Citation
Mustakim, Maimunah
(1998)
Characterisation of Salmonella Enteritidis Isolates from Humans, Animals and Environmental Sources.
Masters thesis, Universiti Putra Malaysia.
Abstract
One hundred and five strains of Salmonella enteritidis isolated
from five different sources including humans, food animals, avian, wild
animals and environments were studied. All isolates were
characterised for their biotype, plasmid profiles and resistance to
antibiotics. Biotyping of the isolates subdivided them into two biotypes
i.e., A and E. Subdivision of the isolates by plasmid profiling identified
fifteen plasmid patterns i.e. PP0 to PP14. Plasmid pattern PP14 was
the most common pattern encountered in 47 (44%) of the total isolates
from various sources. Resistance to antibiotics was not uncommon
with 104 (99%) of the isolates were resistant to more than one
antibiotics. Subdivision by antibiotic resistance pattern exhibited ten
antibiograms designated as R1 to R10. A total of 87 (82%) of the isolates fell into resistant pattern R1 which showed resistant
towards erythromycin, penicillin G and triple sulpha. In conjugations
studies, the ability of transferring antibiotic resistance was
demonstrated in the transconjugants with the concomitant transfer of
the respective plasmid and resistant to tetracycline. Sixty seven
representative strains of S. enteritidis studied for restriction
endonuclease digestion polymorphism by - pulsed-field gel
electrophoresis (REDP-PFGE) exhibited different PFGE fragment
patterns. Digestion with low-frequency-cleavage restriction
endonucleases, i.e., Xbal (5'- TCTAGA-3')and Spel (5'-ACTAGT-3')
produced five and three restriction patterns respectively. Interrelationships
of the PFGE patterns among the isolates could be
determined by the calculation of similarity index, F. The F values
grouped the strains as closely related, unrelated or indistinguishable.
The phage-typed strains of S. enteritidis were subdivided into one
biotypes, eleven plasmid profiles, six resistance patterns and seven
restriction polymorphisms. In general, characterisation by DNA-based
method of plasmid profiling gave more discrimination compared to
other methods. These methods also provide effective adjunct to
antibiotic resistance pattern and phage typing for subdivision of S. enteritidis.
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