Enteroaggregative Escherichia coli virulence markers: positive association with distinct clinical characteristics and segregation into 3 enteropathogenic E. coli serogroups.
BACKGROUND
Enteroaggregative Escherichia coli (EAEC) are a heterogeneous category of emerging pathogens associated with acute and persistent diarrhea.


METHODS
We performed a case-control study to evaluate the association of EAEC strains and their virulence markers with infantile diarrhea in Brasilia, Brazil.


RESULTS
Of the EAEC markers that were tested, only EAEC heat-stable toxin (EAST1), protein involved in colonization (Pic), and the CVD432 sequence showed positive correlation with diarrhea; however, these virulence traits presented associations with distinct clinical characteristics. Although CVD432-positive strains were associated with persistent diarrhea, EAST1-positive strains were statistically correlated with acute diarrhea only in children >6 months of age. Typical EAEC strains were found with equal frequency in case patients and control subjects. O antigens of enteropathogenic E. coli (EPEC) were also sought, and the data showed that the EAEC markers are frequently segregated into 3 EPEC serogroups: O126, O128, and O158.


CONCLUSIONS
The presence of EPEC O antigens along with EAEC markers influenced the positive association of E. coli strains with diarrhea. Concerning the detection of the AA phenotype, the CVD432 sequence presented a low positive predictive value, regardless of its high specificity as a marker.
Pereira
Alex L
AL
Laboratório de Microbiologia, Departamento de Biologia Celular, Universidade de Brasília, Brasília, Brazil.
Ferraz
Lúcia R
LR
Silva
Rejane S N
RS
Giugliano
Loreny G
LG
D001422:Bacterial Adhesion / Q000235:genetics; D001427:Bacterial Toxins / Q000235:genetics; D001938:Brazil; D016022:Case-Control Studies; D003968:Diarrhea, Infantile / Q000382:microbiology*; D004768:Enterotoxins / Q000235:genetics; D004927:Escherichia coli Infections / Q000382:microbiology* / Q000473:pathology; D019453:Escherichia coli O157 / Q000737:chemistry / Q000145:classification* / Q000472:pathogenicity; D029968:Escherichia coli Proteins / Q000235:genetics*; D036781:Fimbriae Proteins / Q000235:genetics; D006801:Humans; D007223:Infant; D012703:Serotyping; D013045:Species Specificity; D014774:Virulence
C079725:AggA protein, E coli; D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; C034151:heat stable toxin (E coli); D036781:Fimbriae Proteins