [e-pub] PMID: 36897327 https://academic.oup.com/jac/advance-article/doi/10.1093/jac/dkad057/7075678