Sensitivity of some smooth strains of Escherichia coli to the bactericidal action of normal human serum

Abstract

The sensitivity to normal human serum of 144 smooth strains of Escherichia coli isolated from cases of urinary tract infection was determined. It was found that serum-sensitive and serum-resistant strains were not randomly distributed throughout the 10 O serogroups commonly associated with urinary infection. A similar distribution was observed when a group of strains isolated from rectal swabs was studied. The results indicate that serum resistance may be related to qualitative characteristics of the O antigen.