A Unique Case of Profound Linezolid-Induced Lactic Acidosis in the Setting of Septic Shock

Introduction: Lactic acidosis is a potentially deadly adverse effect of linezolid therapy. Linezolid-induced lactic acidosis (LILA) can cause confusion in the critical care setting, where lactic acid levels are often used as a marker for hypoperfusion for patients in shock. We present a case of a patient who was admitted with septic shock in the setting of methicillin-resistant Staphylococcus aureus (MRSA) bacteremia and septic arthritis, treated with linezolid. Her course was complicated by a profound lactic acidosis that was disproportionate to the severity of her shock and without any other obvious cause, leading us to a diagnosis of LILA. This case highlights the challenges that LILA can pose in the critical care setting, as well as increase awareness among clinicians of this uncommon but dangerous clinical entity.


Description: A 65 year-old female was transferred from an outside facility where she was diagnosed with MRSA bacteremia in the setting of a right septic shoulder joint and treated with vancomycin. On arrival, she was hypotensive with an initial lactate of 3.2 mMol/L. Due to concern for septic shock and vancomycin treatment failure, linezolid was initiated. Despite adequate resuscitation and stable vasopressor requirements, her lactic acidosis progressively increased. Contrast-enhanced CT imaging of her abdomen was negative for signs of ischemia. Urgent hemodialysis was initiated for acidemia. Lactate levels peaked at 34 mMol/L. Linezolid was suspected to be the cause for lactic acidosis and was discontinued. The patient eventually withdrew from life-sustaining treatment and passed away.


Discussion: LILA is an adverse drug reaction in which 25% of cases result in death. Although early reports linked prolonged therapy with LILA, cases have emerged after short exposure, particularly in critically ill or elderly patients. Distinguishing LILA from septic shock-induced lactic acidosis is challenging but critical. Key clues include disproportionately high lactate that fails to respond to resuscitation, lack of overt perfusion deficits, and exclusion of other causes. In such cases, discontinuing linezolid, along with measures such as hemodialysis, often leads to resolution of LILA. Rapid recognition of LILA is key when it comes to preventing death from acidemia, especially in septic shock.