Enterococcus faecalis

Enterococcus faecalis has refined horizontal gene transfer into something approaching a marketplace. While E. coli exchanges genes somewhat randomly through conjugation, E. faecalis uses pheromone signaling to identify specific partners carrying desirable genetic cargo. Recipient cells release small peptide pheromones that diffuse through the environment. Donor cells carrying conjugative plasmids detect these signals and respond by expressing surface adhesins that enable cell-to-cell contact and DNA transfer. It's bacterial classified advertising: recipients broadcast what they're looking for, and donors with matching offerings respond.

This precision has consequences. E. faecalis transfers antibiotic resistance genes with remarkable efficiency, spreading vancomycin resistance through hospital populations with alarming speed. The pheromone system ensures that transfers occur preferentially between cells where the recipient actually needs the genes—cells already carrying a particular plasmid don't broadcast for it. This prevents wasteful transfers and accelerates the spread of novel resistance genes through susceptible populations.

E. faecalis also demonstrates extraordinary environmental resilience. It survives bile salts, detergents, heavy metals, and extreme temperatures that kill most bacteria. This hardiness enables persistence on hospital surfaces, medical equipment, and in the environment, creating reservoirs for ongoing transmission. The bacterium's strategy combines robust survival infrastructure with sophisticated information exchange—it's built to last and built to learn. For healthcare systems, E. faecalis represents an adversary that combines cockroach-like persistence with internet-like connectivity.