The recommendation attaches a relatively high value to avoiding adverse effects of the medication and the development of antibiotic resistance.
A Cochrane review «Duration of antibacterial treatment for uncomplicated urinary tract infection in women»1 «Milo G, Katchman EA, Paul M, Christiaens T, Baerheim A, Leibovici L. Duration of antibacterial treatment for uncomplicated urinary tract infection in women. Cochrane Database Syst Rev 2005 Apr 18;(2):»1 included 32 studies with a total of 9605 subjects. For symptomatic failure rates, no difference between three-day and 5-10 day antibiotic regimen was seen short-term (RR 1.06, 95% CI 0.88 to 1.28) and long-term follow-up (RR 1.09, 95% CI 0.94 to 1.27). Comparison of the bacteriological failure rates showed that three-day therapy was less effective than 5-10 day therapy for the short-term follow-up, however this difference was observed only in the subgroup of trials that used the same antibiotic in the two treatment arms (RR 1.37, 95% CI 1.07 to 1.74, P = 0.01). This difference was more significant at long-term follow-up (RR 1.43, 95% CI 1.19 to 1.73, P = 0.0002). Adverse effects were significantly more common in the 5-10 day treatment group (RR 0.83, 95% CI 0.74 to 0.93, P = 0.0010). Results were consistent for subgroup and sensitivity analyses.
A meta-analysis «Royer S, DeMerle KM, Dickson RP et al. Shorter Versus Longer Courses of Antibiotics for Infection in Hospitalized Patients: A Systematic Review and Meta-Analysis. J Hosp Med 2018;13(5):336-342. »2 included 19 RCTs involving 2867 hospitalized adults and adolescents with infection (e.g. urinary tract infection, pneumonia, and intra-abdominal infection). There was no significant difference in clinical efficacy (d 1.6% , 95% CI -1.0% to 4.2%; 13 trials, n=1727), in microbiologic cure (d 1.2%, 95% CI -4.1% to 6.4%, 8 trials), short-term mortality (d 0.3%, 95% CI -1.2% to 1.8%, 8 trials), longer-term mortality (d -0.4%, 95% CI -6.3% to 5.5%, 3 trials), or recurrence (d 2.1%, 95% CI -1.2% to 5.3%, 10 trials). Heterogeneity across studies was not significant for any of the primary outcomes.
Another systematic review «Dawson-Hahn EE, Mickan S, Onakpoya I et al. Short-course versus long-course oral antibiotic treatment for infections treated in outpatient settings: a review of systematic reviews. Fam Pract 2017;34(5»3 compared the effectiveness of short and long courses of oral antibiotics for infections treated in outpatient settings. There was no difference in the clinical cure for adults treated with short or long course antibiotics for uncomplicated cystitis (3 vs 5 days or longer) in non-pregnant women (RR 1.10, 95% CI 0.96 to 1.25; 32 studies, n=9605), or elderly women (RR: 0.98, 95% CI:0.62, 1.54; 6 studies, n=431); acute pyelonephritis; acute bacterial sinusitis; or community acquired pneumonia. No adequate evidence about the effect on antibiotic resistance was found.