Antibody coated bacteria in urine of patients with recent spinal injury. Twenty patients with an acute spinal injury were prospectively studied to assess the clinical importance of antibody coated bacteria (ACB) in the urine and the association among the different bacterial species with a positive antibody coated bacteria test. Clinical urinary tract infection was associated with a positive ACB test on 45% of occasions. Three hundred and ninety nine urine samples containing 541 bacterial isolates were assessed for the presence of ACB; 13% were found to be positive and 87% negative for ACB; 67% of urines contained a single bacterial isolate. Pseudomonas aeruginosa was most commonly associated with clinical urinary tract infection, found in 25% of episodes, followed by Proteus mirabilis (17.5%), Klebsiella sp (12.5%), and Proteus morganii (10%). Providencia stuartii, however, was most commonly associated with a positive ACB test (found in 17%). Other bacteria associated with a positive ACB test included Klebsiella sp (14%), Acinetobacter sp (12.5%), Pseudomonas aeruginosa (12%), Citrobacter sp (11.5%). A positive ACB test is not to be expected from a patient with spinal injury who has a catheter in place, and the test may provide a useful guide to identify those patients with an invasive infection. It is doubtful that a decision to treat or not treat bacteriuria could rest on the identification of the bacterial species alone. 