title: Metabolic acidosis and 5-oxoprolinuria induced by flucloxacillin and acetaminophen: a case report.
abstract: BACKGROUND
  Frequent causes of high anion gap metabolic acidosis are well known: ethanol, methanol, and ethylene glycol intoxication; hyperglycemia; lactic or D-lactic acidosis; and impaired renal function. There are other causes, less frequent but also important. This report illustrates a rare case of a patient with increased anion gap metabolic acidosis due to a deficit of the γ-glutamyl cycle that led to 5-oxoproline (acid pyroglutamic) accumulation.
  
  
  METHODS
  An 82-year-old white woman was admitted to our intensive care unit because of septic shock caused by right knee methicillin-sensitive Staphylococcus aureus-induced arthritis. She was treated for 10 days with flucloxacillin and rifampicin and developed metabolic acidosis with high anion gap. Her test results for methanol, ethanol, ethylene glycol, and acetylsalicylic acid were negative. Her glycemia, lactate level, and renal function were normal. However, the result of a urinary assay for pyroglutamate was positive. We concluded that the patient had metabolic acidosis induced by accumulation of 5-oxoproline. We modified her antibiotic treatment, administered acetylcysteine, and her acidosis resolved.
  
  
  CONCLUSIONS
  5-Oxoprolinuria (pyroglutamic acid accumulation) is a rare, probably underdiagnosed cause of transient metabolic acidosis with increased anion gap.
authors.affiliation: Intensive Care Unit, Centre Hospitalier Universitaire (CHU) de Tivoli, Avenue Max Buset 34, 7130, La Louvière, Belgium. clanoy@ulb.ac.be.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Lanoy
authors.affiliation: Intensive Care Unit, Centre Hospitalier Universitaire (CHU) de Tivoli, Avenue Max Buset 34, 7130, La Louvière, Belgium.
authors.forename: Yves
authors.initials: Y
authors.lastname: Bouckaert
mesh_terms: D000082:Acetaminophen / Q000008:administration & dosage / Q000009:adverse effects*; D000136:Acid-Base Equilibrium / Q000187:drug effects; D000138:Acidosis / Q000097:blood* / Q000139:chemically induced* / Q000188:drug therapy; D000369:Aged, 80 and over; D000592:Amino Acid Metabolism, Inborn Errors / Q000097:blood / Q000188:drug therapy*; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000009:adverse effects*; D001170:Arthritis, Infectious / Q000150:complications / Q000188:drug therapy; D005260:Female; D005436:Floxacillin / Q000008:administration & dosage / Q000009:adverse effects*; D005981:Glutathione Synthase / Q000097:blood / Q000172:deficiency*; D006801:Humans; D007719:Knee Joint; D011761:Pyrrolidonecarboxylic Acid / Q000097:blood*; D012772:Shock, Septic / Q000188:drug therapy / Q000382:microbiology; D013203:Staphylococcal Infections / Q000150:complications / Q000188:drug therapy; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents; D000082:Acetaminophen; D005436:Floxacillin; D005981:Glutathione Synthase; D011761:Pyrrolidonecarboxylic Acid
keywords: Anion gap; Antibiotic therapy; Metabolic acidosis; Pyroglutamic acid; Sepsis