Pathogenic E. coli thrive both in gut and bladder

May 9, 2013 § 1 Comment

Uropathogenic E. coli forming intracellular bacterial communities in the outermost cell layer of an infected bladder. The red staining shows communities and bacteria (indicated by arrows); green staining delineates the bladder epithelium; blue staining indicate nuclei of the lower epithelial layers of the bladder. Image made by Indira Mysorekar.

Uropathogenic E. coli form intracellular bacterial communities in the outermost cell layer of an infected bladder. Image courtesy of Scott Hultgren.

Like jet-setting celebrities with homes in more than one location, some pathogenic strains of E. coli make two different places in the human body their homes. In a paper just out in the journal Science Translational Medicine, researchers describe how recurrent urinary tract infections in women may be caused by E. coli strains that can reside in both the gut and bladder.

Ecologically speaking, organisms are thought to adapt to a particular environment and learn how to best survive in that environment’s conditions. The trade-off is the adaptation to that particular environment comes at a cost: The organism is less fit to survive elsewhere.

However, the latest work by a team led by Jeffrey Gordon at Washington University in St. Louis suggests that may not be the case for some strains of E. coli that cause recurrent UTIs in women. These strains happily thrive both in the gut and bladder and can move easily between the two. “These experiments suggest that the organisms may not have to have a huge fitness cost for living in both habitats,” says Gordon. The work points to “another dimension of thinking about the origins of recurrent UTIs.”

In collaboration with Scott Hultgren’s group, also at Washington University in St. Louis, Gordon’s team studied four women who suffered from three consecutive UTIs each. These women were part of a large clinical trial looking into recurrent UTIs. Fecal and urine samples were collected during each of the women’s three UTI episodes. “We wanted to compare each woman to herself as recurrent infections occurred,” explains Gordon. “We asked the question: At any given infection, was there a population of disease-causing microbes, in this case uropathogenic E. coli, that dominated the urinary tract and also were represented in the gut?”

The investigators collected 45 different strains of pathogenic E. coli and carried out multilocus sequence typing and whole genome sequencing. They found that two of the women had the same strains dominate both the gut and bladder in each of their three infections. The other two women each had a shift in the type of strain that occurred in both body habitats between episodes of recurrent UTI. “In one of the women, not only was there whole-scale shift in the types of strain, but the strain that was seen in the last episode resembled a strain found in the other individual who had maintained that strain throughout the three episodes,” says Gordon.

Next, the investigators placed the strains from the woman that underwent a whole-scale shift in mouse models and analyzed the changes that took place in the bacteria. They discovered that the strain that dominated the last UTI episode had increased fitness relative to the earlier strain in both the gut and the bladder.

Pathogenic E. coli strains have evolved a variety of strategies to cause recurrent UTIs in women. One involves formation of intracellular bacterial communities in the bladder wall. These communities can remain quiet, or they can release bacteria to cause infection.

Taken together, Gordon says, the data argue that recurrent UTIs should be viewed from a more holistic perspective. “We have to look at the human body as an ecosystem where very different body habitats can harbor organisms that promote health while, at the same time, contain organisms that can cause disease,” says Gordon. “At least two body habitats, and the spaces between them, such as the periurethral area, should be considered when hunting for the homes of lurking uropathogenic E. coli that cause recurrent bladder infections.”

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§ One Response to Pathogenic E. coli thrive both in gut and bladder

  • Adiolercx says:

    Dr. Cohen. They then reason that they won’t have to go if they don’t drink, so they don’t—which is aulslbteoy the worst thing they can do. The reason: The longer any amount of urine stays in the bladder, the more bacteria there are in it—E. coli doubles its population about every 20 minutes, according to Dr. Staskin. More bacteria mean more pain. Absolutely the best thing a woman can do to fight the burning is drink fluids to flush out the bacteria that are causing the inflammation, Dr. Cohen says. There’s a very strong argument for drinking more fluid both to prevent UTIs and to treat them, Dr. Staskin says. Studies have been performed where bacteria were mechanically introduced into the bladders of volunteers. But voiding just twice effectively sterilized the bladder. Message: The more you drink, the sooner the pain will stop. And a hint: If your urine’s clear, you’re drinking enough. If it’s colored, you’re not.Take a hot bath. This helps relieve pain for many women, says Richard J. Macchia, M.D., professor and chairman of the Department of Urology at the State University of New York Health Science Center at Brooklyn College of Medicine. I don’t think anyone’s researched the exact mechanisms involved, but a hot bath often seems to help where there’s inflammation. Take aspirin or ibuprofen. These are anti-inflammatories, and they do help some people, Dr. Macchia says. They reduce the inflammation in the bladder, and the less inflammation, the less burning. Take vitamin C. About 1,000 milligrams taken throughout the day will acidify the urine enough to interfere with bacterial growth, Dr. Macchia says. This is a good idea if you’re having problems with reinfection or have recurrence in the middle of nowhere without quick access to medical help. Caution: Some antibiotics prescribed for bladder infections don’t work will in acidic urine, so tell your doctor if you’re taking vitamin C. Also tell him how much you’re taking. Vitamin C is not toxic, but 1,000 milligrams is considered a large dose and should have your doctor’s approval.Back away. Wiping from front to back helps prevent infection from recurring, the doctors say. Wiping the wrong way is one of the most common causes of infection and a good way to get repeat infections. Wiping away is pure common sense, you want to move bacteria away from, not toward, the vagina and the opening of the urethra.Go to the bathroom before intercourse. This helps flush out bacteria that may be present in the vagina, the experts say—bacteria that otherwise might be pushed into the bladder by intercourse.Go to the bathroom after intercourse. This is where the myth of your partner’s involvement gets its start—and like most myths, there’s a grain of truth to this one, according to Dr. Staskin. A man’s penis can massage bacteria present in the opening of the urethra into the bladder. Voiding effectively rinses the bladder out. There’s no doubt that UTIs are more common in sexually active women, Dr. Cohen says. But that’s more the result of not knowing how to protect themselves than of sexual activity itself. If bacteria have been pushed into the bladder, urinating will flush most of them out. Reconsider the diaphragm. Diaphragms have been documented as major contributors to those who have stubborn, repeated bladder infections, Dr. Staskin says. Two mechanisms are probably involved: Bacteria colonize the diaphragm itself, which is then inserted deep into the vagina, and the diaphragm interferes with bladder emptying, which means that bacteria already there aren’t flushed out. If this description fits you, you might want to talk to your doctor about another method of birth control.Use pads instead of tampons. No one’s aulslbteoy certain why certain women seem more susceptible to reinfection, but vaginal manipulation of some sort—sex, inserting the diaphragm, putting a tampon in—always seems to precede it, says Joseph Corriere, M.D., director of the Division of Urology at the University of Texas Health Science Center at Houston. I advise those of my patients experiencing chronic infection at the time of menstruation to quit using tampons and replace them with pads, he says.Practice good hygiene. Good hygiene means wearing cotton underwear that keeps you dry, avoiding tight pants that decrease ventilation, and most of all, keeping clean—but sensibly clean. If you don’t bathe to remove bacteria in the perineal region [between vagina and rectum], obviously you run the risk of repeated infection, Dr. Staskin says. But too much can be as bad as too little. Douching constantly can both introduce bacteria into the vagina and rinse out the normal friendly, noninfectious vaginal bacteria, which are then replaced with infectious E. coli. Irritation of the urethra may occur, which may feel like another UTI. Strong antibacterial soaps can do the same thing—and change the vaginal flora enough to make the individual more susceptble to infection. The point: Be clean, but don’t be obsessed.You could also try to drink canberry juice, I heard that works too .

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