Appropriate Treatment with Zosyn for Fever Suspected to be Caused by Bacterial Infection

Risk Assessment

The Infectious Diseases Society of America recommends risk assessment at presentation of fever to determine appropriate antibiotic therapy, venue of treatment, and duration of therapy 3
High-risk patients include those with anticipated prolonged (>7 days) and profound neutropenia (low white blood cell count) 3
High-risk patients also include those with significant medical comorbidities (hypotension, pneumonia, abdominal pain, neurologic changes) 3
Low-risk patients include those with anticipated brief (<7 days) neutropenic periods 3
Low-risk patients also include those with few or no comorbidities 3

The European Society of Clinical Microbiology and Infectious Diseases recommends monotherapy with piperacillin-tazobactam 4.5g IV every 6 hours as first-line therapy for high-risk patients 1, 2, 3
Alternative monotherapy options for high-risk patients include cefepime, meropenem, or imipenem-cilastatin 3
For patients with complications or in centers with high resistance rates, adding an aminoglycoside (such as amikacin) is recommended for severe sepsis or suspected resistant pathogens 1, 2, 4
For patients with complications or in centers with high resistance rates, adding vancomycin is recommended if MRSA is suspected or for clinically unstable patients 1, 2
The Infectious Diseases Society of America recommends combination therapy with oral ciprofloxacin plus amoxicillin-clavulanic acid for low-risk patients 1, 5

For suspected multidrug-resistant infections, consider local resistance patterns when selecting therapy 4, 6
Avoid carbapenems as empiric treatment for community-acquired infections unless specific risk factors are present 7

For microbiologically documented infections, continue appropriate antibiotics for at least the duration of neutropenia (until white blood cell count recovers) or 10-14 days for most bacterial bloodstream infections, soft-tissue infections, and pneumonias 5, 8
For unexplained fever, continue initial regimen until clear signs of marrow recovery (white blood cell count >500 cells/mm³) 5
For low-risk patients who become afebrile, consider step-down to oral therapy after 3 days if clinically stable with no documented infection 5

Persistent fever alone in a stable patient is rarely an indication to alter the antibiotic regimen 9
If fever persists >3 days despite empiric therapy, perform thorough search for source of infection with new blood cultures and other directed diagnostic tests 9
Monitor for adverse effects, particularly risk of acute interstitial nephritis, especially with concomitant use of other nephrotoxic agents 10

Unnecessary addition of vancomycin for persistent fever alone is not recommended 9
Avoid combination therapy with aminoglycosides in stable patients due to increased renal toxicity without improved efficacy 4
Avoid fluoroquinolones when other antibiotics could be used, particularly as empirical monotherapy in severe nosocomial infections 7