Abstracts (first author)
Mechanisms of balancing selection for antibiotic resistance in Streptococcus pneumoniae
Selection for antibiotic resistance shapes the evolution of many human pathogens, and understanding how resistant phenotypes arise and spread remains a challenge for evolutionary models. Streptococcus pneumoniae, or pneumococcus, is a common asymptomatic colonizer of the human nasopharynx. Over the past few decades, strains of pneumococcus have emerged that are resistant to several major classes of antibiotics. Curiously, the resistant phenotypes appear to be stably coexisting with sensitive strains. Previous models have suggested that such coexistence is unlikely in the absence of implausibly high levels of population structure or intra-strain competition. Here, we use a computational model that explicitly incorporates known mechanisms of immune-mediated competition to evaluate these and other hypotheses. We find an expanded set of scenarios that support balancing selection, several of which may shape the coexistence of resistant and sensitive strains in other species.