Cases Of Colibacillosis Research Articles

Avian pathogenic Escherichia coli transmission from broiler breeders to their progeny in an integrated poultry production chain

Early cases of colibacillosis with omphalitis, yolk sac infection and increased mortality were observed in five broiler chicken flocks (A1, A2, A3, A4 and B1) from two broiler breeder flocks A and B, respectively. Avian pathogenic Escherichia Coli (APEC) serotype O78, Fim/Tsh/Iuc pathotype, were isolated from flocks A, A1, A2, A3 and A4, and APEC serotype O139, pathotype Fim/Iuc, from flocks B and B1. APEC O78 strains isolated from broiler chicks A1, A2, A3 and A4, originating from breeder flock A, had the same antibiotic resistance pattern as APEC O139 strains isolated from broiler chicks B1 and breeder B. The random amplified polymorphic DNA technique performed on APEC strains revealed two distinct clusters of genetic similarity: cluster I consisted of some APEC O78 and cluster II of APEC O139. These results indicated that a transmission of APEC strains from adults A and B to their respective progeny could occur. Transmission d' Escherichia coli pathogène aviaire (APEC) à partir de reproducteurs de type chair à leur descendance dans une production intégrée. Les cas précoces de colibacillose avec omphalite, infection du sac vitellin, et augmentation de mortalité, ont été observés dans cinq troupeaux de poulets de chair A1, A2, A3, A4 et B1 issus de deux troupeaux de reproducteurs respectivement A et B. Des Escherichia coli pathogènes aviaires (APEC) sérotype O78, pathotype Fim/Tsh/Iuc ont été isolés des troupeaux A1, A2, A3, A4 et des APEC O139, pathotype Fim/Iuc ont été isolés des troupeaux B et B1. Les souches d'APEC O78 isolées à partir des poulets de chair A1, A2, A3 et A4 issus du troupeau de reproducteurs A, avaient le même profil de résistance aux antibiotiques que les souches de l'APEC O139 isolés des poulets de chair B1 et des reproducteurs B. Les souches d'APEC ont fait l'objet d'une analyse par RAPD qui a révélé que ces souches se répartissaient en deux groupes distincts de similarité génétique : le groupe I comprenant quelques APEC O78, et le groupe II comprenant les APEC O139. Ces résultats ont montré que la transmission des souches d'APEC des adultes A et B à leur descendance respective peut se produire. Übertragung von Escherchia coli (APEC) von Broilerelterntieren auf ihre Nachkommen innerhalb einer integrierten Geflügelproduktionskette In fünf Broilerherden (A1, A2, A3, A4 und B1) von zwei Broilerelterntierherden (A und B) wurden frühe Fälle von Colibazillose verbunden mit Omphalitis, Dottersackinfektion und erhöhter Mortalität beobachtet. Aus den Herden A, A1, A2, A3 und A4 wurden pathogene aviäre Escherichia coli (APEC)-Serotyp O78,-Pathotyp Fim/Tsh/iuc und aus den Herden B und B1 APEC-Serotyp O139, -PathotypFim/Iuc isoliert. Die O78-APEC-Stämme aus den Broilerherden A1, A2, A3 und A4, die von der Broilerelterntierherde A abstammten, wiesen das gleiche Antibiotikaresistenzmuster auf wie die O139-APEC-Stämme aus den Broilern aus Herde B1 und ihrer Elterntierherde B. Die mit den APEC-Stämmen durchgeführte RAPD-Technik ließ zwei verschiedene genetische Cluster erkennen: Cluster I beinhaltete einige der APEC O78- Stämme und Cluster II die APEC O139. Diese Ergebnisse weisen darauf hin, dass eine Übertragung von APEC-Stämmen von den Adulten der Herden A und B auf ihre Nachkommen vorkommen kann. Transmisión de Escherichia coli patógena aviar (APEC) de reproductores a su progenie en una cadena de producción avícola integrada Se observaron casos tempranos de colibacilosis con onfalitis, infección del saco vitelino y mortalidad incrementada en cinco lotes de pollos de engorde A1, A2, A3, A4 y B1 provenientes de dos lotes de reproductores, A y B respectivamente. Se aisló una Escherichia Coli patógena aviar (APEC) serotipo O78, patotipo Fim/Tsh/Iuc de los lotes A, A1, A2, A3, A4 y APEC del serotipo O139 y patotipo Fim/Iuc de los lotes B y B1. Las cepas APEC O78 aisladas de los pollitos A1, A2, A3 y A4, originarios de los lotes de reproductores A, presentaron el mismo patrón de resistencia a los antibióticos que las cepas APEC O139 aisladas de los pollitos de engorde B1 y de los reproductores B. La técnica de RAPD realizada sobre las cepas APEC reveló dos grupos distintos de similaridad genética: el grupo I consistió en algunas APEC O78 y el grupo II en APEC O139. Estos resultados indican que la transmisión de cepas APEC de adultos A y B a su progenie respectiva puede ocurrir.

