Type 2 heat-labile enterotoxin (LT-II)-producing Escherichia coli isolated from ostriches with diarrhea

Nardi, Ana Rita Moraes; Salvadori, Márcia Regina; Coswig, Lia Treptow; Gatti, Maria Sílvia Viccari; Leite, Domingos S.; Valadares, Geórgio Freesz; Neto, Manoel Garcia; Shocken-Iturrino, Ruben Pablo; Blanco, Jesús E.; Yano, Tomomasa

doi:10.1016/j.vetmic.2004.11.005

Cited by 15 publications

(17 citation statements)

References 23 publications

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“…To better define the enterotoxins producing disease in commercial ostriches, Nardi et al (21) reported isolation of four strains of E. coli from the feces of diarrheic ostriches. These strains appeared to be enterotoxigenic.…”

Section: Methodsmentioning

confidence: 99%

“…These strains appeared to be enterotoxigenic. Using antigenic neutralization assays and PCR-based genetic screens, Nardi et al (21) concluded that these strains likely produced a type II HLT. While Nardi's results were consistent with that hypothesis, the data were not of sufficient resolution to determine if those strains encoded either LT-IIa or LT-IIb.…”

Section: Methodsmentioning

confidence: 99%

“…ETEC strains producing HLT with apparent homology to type II enterotoxins have also been isolated from human patients and from other mammals which were exhibiting symptoms of diarrhea (11). Recently, four strains of E. coli obtained from the feces of diarrheic ostriches were identified in an animal clinic in Brazil (21). In vitro cytotoxicity assays using CHO and Vero cells indicated that these strains were toxigenic (21).…”

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confidence: 99%

“…Recently, four strains of E. coli obtained from the feces of diarrheic ostriches were identified in an animal clinic in Brazil (21). In vitro cytotoxicity assays using CHO and Vero cells indicated that these strains were toxigenic (21). The toxic activities produced by these strains could not be neutralized by anti-CT antisera.…”

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LT-IIc, a New Member of the Type II Heat-Labile Enterotoxin Family Encoded by an Escherichia coli Strain Obtained from a Nonmammalian Host

Nawar

King-Lyons

et al. 2010

Infect Immun

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Infections caused by enterotoxigenic Escherichia coli (ETEC)are the leading cause of traveler's diarrhea and the major cause of diarrheal disease in underdeveloped nations, especially among children. ETEC, which is usually transmitted by food or water contaminated with animal or human feces, is estimated to be responsible annually for more than 650 million cases of enteric infections and nearly 800,000 deaths (29). Infection begins with ingestion of bacteria, followed by elaboration of enterotoxin and bacterial colonization of the gut, and presents as a profuse watery diarrhea which disseminates the bacteria back into the environment (10).ETEC strains are lactose-fermenting E. coli strains that produce a heat-labile enterotoxin (LT, hereafter referred to as LT-I), heat-stable enterotoxins (ST), or both and colonization factors which enable ETEC to colonize the small intestine (22). The pathogenesis of ETEC is dependent on the strains' capacity to produce LT-I and/or ST (10, 29). LT-I is closely related functionally, antigenically, and structurally to cholera toxin (CT), the heat-labile enterotoxin produced by Vibrio cholerae. Antiserum against CT neutralizes the toxicity of LT-I, and antiserum against LT-I neutralizes the toxicity of CT (15). Structurally, LT-I and CT are oligomeric proteins composed of an A polypeptide which is noncovalently coupled to a pentameric array of B polypeptides (15). The A polypeptide of LT-I and CT is enzymatically active and catalyzes an ADP-ribosylation of the G s ␣ regulatory protein in the intoxicated cell. Ribosylation of this regulatory protein constitutively activates adenylate cyclase, the enzyme which catalyzes production of cyclic AMP (cAMP) (3,20). Accumulation of cAMP induces the intoxicated cell to secrete electrolytes and chloride ions, thus generating the watery diarrhea, which is symptomatic of intoxication. Intracellular accumulation of cAMP modulates other cellular processes such as protein kinase activity, activation of calcium channels, etc. (15). Binding of LT-I and CT to ganglioside receptors is mediated by the B polypeptides. Gangliosides are members of a heterogeneous family of sialylated glycosphingolipids expressed on the surface of eukaryotic cells (9). Based on these characteristics, LT-I and CT have been designated as members of the large family of toxins known as the A 1 B 5 ADP-ribosylating heat-labile enterotoxins (HLTs).LT-IIa and LT-IIb, two new members of the A 1 B 5 family of HLTs produced by E. coli, were recently described (11,12,27). While it is clear that LT-IIa and LT-IIb are evolutionarily related to LT-I and CT, there are major differences between the two groups of enterotoxins. LT-IIa and LT-IIb are antigenically distinguishable from LT-I and CT and from each other (12). These antigenic differences are reflected in the low amino acid sequence similarity of the A polypeptides and the virtual absence of amino acid sequence homology of the B polypeptides between the two groups (LT-I and CT versus LT-IIa and LT-IIb) (35). To distinguish betwee...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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LT-IIc, a New Member of the Type II Heat-Labile Enterotoxin Family Encoded by an Escherichia coli Strain Obtained from a Nonmammalian Host

