Pathogenesis of bacteriuria and infection in the spinal cord injured patient

Spinal cord injury (SCI) produces profound alterations in lower urinary tract function. Incontinence, elevated intravesical pressure, reflux, stones, and neurological obstruction, commonly found in the spinal cord-injured population, increase the risk of urinary infection. The overall rate of urinary infection in SCI patient is about 2.5 episodes per patient per year. Despite improved methods of treatment, urinary tract morbidity still ranks as the second leading cause of death in the SCI patient. SCI removes the ability of the pontine micturition center and higher centers in the brain to inhibit, control, or coordinate the activity of the vesicourethral unit. As a result, a patient with complete quadriplegia is typically unaware of bladder activity. Bladder contraction is accompanied by vesicosphincter dyssynergia instead of sphincter relaxation. It is widely accepted that intermittent catheterization, when compared with indwelling catheters, reduces the risk of urinary tract infection (UTI) in SCI patients and is the preferred method of bladder drainage in this patient population. Attempts at eliminating bacteriuria associated with indwelling or intermittent catheters have generally been unsuccessful. There is now appreciation of the fact that a creeping adherent biofilm of bacteria frequently ascends through the luminal and external surfaces of an indwelling catheter, often within 8 to 24 hours, leading to bacterial adherence to the bladder surface and correlating with symptomatic infection. The use of antimicrobial agents to clear or prevent bacteriuria in patients on indwelling or intermittent catheterization has had mixed success. Treatment for asymptomatic bacteriuria in SCI patients remains controversial. SCI patients with symptomatic urinary infections should be treated with the most specific, narrowest spectrum antibiotics available for the shortest possible time. Guidelines for selecting antimicrobial agents in SCI patients are similar to guidelines for the treatment of complicated urinary infections in the general population. Characteristics of the quinolones make them well suited to treating UTI in the SCI patient.