What is the significance of anaerobic and aerobic blood cultures detecting both Klebsiella pneumoniae and Escherichia coli (E. coli), with a Gram stain showing Gram-negative bacilli, in a patient with sepsis?

From the Guidelines

The patient with sepsis and polymicrobial bloodstream infection with Klebsiella pneumoniae and Escherichia coli should be treated immediately with broad-spectrum antibiotics, such as a carbapenem (e.g., meropenem 1g IV every 8 hours) or piperacillin-tazobactam 4.5g IV every 6-8 hours, as recommended by the Surviving Sepsis Campaign guidelines 1.

Key Considerations

• The presence of both aerobic and anaerobic blood cultures detecting gram-negative bacilli indicates a high risk of severe infection and potential for rapid clinical deterioration.
• The guidelines recommend obtaining blood cultures before starting antimicrobial therapy, but in this case, treatment should not be delayed, and antibiotics should be started promptly 1.
• The choice of antibiotic should be based on the suspected source of infection, local antimicrobial resistance patterns, and the patient's clinical condition.
• Supportive care with IV fluids, vasopressors if needed, and close monitoring of vital signs and organ function is essential.

Antibiotic Therapy

• A carbapenem (e.g., meropenem 1g IV every 8 hours) or piperacillin-tazobactam 4.5g IV every 6-8 hours is a suitable initial choice for broad-spectrum antibiotic coverage.
• For critically ill patients, consider adding an aminoglycoside (gentamicin 5-7mg/kg IV daily) for the first 48-72 hours.
• Therapy should continue for at least 7-14 days, depending on source control and clinical response.

Source Control and Supportive Care

• The source of infection should be identified and controlled promptly, with common sources including urinary tract, intra-abdominal, or biliary infections.
• Polymicrobial gram-negative bacteremia often indicates an abdominal or genitourinary source.
• Supportive care with IV fluids, vasopressors if needed, and close monitoring of vital signs and organ function is essential.

De-escalation of Antibiotic Therapy

• Once susceptibility results are available, narrow the antibiotic therapy accordingly to reduce resistance development and side effects 1.

From the Research

Patient Condition

The patient has sepsis with anaerobic and aerobic blood cultures detecting both Klebsiella pneumoniae and E. coli, and a Gram stain showing gram-negative bacilli.

Treatment Options

• The patient requires empirical antibiotic treatment that covers a broad spectrum of Gram-negative and Gram-positive bacteria, as recommended in international guidelines 2.
• Combination therapy with an anti-pseudomonal beta-lactam and a fluoroquinolone or an aminoglycoside may be recommended for patients with severe pneumonia or septicemia 2.
• Piperacillin-tazobactam may be considered as a "carbapenem-sparing" option to treat extended-spectrum beta-lactamase producers, but its effectiveness compared to meropenem is still being studied 3, 4.
• Meropenem is a carbapenem that may be effective against E. coli and Klebsiella pneumoniae, but its use may contribute to the development of carbapenem resistance 3, 5.

Antimicrobial Resistance

• High levels of resistance to ampicillin have been recorded for E. coli and Klebsiella pneumoniae strains, with lower resistance levels to carbapenems 5.
• Resistance to 3rd generation cephalosporins varies between 7.47% and 14.6% for E. coli, and between 20.7% and 22.5% for Klebsiella pneumoniae 5.
• Klebsiella pneumoniae strains exhibit higher resistance to carbapenems compared to E. coli 5.

Predicting Sepsis

• Liver fibrosis scores, such as APRI and FIB-4, may be effective in predicting positive blood cultures and sepsis in patients with Klebsiella pneumoniae liver abscess 6.
• APRI and FIB-4 have been identified as independent prognostic factors for positive blood cultures and sepsis in patients with KPLA 6.