The lactoperoxidase system: the influence of iodide and the chemical and antimicrobial stability over the period of about 18 months.

The lactoperoxidase (LP) system is a natural antimicrobial system, the use of which has been suggested as a preservative in foods and pharmaceuticals. The effect of adding iodide to the LP system, the chemical stability and the change in antimicrobial effectiveness during storage was studied. Addition of iodide with thiocyanate increased the fungicidal and bactericidal effect against Candida albicans, Escherichia coli and Staphylococcus aureus. Pseudomonas aeruginosa showed the same inhibition in the LP system with iodide and without iodide. Storage of the LP system in completely filled airtight containers for 18 months caused a 35% loss of the initial thiocyanate concentration. The antimicrobial activity of this LP system was strong enough to kill inocula of 106 cfu ml-1 of the four test organisms within 2 h of contact time. During storage of the air-containing LP system, the concentration of thiocyanate was reduced below detection limit within 7 d, the concentrations of hypothiocyanite and hypoiodite within 350 d. After 516 d the antimicrobial activity of air-containing LP system was strong enough to kill inocula of 106 cfu ml-1 Ps. aeruginosa within 2 h, Staph. aureus within 4 h and Candida albicans and E. coli within 1 week of contact time.

Saponin, an inhibitory agent of carbon dioxide production by white cells: its use in the microbiologic examination of blood components in an automated bacterial culture system.

BACKGROUND: Blood components with a white cell count > 100 x 10(9) per L may cause false-positive results when the BacT/Alert system is used for the microbiologic examination. The effects of different concentrations of saponin on bacterial growth and on carbon dioxide production by blood fractions with a high white cell count, in particular peripheral blood progenitor cells and buffy coats, were investigated. STUDY DESIGN AND METHODS: The effect of saponin on carbon dioxide production was studied by adding different fractions of white cell-rich material (buffy coat or leukapheresis material) to BacT/Alert culture bottles with or without saponin and incubating these bottles. Five bacterial strains were used to inoculate the culture bottles at four levels ranging from about 1 colony-forming unit per mL to about 10(3) colony-forming units per mL. Aerobic and anaerobic bottles with and without saponin were used. RESULTS: It was demonstrated that the addition of 0.5 percent saponin to BacT/Alert culture bottles effectively inhibited carbon dioxide production, without affecting bacterial growth. CONCLUSION: Saponin at a concentration of 0.5 percent is a valuable additive to BacT/Alert culture media because it prevents false-positive results in the examination of white cell-rich blood components.

Gamma irradiation of Sennae Folium. Microbiological and phytochemical studies.

The effect of different doses of gamma irradiation on senna leaves was studied. No changes in sennoside content and composition were observed after irradiation with 25 kGy. It was demonstrated that a minimum dose of 10 kGy was necessary to obtain a product of good microbiological quality. Cold maceration of senna leaves has to be discouraged, because of unavoidable microbial growth. Hot extraction is the method of choice for tea preparation. The rationale of gamma irradiation is discussed.

The suitability of some preservatives in chloroquine phosphate syrup.

In Third World countries chloroquine phosphate syrup is frequently prepared with chloroform as a preservative. Because of the toxic side effects of chloroform the suitability of a number of possible alternatives were investigated. If the chloroquine phosphate syrup is prepared as such, the combination of sorbic acid (1.5 g/l) and citric acid (2 g/l) is preferred. If, however, the chloroquine phosphate syrup is prepared from a stock solution of simple syrup, the relatively low pH may be undesirable, because it may negatively affect the stability or solubility of other medicinal compounds. For a stock solution of simple syrup the combination of methyl paraben (1.8 g/l) and propyl paraben (0.2 g/l) is preferred. Good care must be taken that a layer of condense water cannot be formed.

Formation and antimicrobial activity of complexes of beta-cyclodextrin and some antimycotic imidazole derivatives.

Complex formation between beta-cyclodextrin and six antimycotic imidazole derivatives has been studied. The solubility of all drugs was increased in the presence of beta-cyclodextrin. The smallest increase (approx. 5-fold) was observed for miconazol, and the largest increase (approx. 160-fold) was observed for bifonazol. Apparent 1:1-complex constants were measured and found to decrease in the order: bifonazol greater than ketoconazol greater than tioconazol greater than miconazol greater than itraconazol greater than clotrimazol. The complexes appeared to possess a low, if any, antimicrobial activity. Measurement of inhibition zone sizes, with four test organisms was used to study the release of the antimycotic drugs from topical preparations. The antimycotic drugs were more readily released from topical preparations containing beta-cyclodextrin than from the same vehicles without beta-cyclodextrin. The rationale of beta-cyclodextrin addition to antimycotic topical preparations is discussed.