What is a suitable outpatient antibiotic to continue coverage of anaerobes for a patient being treated for pneumonia with Zosyn (piperacillin-tazobactam)?

From the Guidelines

For a patient transitioning from inpatient Zosyn (piperacillin-tazobactam) treatment for pneumonia to outpatient therapy with anaerobic coverage, amoxicillin-clavulanate (Augmentin) is a good option, as recommended by the American Thoracic Society and Infectious Diseases Society of America 1. The typical adult dosing is 875 mg/125 mg twice daily for 5-7 days, depending on the severity of the infection and clinical response.

• Amoxicillin-clavulanate provides good coverage against many of the same organisms as Zosyn, including anaerobes, though with a narrower spectrum.
• The clavulanic acid component inhibits beta-lactamase enzymes that would otherwise break down the amoxicillin, making it effective against many resistant organisms. Alternatives include clindamycin (300-450 mg orally every 6-8 hours) if the patient has a penicillin allergy, as suggested in the guidelines for the treatment of pneumonia in Taiwan 1. When transitioning from IV to oral therapy, ensure the patient is clinically improving with decreasing oxygen requirements, resolving fever, and improving symptoms before discharge, as outlined in the diagnosis and treatment of adults with community-acquired pneumonia guidelines 1. Patients should complete the full course of antibiotics even if they feel better before completion to prevent recurrence or development of resistance.
• The American Thoracic Society and Infectious Diseases Society of America recommend amoxicillin-clavulanate as a first-line treatment option for outpatient adults with comorbidities, with a strong recommendation and moderate quality of evidence 1.
• The guidelines also suggest that combination therapy with a macrolide or doxycycline may be considered, depending on the patient's specific needs and risk factors.

From the FDA Drug Label

PIPRACIL is indicated for the treatment of serious infections caused by susceptible strains of the designated microorganisms in the conditions listed below: Intra-Abdominal Infections including hepatobiliary and surgical infections caused by E. coli, Pseudomonas aeruginosa, enterococci, Clostridium spp., anaerobic cocci, or Bacteroides spp., including B. fragilis. Because of its broad spectrum of bactericidal activity against gram-positive and gram-negative aerobic and anaerobic bacteria, PIPRACIL is particularly useful for the treatment of mixed infections and presumptive therapy prior to the identification of the causative organisms

A good outpatient antibiotic to continue the patient on that covers anaerobes is piperacillin (PO), as it has been shown to be effective against anaerobic bacteria, including Bacteroides spp. and anaerobic cocci 2.

• Key points:
  • Piperacillin has a broad spectrum of bactericidal activity against gram-positive and gram-negative aerobic and anaerobic bacteria.
  • It is effective against anaerobic bacteria, including Bacteroides spp. and anaerobic cocci.
  • It can be used as single drug therapy in some situations where normally two antibiotics might be employed.

From the Research

Outpatient Antibiotic Options for Pneumonia

To continue treating a patient with pneumonia after being discharged from the hospital, where they were treated with Zosyn (piperacillin/tazobactam), an antibiotic that covers anaerobes is necessary. The following options can be considered:

• Ceftriaxone, as it can cover oral streptococcus and anaerobes implicated in aspiration pneumonia, and has been shown to be as effective as broad-spectrum antibiotics like piperacillin/tazobactam or carbapenems in the treatment of aspiration pneumonia 3.
• Amoxicillin plus clindamycin, as amoxicillin covers a broad spectrum of bacteria and clindamycin is effective against anaerobes, although the combination of ceftriaxone and clindamycin was less effective than piperacillin/tazobactam in the treatment of early non-ventilator hospital-acquired pneumonia 4.

Key Considerations

When choosing an outpatient antibiotic, consider the following:

• The patient's specific infection and the likely causative pathogens
• The antibiotic's spectrum of activity and ability to cover anaerobes
• The potential for antibiotic resistance and the need to minimize broad-spectrum antibiotic use
• The patient's renal function and potential for adverse effects, such as diarrhea and Clostridium difficile infection, which were more common with piperacillin/tazobactam than with amoxicillin plus temocillin 5

Additional Factors

Other factors to consider when selecting an outpatient antibiotic include:

• The cost of the antibiotic, with ceftriaxone being more economical than broad-spectrum antibiotics like piperacillin/tazobactam or carbapenems 3
• The availability of guidelines and evidence-based recommendations for managing community-acquired pneumonia in the outpatient setting 6