[PDF][PDF] Multiple adhesins of streptococci
DL Hasty, I Ofek, HS Courtney, RJ Doyle - Infection and immunity, 1992 - journals.asm.org
DL Hasty, I Ofek, HS Courtney, RJ Doyle
Infection and immunity, 1992•journals.asm.orgHuman streptococcal isolates are confronted with numerous environmental challenges, one
of which is the necessity that they adhere to one or more of the varied mucosal surfaces of
the oropharyngeal cavity between their point of entry into the host and the site where
physiological condi-tions favor colonization. They interact with buccal cells, tonsillar cells,
salivary constituents, and dental pellicles and with other bacteria and their products. To
maintain them-selves in these environments, the streptococci must be able to interact with …
of which is the necessity that they adhere to one or more of the varied mucosal surfaces of
the oropharyngeal cavity between their point of entry into the host and the site where
physiological condi-tions favor colonization. They interact with buccal cells, tonsillar cells,
salivary constituents, and dental pellicles and with other bacteria and their products. To
maintain them-selves in these environments, the streptococci must be able to interact with …
Human streptococcal isolates are confronted with numerous environmental challenges, one of which is the necessity that they adhere to one or more of the varied mucosal surfaces of the oropharyngeal cavity between their point of entry into the host and the site where physiological condi-tions favor colonization. They interact with buccal cells, tonsillar cells, salivary constituents, and dental pellicles and with other bacteria and their products. To maintain them-selves in these environments, the streptococci must be able to interact with different receptors on the distinct surfaces (5, 6, 31). It is not surprising, therefore, that evolutionary pressures would select organisms that are genetically capa-ble of producing more than one class or type of adhesin. Indeed, the concept of multiple adhesins has been recog-nized for over 20 years for gram-negative bacteria, especially members of the family Enterobacteriaceae (27). There is, in fact, no need to bring attention to the concept of multiple adhesins in gram-negative bacteria, so widespread is its acceptance (32). The concept of multiple steps in the process of adhesion has also been proposed for gram-negative bac-teria, such as enteropathogenic Escherichia coli (46) and Mycoplasma pulmonis (51). However, it was more recently that a sufficient body of data accumulated to suggest that similar to gram-negative bacteria, gram-positive bacteria also express multiple adhesins and, further, that the adhesins probably function in distinct kinetic steps. While these are not new concepts, they are not yet widely recognized or accepted for streptococci. It is these concepts that we wish to address, primarily with respect to human streptococcal isolates. For illustration, we shall focus on two streptococcal species that inhabit different niches ofthe upper respiratory tract. One, Streptococcus sanguis, colonizes the tooth sur-face, and the other, Streptococcus pyogenes, colonizes the pharynx and tonsils. We will attempt to marshall the evidence for the expression of multiple adhesins in these species (and perhaps other gram-positive cocci) and develop a general model to explain how multiple adhesins may function to confer an advantage in the colonization of hard and soft tissues.
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