To assess whether argI has an additional role during UTI aside from arginine biosynthesis, we generated allelic replacement strains of UTI89, reintegrating the UTI89 (a B2 strain) or MC4100 (a non-B2 strain) allele of argI (designated argIUTI89 and argIMC4100, respectively) into the original argI locus in UTI89 using a scarless cloning technique (65). The gene discussed is LNCARGI; the disease is bacterial urinary tract infection.