The Other Siblings: Respiratory Infections Caused by Moraxella catarrhalis and Haemophilus influenzae Larry Lutwick, MD, and Laila Fernandes, MD Corresponding author Moraxella catarrhalis Larry Lutwick, MD Infectious Diseases (IIIE), VA Medical Center, 800 Poly Place, Bacteriology Brooklyn, NY 11219, USA. M. catarrhalis is a Gram negative, aerobic diplococcus E-mail:
[email protected] that was initially described by Anton Ghon and Rich- Current Infectious Disease Reports 2006, 8:215–221 ard Pfeiffer as Micrococcus catarrhalis at the end of the Current Science Inc. ISSN 1523-3847 19th century. For most of the first century of its rec- Copyright © 2006 by Current Science Inc. ognition, M. catarrhalis is considered to be a human mucosal commensal organism based on its common finding as an inhabitant of the oropharynx of healthy Respiratory infections remain substantial causes of mor- adults. During a significant amount of this time, based bidity and mortality globally. In this paper, two substantial on phenotypic characteristics as well as microbiologic players in bacterial-associated respiratory disease are colony appearances, the diplococcus was referred to assessed as to their respective roles in children and adults as Neisseria catarrhalis. Of note, in 1963, N. catarrhalis and in the developed and developing world. Moraxella was found to contain two distinct species, catarrhalis catarrhalis, although initially thought to be a nonpathogen, and cinerea [1]. continues to emerge as a cause of upper respiratory Reclassification of the genus of this microorganism disease in children and pneumonia in adults. No vaccine occurred in 1970 when significant phylogenetic dispari- is currently available to prevent M.