The occurrence of siderophores in staphylococci.

In 180 staphylococcal strains of diverse origin belonging to 26 species a hydroxamate class siderophore was detected with chemical test. In 65% of investigated strains it was identified by biological assay as aerobactin. A correlation between hydroxamate siderophore production, species affiliation and pathogenicity was not found. In 14 (7.8%) strains a catechol class siderophore, beside aerobactin, was detected.

Staphylococcal L-asparaginase: antilymphoma and immunosuppressive action.

Staphylococcal L-asparaginase inhibits blastic transformation of human lymphocytes and growth of mice leukemia lymphoblasts L5178Y-R. The enzyme is removed from blood stream of DBA/2 mice very rapidly.

Staphylococcal L-asparaginase: enzyme kinetics.

The ph optimum of purified staphylococcal L-asparaginase (EC 3.5.1.1) was found to be between 8.6 and 8.8. The temperature optimum was 30 degrees-32 degrees C and the highest reaction rate occurred at 30 degrees C. The KM of the enzyme calculated from Lineweaver-Burk plot was 3.71 x 10(-2) M. Besides L-asparaginase, the substrate specificity of enzyme was restricted to N-alpha-acetyl-L-asparagine. D-asparagine, L-aspartic acid and D-glutamic acid were competitive inhibitors. Hg2+ and Cu2+ cations strongly inhibited the enzyme while Na+ and K+ cations strongly stimulated activity. Two SH-groups could be detected after enzyme denaturation with guanidine.

Concentrations of cloxacillin and erythromycin in the tonsils of children after administration of therapeutic doses.

The treatment of infections in the ring of Waldeyer in children is an ever present problem. Most infections are caused by group A streptococci, and various antibiotics are routinely used for their treatment. In many cases, however, this treatment is ineffective as demonstrated by prolonged disease duration and recurrences. This may be due to the resistance of the pathogens to the used antibiotic, too low dose, or inadequate penetration of the drug into the focus of infection. To explain this problem the reported investigation was undertaken carrying out bacteriological investigations of the removed tonsils and determining antibiotic concentrations in tonsil homogenates and in the serum after cloxacillin and erythromycin treatment of 45 children aged 4-14 years subjected to tonsillectomy or adenotomy . It was found that the most frequent aetiological factors in angina and adenoiditis were group A streptococci. Cloxacillin and erythromycin are the antibiotics penetrating well into the lymphoid tissue and reaching high concentrations in the focus of infection but the courses of treatment should not be shorter than 10 days.