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Abstract
Pseudomonas aeruginosa is naturally resistant to a wide spectrum of antibiotics in current use and infections by this bacterium have been found very refractory to chemotherapy. So, in this study, the resistance pattern of Pseudomonas aeruginosa in farm animals was studied phenotypically and genotypically. The present study was carried out on 199 samples randomly collected from different farms at Alexandria and El-Behera governorates as follows: 64 samples from cattle, 34 samples from sheep, 43 samples from fish, and 58 samples from chickens. The samples were directly transported to the laboratory where they were prepared for microbiological examination for isolation of Pseudomonas aeruginosa, determination of antibacterial sensitivity and detection of plasmid, protein profile and metallo-13-lactamase gene, in addition to a pathogenicity study.
A. Incidence of Pseudomonas aeruginosa among different samples:
• Cattle. The results showed that 9 out of 64 samples (14.06%) were positive for Pseudomonas aeruginosa.
Sheep. Four samples out of 34 (11.76%) were positive for the organism.
Fish. Five samples out of 43 (11.63%) were positive for Pseudomonas aeruginosa. Chicken. 10.34% (6 out of 58 samples) had Pseudomonas aeruginosa isolates.
Results of antimicrobial sensitivity:
Twenty four isolates of Pseudomonas aeruginosa were tested against 12 antibacterial agents in this study. The organism was sensitive to ciprofloxacin (100%), norfioxacin (85%), ceftriaxone (60%), cefotaxime Na (45%) and gentamicin (32%). On the other hand, all isolates were resistant to ofloxacin, vancomycin, amoxicillin plus sulbactam, amoxicillin plus clavulanic acid, ampicillin,
sulphamethoxa.zole and chioramphenicol. Plasmid DNA profileanalysis:
Eight Pseudomonas aeruginosa isolates were positive for analysis by using polyacrylamide gel electrophoresis. They carried plasmids with molecular weight ranged from 5 to 20 megadaltons.
Protein profile analysis of Pseudomonas aeruginosa:
SDS-PAGE revealed characteristic variable bands between different isolates, which makes it a possible method for diagnosis and differentiation.
The whole cell protein profile of all examined isolates dominated by the presence of bands with molecular weights ranged from 13.4 to 340 KDa. The Pseudomonas aeruginosa from the same origin had identical protein profile and differ from that of different origin. Detection of metallo--lactamase gene:
Eight isolates representative of different isolate groups were examined for the presence of metallo-f3-lactamase gene, which is responsible for the antibiotic resistance of Pseudomonas aeruginosa. All the isolates examined were positive for the presence of the gene. ‘.Histopathological studies:
The study revealed a similar nature of postmortem microscopic and macroscopic lesions even in clinical signs, but were different in the severity and onset of their appearance.
Also, the results indicated that Pseudomonas aeruginosa had a high pathogenicity to all experimental birds where all inoculated birds died starting at the day till the 15th day post-inoculation with specific lesions in different organs (lung, liver, kidney, muscle, liver).