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Abstract
• A field screening was tried to study the incidence and prevalence of Helicobacter pullorum infection in Assiut Governorate.
• It was found that 354 isolates of 900 samples (39.33%) obtained from chickens included the cloacal swabs (21 out of 300), intestinal samples (192 out of 300) and liver samples (141 of 300) on the basis of phenotypic methods of isolation. No isolation of H. pullorum was obtained from poultry species other than chickens such as turkeys and ducks.
• Only 16 randomly selected isolates of Helicobacter pullorum which identified previously on the basis of phenotypic reactions were investigated for identification of 16S-rRNA gene using polymerase chain reaction. Results elucidated positive amplification of 16S-rRNA gene from all the tested isolates, the matter which mean that all tested isolates belonged to Helicobacter pullorum.
• In this study, 16 randomly selected isolates of Helicobacter pullorum which identified previously on the basis of phenotypic and genotypic methods were investigated for detection of cytolethal distending toxin gene using polymerase chain reaction. Results elucidated positive amplification of cytolethal distending toxin gene from 14 out of the 16 tested isolates, while, 2 isolates were negative, the matter which mean that positive tested isolates possesses cytolethal distending toxin, but its role in pathogenesis in Helicobacter pullorum infection till now had not been clarified.
• Determination of pathogenicity of Helicobacter pullorum by oral experimental infection of day-old chicks with isolates of H. pullorum (1011 CFU/ml) results in 33.3% mortality with retardation of growth and poor conversion rate in survivors. Helicobacter pullorum was re-isolated from caeca, livers, unabsorbed yolk sac, pericardium and air-sacs. While there is no mortality, signs of illness or isolation in negative control birds.
• Five groups of experimentally inoculated embryonating chicken eggs via yolk sac rout of inoculation, with five different Helicobacter pullorum (1010 CFU/ml) isolates showed early embryonic mortality within the same time. Helicobacter pullorum was re-isolated from dead embryos as well as from embryonic membranes and embryonic fluids. While no embryonic mortalities or isolation in the negative control group. This means that there is no variation in the pathogenicity of Helicobacter pullorum isolates of all experimental embryonating chicken eggs.
• Determination of antibacterial susceptibility and resistance patterns of Helicobacter pullorum using minimal inhibitory concentration (MIC) for six antibacterial drugs (ciprofloxacin, gentamycin, colistin, tetracycline, erythromycin and ampicillin) against different eight Helicobacter pullorum isolates revealed that all isolates were resistant to ciprofloxacin, gentamycin and erythromycin, while 7 out of 8 isolates resistant to tetracycline. All isolates were susceptible to colistin and ampicillin.