Thursday, January 14, 2010
Molecular epidemiology of group B Streptococcus
(Conferences / Seminars / Lectures)
The application of molecular evolutionary analyses sequencing data has revealed important findings about the genetic diversity, population structure and variation in virulence among bacterial pathogen populations. Evolutionary analyses have also been applied to epidemiological data to better understand pathogenesis and identify bacterial genotypes associated with disease. Such principles have only recently been applied to group B Streptococcus (GBS), a leading cause of sepsis and meningitis in newborn babies and of varying complications in pregnant women and the elderly with underlying medical conditions. Over time, there have been shifts in the GBS serotype distribution associated with invasive disease and noted increases in antibiotic resistance and asymptomatic colonization frequencies, and incidence of GBS disease in nonpregnant adult and elderly populations. GBS is also a major pathogen of bovines and has been isolated from many other animal species; the transmission dynamics, however are not clear. Genotyping data from bovine and human strains have demonstrated clustering of strains from each source and a subset of overlapping genotypes in both populations, suggesting that some genotypes may be more readily transmitted and better adapted for survival in multiple hosts. More importantly, one GBS genotype (multilocus sequence type (ST)-17) has been shown to disproportionately affect neonates, have enhanced invasiveness, and more frequently cause meningitis; this genotype was also demonstrated to have originated from bovines. While the pathogenic mechanisms behind ST-17-mediated human disease are not known, ST-17 strains and close relatives have distinct virulence gene profiles and were more likely to persist in women before and after antibiotic treatment, indicating an ability to escape antimicrobial action. This talk will highlight how molecular methods and analytical tools have been used to examine epidemiological data to better understand GBS colonization and neonatal disease pathogenesis, and how this methodology can be easily applied to study any infectious disease agent. Presented by Shannon Manning, Ph.D. of Michigan State University's Department of Pediatrics and Human Development as part of the Department of Epidemiology's Spring Seminar Series. more information...