What is the effectiveness of Zosyn (piperacillin/tazobactam) against Moraxella catarrhalis?

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From the Guidelines

Zosyn (piperacillin-tazobactam) is not the first-line treatment for Moraxella catarrhalis infections, according to the British Thoracic Society guideline for bronchiectasis in adults 1. When considering the treatment of Moraxella catarrhalis infections, it's essential to prioritize the most effective and appropriate antibiotic therapy to minimize morbidity, mortality, and improve quality of life.

Key Considerations

  • The British Thoracic Society guideline recommends amoxicillin with clavulanic acid 625 mg three times a day as the first-line treatment for Moraxella catarrhalis infections 1.
  • Alternative second-line treatments include clarithromycin 500 mg twice daily, doxycycline 100 mg twice daily, or ciprofloxacin 500 mg or 750 mg twice daily 1.
  • Zosyn (piperacillin-tazobactam) is a broad-spectrum antibiotic that may be effective against Moraxella catarrhalis, but it is not listed as a first-line or second-line treatment in the guideline 1.

Treatment Approach

  • For uncomplicated Moraxella catarrhalis infections, narrower-spectrum antibiotics like amoxicillin-clavulanate may be more appropriate first-line choices to minimize antimicrobial resistance development.
  • The duration of treatment typically ranges from 7-14 days, depending on the site and severity of infection.
  • Dose adjustments may be necessary for patients with renal impairment.

Conclusion is not allowed, so the answer will be ended here.

From the FDA Drug Label

Aerobic bacteria Gram-negative bacteria ... Moraxella catarrhalis

Piperacillin and tazobactam has been shown to be active against Moraxella catarrhalis in vitro. The efficacy of piperacillin and tazobactam for injection in treating clinical infections caused by Moraxella catarrhalis has not been established in adequate and well-controlled clinical trials, but at least 90 percent of Moraxella catarrhalis exhibit an in vitro minimum inhibitory concentration (MIC) less than or equal to the susceptible breakpoint for piperacillin and tazobactam 2.

From the Research

Moraxella catarrhalis Overview

  • Moraxella catarrhalis is a human-restricted commensal that has developed into an emerging respiratory tract pathogen over the last two decades 3.
  • It is an exclusively human commensal and mucosal pathogen, recognized as one of the major causes of acute otitis media in children 4.
  • M. catarrhalis is also a well-established trigger of approximately 10% of acute inflammatory exacerbations in adults with chronic obstructive pulmonary disease (COPD) 4.

Antimicrobial Susceptibility

  • The widespread production of a beta-lactamase enzyme renders Moraxella catarrhalis resistant to the penicillins 5.
  • Cephalosporins and beta-lactamase inhibitor combinations, such as Zosyn (piperacillin/tazobactam), are effective for treatment of beta-lactamase producers 5.
  • The organism remains nearly universally susceptible to the macrolides, fluoroquinolones, tetracyclines, and the combination of trimethoprim and sulfamethoxazole 5.

Treatment and Vaccine Development

  • Most strains produce beta-lactamase and are thus resistant to ampicillin but susceptible to several classes of oral antimicrobial agents 6.
  • Recent work has elucidated mechanisms of pathogenesis and focused on vaccine development to prevent otitis media in children and respiratory tract infections caused by M. catarrhalis in adults with chronic obstructive pulmonary disease 6.
  • Promising M. catarrhalis target antigens have been characterized in animal models and should soon enter human clinical trials 7.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Moraxella catarrhalis - pathogen or commensal?

Advances in experimental medicine and biology, 2011

Research

Moraxella catarrhalis: clinical significance, antimicrobial susceptibility and BRO beta-lactamases.

European journal of clinical microbiology & infectious diseases : official publication of the European Society of Clinical Microbiology, 1998

Research

Moraxella catarrhalis, a human respiratory tract pathogen.

Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, 2009

Research

Vaccine targets against Moraxella catarrhalis.

Expert opinion on therapeutic targets, 2016

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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