Moraxella catarrhalis VIRULENCE FACTORS: FROM LOS TO Β -LACTAMASES, VACCINE TARGETS AND RESISTANCE MECHANISMS

Moraxella catarrhalis is a Gram-negative diplococcus that causes lower respiratory tract infections in adults and immunocompromised individuals, as well as otitis media in children. Numerous virulence factors associated with M. catarrhalis have been identified. These factors include widely distributed surface lipooligosaccharides (LOS), outer membrane proteins (UspA1, UspA2, UspA2H, OmpCD, Hag/MID, and McaP), type IV pili, biofilm production, iron acquisition systems (CopB, TbpB, LbpB), and β-lactamase production. These structures and systems have been shown to play a critical role in adhesion to epithelial cells, evasion of the immune system, and antibiotic resistance. The prevalence of the LOS A serotype, along with the functional capabilities of the outer membrane proteins UspA1 and PilA to promote adhesion and immune stimulation, make these structures important targets in vaccine development studies. The capacity for biofilm formation and the presence of β-lactamases genes such as bro-1 increase antibiotic resistance, thereby complicating treatment. Recent studies have reported that up to 100% of isolates produce β-lactamases. Iron acquisition systems play a vital role in binding to target cells, protecting against environmental stressors, and bacterial survival. This article provides fundamental information on virulence factors and their potential targets for vaccine development, as well as treatment strategies focusing on high antibiotic resistance and biofilms.