Which of the following statements about the biodisposition of penicillins and cephalosporins is NOT accurate?

* Probenecid inhibits renal tubular secretion of penicillins (not reabsorption) * Beta lactams eliminated by biliary route are: -- Ampicillin -- Nafcillin -- Ceftriaxone -- Cefoperazone * Penicillin G has to be given by i.m. route because it is broken down by gastric acid (decreases oral bioavailability).