CHARACTERISTICS AND PREVALENCE WITHIN SEROGROUP O4 OF A J96-LIKE CLONAL GROUP OF UROPATHOGENIC ESCHERICHIA-COLI O4-H5 CONTAINING THE CLASS-I AND CLASS-III ALLELES OF PAPG

The recent discovery of a geographically dispersed clonal group of Esc herichia coli O4:H5 that includes prototypic uropathogenic strain J96 prompted us to determine the prevalence of J96-like strains within ser ogroup O4 and to further assess the characteristics of such strains. W e used O:K:H;F serotyping, PCR-based genomic fingerprinting, pulsed-fi eld gel electrophoresis (PFGE), multilocus enzyme electrophoresis (MLE E), and PCR detection of the three papG alleles and of the cytotoxic n ecrotizing factor 1 (cnfl) and aerobactin (ner) gene sequences to char acterize the 15 O4 strains among 336 E. coli isolates from three clini cal collections (187 from mixed-source bacteremia, 75 from urosepsis, and 74 from acute cystitis). J96-like strains constituted approximatel y half of the O4 strains, or 2% of the total population. In contrast t o other O4 strains, the J96-like strains characteristically exhibited specific group III capsular antigens, the H5 flagellar and F13 fimbria l antigens, a distinctive PCR genomic fingerprint, the class III papG allele (plus, in 50% of strains, the enigmatic class I papG allele), a nd cnfl but lacked aer. A subset of these strains was remarkably homog eneous with respect to all these characteristics and exhibited a disti nctive PFGE fingerprint and MLEE pattern. These findings clarify the e pidemiological relevance of J96 as a model extraintestinal pathogen, p rovide further evidence of the class I papG allele outside of strain J 96, and offer insights into the evolution of E. coli serogroup O4.