Department of Biomedical Sciences, Oakland University William Beaumont School of Medicine Rochester, MI, USA.
Front Microbiol. 2013 Jun 18;4:162. doi: 10.3389/fmicb.2013.00162. eCollection 2013.
Urinary tract infections (UTIs) are a very most common type of infection worldwide, and result in billions of dollars in medical care costs. Escherichia coli is the infective agent for 80-90% of all UTIs. Green tea, derived from leaves of the Camellia sinensis plant has been shown to have various potential health benefits (e.g., cardiovascular disease and cancer). The major beneficial components of green tea have been characterized, and are now known to be polyphenolic catechins. The main catechins in green tea are (-)-epicatechin-3-gallate, (-)-epigallocatechin (EGC), (-)-epicatechin, and (-)-epigallocatechin-3-gallate (EGCG). EGCG and EGC have been shown to have the greatest antimicrobial effects, but only EGC has been shown to be excreted in urine. Isolates of E. coli from UTIs collected between 2007 and 2008 were characterized for antimicrobial resistance to standard drugs. Then 80 of these isolates, representing a wide spectrum of antimicrobial susceptibility patterns, were selected for testing using an extract of green tea.
The concentrations of green tea extract tested were 0, 2.5, 3.0, 3.5, and 4.0 mg/ml. All of the strains tested, except one, had minimum inhibitory concentrations (MICs) of ≤4.0 mg/ml (99%), with 94% of the isolates having an MIC of ≤3.5 mg/ml, 76% of the isolates having an MIC of ≤3.0 mg/ml, 40% of the isolates having an MIC of ≤2.5 mg/ml. Two control strains varied in susceptibility, one having an MIC of ≤2.5 mg/ml,and the other having an MIC of ≤3.5 mg/ml.
Since EGC has been shown to have antimicrobial effects on E. coli, and EGC has been shown to be excreted in the urine in a high enough concentration to potentially be effective as an antimicrobial; these MIC results suggest that ingesting green tea could have potential antimicrobial effects on UTIs caused by E. coli.
尿路感染（UTIs）是全球非常常见的一种感染类型，导致数十亿美元的医疗费用。大肠杆菌是 80-90%的所有 UTIs 的感染源。绿茶来源于茶树的叶子，已被证明具有多种潜在的健康益处（例如，心血管疾病和癌症）。绿茶的主要有益成分已经被描述出来，现在已知是多酚类儿茶素。绿茶中的主要儿茶素是（-）-表没食子儿茶素-3-没食子酸酯、（-）-表儿茶素（EGC）、（-）-表儿茶素和（-）-表没食子儿茶素-3-没食子酸酯（EGCG）。EGCG 和 EGC 已被证明具有最大的抗菌作用，但只有 EGC 已被证明在尿液中排泄。从 2007 年至 2008 年收集的 UTI 大肠杆菌分离株的特征在于对标准药物的抗菌耐药性。然后，从 80 个具有广泛抗菌敏感性模式的分离株中选择了代表，用于使用绿茶提取物进行测试。
测试的绿茶提取物浓度为 0、2.5、3.0、3.5 和 4.0mg/ml。除了一个，所有测试的菌株的最低抑菌浓度（MIC）均≤4.0mg/ml（99%），94%的分离株的 MIC 为≤3.5mg/ml，76%的分离株的 MIC 为≤3.0mg/ml，40%的分离株的 MIC 为≤2.5mg/ml。两种对照菌株的敏感性不同，一种的 MIC 为≤2.5mg/ml，另一种的 MIC 为≤3.5mg/ml。
由于 EGC 已被证明对大肠杆菌具有抗菌作用，并且 EGC 已被证明在尿液中排泄的浓度足以有效地作为一种抗菌剂；这些 MIC 结果表明，摄入绿茶可能对由大肠杆菌引起的 UTI 具有潜在的抗菌作用。
