Matsumoto T, Tanaka M, Ogata N, Mizunoe Y, Takahashi K, Kumazawa J
Department of Urology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
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.
内毒素是革兰氏阴性杆菌（GNR）外膜的一种成分。由于GNR是大多数尿路感染（UTI）的致病菌，我们使用显色内毒素特异性检测法测量了尿液中的内毒素浓度，并研究了其在疑似UTI患者中的诊断效用。在所有18份内毒素浓度超过350 pg/ml的尿液样本以及2份内毒素浓度为10 - 350 pg/ml的样本中，检测到GNR的计数为10(4) cfu/ml。3份革兰氏阳性球菌（GPC）培养阳性的样本、2份含有各种细菌污染物的样本以及所有37份培养无生长的样本，其内毒素检测均为阴性。在抗生素给药5小时后采集的两份尿液样本，GNR培养呈阴性，但内毒素浓度显著。在一项体外实验中，尿液中残留的抗生素浓度抑制了细菌生长，导致培养结果为假阴性。这些结果表明，显色内毒素检测法是诊断由GNR引起的UTI以及检测GNR假阴性培养结果的可靠方法。
