Woodman A J, Vidic J, Newman H N, Marsh P D
J Med Microbiol. 1985 Feb;19(1):15-23. doi: 10.1099/00222615-19-1-15.
Healthy adult volunteers received either single or repeated 3-g doses of amoxycillin by mouth at weekly intervals on three occasions. The salivary flora of each volunteer was monitored before, during and up to 11 weeks after the final dose of antibiotic. Viable counts of anaerobic bacteria, streptococci and streptococci resistant to amoxycillin 2 mg/L and 40 mg/L were determined in samples of saliva. All 20 volunteers harboured low numbers of streptococci resistant to amoxycillin 2 mg/L (mean count = 6.57 X 10(3) cfu/ml of saliva) before administration of the antibiotic; much lower carriage rates (45%) were observed for bacteria resistant to amoxycillin 40 mg/L (mean count = 116 cfu/ml of saliva). Each dose of amoxycillin had a rapid but transient effect on the numbers of salivary bacteria. A placebo lacking the antibiotic had no effect. A single 3-g dose of amoxycillin had little or no effect on the numbers of resistant streptococci and, therefore, it was concluded that in patients at risk of infective endocarditis a second prophylactic dose would not be invalidated. The numbers of resistant streptococci increased significantly after the second and third doses of amoxycillin, and persisted for 4-7 weeks. Consequently, in at-risk patients requiring repeated dental procedures liable to produce bacteraemia, either alternative antibiotic regimens should be used each time or intervals of at least 4 weeks should be left between treatment sessions.
健康成年志愿者分单次或多次口服3克阿莫西林，每周一次，共三次。在每次服用抗生素前、服药期间以及最后一剂抗生素服用后长达11周的时间里，对每位志愿者的唾液菌群进行监测。测定唾液样本中厌氧菌、链球菌以及对2毫克/升和40毫克/升阿莫西林耐药的链球菌的活菌计数。在使用抗生素前，所有20名志愿者口腔中对2毫克/升阿莫西林耐药的链球菌数量较少（平均计数=6.57×10³cfu/毫升唾液）；对40毫克/升阿莫西林耐药的细菌携带率则低得多（45%）（平均计数=116 cfu/毫升唾液）。每剂阿莫西林对唾液细菌数量都有迅速但短暂的影响。不含抗生素的安慰剂则无此作用。单次3克剂量的阿莫西林对耐药链球菌数量几乎没有影响，因此得出结论，对于有感染性心内膜炎风险的患者，第二次预防性用药不会无效。在第二次和第三次服用阿莫西林后，耐药链球菌数量显著增加，并持续4至7周。因此，对于有风险且需要反复进行易导致菌血症的牙科手术的患者，每次应使用其他抗生素治疗方案，或者治疗间隔至少应留4周。
