Antibiotics and urinary infections: too much too often?

Townsend Letter for Doctors and Patients,  Nov, 2005  by Gina L. Nick

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Introduction

Women have a 50% lifetime incidence of urinary infections, and an 80% chance of recurrence. There are millions of incidents every year in the United states alone. The cost is over $1 billion. (1) These infections are always treated with antibiotics. As a result, urinary pathogens are becoming increasingly resistant, causing alarms to be raised, since pharmaceutical companies are in a tight race to keep up with emerging antimicrobial resistance on all fronts--viruses, bacteria, tuberculosis, malaria--everywhere drugs are used widely, promiscuously and often ill-advisedly, for short term benefits.

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Amoxicillin and cephalosporins, once standard treatments, are now ineffective against over 20% of E. coli, the most common urinary pathogen, so that more expensive and often more dangerous drugs must be substituted. A three-day course of trimethoprim-sulfamethoxazole is a current standard, but resistance to this combination also exceeds 20% in the US and up to 50% overseas, where control of antibiotic usage ranges from inadequate to absent. (2,3)

To compound the problem, antibiotics fed to livestock add to the pool of resistant organisms. There is convincing evidence that these organisms transfer to humans, causing urinary infections as well as gastrointestinal disease (4-6) and making urinary infections food-borne illnesses.

There is also a growing body of evidence that suggests antibiotic use may increase the risk of breast cancer in women. (7) The hypothesis is of interest to those involved with complementary and alternative medicine. It suggests that the diminution of intestinal flora consequent upon the use of systemic antibiotics impairs their ability to metabolize phytochemicals in food that are useful in preventing hormone-related malignancies.

Nevertheless, antibiotics and antimicrobials of all kinds have been considered one of the most miraculous discoveries of modern medicine. As a consequence, practitioners are loath to forego their use, and pharmaceutical companies have been slow to search for alternatives. Yet alternatives exist, are effective, and are poised to receive far greater recognition than they have had heretofore.

Natural Medicines for The Prevention and Treatment of UTIs

There are two distinct mechanisms by which natural products can favorably affect urinary infections. The first is the obvious germ killing function. Clearly most antibiotics are derived from nature, so it is no surprise that there are still some out there. The other mechanism has not yet been exploited by the pharmaceutical industry--that of altering the adhesive properties of bacteria whereby they attach to urinary epithelial cells. (8) D-mannose and cranberry are believed to possess this latter activity; uva ursi and juniper have direct microbicidal properties.

D-Mannose

D-mannose is an isomer of glucose. Some E. coli strains variably adhere to mannose residues on urinary epithelial cells, apparently more strongly at earlier stages of colonization. (9) Although the relationship is complex, d-mannose has been shown to reduce bacteriuria in rats in a dose dependent manner (10,11) and has been used safely in humans. (12,13)

Cranberry (Vaccinium macrocarpon)

Cranberry juice has a long folk history of efficacy in urinary infections, though controlled studies have been less than exciting. Its effect is unlikely to be urine acidification, since that lasts but a few minutes. (14) Cranberry and other berries contain proanthocyanidins that inhibit bactrerial adherence to urinary epithelium. (15) One study found that cranberry juice reduced the rate of recurrence of urinary infections in elderly women. (16) Other studies are few and of such questionable quality that no definite conclusions can be drawn from them other then to say that more quality research is needed. (17)

Uva Ursi (Arctostaphylos uva-ursi)

The leaves of this North American native mountain shrub contain the glycoside arbutoside (arbutin) and other agents with antibacterial activity. (18,19) A month of uva ursi extract given to women with recurrent cystitis reduced the recurrence rate from 23% (with placebo) to zero for the entire year following treatment. No adverse effects were noted. (20) Arbutoside is hydrolyzed in the gut to produce hydroquinone, which acts directly as a antimicrobial when it arrives in the bladder. There is some disagreement in the literature as to whether or not the urine must be alkaline for this effect to be realized. (14,19) A urine pH >7 is an unusual circumstance in the absence of certain alkalinizing pathogens. There is some evidence that long-term exposure to hydroquinone in an industrial setting may be carcinogenic, (21) so preventive studies of this chemical are rare, and the German Commission E approves the use of uva ursi only for short-term treatment. (22)

Juniper (Juniperus)

Various species of juniper contain cedrenes and other terpenoids with demonstrated antimicrobial activity. There is also a suggestion that juniper contains diuretics. Again, research is minimal, both to identify the active chemicals and to demonstrate clinical effectiveness. (14)