Genotyping of urinary and fecal Proteus mirabilis isolates from individuals with long-term urinary catheters

Excerpt

Bacterial colonization of the urinary tract is probably inevitable in those individuals undergoing long-term urinary catheterization. In approximately half of cases this leads to the complication of catheter encrustation, whereby the drainage lumen of the catheter is recurrently obstructed by crystalline biofilm, causing painful retention of urine or incontinence [1]. This is usually caused by organisms possessing the enzyme urease, particularly Proteus mirabilis [2]. Colonization usually occurs by the ascending route via the catheter, either through the internal drainage lumen as a result of contamination of the drainage apparatus, or along the external catheter surface by bacteria from the urethral meatus [3]. The external route is thought to be more important since closed drainage systems have become standard, and one phenotyping study of bacteriuria in subjects with short-term catheterization suggested an endogenous gastrointestinal origin for several common species [4]. In long-term catheterization, however, the closed system is broken regularly to change the drainage bag, allowing for possible bacterial transfer from exogenous sources. The origin of P. mirabilis colonization is therefore unclear. An understanding of the source of the strains found in long-term catheter users could help in devising protocols to prevent colonization. To investigate this, we have used Dienes typing and pulsed-field gel electrophoresis (PFGE), as both have proved highly discriminatory in previous epidemiological studies of P. mirabilis [5]. …