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Retracted: Novel NADâindependent Avibacterium paragallinarum: Isolation, characterization and molecular identification in Iran
Abstract Background Infectious coryza (IC) is an invasive upper respiratory disease caused by Avibacterium paragallinarum that affects birds, particularly chickens. The objective of this study is to isolate, characterize and molecularly identify the bacterium A. paragallinarum in poultry birds, as well as to determine its antibiotic sensitivity and resistance. Methods A total of 10 chickens from four different Iranian farms with typical IC symptoms were used in this study. The nasal swabs were streaked onto chocolate agar plates and blood agar plates and incubated at 37°C in 5% CO2 for 24 to 48 h. As part of the identification of bacteria, bacteriological observations and polymerase chain reaction (PCR) testing are conducted. The antibiotic sensitivity tests were also performed using the disk diffusion method against A. paragallinarum and the prevalence in different farms was determined. Results By using biochemical assays and PCR analyses, seven strains of A. paragallinarum were isolated from samples of four chicken farms with typical IC clinical signs. Most isolates (4/7) showed the typical requirement for nicotinamide adenine dinucleotide (NAD) and an enriched CO2 atmosphere for growth. Three of the seven strains of A. paragallinarum were found to be novel NADâindependent under anaerobic conditions. There was one biochemical biovar identified in terms of carbohydrate fermentation patterns, although changes in maltose carbohydrate fermentation patterns were detected in the No. 5 strain. All isolates were sensitive to gentamicin and spectinomycin. Three novel NADâindependent strains (Nos.1, 5 and 7) were found to be multidrugâresistant (MDR) and resistant to at least three classes of antibiotics. There was greater antibiotic resistance in the three NADâindependent isolates than in normal NADâdependent bacteria. Conclusion By discovering NADâindependent forms of A. paragallinarum, these species have a greater range than previously believed. A clear, cautious approach should be taken in diagnosing and possibly controlling IC