<qa>  What is a 3rd generation cephalosporin that exposes the intestinal microSelection of resistant bacteria within the microbiota constitutes the main mechanism for the emergence and the diffusion of bacterial resistance to antibiotics. Ceftriaxone is a 3rd generation cephalosporin that exposes the intestinal microbiota to an important selecting pressure, due to its high biliary clearance. It is thereby suspected to have an important role in the emergence of resistance of enterobacteria to 3rd generation cephalosporins. Its pharmacokinetics features allow a once daily administration, and it is more largely used than cefotaxime, which requires ter in die injections but whose mainly urinary elimination suggest a lower impact on the intestinal microbiota. 