Now that people are increasingly using lactated ringers as the go to resuscitation fluid this issue will arise more frequently. The main concern is with ceftriaxone. Although I have heard mention of problems with other antibiotics I was not able to find any documented issues other than with ceftriaxone. The principal contraindication for concomitant use of LR and ceftriaxone is in neonates. They can be used together in adults but certain precautions apply. Here are two references outlining them  .