Moraxella catarrhalis

Moraxella catarrhalis is a gram-negative, aerobic, oxidase-positive diplococcus which may both colonise and cause respiratory tract-associated infection in humans.

Moraxella catarrhalis is a gram-negative, aerobic, oxidase-positive diplococcus which may both colonise and cause respiratory tract-associated infection in humans.

M. catarrhalis was previously placed in a separate genus named Branhamella. The rationale for this was that other members of the genus Moraxella are rod-shaped and rarely caused infections in humans. However results from DNA hybridization studies and 16S rRNA sequence comparisons were used to justify inclusion of the species catarrhalis in the genus Moraxella. Consequently, the name Moraxella catarrhalis is currently preferred for these bacteria. Nevertheless, some in the medical field continue to call these bacteria Branhamella catarrhalis.

Clinically, these bacteria are known to cause bronchitis, sinusitis, laryngitis and otitis media. Elderly patients and long-term heavy smokers with chronic pulmonary disease should be aware that M. catarrhalis is associated with bronchopneumonia, as well as exacerbations of existing chronic obstructive pulmonary disease (COPD).

Treatment options include antibiotic therapy or a so-called “watchful waiting” approach. The great majority of clinical isolates of this organism produce beta-lactamases and are resistant to penicillin, with some suggestion of trimethoprim resistance in certain regions of the world. It is susceptible to trimethoprim-sulfamethoxazole (TMP-SMZ), fluoroquinolones, and most second and third generation cephalosporins. In addition, M. catarrhalis infection may be treated with erythromycin and amoxicillin-clavulanate (Augmentin®).

The peak rate of colonisation by M. catarrhalis appears to occur at approximately 2 years of age, with a striking difference in colonisation rates between children and adults (very high to very low).

Current research priorities involve trying to find a suitable vaccine for this genotypically diverse organism, as well as determining factors involved with virulence e.g. complement resistance.

• Moraxella catarrhalis treatment ^[1]

• Preferred regimen(1): TMP-SMX 1DS PO bid
• Preferred regimen(2): Erythromycin 500 mg PO qid
• Preferred regimen(3): Clarithromycin 500 mg PO bid or XL 1 g PO qd
• Preferred regimen(4): Azithromycin 500 mg PO single dose THEN 250 mg PO qd
• Preferred regimen(5): Doxycycline 100 mg PO/IV bid/q12h
• Preferred regimen(6): Cefprozil 200-500 mg PO bid
• Preferred regimen(7): Cefpodoxime 200-400 mg PO bid
• Preferred regimen(8): Cefuroxime 250-500 mg PO bid
• Preferred regimen(9): Cefdinir 300 mg PO bid
• Preferred regimen(10): Moxifloxacin 400 mg IV/PO qd
• Preferred regimen(11): Levofloxacin 500 mg IV/PO qd
• Preferred regimen(12): Amoxicillin clavulanate 875/125 mg PO bid or XL 2000/125 PO bid

• Murray, P (2005). Medical Microbiology (5th ed. ed.). Mosby. pp. p. 365. ISBN 0-323-03303-2. Unknown parameter |coauthors= ignored (help)CS1 maint: Extra text (link)

• Tierney, L.; et al. (October 19, 2005). Current Medical Diagnosis and Treatment (45th ed. ed.). McGraw Hill Medical. pp. p. 1501. ISBN 0-07-145410-1.CS1 maint: Explicit use of et al. (link) CS1 maint: Extra text (link)

Template:WikiDoc Sources