Comparison of Clearance Rates of Virulent and Avirulent Escherichia coli in Turkeys after Aerosol Exposure

Arp, L. H.; Graham, Chris; Cheville, N. F.

doi:10.2307/1589568

Cited by 22 publications

(8 citation statements)

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“…Virulent avian E. coli strains colonize the tracheas of experimentally infected birds in greater numbers than avirulent strains (16), are cleared less quickly from the respiratory tract, and can produce a bacteremia after aerosol exposure (4). Piliated E. coli strains are more virulent for chickens than nonpiliated strains (5,17,46).…”

Section: Discussionmentioning

confidence: 99%

Colonization of the Respiratory Tract by a Virulent Strain of Avian Escherichia coli Requires Carriage of a Conjugative Plasmid

Ginns¹,

Benham²,

Adams

et al. 2000

Infect Immun

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The E3 strain of E. coli was isolated in an outbreak of respiratory disease in broiler chickens, and experimental aerosol exposure of chickens to this strain induced disease similar to that seen in the field. In order to establish whether the virulent phenotype of this strain was associated with carriage of particular plasmids, four plasmid-cured derivatives, each lacking two or more of the plasmids carried by the wild-type strain, were assessed for virulence. Virulence was found to be associated with one large plasmid, pVM01. Plasmid pVM01 was marked by introduction of the transposon TnphoA, carrying kanamycin resistance, and was then cloned by transformation of E. coli strain DH5␣. The cloned plasmid was then reintroduced by conjugation into an avirulent plasmid-cured derivative of strain E3 which lacked pVM01. The conjugant was shown to be as virulent as the wild-type strain E3, establishing that this plasmid is required for virulence following aerosol exposure. This virulence plasmid conferred expression of a hydroxamate siderophore, but not colicins, on both strain E3 and strain DH5␣. Carriage of this plasmid was required for strain E3 to colonize the respiratory tracts of chickens but was not necessary for colonization of the gastrointestinal tract. However, the virulence plasmid did not confer virulence, or the capacity to colonize the respiratory tract, on strain DH5␣. Thus, these studies have established that infection of chickens with E. coli strain E3 by the respiratory route is dependent on carriage of a conjugative virulence plasmid, which confers the capacity to colonize specifically the respiratory tract and which also carries genes for expression of a hydroxymate siderophore. These findings will facilitate identification of the specific genes required for virulence in these pathogens.Lower-respiratory-tract infections are the most common disease syndrome associated with Escherichia coli in poultry. Although in extreme cases mortality can be over 20%, it is the high morbidity and associated loss in productivity which is responsible for the greatest economic loss (31).There is evidence to suggest that virulent strains of avian E. coli belong to a limited number of clone complexes (60,61) and that particular clones may be specific to particular manifestations of E. coli infection (47). A number of characteristics have been associated with virulence in avian E. coli, including colicin V production (22, 23, 50, 59), adhesins (17, 18, 20, 32, 46, 67), serum resistance (21,37,47,48,59,66), and iron sequestering (37,41,43,47,59,63), but specific attempts to establish the requirements of these factors for virulence are limited. While initial studies of avian E. coli led to the conclusion that certain serogroups, O1, O2, and O78 in particular, were more commonly associated with colibacillosis (27,28,29,33,35,36), the most prevalent serotypes vary with geographic location and many isolates are untypeable (3,6,12,19,38,45).Although plasmid-encoded virulence genes have been well investigated and described fo...

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Section: Discussionmentioning

confidence: 99%

Colonization of the Respiratory Tract by a Virulent Strain of Avian Escherichia coli Requires Carriage of a Conjugative Plasmid

Ginns¹,

Benham²,

Adams

et al. 2000

Infect Immun

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“…In avian species, the organism usually infects the respiratory tract, with bacteraemic strains passing through the mucosa, entering the blood stream, and causing a variety of diseases, including colisepticemia, airsacculitis, and pericarditis (17,22,38,39). The observations that most E. coli isolates commonly associated with colibacillosis in domestic poultry belong to a limited number of serotypes, usually 01, 02, and 078 (8,16,31), exhibit certain patterns of carbohydrate fermentation (13, 14) and antibiotic resistance (8,15,19,20) and express specific adhesins (5,9,12,23,24,40) has lent strong support to the hypothesis that strains causing respiratory disease are a genetically distinct group of pathogenic strains that possess specific virulence factors (4,5,9,32).Recently, the extent to which serological classification of E. coli isolates reflects degrees of genetic relatedness among strains has been seriously questioned. Electrophoretic analyses of variation in outer membrane proteins (1, 2) and water-soluble enzymes (6,27,34,35) have provided clear evidence that many serogroups, based on single antigenic determinants, are genetically heterogeneous and that even closely related isolates with identical or nearly identical electrophoretic profiles can exhibit distinct serotypes.…”

