The diarrheal response of humans to some classic serotypes of enteropathogenic Escherichia coli is dependent on a plasmid encoding an enteroadhesiveness factor.
Isolates of the most common O serogroups of enteropathogenic Escherichia coli (EPEC) associated with infant diarrhea (designated class I) adhere to Hep-2 cells; the genes for this adhesin, termed EPEC adherence factor (EAF), are located on plasmids 50-70 MDa in size. Volunteers ingested 10(10) organisms of an O127:H6 Hep-2-adhesive class I strain (E2348/69) or its plasmid-minus, nonadhesive derivative. Diarrhea occurred in nine of 10 volunteers who ingested the parent strain (mean, 1,178 ml) but in only two of nine who took the plasmid-minus variant (mean, 433 ml; P less than .006). All volunteers ill from strain E2348/69 mounted serum IgA and IgG responses to a 94-kDa plasmid-associated outer membrane protein of E2348/69; this protein was found in other class I EPEC but not in enterotoxigenic or meningitic strains. The 50-70-MDa EAF plasmid seems necessary for full expression of pathogenicity in EPEC that exhibit Hep-2 adhesiveness. EPEC isolates of certain other, less common, O serogroups (O44, O86, and O114) are rarely Hep-2 adhesive. These EPEC, designated class II, possess distinct 50-70 MDa plasmids lacking EAF genes. Diarrhea was caused by 10(8) or 10(10) organisms of an O114:H2 class II EPEC strain (mean, 1,156 ml) in six of 11 volunteers. This result confirmed that class II EPEC are pathogenic by a mechanism not involving Hep-2 adhesiveness.
Levine
M M
MM
Nataro
J P
JP
Karch
H
H
Baldini
M M
MM
Kaper
J B
JB
Black
R E
RE
Clements
M L
ML
O'Brien
A D
AD
D018830:Adhesins, Escherichia coli; D000268:Adhesiveness; D000293:Adolescent; D000328:Adult; D000907:Antibodies, Bacterial / Q000032:analysis; D001425:Bacterial Outer Membrane Proteins / Q000032:analysis / Q000235:genetics / Q000276:immunology; D001426:Bacterial Proteins / Q000235:genetics*; D001427:Bacterial Toxins / Q000096:biosynthesis; D003967:Diarrhea / Q000382:microbiology*; D004926:Escherichia coli / Q000235:genetics* / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000382:microbiology*; D006801:Humans; D007070:Immunoglobulin A / Q000032:analysis; D007074:Immunoglobulin G / Q000032:analysis; D010957:Plasmids; D022603:Shiga Toxins
D018830:Adhesins, Escherichia coli; D000907:Antibodies, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D022603:Shiga Toxins