Japanese Journal of Veterinary Research;Volume 6, Number 1

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STUDIES ON STAPHYLOCOCCI FROM THE BOVINE UDDER : I. BIOLOGICAL CHARACTERISTICS OF STAPHYLOCOCCI AND SOME OBSERVATIONS ON THE PATHOGENIC STRAINS

NAKAGAWA, Masaro

Permalink : http://hdl.handle.net/2115/1724
JaLCDOI : 10.14943/jjvr.6.1.19

Abstract

In the present paper, the biological characters, especially criteria for the pathogenicity, of staphylococci of 515 strains encountered in the udder were investigated in detail. The results are summarized as follows : 1. Out of 678 strains of micrococci isolated from milk, 515 were classified as staphylococci and the rest were identified as belonging to nine species, according to BERGEY'S Manual (1948). 2. Out of the 515 strains above mentioned, about 65% were orange pigment producers (Staph. aureus), 31% white pigment producers (Staph. albus) and 3% lemon yellow pigment producers (Staph. citreus). 3. In 336 strains which were classed as Staph. aureus, mannitol fermenters were observed in high percentage (75.7%), furthermore, 47.2% of 163 albus strains and 43.7% of 16 citreus strains also fermented mannitol. 4. Coagulase test was carried out on rabbit, horse, sheep and cow plasmas, and it was found that amongst them rabbit plasma was most easily clotted by staphylococci. 5. Rabbit plasma, mixed with that of horse or sheep at the rate of 1 : 4,could be used instead of rabbit plasma alone, but there is tardiness of coagulation. 6. Sheep and cow red cells were most suitable for the detection of α- and β-hemolysin, while for the detection of δ-lysin human or horse blood should be used. One hundred and seventy strains (33%) out of 515 examined produced hemolysin and the great majority of these hemolytic strains showed complex (αβ, αδ, βδ and αβδ) hemolysin patterns. Moreover, β-hemolysin was demonstrated in most of the hemolytic strains. 7. Almost all hemolytic staphylococci (165 strains out of 170) and 24 (7.0%) of 345 strains showing weak or no hemolysis were coagulase producers. 8. No significant correlation can be suggested between pigment formation or mannitol fermentation and the ability of producing coagulase or hemolysin. Furthermore, pigment production and mannitol fermentation do not serve to distinguish pathogenic strains from non-pathogenic varieties. 9. Enterotoxigenicity was demonstrated in 23 strains of 25 hemolytic and coagulase producers, however, non-hemolytic coagulase-negative 4 strains were not at all enterotoxigenic. 10. The majority of staphylococci giving irritation to bovine udder were hemolytic or coagulase positive, but it cannot be concluded that all strains reacting negatively in these properties are non pathogenic. 11. Seventy-five (41.2%) of 182 coagulase-positive strains were phage-typed, the majority (62.6%) of them were susceptible to the phages of Group III. However, all of 100 coagulase-negative strains were insusceptible to any of the test phages.

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