Molecular identification and antibiogram profiling of Avibacterium Paragallinarum and co-pathogenic bacteria assiciated with respiratory infections in chickens at Groot Aub settlement, Khomas region
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Date
2021
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Publisher
University of Namibia
Abstract
This study was undertaken to isolate, characterize and profile Avibacterium
paragallinarum and some co-pathogenic bacteria for antibiotic sensitivity. Avibacterium paragallinarum is the etiologic agent of infectious coryza, a highly infectious respiratory disease of chickens. This disease is of economic importance because it is known to cause economic losses in the poultry industry through slow growth in young birds and declined egg production in layers. Symptoms of the disease include watery eyes, nasal and ocular discharges, sticky eyes (closed eyes), facial swelling and a reduction in egg production. Twenty (20) swab samples were collected from chickens displaying disease symptoms in the Groot Aub area (45 km south of Windhoek). The swabs were inoculated on blood and chocolate agar plates for isolation of the bacteria, followed by DNA extraction and
amplification by polymerase chain reaction (PCR), and ultimately identification of the
bacteria by sequencing analysis. For antibiogram profiling, morphologically distinct,
lone standing colonies from the axenic cultures were subjected to antibiotic sensitivity testing using the disc diffusion method. In total, samples were collected from 20 chickens, 20% of which were solely positive for Avibacterium paragallinarum, 20% had Avibacterium paragallinarum simultaneously occurring with other co-pathogenic bacteria, whereas the co-pathogenic bacteria were isolated from 60% of chickens. Among some of the identified co-pathogenic bacteria were Escherichia coli, Pasteurella multocida and Staphylococcus chromogenes. The findings suggest that infectious coryza symptoms are not just specific to Avibacterium paragallinarum, but infection of chickens by other bacteria such E. coli, Pasteurella multocida and Staphylococcus species also result in the same symptoms being displayed. Antibiotic sensitivity tests showed that the isolated Avibacterium paragallinarum field strains were susceptible to tetracycline and ampicillin, but resistant to gentamycin, ciprofloxacin and trimethoprim sulfamethoxazole. On the contrary, all isolated co-pathogenic bacteria were resistant to tetracycline and sensitive to trimethoprim sulfamethoxazole, ampicillin and ciprofloxacin. These results indicate that Avibacterium paragallinarum is more likely to be isolated in acute cases. Therefore, for better disease control and prevention, isolation and confirmation is of utmost importance so that right control measures are applied.
Description
A mini thesis submitted in partial fulfillment of the requirements for the Degree of Master of Science (Microbiology)
Keywords
Avibacterium paragallinarum, Co-pathogenic bacteria,, Infectious coryza