We do theoretical and empirical studies of the population biology and evolution of bacteria and their accessory genetic elements and the population dynamics, evolution, and control of infectious disease. Our theoretical work involves the development and analysis of the properties of mathematical and computer simulation models. Our empirical studies include experiments with laboratory populations (chemostat and serial transfer culture) of bacteria (primarily, but not exclusively E. coli) and their plasmids, phage, and transposons. We also do studies of bacteria and their plasmids and phage isolated from natural populations.

Currently, the students, postdocs, and technician working with me and me, when I am lucky, (the "we" in this description) are engaged in 10 distinct projects. The majority of these investigations are concerned with the population biology of bacterial infections and their control by the immune response and antibiotics: (1) the within-host population dynamics of bacterial sepsis, (2) the within-host population dynamics of the control of bacterial infections with single and multiple antibiotics, (3) the fitness cost of chromosomal antibiotic resistance (streptomycin and rifampicin) and the population genetics and molecular biology of compensation for those costs (primarily by second-site mutations), (4) the between-host population genetics and epidemiology of antibiotic resistance, (5) the evolution of multiple antibiotic resistance plasmids. We are also engaged in a study of (6) the population dynamics of temperate bacteriophage and the evolution of lysogeny, (7) the population genetics and conditions for the evolution of mutator genes, and (8) the effect of generation time on the rate of base substitution mutation. All of the above investigations have empirical as well as theoretical components and the study of the epidemiology of antibiotic resistance includes a survey of the distribution of antibiotic resistance in the enteric bacteria of children in a daycare center. Finally, we are engaged in two purely theoretical studies: (9) the within-host population dynamics and pathogenesis of HIV/AIDS, and (10) the between host population dynamics (epidemiology), evolution, and control (by treatment and vaccination) of HIV and other long-term microparasite infections.