Irene Alexeevna Machoshvili

Effect of media on spore yield and thermal resistance of Bacillus stearothermophilus.

The interference of eight components in the yield of sporulation and thermal resistance to moist heat (121 degrees C) of Bacillus stearothermophilus spores suspended in 0.02 M calcium acetate solution and inoculated on paper strips previously treated with calcium acetate/calcium hydroxide was studied. The spore yield of 1.0 x 10(8)mL was developed at 62 degrees C in 17 media containing different concentrations of D-glucose, sodium chloride, L-glutamic acid, yeast extract, peptone, manganese sulfate, potassium phosphate, and ammonium phosphate. The combined effects of yeast extract, peptone, and glucose contributed positively to the spore yield and to the stability of the thermal resistance of both spores in suspension and on strips.

Tratamento químico de hortaliças poluídas

Das amostras de hortalicas em folhas coletadas no periodo de abril a agosto de 1981, no Entreposto Comercial da Cidade de Sao Paulo, SP (Brasil), 75% e 57% apresentaram contagens de coliformes fecais e de Escherichia coli, por grama de produto, superiores a 2 x 10² respectivamente; e em 85% constatou-se a presenca de parasitas protozoarios ou/e helmintos. O tratamento quimico das folhas de alface (Lactuca sativa), com solucao de hipoclorito de sodio, por um periodo de exposicao de 10 min a concentracao de 40 ppm de cloro livre, mostrou-se eficaz do ponto de vista parasitologico.

Intracellular release of recombinant green fluorescent protein (gfp uv ) from Escherichia coli

The recombinant green fluorescent protein (gfp(uv)) was expressed by Escherichia coli DH5-alpha cells transformed with the plasmid pGFPuv. The gfp(uv) was selectively permeabilized from the cells in buffer solution (25 mM Tris-HCl, pH 8.0), after freezing (-70 degrees C for 15 h), by four freeze (-20 degrees C)/thaw cycles interlaid by sonication. The average content of released gfp(uv) (experiment 2) was 7.76, 34.58, 39.38, 12.90, and 5.38%, for the initial freezing (-70 degrees C) and the first, second, third and fourth freeze/thaw cycles, respectively. Superfusion on freezing was observed between -11 degrees C and -14 degrees C, after which it reached -20 degrees C at 0.83 degrees C/min.

The Effect of Bioindicator Preparation and Storage on Thermal Resistance of Bacillus stearothermophilus Spores

Paper strips inoculated with spores of Bacillus stearothermophilus ATCC 7953 were conventionally dried (lot 1) and lyophilized (lot 2); stored in defined environments of 32 and 86% relative humidity at 10, 25 and 33 degrees C for 210 d; and submitted to moist heat treatments at 121 degrees C. A significant decrease in thermal resistance from initial starting levels was found for lyophilized bioindicators stored at 86% relative humidity. The respective average D121 degrees C values were 1.55+/-0.05 and 1.37+/-0.10 min for lyophilized bioindicators stored at 32 and 86% relative humidity; and 1.65+/-0.15 min and 1.57+/-0.11 min for dried bioindicators stored in the same environments.

Inactivation of Brazilian wild type and enterotoxigenicEscherichia coli by chlorine

The kinetic inactivation parameters of four wild strains and two enterotoxigenic strains ofEscherichia coli exposed to commercial calcium hypochlorite were determined. The four wild strains (1A, 3C, 4D and 8H) were isolated from lettuce bought in São Paulo (Brazil), and the two enterotoxigenic strains (TR69 and TR101) were originally isolated from human patients. Decimal reduction time ‘D’, for 10 mg L−1 available chlorine at pH 6.8, varied between 71.4 s for the wild strain 4D and 31.3 s for the toxigenic strain. The ‘D’ values obtained for wild strain 1A exposed to 5.0 mg L−1 available chlorine at pH 6.8 varied between 111.1 s and 41.7 s. The ‘D’ values obtained forE. coli strain TR69 exposed to 10 mg L−1 available chlorine varied from 15.2 s at pH 5.4 up to 83.3 s at pH 8.2. The use of the most resistant wild strain ofE. coli as a biological standard assures maximal effectiveness in controlling water contamination by chlorination.

The Effect of Composition of Parenteral Solution on the Thermal Resistance of Bacillus stearothermophilus and Bacillus subtilis Spores

Large-volume parenteral solutions were submitted to heat treatments after being inoculated with Bacillus stearothermophilus ATCC 7953 (Tr=121°C) and Bacillus subtilis ATCC 9372 (Tr=104.5°C) spores. The average decimal reduction time for B. stearothermophilus ranged from a D121°C value of 1.31 to 3.14 min, in glucophysiologic and Ringer’s solutions respectively. For B. subtilis, D104.5°C value increased from 0.69 to 1.37 min, in Ringer’s (pH=5.91) and 50% glucose (pH 3.05) solutions respectively. The z value ranged from 7.95°C (20% mannitol solution) to 13.14°C (50% glucose solution), corresponding to an activation energy (Ea) of 81.48 and 49.30 kcal/mol, respectively.

Evaluation of the sterilization efficacy of domestic electric drills used in orthopaedic surgeries

It is estimated that electric drills (ED) have been used in orthopaedic surgeries for bone drilling for more than 50 years in Brazilian hospitals. It is an electric, thermosensitive equipment, not indicated for surgical use, which has not been previously evaluated regarding the sterilization efficacy, being suspect of infection risk. This study evaluated the efficacy of sterilization by ethylene oxide (EtO) of new drills that were intentionally contaminated with Bacillus atrophaeus spores. An experimental, laboratory, randomized applied research was developed, where 16 electric drills were analyzed, in addition to positive and negative controls. All the previously cleaned and sterilized equipment were submitted to contamination by spores. The experimental group was submitted to cleaning and sterilization by EtO and test of sterility by filtration through a 0.45 >m membrane. The membranes were cultivated and Gram and

Bacillus stearothermophilus spores on strips. Calibration of thermoresistance kinetics to prior biological validation

Filter-paper strips saturated with Bacillus stearothermophilus spores were prepared and then stored for up to 1470 days. The strips were used to measures spore activation time and death kinetics in two systems: a serum bottle/oil bath combination, and glassine packages in a gravity autoclave. The data collected were analyzed primarily by analysis of variance and the interaction of spore storage time, processing temperature, inertial time and exposure time was determined.