許多婦女朋友為了反覆泌尿道感染困擾，泌尿科醫師常常會建議病人服用蔓越莓製成的健康食品預防發作。不過2016年11 月《美國醫學會期刊》上發表一則臨床試驗，收集了147位住在護理之家的年老女性，隨機分為兩群，一群服用一天兩顆蔓越莓錠（有效成份proanthocyanidin達72毫克，約590毫升的蔓越莓純汁），另一群則使用安慰劑，比較兩者在一年之內發生膿尿與細菌尿，甚至泌尿道感染的次數。結果顯示有服用蔓越莓錠者產生膿尿與細菌尿的比率是29.1%，而服用安慰劑那群則是29.0%，兩者沒有差異。而有症狀的泌尿道感染、住院，或是死亡，在一年內兩者也沒有差異。

這個研究結果可能會讓許多婦女朋友非常緊張，但這只是一個147位患者的研究，一來接受試驗的人數並不夠多，二來對象都是身體較為虛弱者，不一定能夠代表其他婦女朋友的狀況。三來2012年《美國醫學會期刊》的大型研究，收集了10個類似的臨床研究，分析了1494位病人，結果發現蔓越莓還是能夠達到預防泌尿道感染的效果。四來臨床上醫師們也觀察到某些病人服用蔓越蔓後的確有幫助。因此如果服用後沒有不適，經濟又許可，為反覆泌尿道感染所苦的婦女朋友們仍不妨一試；當然不可以把蔓越莓當成預防泌尿道感染的唯一方式：平時多喝水、少憋尿、保持私處的通風清潔、適度的飲用優酪乳補充乳酸菌，也都可以幫助預防泌尿道感染的發生。

Importance
Bacteriuria plus pyuria is highly prevalent among older women living in nursing homes. Cranberry capsules are an understudied, nonantimicrobial prevention strategy used in this population.

Objective
To test the effect of 2 oral cranberry capsules once a day on presence of bacteriuria plus pyuria among women residing in nursing homes.

Design, Setting, and Participants
Double-blind, randomized, placebo-controlled efficacy trial with stratification by nursing home and involving 185 English-speaking women aged 65 years or older, with or without bacteriuria plus pyuria at baseline, residing in 21 nursing homes located within 50 miles (80 km) of New Haven, Connecticut (August 24, 2012-October 26, 2015).

Interventions
Two oral cranberry capsules, each capsule containing 36 mg of the active ingredient proanthocyanidin (ie, 72 mg total, equivalent to 20 ounces of cranberry juice) vs placebo administered once a day in 92 treatment and 93 control group participants.

Main Outcomes and Measures
Presence of bacteriuria (ie, at least 105 colony-forming units [CFUs] per milliliter of 1 or 2 microorganisms in urine culture) plus pyuria (ie, any number of white blood cells on urinalysis) assessed every 2 months over the 1-year study surveillance; any positive finding was considered to meet the primary outcome. Secondary outcomes were symptomatic urinary tract infection (UTI), all-cause death, all-cause hospitalization, all multidrug antibiotic–resistant organisms, antibiotics administered for suspected UTI, and total antimicrobial administration.

Results
Of the 185 randomized study participants (mean age, 86.4 years [SD, 8.2], 90.3% white, 31.4% with bacteriuria plus pyuria at baseline), 147 completed the study. Overall adherence was 80.1%. Unadjusted results showed the presence of bacteriuria plus pyuria in 25.5% (95% CI, 18.6%-33.9%) of the treatment group and in 29.5% (95% CI, 22.2%-37.9%) of the control group. The adjusted generalized estimating equations model that accounted for missing data and covariates showed no significant difference in the presence of bacteriuria plus pyuria between the treatment group vs the control group (29.1% vs 29.0%; OR, 1.01; 95% CI, 0.61-1.66; P = .98). There were no significant differences in number of symptomatic UTIs (10 episodes in the treatment group vs 12 in the control group), rates of death (17 vs 16 deaths; 20.4 vs 19.1 deaths/100 person-years; rate ratio [RR], 1.07; 95% CI, 0.54-2.12), hospitalization (33 vs 50 admissions; 39.7 vs 59.6 hospitalizations/100 person-years; RR, 0.67; 95% CI, 0.32-1.40), bacteriuria associated with multidrug-resistant gram-negative bacilli (9 vs 24 episodes; 10.8 vs 28.6 episodes/100 person-years; RR, 0.38; 95% CI, 0.10-1.46), antibiotics administered for suspected UTIs (692 vs 909 antibiotic days; 8.3 vs 10.8 antibiotic days/person-year; RR, 0.77; 95% CI, 0.44-1.33), or total antimicrobial utilization (1415 vs 1883 antimicrobial days; 17.0 vs 22.4 antimicrobial days/person-year; RR, 0.76; 95% CI, 0.46-1.25).

Conclusions and Relevance
Among older women residing in nursing homes, administration of cranberry capsules vs placebo resulted in no significant difference in presence of bacteriuria plus pyuria over 1 year.