When are broad-spectrum antibiotics indicated in the treatment of systemic inflammatory response syndrome (SIRS)?

Updated: May 07, 2018
  • Author: Lewis J Kaplan, MD, FACS, FCCM, FCCP; Chief Editor: Michael R Pinsky, MD, CM, Dr(HC), FCCP, FAPS, MCCM  more...
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Because of increasing bacterial resistance, broad-spectrum antibiotics should be initiated when an infectious cause for SIRS is a concern but no specific infection is diagnosed. With the increasing prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in the community, vancomycin or another anti-MRSA therapy should be considered. Recent exposure to antibiotics (typically within 3 months) must be considered when choosing empiric regimens, because recent antibiotic therapy increases the risk for resistant pathogens.

Gram-negative coverage with cefepime, piperacillin-tazobactam, carbapenem (imipenem, meropenem, or doripenem), or a quinolone is reasonable. Care must be taken not to use an antibiotic to which the patient is allergic, which may be a second hit and lead to worsening SIRS; penicillin allergy is a particular concern, given its prevalence. A quinolone or aztreonam is a reasonable choice for gram-negative coverage in patients with a penicillin allergy. If aztreonam is used, gram-positive coverage (with an agent such as vancomycin) should be initiated as well, until culture results are available.

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