Reduced phase switch capacity and functional adhesin expression of type 1-fimbriated Escherichia coli from immunoglobulin A-deficient individuals.
The mannose-specific adhesin of type 1 fimbriae is the most common adhesin in Escherichia coli. One receptor for this adhesin is the carbohydrate chains of secretory immunoglobulin A (S-IgA), and intestinal E. coli from IgA-deficient individuals has a reduced capacity to adhere to mannose-containing receptors. Here, we investigated the expression of the mannose-specific adhesin and its capacity to switch to the fimbriated phenotype in colonic resident and transient E. coli strains isolated from control (n = 16) and IgA-deficient (n = 17) persons. Resident E. coli strains from IgA-deficient individuals displayed weaker mannose-specific adherence to colonic cells than resident strains from control individuals (21 versus 44 bacteria/cell, P = 0.0009) due to three mechanisms: a lower carriage rate of the fimH gene (90% versus 97%, not significant), more frequent failure to switch on the fim genes (30% versus 6%, P = 0.02), and the reduced adhesive potential of fimH(+) isolates capable of phase switch (26 versus 46 bacteria/cell, P = 0.02). On the other hand, resident strains from IgA-deficient individuals displayed stronger mannose-resistant adherence than resident strains from control individuals (P = 0.04) and transient strains from IgA-deficient individuals (P = 0.01). The presence of S-IgA appears to favor the establishment of E. coli clones which readily express mannose-specific adhesins in the bowel microbiota.
Nowrouzian
Forough L
FL
Department of Clinical Bacteriology, Guldhedsgatan 10, S-413 46 Göteborg, Sweden. forough.nowrouzian@microbio.gu.se
Friman
Vanda
V
Adlerberth
Ingegerd
I
Wold
Agnes E
AE
D018829:Adhesins, Bacterial / Q000096:biosynthesis* / Q000235:genetics; D000293:Adolescent; D000328:Adult; D000368:Aged; D001422:Bacterial Adhesion; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D005260:Female; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000378:metabolism*; D019073:HT29 Cells; D006801:Humans; D017098:IgA Deficiency / Q000382:microbiology*; D008297:Male; D008358:Mannose / Q000378:metabolism; D008875:Middle Aged; D016133:Polymerase Chain Reaction
D018829:Adhesins, Bacterial; D004269:DNA, Bacterial; D008358:Mannose