Rapid Detection of Virulence-Associated Genes in Avian Pathogenic Escherichia coli by Multiplex Polymerase Chain Reaction

Based on recently published prevalence data of virulence-associated factors in avian pathogenic Escherichia coli (APEC) and their roles in the pathogenesis of colibacillosis, we developed a multiplex polymerase chain reaction (PCR) as a molecular tool supplementing current diagnostic schemes that mainly rely on serological examination of strains isolated from diseased birds. Multiple isolates of E. coli from clinical cases of colibacillosis known to possess different combinations of eight genes were used as sources of template DNA to develop the multiplex PCR protocol, targeting genes for P-fimbriae (papC), aerobactin (iucD), iron-repressible protein (irp2), temperature-sensitive hemagglutinin (tsh), vacuolating autotransporter toxin (vat), enteroaggregative toxin (astA), increased serum survival protein (iss), and colicin V plasmid operon genes (cva/cvi). In order to verify the usefulness of this diagnostic tool, E. coli strains isolated from fecal samples of clinically healthy chickens were also included in this study, as were uropathogenic (UPEC), necrotoxigenic, and diarrhegenic E. coli strains. The application of the multiplex PCR protocol to 14 E. coli strains isolated from septicemic poultry showed that these strains harbored four to eight of the genes mentioned above. In contrast, those isolates that have been shown to be nonpathogenic for 5-wk-old chickens possessed either none or, at most, three of these genes. We found only one enterohemorrhagic (EHEC), one enteropathogenic (EPEC), and two enterotoxic (ETEC) E. coli strains positive for irp2, and another two ETEC strains positive for astA. As expected, UPEC isolates yielded different combinations of the genes iss, papC, iucD, irp2, and a sequence similar to vat. However, neither the colicin V operon genes cva/cvi nor tsh were amplified in UPEC isolates. The multiplex PCR results were compared with those obtained by DNA-DNA-hybridization analyses to validate the specificity of oligonucleotide primers, and the protocol was concluded to be a useful, sensitive, and rapid assay system to detect avian pathogenic E. coli and differentiate them from nonpathogenic strains and those belonging to other pathotypes.

Antimicrobial susceptibility and molecular characterization of avian pathogenic Escherichia coli isolates

Ninety-five avian pathogenic Escherichia coli (APEC) isolates recovered from diagnosed cases of avian colibacillosis from North Georgia between 1996 and 2000 were serotyped and examined for typical virulence-factors, susceptibility to antimicrobials of human and veterinary significance, and genetic relatedness. Twenty different serotypes were identified, with O78 being the most common (12%). The majority of the avian E. coli isolates (60%), however, were non-typeable with standard O antisera. Eighty-four percent of isolates were PCR positive for the temperature-sensitive hemagglutinin (tsh) gene and 86% positive for the increased serum survival (iss) gene. Multiple antimicrobial-resistant phenotypes (> or =3 antimicrobials) were observed in 92% of E. coli isolates, with the majority of isolates displaying resistance to sulfamethoxazole (93%), tetracycline (87%), streptomycin (86%), gentamicin (69%), and nalidixic acid (59%). Fifty-six E. coli isolates displaying resistance to nalidixic acid were co-resistant to difloxacin (57%), enrofloxacin (16%), gatifloxacin (2%), and levofloxacin (2%). DNA sequencing revealed point mutations in gyrA (Ser83-Leu, Asp87-Tyr, Asp87-Gly, Asp87-Ala), gyrB (Glu466-Asp, Asp426-Thr), and parC (Ser80-Ile, Ser80-Arg). No mutations were observed in parE. Twelve of the quinolone-resistant E. coli isolates were tolerant to cyclohexane, a marker for upregulation of the acrAB multi-drug resistance efflux pump. Quinolone-resistant isolates were further genetically characterized via ribotyping. Twenty-two distinct ribogroups were identified, with 61% of isolates clustering into four major ribogroups, indicating that quinolone resistance has emerged among multiple avian pathogenic E. coli serogroups and chromosomal backgrounds.

