A microbiological version of the Anna Karenina principle is a new paradigm suggested by Dr. Rebecca Vega-Thurber, Dr. Jesse Zaneveld, and Graduate Student Ryan McMinds--one that has key implications for a more personalized approach to antibiotic therapy, management of chronic disease and other aspects of medical care. The principle gets its name from the opening line of the novel Anna Karenina by 19th cetury Russian author Leo Tolstoy: "All happy families are alike; each unhappy family is unhappy in its own way."