Contributions of Molecular Epidemiology to the Understanding of Infectious Disease Transmission, Pathogenesis, and Evolution

Purpose Describe the contributions of molecular genetics to our understanding of the molecular epidemiology of infectious diseases caused by bacteria. Methods Synthesize the literature, highlighting work on Escherichia coli and Group B streptococcus. Results 1) Commensal bacteria are genetically and phenotypically diverse. 2) Disease-causing strains of commensal bacteria often have special characteristics than allow them to be distinguished from common inhabitants. 3) Colonization by commensal bacteria is dynamic. 4) Commensal bacteria are transmitted between individuals. Conclusions Applications of epidemiologic principles to bacterial populations gives insight into the natural history of colonization and transmission in the human host.