What is the treatment for a moderate load of Escherichia coli (E. coli) and Enterococcus (Enterococci) infection?

From the Guidelines

For treating a medium amount of E. coli and Enterococcus faecalis (100,000-10 million organisms), I strongly recommend using ertapenem as a single-agent therapy due to its broad-spectrum activity against enteric gram-negative aerobic and facultative bacilli and enteric gram-positive streptococci, as suggested by the guidelines 1.

Treatment Options

• Ertapenem is a preferred choice for adult patients with mild-to-moderate community-acquired infection, as it provides coverage for obligate anaerobic bacilli and has been shown to be effective against E. coli and Enterococcus faecalis 1.
• Alternative options include ticarcillin-clavulanate, cefoxitin, moxifloxacin, or tigecycline as single-agent therapy, or combinations of metronidazole with cefazolin, cefuroxime, ceftriaxone, cefotaxime, levofloxacin, or ciprofloxacin 1.
• However, ampicillin-sulbactam is not recommended due to high rates of resistance among community-acquired E. coli, and cefotetan and clindamycin are not recommended due to increasing prevalence of resistance among the Bacteroides fragilis group 1.

Important Considerations

• Empiric coverage of Enterococcus is not necessary in patients with community-acquired intra-abdominal infection, as suggested by the guidelines 1.
• The use of agents with substantial anti-Pseudomonal activity is not recommended for patients with mild-to-moderate community-acquired infection, as they may carry a greater risk of toxicity and facilitate acquisition of more-resistant organisms 1.
• Antimicrobial selection should be based on local microbiologic data, cost advantage, allergies, and formulary availability, as no outcome differences have been identified in randomized controlled trials 1.

From the FDA Drug Label

Amoxicillin for oral suspension is indicated in the treatment of infections due to susceptible (ONLY β-lactamase–negative) isolates of Escherichia coli, Proteus mirabilis, or Enterococcus faecalis

• Treatment Indication: The drug label indicates that amoxicillin is used to treat infections caused by E. coli and Enterococcus faecalis.
• Key Consideration: The label specifies that the isolates must be β-lactamase–negative, and it does not provide specific guidance on the treatment of Enterococcus fasciculus.
• Dosage and Administration: The label recommends treatment for a minimum of 48 to 72 hours beyond the time that the patient becomes asymptomatic, or evidence of bacterial eradication has been obtained 2. However, the label does not provide specific dosage recommendations for a medium amount of E. coli and Enterococcus fasciculus with a load between 100,000 and 10 million. Given the information provided and the need for a conservative clinical decision, it is not possible to provide a definitive treatment plan.

From the Research

Treatment Options for E. coli and Enterococcus fasciculus

• The provided studies focus on the treatment of Enterococcus faecalis infections, with no direct mention of E. coli or Enterococcus fasciculus.
• However, the studies suggest that combination antibiotic therapy, such as ampicillin plus ceftriaxone, may be effective in treating Enterococcus faecalis infections 3, 4, 5, 6.
• For Enterococcus faecalis infections with elevated penicillin MICs, alternative dual-beta-lactam combinations, such as meropenem plus ceftriaxone or ertapenem plus ceftriaxone, may be considered 4.
• Glycopeptides, such as vancomycin, may not be necessary for ampicillin-susceptible Enterococcus faecalis/faecium bacteremia, and ampicillin-containing regimens may be a better option 7.

Considerations for Treatment

• The choice of antibiotic therapy should be based on the severity of the infection, the susceptibility of the isolate, and the potential for adverse events 3, 6.
• Nephrotoxicity is a significant concern with certain antibiotic combinations, such as ampicillin plus gentamicin, and alternative regimens, such as ampicillin plus ceftriaxone, may be preferred 3, 6.
• Further research is needed to improve patient outcomes and to determine the optimal treatment strategies for Enterococcus faecalis infections 5.