Significance of urinary endotoxin concentration in patients with urinary tract infection

Urol Res. 1991;19(5):293-5. doi: 10.1007/BF00299061.


Endotoxin is a component of the outer membrane of gram-negative rods (GNR). Since GNR are responsible for the majority of urinary tract infection (UTI), we measured the concentration of endotoxin in urine using chromogenic endotoxin-specific assay and examined its diagnostic utility in patients with suspected UTI. In all 18 urine samples with an endotoxin concentration exceeding 350 pg/ml and 2 samples with 10-350 pg/ml of endotoxin concentration, GNR were detected at a count of 10(4) cfu/ml. Negative for endotoxin were 3 samples of culture positive for gram-positive cocci (GPC), 2 samples containing various bacterial contaminants and all 37 samples with no growth on culture. Two urine samples collected 5 h after antibiotic dosage showed negative culture for GNR but a significant concentration of endotoxin. In an in vitro experiment, a residual concentration of antibiotic in urine inhibited bacterial growth, leading to a false-negative culture. These results suggest that chromogenic endotoxin assay is a reliable method for diagnosing UTI caused by GNR and detecting false-negative culture of GNR.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Chromogenic Compounds
  • Endotoxins / urine*
  • False Negative Reactions
  • Female
  • Gram-Negative Bacterial Infections / diagnosis
  • Gram-Negative Bacterial Infections / urine*
  • Humans
  • Male
  • Middle Aged
  • Urinary Tract Infections / diagnosis
  • Urinary Tract Infections / microbiology
  • Urinary Tract Infections / urine*


  • Chromogenic Compounds
  • Endotoxins