The effects of cranberries on preventing urinary tract infections in dogs

Abstract

小動物的泌尿道感染是一種很常見的問題，一般來說，雌性會較雄性好發。最普遍造成泌尿道感染的病原是細菌，其中又以大腸桿菌最為常見。大腸桿菌具有線毛，可使其黏附至泌尿道黏膜上皮。許多研究指出，蔓越莓或其製品可破壞細菌的黏附，因此可避免感染的發生。雖然在人已有相當多的研究證實蔓越莓可有效預防泌尿道的感染，但在狗，這方面的研究卻非常少。因此，此篇研究擬探討蔓越莓對預防犬泌尿道感染的效果為何。此研究分成兩個部份，第一個部分為臨床調查。在臨床調查方面，分成兩組，一組單獨給予抗菌劑(cephalexin) ，另外一組單獨給予商品化蔓越莓萃取物，分別觀察其預防效果。12隻狗在過去一年內，皆至少有3次以上泌尿道感染的病史。在實驗期間，綜合尿檢和尿液培養結果，發現兩組內的所有犬隻在六個月內，皆無任何泌尿道感染的情形發生。在本篇研究的第二部份，總共有六隻健康犬隻被給予商品化蔓越莓萃取物，並且分別在給予前、給予後一個月以及給予後兩個月各採尿一次，之後將所有的尿液樣本進行抑菌試驗、抗黏附試驗以及顯微鏡觀察。在抑菌試驗方面，所有的尿液樣本皆無抑菌圈的產生。與蔓越莓給予前的尿液相比較，在給予後一個月以及兩個月的尿液皆可使細菌黏附力顯著性下降(P < 0.05)。給予蔓越莓前，顯微鏡下觀察黏附在每個犬腎臟細胞周圍的細菌數目平均為101.84個；給予蔓越莓後一個月和兩個月的尿液會因減少細菌的黏附力，而使得顯微鏡下黏附在每個犬腎臟細胞周圍的細菌數目下降，分別平均為16.44與4個(P < 0.05)。結論，蔓越莓可藉由抑制細菌黏附至泌尿道上皮細胞來預防感染的發生，且雖然使用抗菌劑與蔓越莓皆可預防泌尿道的感染，但給予蔓越莓預防較不易有抗藥性的問題產生。

Urinary tract infections (UTIs) is one of the most common problems in small animals, especially female. UTIs are most often caused by bacteria; Escherichia coli (E.coli) is the most common uropathogen. What facilitate the adhesion of E.coli to uroepithelial cells is fimbriae. Many studies show that cranberry products impair bacterial adherence, thus preventing UTIs. Although lots of studies indicate that cranberry supplement can prevent UTIs in women, there are few study about the relationship between cranberry and canine UTIs. Therefore, the effect of cranberry on preventing UTIs was investigated. There were two parts of this study. The first part was clinical investigation. There were two groups in clinical investigation, including cephalexin and commercial cranberry extracts (CE) groups. Each group had six dogs which undergo at least 3 times UTIs in the past year, but all of them have already recovered from UTIs. Investigated for 6 months, there were no reccurent infections in both groups. In the second part, there were six healthy dogs given CE and collected their urine samples three times, including before intake of CE (PRE group), after 30 days (30-DAY group) and 60 days (60-DAY group). All urine samples were proceeded bacteriostasis, anti-adhesion test and microscopy observation. All of urine samples were no inhibition zone. Compared with PRE group, bacterial adhesion was reduced in both of 30-DAY and 60-DAY groups (P < 0.05). Under Microscopy observation that bacterial adherence to Madin-Darby Canine Kidney (MDCK) cells was weaker when bacteria in both of 30-DAY and 60-DAY groups (mean 16.44 and 4 bacteria per cell, respectively) compared with bacteria grown in PRE urine samples (mean 101.84 bacteria per cell) (P < 0.05). In conclusions, cranberry is benefit to prevent canine UTIs because of inhibition of bacterial attachment and less antibiotic-resistance problem.