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Molecular Characterisation of Bacteriophage K Towards Applications for the Biocontrol of Pathogenic Staphylococci.
O'Flaherty, Sarah Flynn, James Coffey, Aidan Fitzgerald, Gerald F Meaney, William J Ross, R Paul
O'Flaherty, Sarah
Flynn, James
Coffey, Aidan
Fitzgerald, Gerald F
Meaney, William J
Ross, R Paul
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2006-01-01
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O'Flaherty, S., Flynn, J., Coffey, A., Fitzgerald, G., Meaney, W., Ross, P. Molecular Characterisation of Bacteriophage K Towards Applications for the Biocontrol of Pathogenic Staphylococci, End of Project Reports, Teagasc, 2006.
Abstract
The aim of this work was to characterise staphylococcal bacteriophage (a
bacterial virus) and to assess their potential as therapeutic agents against pathogenic
strains of Staphylococcus aureus, particularly mastitis-causing strains. The project
included the use of two newly isolated phage CS1 and DW2, and an existing
polyvalent phage. The new phage were isolated from the farmyard and characterised
by electron microscopy and restriction analysis. Both phage were shown to belong to
the Siphoviridae family and were lytic for representatives of all three clonal groups of
Irish mastitis-associated staphylococci. A cocktail of three phage (CS1, DW2 and K)
at 108 (plaque forming units) PFU/ml was infused into cows teats in animal trials.
The lack of an increase in somatic cell counts in milks indicated strongly that the
phage did not irritate the animal. In addition, the most potent phage used in this
study, phage K, was further studied by genome sequencing, which revealed a linear
DNA genome of 127,395 base pairs, which encodes 118 putative ORFs (open reading
frames). Interesting features of the genome include; 1) a region exhibiting high
homology to the structural module from Listeria phage A511, 2) genes which
potentially encodes proteins necessary for its own replisome, 3) an absence of GATC
sites and 4) three introns encoding putative endonucleases were located in the
genome, (two in the putative DNA polymerase gene and one in the lysin gene).
Unlike both CS1 and DW2, the polyvalent phage K, exhibited a broad host range
within the genus Staphylococcus. In in vitro inhibitory assays, phage K lysed all
staphylococcal strains tested including nine different species. In preliminary
application-type studies, anti-staphylococcal activity was also evident in a hand wash
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and phage cream. An unexpected result was the observation that phage K was unable
to replicate in raw milk, which could limit its applications in mastitis treatments. This
may have been due to clumping of the bacteria caused by immunoglobulins.
However, inhibition activity was lost after milk was heat-treated. The overall results
in this study provide new insights into the biology of the broad host range phage K
and indicate that phage K has potential for treatment and prevention of infections
caused by pathogenic staphylococci.