In the Keller lab we focus our research on Streptococcus pneumoniae (the pneumococcus). We want to better understand what variations in the gene content of the pneumococcus along with differences in environmental factors that influence interactions with the human host. The pneumococcal pangenome and differences in gene expression greatly influence how the pneumococcus interacts with human tissue. Changes in the local environment; microbiome, antimicrobials, underlying conditions of the host, and contaminants alters the pneumococcal response to the host. Through the use of various in vitro and in vivo models, gene engineering, and microscopy we attempt to understand the underlying mechanism between complex interactions of the pneumococcus, host, and numerous environmental influences.

Establishing an infection requires overcoming not only host defenses but also resident microbes. The Keller lab is interested in how S. pneumoniae colonizes in the presence of other bacteria along with how variations in the populations alter pneumococcal responses. We are also interesting in examining the role microplastics in interspecies interactions with both other bacteria and the host.

Microbiomes and Environmental Impact

Middle Ear Infections

S. pneumoniae is one of the main causes of middle ear infections and can commonly be polymicrobial in nature. It is poorly understood how mixed species infections alter patient outcomes. We are interested in the progression and treatment of mixed species infections of the middle ear and the effects of underlying conditions.


The diversity of the pneumococcal pangenome provides unique opportunities to examine the role of accessory genes in pneumococcal biology. The lab is also interested in examining how small variations, in both core and accessory genome, alter interactions with various host derived proteins and host tissues.

The Keller lab is also interested in understanding novel mechanisms of antibiotic resistance, including noninheritable resistance mechanisms. We approach these resistance mechanisms through examining regulatory processes for gene expression. We are interested in how changes in gene regulation through external signaling process change gene expression and alter resistance susceptibility.

Resistance and Gene Regulation