RECURRENT URINARY TRACT INFECTION
Category: Urology
Abstract : Recurrent urinary tract infection Recurrent UTI is defined as >2 infections in 6 months, or 3 within 12 months. It may be due to reinfection (i.e. infection by a different bacteria) or bacterial persistence (infection by the same organism originating from a focus within the urinary tract). Bacterial persistence implies the presence of bacteria within a site in the urinary tract, th
Recurrent urinary tract infection
Recurrent UTI is defined as >2 infections in 6 months, or 3 within 12 months. It may be due to reinfection (i.e. infection by a different bacteria) or bacterial persistence (infection by the same organism originating from a focus within the urinary tract).
Bacterial persistence
implies the presence of bacteria within a site in the urinary tract, the presence of which leads to repeat episodes of infection. Such sites include kidney stones; the chronically infected pro-state (chronic bacterial prostatitis); bacteria within an obstructed or atrophic infected kidney; bacteria gaining access to the urinary tract via a fistula (with bowel or vagina); bacteria within a urethral diverticulum. Thus, recurrent urinary infection due to bacterial persistence implies a functional or anatomical problem, and that the recurrent UTIs will not resolve until this underlying problem has been addressed.
Reinfections
usually occur after a prolonged interval (months) from the previous infection and are often caused by a different organism than the previous infecting bacterium. Bacterial persistence usually leads to frequent recurrence of infection (within days or weeks) and the infecting organism is usually the same organism as that causing the previous infection(s).
Women with reinfection do not usually have an underlying functional or anatomical abnormality. Reinfections in women are associated with increased vaginal mucosal receptivity for uropathogens and ascending colonization from the faecal flora. These women cannot be cured of their predisposition to recurrent UTIs, but they can be managed by a variety of techniques (see below). Men with reinfection may have underlying BOO (due to BPE or a urethral stricture), which makes them more likely to develop a repeat infection, but between infections their urine is sterile (i.e. they do not have bacterial persistence between symptomatic UTIs). A urethrogram, flexible cystoscopy, post-void bladder ultrasound for residual urine volume, and, in some cases, urodynamics may be helpful in establishing the potential causes.
As stated above, both men and women with bacterial persistence usually have an underlying functional or anatomical abnormality and they can potentially be cured of their recurrent UTIs, if this abnormality can be identified and corrected.
Management of women with recurrent UTIs due to reinfection
Most urologists will arrange a series of screening tests (KUB X-ray, renal ultrasound, flexible cystoscopy) to double check there is no potential source of bacterial persistence (i.e. to confirm that they are dealing with a ‘simple’ case of reinfection rather than one of bacterial persistence). In the absence of finding an underlying functional or anatomic abnormality, these patients cannot be cured of their tendency to recurrent urinary infection, but they can be managed in one of the following ways:
Avoidance of spermicides used with the diaphragm or on condoms
Spermicides containing nonoxynol-9 reduce vaginal colonization with
lactobacilli and may enhance E. coli adherence to urothelial cells. Recommend an alternative form of contraception.
Estrogen replacement therapy
Lack of estrogen in post-menopausal women causes loss of vaginal lactobacilli and increased colonization by E. coli. Estrogen replacement can result in recolonization of the vagina with lactobacilli and eliminate colonization with bacterial uropathogens.
Low-dose antibiotic prophylaxis
Oral antimicrobial therapy with full-dose oral tetracyclines, ampicillin, sulphonamides, amoxicillin, and cephalexin causes resistant strains in the faecal flora and subsequent resistant UTIs. However, trimethoprim, nitrofurantoin, low-dose cephalexin, and the fluoroquinolones have a minimal adverse effects on the faecal and vaginal flora.
- Efficacy of prophylaxis. Recurrences of UTI may be reduced by as much as 90% when compared with placebo. Prophylactic therapy requires only a small dose of an antimicrobial agent, generally given at bedtime for 6 to 12 months. Symptomatic reinfection during prophylactic therapy is managed with a full therapeutic dose with the same prophylactic antibiotic or another antibiotic. Prophylaxis can then be restarted. Symptomatic reinfection immediately after cessation of prophylactic therapy is managed by restarting nightly prophylaxis.
