Management of Bacteremia

Initial Empiric Therapy Strategy

Gram-negative bacteremia requires more aggressive empiric therapy with broader-spectrum agents and carries significantly higher mortality (18%) compared to gram-positive bacteremia (5%) 1
The American College of Physicians recommends empiric therapy that includes agents with reliable activity against gram-negative bacilli, particularly in critically ill patients, those with sepsis, neutropenia, femoral catheters, or known gram-negative infection foci 2
Recommended first-line empiric regimens for suspected gram-negative bacteremia include carbapenems, antipseudomonal cephalosporins, piperacillin-tazobactam, and combination therapy with aminoglycoside plus antipseudomonal penicillin or extended-spectrum cephalosporin 2
For critically ill patients with recent MDR gram-negative colonization or infection, the Infectious Diseases Society of America recommends using two antimicrobial agents of different classes with gram-negative activity as initial therapy 2, 3
For suspected gram-positive bacteremia, the Infectious Diseases Society of America recommends β-lactam antibiotics as first choice for S. aureus bacteremia when susceptible, with nafcillin or oxacillin for methicillin-susceptible strains 4

Non-tunneled CVCs with gram-negative bacteremia should be removed, followed by 10-14 days of appropriate antimicrobial therapy, as recommended by the Infectious Diseases Society of America 4, 3
For certain high-risk gram-negative organisms, the Infectious Diseases Society of America strongly considers catheter removal even if bacteremia appears controlled, due to higher treatment failure rates 4, 5
Tunneled CVCs with gram-negative bacteremia in stable patients without organ dysfunction can be treated with 14 days of systemic plus antibiotic lock therapy if catheter cannot be removed, as recommended by the Infectious Diseases Society of America 4, 3
For S. aureus bacteremia, the Infectious Diseases Society of America recommends removing non-tunneled CVCs immediately and inserting new catheter at different site 4

The standard duration for uncomplicated gram-negative bacteremia is 7-14 days, as recommended by the Infectious Diseases Society of America 2, 3
Recent high-quality evidence supports 7 days of treatment for gram-negative bacteremia from urinary sources when source control is achieved, as published in JAMA network open 6
For S. aureus bacteremia with negative TEE and catheter removed, the Infectious Diseases Society of America recommends 14 days of treatment 4
For S. aureus bacteremia with endocarditis, the Infectious Diseases Society of America recommends 4-6 weeks of treatment 4

Once culture and susceptibility results are available, the Infectious Diseases Society of America recommends de-escalating to single appropriate antibiotic for remainder of treatment course 2, 3
De-escalation reduces antibiotic exposure while maintaining efficacy, as recommended by the Infectious Diseases Society of America 2
For gram-negative infections, oral fluoroquinolones may be preferred for completion therapy, as demonstrated in Clinical Infectious Diseases 4, 5

Mortality rates differ substantially between gram-negative and gram-positive bacteremia, with 18% mortality for gram-negative and 5% for gram-positive, as reported in Annals of Oncology 1
Septic shock with bacteremia has a mortality rate as high as 36% if MASCC score <15, as reported in Annals of Oncology 1

The Infectious Diseases Society of America recommends never using vancomycin empirically for suspected S. aureus when β-lactams are appropriate, as this leads to inferior outcomes and promotes resistance 4
The Infectious Diseases Society of America recommends avoiding inadequate antimicrobial therapy with limited gram-negative coverage for bloodstream infections, as this increases morbidity and mortality 2
The Infectious Diseases Society of America recommends not continuing antibiotics until all symptoms resolve, but rather following evidence-based duration recommendations to avoid unnecessary antibiotic exposure 3