Determination of Escherichia coli O types by allele-specific polymerase chain reaction:: application to the O types involved in human septicemia

Escherichia coli can be serotyped by determination of somatic (0), capsular (K), and flagellar (H) antigens, and clear associations exist between specific 0 antigens and pathogenic behavior. However, E. coli is very challenging to 0 type with traditional serologic methods, making new methods for E. coli somatic antigen detection highly desirable. Here, we describe a simple alternative molecular method for determination of the E. coli 0 type based on allele-specific polymerase chain reaction amplification of the 5' portion of the rfb locus. We present our application of this new method to the detection of the 12 principal 0 types (01, 02, 04, 06, 07, 012, 015, 016, 018, 025, 075, and 0 157) found among bloodstream isolates of E. coli. This method allowed us to determine the 0 types of 153 strains previously typed using reference methods with an accuracy exceeding 90%. Moreover, some rough or nonagglutinating strains can be successfully typed. (c) 2007 Elsevier Inc. All rights reserved.