All authors read and approved the final manuscript.”
“Background Moraxella catarrhalis, formerly known as both Neisseria catarrhalis and Branhamella

catarrhalis [1], is a gram-negative bacterium that can Fludarabine chemical structure frequently be isolated from the nasopharynx of healthy persons [2–4]. For many years, M. catarrhalis was considered to be a harmless commensal [1–4]. About twenty years ago, it was acknowledged that M. catarrhalis was a pathogen of the respiratory tract [5], and since then much evidence has accumulated which indicates that M. catarrhalis causes disease in both adults and children. M. catarrhalis is one of the three most important causes of otitis media in infants and very young children [3, 6]. In adults, this bacterium can cause infectious exacerbations of chronic obstructive pulmonary disease (COPD), and one recent study estimates that, in the United GDC-0994 cost States alone, M. catarrhalis

may cause 2 million-4 million infectious exacerbations of COPD annually [7]. The ability of M. catarrhalis to colonize the mucosa of the upper respiratory tract (i.e., nasopharynx) is undoubtedly linked to its expression of different adhesins for various human cells and antigens [8–15]. In addition, this bacterium clearly has the metabolic capability to survive and grow in this environment in the presence of the normal flora. A recent study [16] identified a number of different metabolic pathways encoded by the M. catarrhalis ATCC 43617 genome which could be involved in the colonization process. It is likely that M. catarrhalis forms a biofilm in concert with these Adriamycin solubility dmso other bacteria in the nasopharynx [17], although only a few M. catarrhalis gene products relevant to biofilm formation have been identified to date [13, 18, 19]. Similarly, there is little known about what extracellular gene products are synthesized by M. catarrhalis and released into the extracellular milieu. A study from Campagnari and colleagues [15] found that one or

two very large proteins with some similarity to the filamentous hemagglutinin (FhaB) of Bordetella pertussis could be found in M. catarrhalis culture supernatant fluid. Using the nucleotide sequence of the genome of M. catarrhalis ATCC 43617, Murphy and ADAM7 co-workers [20] identified a large number (i.e., 348) of proteins that had signal sequences, among which may be proteins that are released from the M. catarrhalis cell. Another group showed that M. catarrhalis culture supernatant fluid contained several different proteins as detected by SDS-PAGE analysis, but the identity of the individual proteins was not determined [21]. In the present study, we report the first identification of a bacteriocin that is produced by M. catarrhalis. Bacteriocins are proteins or peptides secreted or released by some bacteria that can effect both intraspecies and interspecies killing, and are responsible for some types of bacterial antagonism [for reviews see [22, 23]].