Nawar

King-Lyons

et al. 2010

Infect Immun

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“…The serogroup O15:H8 was reported as an important agent of diarrhea in ostriches, due to type 2 heat-labile enterotoxin (LT II) production (Nardi et al 2005). There are only a few reports demonstrating that E. coli strains isolated from avian can produce toxins (Tsuji et al 1990, Blanco et al 1997a, Parreira et al 1998, Salvatori et al 2001, Parreira & Gyles, 2003.…”

Section: Discussionmentioning

confidence: 99%

Serogroups and virulence genes of Escherichia coli isolated from psittacine birds

et al. 2011

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916Pesq. Vet. Bras. 31(10):916-921, outubro 2011 RESUMO.-[Sorogrupos e genes de virulência em Escherichia coli isoladas de psitacídeos.] Amostras de Escherichia coli isoladas de 24 psitacídeos doentes foram sorogrupadas e investigadas para a presença de genes que codiϐicam os seguintes fatores de virulência: attaching e effacing (eae), plasmídeo EAF (EAF), pili associado à pielonefrite (pap), ϐímbria S (sfa), adesina aϐimbrial (afa), cápsula K1 (neu), curli (crl, csgA), hemaglutinina termosensível (tsh), enterotoxina termo-estável 1 de E. coli enteroagregativa (astA), toxina termolábil (LT) e toxina termoestável (STa e STb), Shiga-like toxinas (stx1 e stx2), fator citotóxico necrotizante 1 (cnf1), hemolisina (hly), produção de aerobactina (iuc) e resistência sérica (iss). Os resultados mostraram que os isolados pertenciam a 12 sorogrupos: O7; O15; O21; O23; O54; O64; O76; O84; O88; O128; O152 e O166. Os genes de virulência encontrados foram: crl em todos os isolados, pap em 10 isolados, iss em sete isolados, csgA em cinco isolados, iuc e tsh em três isolados e eae em dois isolados. A combinação dos genes de virulência revelou 11 perϐis genotípicos distintos. Todas as amostras foram negativas para os genes que codiϐicam EAF, EAEC, K1, sfa, afa, hly, cnf, LT, STa, STb, stx1 e stx2. Estes resultados demonstraram que algumas amostras de E. coli isoladas de psitacídeos apresentam os mesmos fatores de virulência presentes nos patotipos de E. coli patogênicas para aves (APEC), uropatogênicas (UPEC) e E. coli enteropatogênicas (EPEC). Escherichia coli isolates from 24 sick psittacine birds were serogrouped and investigated for the presence of genes encoding the following virulence factors: attaching and effacing (eae), enteropathogenic E. coli EAF plasmid (EAF), pili associated with pyelonephritis (pap), S ϐimbriae (sfa), aϐimbrial adhesin (afa), capsule K1 (neu), curli (crl, csgA), temperature--sensitive hemagglutinin (tsh), enteroaggregative heat-stable enterotoxin-1 (astA), heat--stable enterotoxin -1 heat labile (LT) and heat stable (STa and STb) enterotoxins, Shiga-like toxins (stx1 and stx2), cytotoxic necrotizing factor 1 (cnf1), haemolysin (hly), aerobactin production (iuc) and serum resistance (iss). The results showed that the isolates belonged to 12 serogroups: O7; O15; O21; O23; O54; O64; O76; O84; O88; O128; O152 and O166. The virulence genes found were: crl in all isolates, pap in 10 isolates, iss in seven isolates, csgA in ϐive isolates, iuc and tsh in three isolates and eae in two isolates. The combination of virulence genes revealed 11 different genotypic patterns. All strains were negative for genes encoding for EAF, EAEC, K1, sfa, afa, hly, cnf, LT, STa, STb, stx1 and stx2. Our ϐindings showed that some E. coli isolated from psittacine birds present the same virulence factors as avian pathogenic E. coli (APEC), uropathogenic E. coli (UPEC) and Enteropathogenic E. coli (EPEC) pathotypes. Serogroups and virulence genes of

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Colibacillosis

Nolan¹,

Vaillancourt²,

Barbieri³

et al. 2019

Diseases of Poultry

116

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Type 2 heat-labile enterotoxin (LT-II)-producing Escherichia coli isolated from ostriches with diarrhea

Cited by 15 publications

References 23 publications

LT-IIc, a New Member of the Type II Heat-Labile Enterotoxin Family Encoded by an Escherichia coli Strain Obtained from a Nonmammalian Host

LT-IIc, a New Member of the Type II Heat-Labile Enterotoxin Family Encoded by an Escherichia coli Strain Obtained from a Nonmammalian Host

Serogroups and virulence genes of Escherichia coli isolated from psittacine birds

Colibacillosis

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