Biological Properties, Phage Typing and Antimicrobial Susceptibility of Staphylococcus aureus Isolated from Dermatitis in Laboratory Mice

Abstract
The characteristics of 167 isolates of S. aureus from 106 mice suffering dermatitis were examined. All 167 isolates coagulated both rabbit and human plasmas and 161 of them also coagulated bovine plasma. All the isolates produced heat-stable and heat-labile DNase, phosphatase and yellow pigment, reduced nitrate, hydrolysed egg yolk, Tween 80, and hippurate, and grew on crystal violet agar in colonies of the negative type C and on medium with 10% NaCl. The majority of them produced fibrinolysin, protease and acetoin. Fifty-three percent were gelatinase positive. In hemolysis tests, 25, 57 and 45 isolates showed α-, β-, αβ-hemolysis, respectively. Forty isolates did not produce hemolysins in the rabbit and sheep blood agar. All of 75 isolates tested produced acid from fructose, galactose, glucose, glycerol and mannose, but did not from arabinose, dextrin, inulin, raffinose, salicin, sorbitol and xylose. Most of these isolates produced acid from lactose, mannitol, sucrose and trehalose. All of the 75 isolates were highly sensitive to penicillin, methylphenylisoxazolyl penicillin, erythromycin, spiramycin, lincomycin, chloramphenicol, tetracycline, kanamycin, gentamicin and cepaloridine, but were resistant to sulfisoxazole. With phages of the human set, all 167 isolates were typable at 100×RTD. All but one of the typable isolates belonged to mixed lytic groups. These were I+III (35 isolates), I+M (1), I+III+M (124) and I+II+III+M (6), with long phage patterns. When the 167 isolates were biotyped as described by Hájek and Maršálek [7, 8], 5 belonged to biotype A, 1 to biotype B and 60 to biotype C. The remaining 101 isolates could not be assigned to any of the known biotypes. They produced fibrinolysin and grew in negative type (violet) colonies on crystal violet agar, criteria considered to be reliable for characterization of human isolates, but, at the same time, they coagulated bovine plasma, a character posessed by isolates of bovine origin. Thus these 101 isolates showed properties intermediate between biotypes A and C.

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