Sommers D K
S Afr Med J. 1983 Jul 23;64(4):123-6.
The ideal antibacterial drug for urinary tract infections should eliminate most urinary pathogens but not alter the colonic flora. Levels in the urine can be attained with the beta-lactam and aminoglycoside antibiotics which are up to several powers of 10 higher than the minimal inhibitory concentration values of the causative organisms. At these levels even penicillin G eliminates many Gram-negative urinary pathogens. Trimethoprim has a lesser propensity to select resistant organisms than most other antimicrobials. It occurs in vaginal secretions and reduces the number of Enterobacteriaceae surrounding the urethral orifice, thereby diminishing the chance of an ascending reinfection, and it is often effective in the treatment of bacterial prostatitis as it reaches therapeutic concentrations in prostatic secretions. Tetracycline therapy, however, carries a substantial chance of bacterial resistance at the next reinfection of the urinary tract, as these antibiotics produce almost uniform resistance in Escherichia coli in the faecal flora. Failure to respond to single-dose therapy actually implies the presence of antibody-coated bacteria in the urine, which in turn implies an upper tract or prostatic infection. This is an easy means of indicating which patients require further evaluation by intravenous pyelography or cystoscopy.
治疗尿路感染的理想抗菌药物应能清除大多数尿路病原体，但不改变结肠菌群。β-内酰胺类和氨基糖苷类抗生素在尿液中可达到较高浓度，比致病微生物的最低抑菌浓度值高出几个数量级。在这些浓度下，即使是青霉素G也能清除许多革兰氏阴性尿路病原体。与大多数其他抗菌药物相比，甲氧苄啶产生耐药菌的倾向较小。它存在于阴道分泌物中，可减少尿道口周围肠杆菌科细菌的数量，从而降低上行再感染的几率，并且由于它在前列腺分泌物中能达到治疗浓度，所以对细菌性前列腺炎通常有效。然而，四环素治疗会使尿路再次感染时细菌产生耐药性的几率大幅增加，因为这些抗生素会使粪便菌群中的大肠杆菌几乎全部产生耐药性。单剂量治疗无效实际上意味着尿液中存在抗体包裹细菌，这反过来意味着上尿路或前列腺感染。这是一种简便的方法，可用于指示哪些患者需要通过静脉肾盂造影或膀胱镜检查进行进一步评估。
