The goal of this research program is to understand the natural history of asymptomatic bacteriuria in the renal transplant patients, to determine if screening for asymptomatic bacteriuria and identification of key host characteristics and virulence factors present on uropathogenic bacteria identifies a sub-population of patients with asymptomatic bacteriuria that are at risk to develop symptomatic urinary tract infection. Ultimately, the knowledge obtained from this study will prevent inappropriate antibiotic use and may identify whether certain bacterial isolates predispose to renal allograft injury. We will test the hypothesis that (i) asymptomatic bacteriuria is common in the renal allograft recipient and (ii) that symptomatic urinary tract infection and renal allograft dysfunction do not occur unless key host susceptibility factors and uropathogenic bacterial virulence factors are present.