Centers for Disease Control and Prevention, Retired
Consultant, CDC/RDB/Streptococcus Laboratory
My PhD and post-doctoral work centered upon identifying genes required for bacterial cell division and sporulation (1985-1993). During my 28 years at the US Centers for Disease Control and Prevention, I have focused primarily on surveillance of circulating strains of the 3 major streptococcal pathogens, S. pneumoniae, S. pyogenes, and S. agalactiae. Up until about 12 years ago I naively believed that PCR-based detection of sequences specific for pneumococcal capsular serotypes in upper respiratory specimens would also be specific for the pneumococcal species itself. I soon realized that in different pneumococcal carriage surveys that “pneumococcal serotype-specific” PCR amplicons were more commonly indicative of non-pneumococcal species such as Streptococcus mitis, Streptococcus oralis, and Streptococcus infantis that expressed these same serotypes. It is possible that the broad species diversity of capsular serotype expression in the human upper respiratory tract has profoundly affected the global landscape of pneumococcal disease and population immunity. It follows also that analyses of more representatives of pneumococcal cps operons within related streptococcal species might answer questions of the species origins of different serotypes and frequencies of interspecies cps transfer events. The elucidation of the capsular serotype overlap between the Mitis group species is at a very early stage. Here I will summarize some of our findings.

Moderator Of 1 Session

Session Type
Meet-the-Expert Session
Date
Mon, 20.06.2022
Session Time
14:00 - 15:00
Room
Grand Ballroom West
Session Description
In this session we will try to address the question of why S. pneumoniae is a common bacterial pathogen whereas its closest relative S. mitis only rarely causes serious infections, with an emphasis on the role of the capsule.
(1) Describe what we know of the only recently acknowledged capsular serotype overlap between pneumococci and related species in contemporary carriage surveys; discuss potential impact on pneumococcal epidemiology and vaccinology.
(2) Describe and discuss the comparative phenotypes of S. mitis and S. pneumoniae strains expressing capsules of the same serotype.
(3) Further discussion of S. mitis and S. pneumoniae phenotypes relevant for virulence related to genotypic differences.

Please note: All MTE sessions are designed to encourage active learning and to concentrate on close interaction between audience and speakers. The MTE session organisers have provided at least 15 minutes for active discussions in their agenda.

Presenter Of 2 Presentations

Capsular serotype species overlap in carriage; Pneumococcal serotype surveillance practices (ID 952)

Session Type
Meet-the-Expert Session
Date
Mon, 20.06.2022
Session Time
14:00 - 15:00
Room
Grand Ballroom West
Lecture Time
14:05 - 14:13

Cross-species capsular biosynthetic operon comparisons; Lab capsular serology and killing experiments (ID 953)

Session Type
Meet-the-Expert Session
Date
Mon, 20.06.2022
Session Time
14:00 - 15:00
Room
Grand Ballroom West
Lecture Time
14:13 - 14:21