Table 1.

Uropathogens tested for causing falsely low or false-negative EtG or EtS results as a result of hydrolysis by bacterial β-glucuronidase and sulfatase.

Uropathogen identifiedUrine specimens tested, nSpecimens causing hydrolysis of EtG,1 n (%)Specimens causing hydrolysis of EtS,1 n
E. coli2517 (68)20
Enterococcus sp.50 (0)0
Group B streptococci30 (0)0
K. pneumoniae31 (33)30
Proteus mirabilis20 (0)0
Pseudomonas aeruginosa20 (0)0
Staphylococcus saprophyticus20 (0)0
Citrobacter freundii10 (0)0
E. cloacae11 (100)30
E. aerogenes10 (0)0
Morganella morganii10 (0)0
  • 1 EtG and EtS (1 mg/L of each) were added to fresh UTI specimens, which were then stored in sealed plastic vials (without preservative) at 22 °C for 1–5 days, after which EtG and EtS were measured by LC-MS.

  • 2 Bacterial count, 103 to >105 CFU/mL.

  • 3 Bacterial count, >105 CFU/mL.