Infections: Pathogenesis and Vaccine Development.

is a major causative agent of community-acquired pneumonia which can lead to both acute upper and lower respiratory tract inflammation, and extrapulmonary syndromes. Refractory pneumonia caused by can be life-threatening, especially in infants and the elderly. Here, based on a comprehensive review of the scientific literature related to the respective area, we summarize the virulence factors of and the major pathogenic mechanisms mediated by the pathogen: adhesion to host cells, direct cytotoxicity against host cells, inflammatory response-induced immune injury, and immune evasion. The increasing rate of macrolide-resistant strains and the harmful side effects of other sensitive antibiotics (e.g., respiratory quinolones and tetracyclines) in young children make it difficult to treat, and increase the health risk or re-infections. Hence, there is an urgent need for development of an effective vaccine to prevent infections in children. Various types of vaccines have been reported, including whole-cell vaccines (inactivated and live-attenuated vaccines), subunit vaccines (involving protein P1, protein P30, protein P116 and CARDS toxin) and DNA vaccines. This narrative review summarizes the key pathogenic mechanisms underlying infection and highlights the relevant vaccines that have been developed and their reported effectiveness.