From the Guidelines
Moraxella catarrhalis infections should be treated with amoxicillin with clavulanic acid 625 mg three times a day for 14 days as the first-line treatment, according to the British Thoracic Society guideline for bronchiectasis in adults 1. When considering treatment options for Moraxella catarrhalis, it is essential to note that nearly all strains produce beta-lactamase, making them resistant to amoxicillin alone. The addition of clavulanic acid, a beta-lactamase inhibitor, is necessary to effectively treat the infection. Some key points to consider when treating Moraxella catarrhalis infections include:
- The importance of using amoxicillin with clavulanic acid as the first-line treatment, due to its effectiveness against beta-lactamase producing strains 1.
- Alternative treatment options, such as clarithromycin, doxycycline, or ciprofloxacin, can be considered for patients who are allergic to penicillin or have other contraindications to amoxicillin with clavulanic acid 1.
- The duration of treatment is typically 14 days, as recommended by the British Thoracic Society guideline for bronchiectasis in adults 1.
- It is crucial to be aware of potential resistance patterns and adjust treatment accordingly, as well as to consider the patient's individual needs and medical history when selecting an antibiotic regimen. In terms of specific treatment regimens, the British Thoracic Society guideline recommends:
- Amoxicillin with clavulanic acid 625 mg three times a day for 14 days as the first-line treatment 1.
- Clarithromycin 500 mg twice daily, doxycycline 100 mg twice daily, or ciprofloxacin 500 mg or 750 mg twice daily as alternative treatment options 1.
From the Research
Overview of Moraxella catarrhalis
- Moraxella catarrhalis is a human respiratory tract pathogen that causes various infections, including otitis media and acute exacerbations of chronic bronchitis 2
- It is an exclusively human pathogen and is a common cause of otitis media in infants and children, causing 15%-20% of acute otitis media episodes 2
Antimicrobial Resistance
- The prevalence of ampicillin-resistant Moraxella catarrhalis has been reported to be high, with 97.7% of isolates resistant in Taiwan in the 1990s 3
- A study in 1997 found that 71.3% of Moraxella catarrhalis isolates produced beta-lactamase(s), and 56,32, and 1 isolates were resistant to penicillin G, ampicillin, and cotrimoxazole, respectively 4
- Another study in 2012 found that 97.8% of Moraxella catarrhalis isolates were beta-lactamase-producing, and all isolates were susceptible to amoxicillin + clavulanate, chloramphenicol, cefixime, ciprofloxacin, erythromycin, levofloxacin, moxifloxacin, and roxithromycin 3
Antibiotic Susceptibility
- Moraxella catarrhalis isolates have been found to be susceptible to various antibiotics, including amoxicillin-clavulanate, doxycycline, clarithromycin, cefuroxime, levofloxacin, and trimethoprimsulfamethoxazole 5
- A study in 2014 found that all 117 clinical Moraxella catarrhalis isolates tested were sensitive to amoxicillin-clavulanate, doxycycline, clarithromycin, levofloxacin, and trimethoprimsulfamethoxazole, with one isolate being intermediately resistant to cefuroxime 5
- Cefaclor has been found to be effective in the treatment of upper and lower respiratory tract infections caused by Moraxella catarrhalis, with 86% of patients showing improvement in symptoms 6
Treatment and Prevention
- Amoxicillin + clavulanate is considered the antimicrobial therapy of choice for Moraxella catarrhalis infections 3
- Continued surveillance of antimicrobial susceptibility and application of control measures against further transmission are required to inhibit the emergence of resistant strains 3
- Recent work has focused on vaccine development to prevent otitis media in children and respiratory tract infections caused by Moraxella catarrhalis in adults with chronic obstructive pulmonary disease 2