- Trimethoprim. The gut is a reservoir for organisms that colonize the periurethral area and which may subsequently cause episodes of acute cystitis in young women. Trimethoprim eradicates gram-negative aerobic flora from the gut and vaginal fluid (i.e. it eliminates the pathogens from the infective source). Trimethoprim is also concentrated in bactericidal concentrations in the urine following an oral dose.
Adverse reactions: blood dyscrasias due to bone marrow depression; rarely, Stevens–Johnson syndrome; allergic reactions; rarely, erythema multiforme, toxic epidermal necrolysis (photosensitivity).
- Nitrofurantoin is completely absorbed and/or degraded/inactivated in the upper intestinal tract and therefore has no effect on gut flora. It is present for brief periods at high concentrations in the urine and leads to repeated elimination of bacteria from the urine. Nitrofurantoin prophylaxis therefore does not lead to a change in vaginal or introital colonization with Enterobacteria. The bacteria colonizing the vagina remain susceptible to nitrofurantoin because of the lack of bacterial resistance in the fecal flora.
Adverse reactions: include acute pulmonary reactions (pulmonary fibrosis has been reported), allergic reactions (angioedema, anaphylaxis, urticaria, rash and pruritus), peripheral neuropathy, blood dyscrasias (agranulocytosis, thrombocytopenia, aplastic anaemia), liver damage, lupus erythematosus-like syndrome, and chronic pulmonary reactions. The risk of an adverse reaction increases with age, with the greatest number occurring in patients older than 50 years.
- Cephalexin at 250mg or less nightly is an excellent prophylactic agent because faecal resistance does not develop at this low dosage.
- Adverse reactions: allergic reactions.
- Fluoroquinolones (e.g. Ciprofloxacin). Short courses eradicate Enterobacteria from the faecal and vaginal flora. Adverse reactions to quinolones: tendon damage (including rupture), which may occur within 48h of starting treatment (quinolones are contraindicated in patients with a history of tendon disorders related to quinolone use; elderly patients are more prone to tendonitis; risk of tendon rupture is increased by the concomitant use of corticosteroids; discontinue quinolone immediately if tendonitis suspected). Other adverse reactions: arthropathy in children; Stevens–Johnson syndrome; allergic reactions.
Natural yoghurt applied to the vulva and vagina can help restore normal vaginal flora, thereby improving the natural resistance to recurrent infections.
Post-intercourse antibiotic prophylaxis
Sexual intercourse has been established as an important risk factor for acute cystitis in women and women who use the diaphragm have a significantly greater risk of UTI than women who use other contraceptive methods. Post-intercourse therapy with antimicrobials such as nitrofurantoin, cephalexin, or tri-methoprim, taken as a single dose, effectively reduces the incidence of reinfection.
Self-start therapy
Women keep a home supply of an antibiotic (e.g. trimethoprim, nitrofurantoin, a fluoroquinolone) and start treatment when they develop symptoms suggestive of UTI.
Management of men and women with recurrent UTIs due to bacterial persistence
Investigations These are directed at identifying the potential causes of bacterial persistence, outlined above.
- KUB X-ray to detect radio-opaque renal calculi.
- Renal ultrasound to detect hydronephrosis and renal calculi. If hydro-nephrosis is present, but the ureter is not dilated, consider the possibility of a radio-opaque stone obstructing the PUJ (this will usually be seen as an acoustic shadow on the ultrasound; arrange a CTU if no stone is seen) or a PUJO (arrange a MAG3 renogram to determine the presence/absence of PUJO).
- Determination of post-void residual urine volume by bladder ultrasound.
- IVU or CTU where a stone is suspected, but not identified on plain X-ray or ultrasound.
- Flexible cystoscopy to identify possible causes of recurrent UTIs such as bladder stones, an underlying bladder cancer (rare), urethral or bladder neck stricture, fistula.
Treatment: depends on the functional or anatomical abnormality which is identified as the cause of the bacterial persistence. If a stone is identified, this should be removed. If there is obstruction (e.g. BPO, PUJO, DSD in spinal injured patients), this should be corrected.
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