Production and release of heat-labile toxin by wild-type human-derived enterotoxigenic Escherichia coli.
Production and release of heat-labile toxin (LT) by wild-type enterotoxigenic Escherichia coli (ETEC) strains, isolated from diarrheic and asymptomatic Brazilian children, was studied under in vitro and in vivo conditions. Based on a set of 26 genetically diverse LT(+) enterotoxigenic E. coli strains, cell-bound LT concentrations varied from 49.8 to 2415 ng mL(-1). The amounts of toxin released in culture supernatants ranged from 0% to 50% of the total synthesized toxin. The amount of LT associated with secreted membrane vesicles represented <5% of the total toxin detected in culture supernatants. ETEC strains secreting higher amounts of LT, but not those producing high intracellular levels of cell-bound toxin, elicited enhanced fluid accumulation in tied rabbit ileal loops, suggesting that the strain-specific differences in production and secretion of LT correlates with symptoms induced in vivo. However, no clear correlation was established between the ability to produce and secrete LT and the clinical symptoms of the infected individuals. The present results indicate that production and release of LT by wild-type human-derived ETEC strains are heterogeneous traits under both in vitro and in vivo growth conditions and may impact the clinical outcomes of infected individuals.
Lasaro
Melissa Ang Simões
MA
Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil.
Rodrigues
Juliana Falcão
JF
Mathias-Santos
Camila
C
Guth
Beatriz Ernestina Cabílio
BE
Régua-Mangia
Adriana
A
Piantino Ferreira
Antônio José
AJ
Takagi
Mickie
M
Cabrera-Crespo
Joaquin
J
Sbrogio-Almeida
Maria Elisabete
ME
de Souza Ferreira
Luís Carlos
LC
D000818:Animals; D004768:Enterotoxins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D004927:Escherichia coli Infections / Q000382:microbiology; D006358:Hot Temperature; D006801:Humans; D011817:Rabbits
D004768:Enterotoxins