VIRULENCE AND OTHER PHENOTYPIC CHARACTERISTICS OF URINARY ISOLATES OFCYSTEINE-REQUIRING ESCHERICHIA-COLI

Urinary isolates of cysteine-requiring Escherichia coil were found to be generally lacking in virulence factors commonly associated with uro pathogenic strains. The proportion of auxotrophic strains showing type -1 fimbriation, haemolysin production, motility and sensitivity to nor mal human serum was significantly less than that of a comparable numbe r of urinary isolates of prototrophic E. coli, although the proportion in both groups possessing K1 antigen was similar. Furthermore, the bi otyping and serogrouping of these and other strains from systemic infe ctions demonstrated a high degree of phenotypic diversity. This is fur ther evidence that infection with these auxotrophs results from a comb ination of decreased host resistance and a physiological condition con ducive to the random selection of these auxotrophs in vivo.