| Acinetobacter baumannii is an opportunistic pathogen widely existing in natureand constituting a normal flora on human skin surface. Due to its good tolerace oftemperature and pH, they are able to stay on the surfaces of various items for a longtime. Acinetobacter baumannii infection is usually hospital-acquired, and its clinicalisolating rate is only second to non-fermenting bacteria of Pseudomonas aeruginosa.Through adhereing to the nurses’ hands and surfaces of all kinds of medicalequipments, it causes across-spreading via human contaction. With the extensive usesof antibiotics, drug resistance rates of Acinetobacter baumannii gradually rise, andmulti-drug resistant strains (MDR) have been reported around the world, whichattracts wide attention, yet it is rarely been reported as a pathogenic source of chicken.In recent years, cases of human infected by avian diseases have frequently beenreported, which brings great harm to farming industry and human health. Therefore itis of high public health significance to study the pathogenesis of Acinetobacterbaumannii.In this study, Acinetobacter baumannii strain CCGGD201101was isolated from adead chicken in a chick farm in Jilin Province of China, and using molecular biologyand proteomics methods the characteristics of Acinetobacter baumannii and itsbacterial protein related with pathogenic virulence factors were studied. Firstlyclinical symptoms and anatomic pathological changes of the dead chicken wererecorded, and the pathogenic bacteria were confirmed to be Acinetobacter baumannii by physiological and biochemical tests and16S rDNA sequencing. Compared withAcinetobacter baumannii standard strain ATCC19606as a control, CCGGD201101strain was used to infect animals and the median lethal dose was determined so as toverify its bacteria toxicity. Then the bacterial proteins of the isolated and standardstrains were respectively extracted, purified and quantified, two-dimensionalFluorescence Difference Gel Electrophoresis (2D-DIGE) technology was applied toscreen the differentially expressed protein (p<0.05), and the selected proteins wereanalyzed by MALDI-TOF/TOF-MS mass spectrometry. Finally genes possibllyassociated with pathogenicity were selected and studied by relative quantitativereal-time PCR with16S rRNA as reference gene. The results showed the colony thepathogenic bacteria isolated from the liver of dead chicken by clinical inspection withround, white, opaque, middle raised, smooth, and neat edge colony forms wereGram-negative ball-bacilli bacteria by microscopic examination. The1501bp targetfragment of16S rDNA was amplified, and via sequencing the identity of16S rDNAof CCGGD201101strain was100%with many strains of Acinetobacter baumannii inGenBank, and physiological and biochemical tests further confirmed that thepathogenic strain CCGGD201101was Acinetobacter baumannii. The median lethaldoses of the isolated and standard strains were1.259×106CFU and1.585×107CFUrespectively, and the isolated strain apparently showed pathogenity.44upregulatedproteins were screened by2D-DIGE and14proteins were identified through proteinprofile including hemolysin, ferrichrome-iron receptor, pili proteins (protein CsuA/B),glycine zipper, serine proteases hypothetical protein, assumed surface antigen,DcaP-like protein, Long-chain fatty acid transport protein,3-oxoacyl-ACP reductase,nitroreductase, The carbapenem Resistance-Associated hypothetical protein, vitaminB12receptor precursor, Chain G, Crystal Structure Of Ompa Peptidoglycan-bindingDomain and the assumed protein. Hemolysin and ferrichrome-iron receptor wereassumed to be associated with pathogenity, and using relative quantitative real-time PCR the hemolysin hly gene and ferrichrome-iron receptor fiR gene were confirmedto be significantly upregulated in the isolated strain CCGGD201101compared withstandard strain ATCC19606, which further implyed they were related with pathogenicfactors of Acinetobacter baumannii. |
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