Green tea as an adjunctive therapy for treatment of acute uncomplicated cystitis in women: A randomized clinical trial
Introduction
Urinary tract infections (UTIs) are of the most common infections occurring frequently in both community and hospital settings, and result in high annual healthcare costs [1]. UTIs are known as diseases of females because of sex-based differences in anatomic and physiologic characteristics [2]. The bladder infections in healthy premenopausal and non-pregnant women with normal structure of genitourinary tract are referred to as acute uncomplicated cystitis which is classified as lower UTI. In women, uropatogenic Escherichia coli (E.coli) is the most common cause of uncomplicated UTIs, and it is responsible for 75–95% of these infections [3].
Trimethoprim–sulfamethoxazole (co-trimoxazole) is an inexpensive, well tolerated, and effective antibiotic that has been traditionally used to treat acute uncomplicated cystitis as the first line choice. However, co-trimoxazole resistance among E. coli strains has significantly increased worldwide in recent years. Considering this fact, it is recommended that if the prevalence of co-trimoxazole resistance among E. coli strains is equal to or more than 20% in a region, other first line antimicrobial agents should be chosen [4]. High rate resistance to co-trimoxazole causes poor outcome, increases drug costs, and limits the use of this valuable antibiotic. Also, co-trimoxazole resistance has been related to the emergence of multidrug-resistant uropathogens [5]. Consequently, a new interest is grown to use herbs with antibacterial activity against uropatogenic E. coli to treat acute uncomplicated cystitis and reduce antibacterial resistance [6].
Green tea is a type of tea that is made from non-fermented leaves of the camellia sinensis L. This safe, cheap, available and popular beverage is consumed worldwide, traditionally in Asian countries [6,7]. This ancient plant has various health benefits such as anti-inflammatory, antiarthritic, antibacterial, antiangiogenic, antioxidative, antiviral, and neuroprotective effects [7]. Most of these health beneficial properties of green tea are attributed to its polyphenolic compounds, particularly catechins. The major green tea catechins are (−)-epicatechin (EC), (−)- epicatechin-3-gallate (ECG), (−)-epigallocatechin (EGC), and (−)-epigallocatechin-3-gallate (EGCG) [8,9]. EGC and EGCG have the highest amounts in green tea and also have the greatest antimicrobial effects, but only EGC is excreted in urine [1]. It has been reported that 3.3% of ingested EGC is excreted in urine [9].
Some in vitro studies have shown the antimicrobial effects of catechins against E. coli and also the synergistic effects between catechins and antibiotics such as co-trimoxazole and quinolones against E. coli [6]. Furthermore, it has been proposed that the amount of EGC excreted in urine after ingesting one cup of 7.5 g green tea would be good enough to produce minimum inhibitory concentrations of EGC [1]. To the best of our knowledge, since there has been no human study to investigate the effects of green tea on UTIs, the present study was designed to evaluate the efficacy of green tea as an adjunctive therapy to standard antimicrobial treatment in women with acute uncomplicated cystitis.
Section snippets
Study design, setting, and participants
This randomized, blinded, placebo-controlled trial was conducted in Besat Clinic affiliated to Kerman University of Medical Sciences, Kerman, Iran from August to October 2017. The patients, physician, and outcome assessor were blinded to intervention assignment. The study protocol was approved by the ethical committee of Kerman University of Medical Sciences. In addition, the trial was registered in the Iranian Registry of Clinical Trial (IRCT201506156026N3). All the participants signed an
Results
Among 107 eligible patients, only 70 patients completed this trial. The mean ± SD of the participants' age was 33.91 ± 11.57 years in the placebo group and 30.60 ± 10.58 in the green tea group. No statistically significant difference regarding age was detected between the two groups. The duration of the symptoms before receiving the treatment was 14.49 ± 7.84 days in the placebo group and 10.89 ± 9.05 in the green tea group. Also, there was not any statistically significant difference between
Discussion
The present study demonstrated that green tea as an adjunctive therapy had significant effects on treating acute uncomplicated cystitis in women. This result could be related to antibacterial effects of green tea EGC and its synergistic effects with antibiotics. Different in vitro studies have reported the antimicrobial effects of green tea catechins against E. coli with different mechanisms [1,6,14,15]. In one of these studies, it was found that 99% of the E. coli strains isolated from UTIs
Conclusion
It was concluded that green tea was an effective adjunct to co-trimoxazole to treat acute uncomplicated cystitis in women. However, further studies are required to confirm the results of the present study.
Funding
The authors are thankful to Iran's National Elites Foundation (Tehran, Iran) for providing financial support for this study.
Conflicts of interest
The authors declared that there is no conflict of interest.
Acknowledgements
The authors are grateful to Dr. Mohammad Reza Baneshi for his assistance with the statistical analysis and advice, and to Ehsan Mehrabi Kermani for editing the English text.
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