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Background: Prior to the selection of disinfectants for low, intermediate and high (sterilizing) levels, the decimal reduction time, D-value, for the most common and persistent bacteria identified at a health care facility should be determined. Methods: The D-value was determined by inoculating 100 mL of disinfecting solution with 1 mL of a bacterial suspension (104 - 105 CFU/mL for vegetative and spore forms). At regular intervals, 1 mL aliquots of this mixture were transferred to 8 mL of growth media containing a neutralizing agent, and incubated at optimal conditions for the microorganism. Results: The highest D-values for various bacteria were determined for the following solutions: (i) 0.1% sodium dichloroisocyanurate (pH 7.0) -- E. coli and A. calcoaceticus (D = 5.9 min); (ii) sodium hypochlorite (pH 7.0) at 0.025% for B. stearothermophilus (D = 24 min), E. coli and E. cloacae (D = 7.5 min); at 0.05% for B. stearothermophilus (D = 9.4 min) and E. coli (D = 6.1 min) and 0.1% for B. stearothermophilus (D = 3.5 min) and B. subtilis (D = 3.2 min); (iii) 2.0% glutaraldehyde (pH 7.4) -- B. stearothermophilus, B. subtilis (D = 25 min) and E. coli (D = 7.1 min); (iv) 0.5% formaldehyde (pH 6.5) -- B. subtilis (D = 11.8 min), B. stearothermophilus (D = 10.9 min) and A. calcoaceticus (D = 5.2 min); (v) 2.0% chlorhexidine (pH 6.2) -- B. stearothermophilus (D = 9.1 min), and at 0.4% for E. cloacae (D = 8.3 min); (vi) 1.0% Minncare® (peracetic acid and hydrogen peroxide, pH 2.3) -- B. stearothermophilus (D = 9.1 min) and E. coli (D = 6.7 min). Conclusions: The suspension studies were an indication of the disinfectant efficacy on a surface. The data in this study reflect the formulations used and may vary from product to product. The expected effectiveness from the studied formulations showed that the tested agents can be recommended for surface disinfection as stated in present guidelines and emphasizes the importance and need to develop routine and novel programs to evaluate product utility. [ABSTRACT FROM AUTHOR]

Background: Due to the growing number of outbreaks of infection in hospital nurseries, it becomes essential to set up a sanitation program that indicates that the appropriate chemical agent was chosen for application in the most effective way. Method: For the purpose of evaluating the efficacy of a chemical agent, the minimum inhibitory concentration (MIC) was reached by the classic method of successive broth dilutions. The reference bacteria utilized were Bacillus subtilis var. globigii ATCC 9372, Bacillus stearother mophilus ATCC 7953, Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923. The strains of Enterobacter cloacae IAL 1976 (Adolfo Lutz Institute), Serratia marcescens IAL 1478 and Acinetobactev calcoaceticus IAL 124 (ATCC 19606), were isolated from material collected from babies involved in outbreaks of infection in hospital nurseries. Results: The MIC intervals, which reduced bacteria populations over 08 log10, were: 59 to 156 mg/L of quaternarium ammonium compounds (QACs); 63 to 10000 mg/L of chlorhexidine digluconate; 1375 to 3250 mg/L of glutaraldehyde; 39 to 246 mg/L of formaldehyde; 43750 to 87500 mg/L of isopropanol or ethanol; 1250 to 6250 mg/L of iodine in polyvinyl-pyrolidone complexes, 150 to 4491 mg/L of chlorine-releasing-agents (CRAs); 469 to 2500 mg/L of hydrogen peroxide; and, 2310 to 18500 mg/L of peracetic acid. Conclusions: Chlorhexidine showed non inhibitory activity over germinating spores. A. calcoaceticus, was observed to show resistance to the majority of the agents tested, followed by E. cloacae and S. marcescens [ABSTRACT FROM AUTHOR]

Nisin is a natural peptide used as a preservative in a variety of food products, in which it inhibits mainly Gram-positive bacterial growth, including multidrug-resistant pathogens. However, its application range depends on the cost-effective production and purification of this molecule. Our group has previously produced nisin by Lactococcus lactis cultivation in milk whey, which is an industrial residue from dairy production. To our knowledge, no report used milk whey as a culture medium, although several investigators have purified nisin using different techniques. We thus aimed to establish a low-cost purification of nisin obtained by this process. Samples were diluted in ammonium sulphate, applied onto HIC columns (butyl sepharose CL 4B matrix), and eluted with Milli-Q water or PBS. Elution fractions were monitored for protein content and nisin antibacterial activity. Water elution resulted in purification factor values (270, commercial nisin; 775, nisin produced in-house) higher than those obtained with PBS elution. We concluded that purification of nisin does not require precipitation with ammonium sulphate, therefore allowing step/cost reduction. Moreover, purification from milk whey using HIC provides nisin with high activity and low salt content, which can further be applied to a variety of areas. [ABSTRACT FROM AUTHOR]

Background: Transformed cells of Escherichia coli DH5-alpha with pGFPuv, induced by IPTG (isopropyl-beta-d-thiogalactopyranoside), express the green fluorescent protein (gfpuv) during growth phases. E. coli subjected to the combination of selective permeation by freezing/thawing/sonication cycles followed by the three-phase partitioning extraction (TPP) method were compared to the direct application of TPP to the same culture of E. coli on releasing gfpuv from the over-expressing cells., Material and Methods: Cultures (37 degrees C/100 rpm/ 24 h; mu = 0.99 h(-1)-1.10 h(-1)) of transformed (pGFP) Escherichia coli DH5-alpha, expressing the green fluorescent protein (gfpuv, absorbance at 394 nm and emission at 509 nm) were sonicated in successive intervals of sonication (25 vibrations/pulse) to determine the maximum amount of gfpuv released from the cells. For selective permeation, the transformed previously frozen (-75 degrees C) cells were subjected to three freeze/thaw (-20 degrees C/ 0.83 degrees C/min) cycles interlaid by sonication (3 pulses/6 seconds/25 vibrations). The intracellular permeate with gfpuv in extraction buffer (TE) solution (25 mM Tris-HCl, pH 8.0, 1 mM beta-mercaptoethanol beta-ME, 0.1 mM PMSF) was subjected to the three-phase partitioning (TPP) method with t-butanol and 1.6 M ammonium sulfate. Sonication efficiency was verified on the application to the cells previously treated by the TPP method. The intra-cell releases were mixed and eluted through methyl HIC column with a buffer solution (10 mM Tris-HCl, 10 mM EDTA, pH 8.0)., Results: The sonication maximum released amount obtained from the cells was 327.67 microg gfpuv/mL (20.73 microg gfpuv/mg total proteins-BSA), after 9 min of treatment. Through the selective permeation by three repeated freezing/thawing/sonication cycles applied to the cells, a close content of 241.19 microg gfpuv/mL (29.74 microg gfpuv/mg BSA) was obtained. The specific mass range of gfpuv released from the same cultures, by the three-phase partitioning (TPP) method, in relation to total proteins, was higher, between 107.28 microg/mg and 135.10 microg/mg., Conclusions: The selective permeation of gfpuv by freezing/thawing/sonication followed by TPP separation method was equivalent to the amount of gfpuv extracted from the cells directly by TPP; although selective permeation extracts showed better elution through the HIC column.