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In most cases, cystitis is caused by the appearance of a strain of Escherichia coli in the bladder coming from the intestine. The urinary microbiota is also modified in cases of infection.

Excessive hygiene is a risk factor

Cystitis affects 30% of women over the course of their life. Risk factors include urinary tract obstruction, sexual relations, urinary catheters, neurological dysfunction, and pregnancy. An excess of intimate hygiene is also a risk factor, likely at least as common as a lack of hygiene1,2.

Bacteria of intestinal origin

The infection is of bacterial origin. The strains involved are naturally present in the intestinal microbiota, but are distinct from those that cause intestinal infections3,4Escherichia coli is the primary pathogenic agent and the strains in question are part of the “ExPEC” group (Extraintestinal Pathogenic E. Coli). Comparison of urinary microbiota in women with interstitial cystitis reveals a reduction in microbial diversity and an increase of lactobacilli compared to healthy women5.

Alternatives to antibiotics

Treatment is based on antibiotics, but the increase in antibiotic resistance is a major concern and alternatives are being sought out. Work is being done to prevent recurrences with vaginal applications or oral intake  of lactobacilli. It has proven effective for certain strains of L. rhamnosus, L. reuteri, and L. crispatus6,7,8. The level of proof, however, is too weak for clinical use6,7. Cranberry seems to be effective in preventing recurrence, but it remains to be proven9

1. Whiteside SA et al. The microbiome of the urinary tract--a role beyond infection. Nat Rev Urol 2015 ; 12 : 81-90.
2. Hilt EE et al. Urine is not sterile: use of enhanced urine culture techniques to detect resident bacterial flora in the adult female bladder. J Clin Microbiol 2014 ; 52 : 871-6.
3. Köhler CD, Dobrindt U. What defines extraintestinal pathogenic Escherichia coli? Int J Med Microbiol 2011 ; 301 : 642-7.
4. Starcic Erjavec M et al. Virulence potential for extraintestinal infections among commensal Escherichia coli isolated from healthy humans†the Trojan horse within our gut. FEMS Microbiol Lett 2015 ; 362 : fnu061.
5. Siddiqui H. et al. Alterations of microbiota in urine from women with interstitial cystitis. BMC Microbiol. 2012 Sep 13;12:205. doi: 10.1186/1471-2180-12-205. 
6. Beerepoot MA et al. Nonantibiotic prophylaxis for recurrent urinary tract infections: a systematic review and meta-analysis of randomized controlled trials. J Urol 2013 ; 190 : 1981-9.
7. Reid G et al. Oral use of Lactobacillus rhamnosus GR-1 and L. fermentum RC-14 significantly alters vaginal flora: randomized, placebo-controlled trial in 64 healthy women. FEMS Immunol Med Microbiol 2003 35 : 131-4.
8. Stapleton AE et al. Randomized, placebo-controlled phase 2 trial of a Lactobacillus crispatus probiotic given intravaginally for prevention of recurrent urinary tract infection. Clin Infect Dis. 2011 May;52(10):1212-7
9. Kontiokari T et al. Randomised trial of cranberry-lingonberry juice and Lactobacillus GG drink for the prevention of urinary tract infections in women. BMJ 2001 ; 322 : 1571.



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