This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diabetes Mellitus, Subject name: Medicine
A diabetic normotensive patient of Enterococcus faecalis sepsis, on intravenous Linezolid developed high anion gap metabolic acidosis with increased serum lactate and negative ketone. The acid base abnormality is most probably? 
Select and explain. 
A. Type A lactic acidosis due to septic shock, B. Metabolic acidosis of unceain etiology, C. Diabetic ketoacidosis, D. Type B lactic acidosis due to linezolid
D: Type B lactic acidosis due to linezolid
Answer: D: Type B lactic acidosis due to linezolid 
Explanation: The given case is of high anion gap metabolic acidosis with increased serum lactate and negative ketones. This rules out choice B and C. Lactic acidosis of type A variety occurs due to poor tissue perfusion and occurs due to Shock or cardiac failure Severe Anemia Mitochondrial enzyme defects Carbon monoxide poisoning, Cyanide poisoning Lactic acidosis of type B occurs due to Malignancies Diabetes Mellitus Renal or hepatic failure Thiamine deficiency Severe Infections (Cholera, Malaria) Seizures Drugs/toxins (biguanides, ethanol, methanol, propylene glycol, isoniazid, and fructose and Nucleoside analogue reverse transcriptase inhibitors in HIV and linezolid) Extra edge Enterococcus Endocarditis E. faecalis >>E.faecium Resistant to many antimicrobial agents Rx--Combination of b-lactam antibiotics with aminoglycoside -Synergistic and bactericidal effects