As far as we know this is the first study conducted to directly assess the potential benefit of AC extracts in the prevention of PCUTIs. Recently published reviews on urinary tract infections management include the use of AC products, but none specifically address postcoital UTI [8–11]. In a systematic review of literature carried out on the use of AC in chronic urinary infections, no studies on postcoital use of AC were found .
AC is a widely used and recommended remedy for prophylaxis of UTI and several clinical trials have documented its efficacy in women with recurrent UTI [4, 13, 14]. AC contains type A proanthocyanidin (PAC) that inhibits adherence, in doing so preventing the colonization of the E. coli uropathogen in the vaginal mucosa and reducing the frequency of bacteriuria, and this effect occurs in a dose dependent manner [15–19].
According to a recent updated Cochrane review , AC juice does not appear to have a significant benefit in preventing UTI, even though on a prior update it appeared that there was some evidence that AC juice may decrease the number of symptomatic UTIs over a 12 month period, particularly for women with recurrent UTIs . However, the update recommended more studies to evaluate AC products such as tablets or capsules on women with recurrent UTIs (20). In a randomized controlled trial in elderly women to compare the efficacy in preventing UTI of AC capsules versus trimethoprim in preventing UTI, there were no significantly differences between groups concerning time to first recurrence of UTI, and trimethoprim had a very limited advantage over AC in the prevention of recurrent UTI in older women, but had more adverse effects and withdrawals . In the elderly population there was only one clinical trial with asymptomatic bacteriuria, which showed that bacteriuria and pyuria were significantly reduced in women taking AC juice in comparison with women who received placebo . Several meta-analyses have established that recurrence rates over 1 year are reduced approximately 35% in young to middle-aged women .
The results of the present study confirmed the efficacy of Cys as previously described, with a significant decrease of 75% in the number of PCUTIs after 3 months of Cys intake, until 93% after 6 months. Although the composition of effective AC products and its dosage in UTI prophylaxis have not yet been defined, 13 it has been demonstrated that AC extract containing higher doses of PACs produce a greater benefit  and a dose of 118 mg/day of PACs has demonstrated a significant efficacy in different clinical trials with Cys .
The current management of recurrent UTI involves repeated courses of antibiotics or subtherapeutic, long-term antibiotic prophylaxis . However, adverse effects are common with these treatments, as well as increasing antibiotic resistance . The increasing prevalence of E. coli isolates (the most common uropathogen) that are resistant to antimicrobial agents, together with the high costs of antibiotic treatments, have stimulated interest in novel non-antibiotic methods for the prevention of UTI . Given the reduction of the number of antibiotic treatments per patient with the use of Cys, as demonstrated by the results of the present study, this should theoretically decrease occurrence of microbial resistance.
Prevention of recurrent UTIs includes early postcoital voiding habits [29, 30]. In fact, the American College of Obstetricians and Gynecologists District II NYS recommends urinating after sexual intercourse to prevent recurrent cystitis. Nevertheless, there is no proven association between recurrent UTIs and pre or postcoital voiding patterns, frequency of urination, wiping patterns, douching, use of tight undergarments, or delayed voiding habits [31, 32]. The results from the present study showed increasing urinating habits before and after sexual intercourse of approximately 20% already after 3 months of AC extract daily intake. Furthermore, as there were no changes in vaginal hygiene during the study, the improvement seen in PCUTIs was mainly attributable to Cys daily intake.
One issue for discussion is the pattern of treatment to be administered. We decided a treatment of 3 days simulating the guidelines of antibiotic treatment in PCUTI . However, based on the dose dependent effect of PAC and previous experience with antibiotic profilaxis in PCUTI, we suspect that the administration of higher doses in a shorter interval of time should be equally effective.
Urinary tract infections have an detrimental impact on patients QoL [34, 35]. Although uncomplicated UTI in women is considered to be a relatively benign and self-limiting condition, it is responsible for significant symptomatology, morbidity and loss of QoL and causes unnecessary suffering, affecting patient’s daily activities, social functioning and wellbeing, and sexual intercourse which, is not satisfactory . Consequently, a decrease of recurrent symptomatic infections should relate to an increase of QoL. In the present study we use a VAS score to assess QoL. Although not a standardized method for assessing QoL, we selected it for its simple completion and interpretation. There was a significant increase of 20% in the QoL evaluation related to the decrease found in the mean number of PCUTIs in which patients had taken antibiotics after 6 months of Cys daily intake.
Finally, in the present study there was a significant reduction of patients with symptomatic infections after 3 months and again after 6 months. It should be taken into account that urine cultures were only carried out in presence of PCUTIs, therefore the high percentage of women with culture not done should be considered as a treatment success. Thus Cys improves QoL decreasing infections derived from sexual intercourse. Further studies are needed to confirm results obtained in this pilot study.
The use of AC products appears to be safe. The present study confirmed the safe profile of Cys as there were no adverse events at all. Prophylaxis of Cys seems to be a promising option to decrease the number of PCUTIs and therefore increase QoL.
The results of this pilot study are not significant due to the short follow-up period and the limited number of patients. We believe is needed a randomized placebo controlled study with at least 50 patients and follow up should be one year. However, over longer periods of time changes in sexual habits, contraception methods, or regular partner can occur, which may invalidate the study.