What Is the relationship between Vitamin K & Antibiotics? What is the effect of antibiotics on Vitamin K?

Antibiotics can precipitate Vitamin K deficiency.

There are two natural sources of vitamin K.

Vitamin K1 comes from vegetable and animal sources.

Vitamin K2 is synthesized by enteric bacterial flora and is found in hepatic tissue.

Vitamin K deficiency in adults can be seen with chronic small-intestinal disease, in those with obstructed biliary tracts, after small-bowel
resection, or in those on broad-spectrum antibiotics. As a result of reducing gut bacteria,antibiotics can precipitate vitamin K deficiency.

Expected Clinical scenario-

You are seeing a patient in follow-up 2 weeks after hospitalization. The patient is recovering from nosocomical pneumonia due to a resistant Pseudomonas . His hospital course was complicated by a deep venous thrombosis. The patient is currently on IV piperacillin/ tazobactam and tobramycin via a tunneled catheter, warfarin. Laboratory data this morning show an INR of 8.2. At hospital discharge his INR was stable at 2.5. He has no history of liver disease. What is the most likely cause of the elevated INR?

A. The patient has inadvertently overdosed.
B. The patient has developed a recurrent deep venous thrombosis, which has affected the laboratory data.
C. The patient is deficient in vitamin K and needs supplementation.
D. The warfarin prescription was written incorrectly at the time of discharge.