ABSTRACT
Until 1985, the genus Streptococcus was clubbed with Enterococcus and Lactococcus, which was split into three genera after the publication of Bergy's manual [1]. The first attempt to differentiate streptococci by Shottmuller in 1903 relied on blood agar that distinguishes strains on the basis of their hemolytic capacity. Streptococcus is one of the most common pathogens that causes a spectrum of clinical diseases, ranging from mild, superficial skin infections to severe, life-threatening systemic infections. Among the different strains, some are part of the native niche that are involved in opportunistic infections such as dental caries, and others are exogenous pathogens [2]. Despite being in existence for time immemorial, streptococcal infections, especially those caused by Group A Streptococcus (GAS) remain a significant health problem worldwide [3]. Group B Streptococcus (GBS) mainly targets neonates and colonizes through vertical transmission from the maternal side [4]. Even though an increasing number of streptococcal vaccines are available, many serotypes within the Streptococcus genus are yet to be treated through vaccination [5]. In order to facilitate more effective control of streptococcal infections, further studies are urgently needed in relation to their epidemiology, resistance to antimicrobial agents, and pathogenic mechanism. This chapter focuses on the human pathogenic streptococci and covers (1) classification and morphology, (2) life cycle and epidemiology, (3) infections caused by various streptococcal strains, and (4) vaccine development and the role of genomic and proteomic analyses in guiding the development of safe, efficacious, and broadly protective vaccines.