Chicken Embryo Lethality Assay for Determining the Virulence of Avian Escherichia coli Isolates

Multiple isolates of Escherichia coli from clinical cases of colibacillosis and E. coli from the intestinal tracts of normal broilers at slaughter were assayed by the embryo lethality test to determine their virulence. The assay was repeated five times in order to establish reproducibility and determine the statistical parameters of the test. This study showed that the inoculation of approximately 100 colony-forming units in the allantoic cavity of 12-day-old embryos discriminated between virulent and avirulent E. coli isolates. Gross lesions included cranial and skin hemorrhages in addition to encephalomalacia in embryos inoculated with virulent isolates. Abnormalities were observed by microscopic examination of the heart, brain, and liver in embryos inoculated with virulent isolates. Analysis of data indicated that the length of the test should be 4 days. In the virulent group, day 2 postinoculation had the most significant death patterns. Sample size calculations indicated that 11 embryos are sufficient for the assay. On the basis of death rates, isolates considered to be avirulent had an embryo death rate of <10%, moderately or secondary pathogens had a 10%-29% death rate, and virulent isolates had a death rate of >29%. An important aspect of this assay is the accessibility of good-quality fertile embryonated eggs.

Apramycin: minimal inhibitory concentrations for avian Escherichia coli and serum levels after intramuscular injection in turkeys.

The minimal inhibitory concentrations (MIC) of apramycin, a unique aminocyclitol antibiotic, for 100 Escherichia coli isolates recovered from clinical cases of avian colibacillosis were determined using the agar dilution method. All isolates were inhibited at apramycin concentration of 8.0 micrograms/ml; 90 and 50% of the isolates were inhibited at 6.6 and 3.4 micrograms/ml, respectively. A commercial injectable product containing 200 mg apramycin/ml was administered intramuscularly (i.m.) to groups of 6- and 12-week-old turkeys at 10, 15 and 20 mg/kg. Apramycin was quickly absorbed from the i.m. injection site. Mean peak serum drug concentrations were reached 1 h after treatment and were 19.5, 27.5 and 36.0 micrograms/ml, respectively. The serum elimination half-life (t 1/2) of the drug ranged between 1.75 h for the 10 mg/kg dose and 2.5 h for the 20 mg/kg dose. Very low concentrations of the drug were found 24 h after treatment. Duration of serum apramycin concentrations in relation to the MIC, dose, and age of birds was determined.

The Colicinogenic Properties of Porcine Escherichia Coli Strains

The colicine production of 789 porcine E. coli strains was investigated in temperatures of 37°G and 40 °C respectively. The results are expressed in tabular form. It was found that of 435 strains isolated from an equal number of colibacillosis cases about 60 % were coli-cinogenic, 52.4 % producing colicine in both incubation temperatures used, whereas of 354 strains isolated in the intestinal content of healthy pigs only 17 % produced colicine. The inhibitive zone formed by strains belonging to O-groups 141ab and 141ac was significantly larger than that formed by other serological groups. It was found that in nearly all colicinogenic strains the inhibitive zone was larger when incubated at 40 °C than at 37 °C. The higher incubation temperature is recommended in determination of colicine production of porcine E. coli strains.