mentioning

confidence: 95%

Genetic relationships among pathogenic strains of avian Escherichia coli

Whittam

Wilson

1988

Infect Immun

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Genetic relationships among 79 strains of Escherichia coli, isolated mostly from diseased chickens, were estimated on the basis of allelic variation at 15 enzyme-encoding loci, determined by multilocus enzyme electrophoresis. All 15 loci were polymorphic, with an average of 4.1 alielic states per locus. Comparisons of the observed combinations of alleles among strains revealed 37 distinct multilocus genotypes that were used to define naturally occurring cell lineages or clones. Two-thirds of the isolates were classified into 10 clones, including a single multilocus genotype that accounted for about a third of all isolates. For isolates of these clones, there was a high concordance (76%) between identity in multilocus genotype, O:K:H serotype, and pattern of resistance to five antibiotics. Cluster analysis disclosed two major complexes of closely related clones, in which more than 50% of the isolates were associated with localized infections (airsacculitis and pericarditis). Both complexes contained isolates with serotype 02:K1, indicating that this serotype can occur on diverse chromosomal backgrounds. The results suggest that colibacillosis within avian populations is caused by a relatively limited number of pathogenic clones representing at least two distinct clone complexes.Escherichia coli is a well known cause of extraintestinal infections in humans and domesticated animals. In avian species, the organism usually infects the respiratory tract, with bacteraemic strains passing through the mucosa, entering the blood stream, and causing a variety of diseases, including colisepticemia, airsacculitis, and pericarditis (17,22,38,39). The observations that most E. coli isolates commonly associated with colibacillosis in domestic poultry belong to a limited number of serotypes, usually 01, 02, and 078 (8,16,31), exhibit certain patterns of carbohydrate fermentation (13, 14) and antibiotic resistance (8,15,19,20) and express specific adhesins (5,9,12,23,24,40) has lent strong support to the hypothesis that strains causing respiratory disease are a genetically distinct group of pathogenic strains that possess specific virulence factors (4,5,9,32).Recently, the extent to which serological classification of E. coli isolates reflects degrees of genetic relatedness among strains has been seriously questioned. Electrophoretic analyses of variation in outer membrane proteins (1, 2) and water-soluble enzymes (6,27,34,35) have provided clear evidence that many serogroups, based on single antigenic determinants, are genetically heterogeneous and that even closely related isolates with identical or nearly identical electrophoretic profiles can exhibit distinct serotypes. However, several of these investigations (1,2,25,35) have also provided strong support for the clone concept (30), that is, the hypothesis that populations of E. coli are structured into stable cell lineages or clones with low rates of homologous recombination between lineages (for recent reviews of the clonal hypothesis, see references 3 and 34). Although the ...

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“…Strains EC1 and EC3 have been used in previous studies as VO78 and AV02 (Arp et al, 1979;Arp and Cheville, 1981). The serotypes of strains EC1, EC27 and EC3 were 078:K80:H9, 078:K3:H9, and 02:K-:H6, respectively.…”

Section: Escherichia Coli Strainsmentioning

confidence: 99%

“…One-day-old Broad-Breasted White turkeys were obtained commercially and raised to 3 weeks of age in isolation rooms (Arp et al, 1979). Experimental design Turkeys were given 1 ml of E. coli inoculum intravenously (i.v.)…”

Section: Turkeysmentioning

confidence: 99%

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Pathology of spleen and liver in turkeys inoculated withescherichia coli¹

1982

Avian Pathology

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SUMMARYLesions of spleen and liver were studied by light and electron microscopy in 3-week-old turkeys inoculated intravenously with Escherichia coli. Spleen and liver of turkeys given avirulent E. coli were hyperaemic and had increased numbers of heterophils. Aggregates of heterophils were in the splenic red pulp and hepatic sinusoids. Turkeys given virulent strains of E. coli had intense heterophil infiltration in spleen and slightly increased numbers of heterophils in liver. In these spleens, reticular sheaths . (ellipsoids) contained large aggregates of heterophils, fibrin, and thrombocytes 2 to 8 hours postinoculation. Turkeys given virulent E. coli and killed in extremis had hypaeremic red pulp and fibrinopurulent exudates and haemorrhage in splenic white pulp. Livers of birds killed in extremis were turgid, friable and engorged with dark blood. Centrolobular hepatocytes were individualised and vacuolated. The dilated sinusoids contained fibrin, erythrocytes, heterophils and bacterial colonies. Phagosomes of hepatic macrophages contained up to 10 structurally normal bacilli, whereas heterophils contained bacilli with altered cell walls. Thrombi, composed of thrombocyte aggregates and fibrin, were common in small hepatic veins. These studies indicate that early bacteraemia with virulent E. coli leads to intense fibrinopurulent splenitis. Progressive bacteraemia is associated with pooling of blood in viscera, intravascular coagulation, and venous thrombosis and bacterial colonisation in liver.

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Comparison of Clearance Rates of Virulent and Avirulent Escherichia coli in Turkeys after Aerosol Exposure

Cited by 22 publications

References 5 publications

Colonization of the Respiratory Tract by a Virulent Strain of Avian Escherichia coli Requires Carriage of a Conjugative Plasmid

Colonization of the Respiratory Tract by a Virulent Strain of Avian Escherichia coli Requires Carriage of a Conjugative Plasmid

Genetic relationships among pathogenic strains of avian Escherichia coli

Pathology of spleen and liver in turkeys inoculated withescherichia coli¹

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Comparison of Clearance Rates of Virulent and Avirulent Escherichia coli in Turkeys after Aerosol Exposure

Cited by 22 publications

References 5 publications

Colonization of the Respiratory Tract by a Virulent Strain of Avian Escherichia coli Requires Carriage of a Conjugative Plasmid

Colonization of the Respiratory Tract by a Virulent Strain of Avian Escherichia coli Requires Carriage of a Conjugative Plasmid

Genetic relationships among pathogenic strains of avian Escherichia coli

Pathology of spleen and liver in turkeys inoculated withescherichia coli1

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Pathology of spleen and liver in turkeys inoculated withescherichia coli¹