ANALYSIS OF GRAM-NEGATIVE RECOLONIZATION OF THE NEUROPATHIC BLADDER AMONG PATIENTS WITH SPINAL-CORD INJURIES

Over a 4 year period, 119 acute spinal cord injury (SCI) patients were enrolled in this study. The 101 males and 18 females had a mean age o f 35.9 years (range 16-87). Sixty-two patients were tetraplegic and 57 were paraplegic. All patients had a urine specimen taken for culture, colony count and sensitivity once weekly while they were receiving in termittent catheterization. Of these, 22 patients (18.5%), none of who m had underlying genito-urinary (GU) pathology, developed recolonizati on by an organism of the same species and genus previously cultured. A ll 22 reached sterile urine between colonizations after being treated with antibiotics for at least 7 days. The 16 males and six females had a mean age of 35.1 years (range 17-79). Sixteen were tetraplegic and six were paraplegic. Plasmid analysis (PA) was used to determine wheth er these recolonizations were from the same or from a different strain . In those instances where the bacteria harbored no plasmids or where the results of plasmid analysis were otherwise inconclusive, bacteria were also compared using restriction fragment length polymorphism (RFL P) analysis. Recolonization was caused primarily by E. coli and K. pne umoniae. While there was no significant difference between the two org anisms with respect to the number of days when sterile urine occurred to the time when recolonization was observed, there were significant d ifferences seen in both organisms with regard to the time lapse from o ne colonization to the next: the average number of days to recolonizat ion with an identical organism was 10.3 days, whereas with a different strain it was 15.9 days (P<0.04). When a different organism was cultu red between the recolonizations, the mean recolonization interval was 17.9 days. When no intervening organism occurred, the interval was 9.5 days (P<0.005). Both intervals measured the days from the first steri le urine after the first colonization to the next colonization. These data indicate the proclivity for two common Gram negative normal bowel inhabitants to recolonize the neuropathic bladder of spinal cord inju red patients even after adequate treatment. PA and RFLP provide a mean s of discriminating between relapses by the same organism versus recur rences by a different organism of the same species and genus. Those wi th the same identity tend to recur sooner than those of different iden tities and may be suspected when relapse occurs within two weeks of ce ssation of 7 day course of antibiotics. While an intervening organism may delay the relapse (or recurrence), it does not prevent it and iden tical organisms can reappear even after adequate therapeutic regimens. Since none of the patients in this study had GU pathology, recoloniza tion by an identical strain (relapse) does not necessarily warrant an extensive investigation for disease within the GU tract.