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At least 1,099 records · Page 61Linked to original sources
PubMed2000

Survival and growth of Salmonella baildon in shredded lettuce and diced tomatoes, and effectiveness of chlorinated water as a sanitizer.

An outbreak of salmonellosis associated with diced tomatoes occurred in the United States in 1999. Experiments were done to determine the efficacy of chlorine in killing Salmonella baildon, the causative serotype, inoculated onto shredded lettuce and diced tomatoes, and to determine survival characteristics of the organism on these produce items stored at 4 degrees C for up to 12 days and on tomatoes stored at 21 or 30 degrees C for up to 72 h. Populations of S. baildon in lettuce and tomatoes (pH 4.51 +/- 0.02) inoculated with 3.60 log10 and 3.86 log10 cfu/g, respectively, were reduced by less than 1 log when the produce was immersed for 40 s in a 120 or 200 microg/ml free chlorine solution. Produce inoculated with 0.60-0.86 log10 cfu/g was positive for the pathogen after treatment with 200 microg/ml chlorine. Initial populations of 3.28 and 3.40 log10 cfu/g of lettuce and tomatoes, respectively, decreased by about 2 log10 cfu/g during storage for 12 days at 4 degrees C. One of six samples of lettuce initially containing 0.28 log10 cfu of S. baildon per gram was positive after storage for 12 days, but the pathogen was not detected in tomatoes analyzed within 15 min of inoculation with 0.40 log10 cfu/g. While the number of viable cells decreased during storage at 4 degrees C, initial populations of 0.28 log10 cfu/g of shredded lettuce and 3.40 log10 cfu/g of diced tomatoes are not reduced to undetectable levels during storage at 4 degrees C for 12 days. Tolerance of S. baildon to an acidic pH (4.5) was not influenced by the pH (4.5, 5.8, or 7.2) of the medium in which it was grown, suggesting that this strain possesses unusual resistance to acid pH. The pathogen grew in diced tomatoes (pH 4.40 +/- 0.01) from an initial population of 0.79 log10 cfu/g to 5.32 and 7.00 log10 cfu/g within 24 h at 21 and 30 degrees C, respectively.

Chlorine↗
PubMed1993

Evolution of udder hygiene. Premilking teat sanitation.

Compared with post-milking teat dipping, predipping is in its infancy. Few controlled studies have been published on premilking teat disinfection/sanitation. Experimental challenge procedures resulted in consistent reductions for predipping compared with no udder preparation and conventional udder preparation, indicating a potential for effectiveness. Challenge studies that included the treatments of predip only and postdip only indicated that interactions during the milking process require elucidation. Positive benefits have been observed for predipping in field trials among some herds, but wide variation has been observed between herds in all field trial evaluations. Parity, DIM, and season of the year had major interactions on efficacy of predipping in Pankey et al's 1987 report; other trials have been of shorter duration and precluded analysis of these interactions. Interactions among these variables influenced incidence of mastitis by environmental pathogens. The length of time after milking before teats are contaminated probably is a major influence on predip efficacy. Predipping has reduced incidence of new IMIs and new cases of clinical mastitis. Unfortunately, certain factors negated these positive effects. These factors need to be defined. Producers should monitor effects of predipping to determine whether the investment in product and time has an economic return under the conditions of their dairy.

Animals↗
PubMed1990

Faecal contamination of water and fingertip-rinses as a method for evaluating the effect of low-cost water supply and sanitation activities on faeco-oral disease transmission. I. A case study in rural north-east Thailand.

Most villagers in north-east Thailand carry water to their homes and store it in separate containers depending on its subsequent use. In one village, information on water use was collated with the bacteriological quality of stored water, water sources and fingertip-rinses. Stored water quality was a function of water-related activities rather than quality at source (P less than 0.0001). Specifically water used for toilet, washing dishes and cooking-related activities was much more contaminated with faecal bacteria than that used for drinking and cooking. Salmonella spp. was significantly more common in water used for washing dishes than drinking (P less than 0.05). Escherichia coli contamination of fingertip-rinses was strongly associated with the individual's activity prior to testing (P less than 0.0001); child care, food and water-related activities produced much higher levels of fingertip contamination than others. Dirty utensils used for cooking and eating were usually left to soak and faecal bacterial growth occurred in this grossly contaminated soak-water. Cross-contamination via water handling was the main mechanism of stored water pollution. These results were used to develop a hygiene intervention study presented in a companion paper.

Bacteria↗
PubMed1990

Faecal contamination of water and fingertip-rinses as a method for evaluating the effect of low-cost water supply and sanitation activities on faeco-oral disease transmission. II. A hygiene intervention study in rural north-east Thailand.

An intervention study was developed from risk-factors associated with faeco-oral transmission, based on the levels of contamination in stored water and fingertip-rinses from households in rural north-east Thailand. This was designed to improve: (a) handwashing, particularly before cooking/eating and after defecation: (b) washing dishes immediately after use. Verbal messages were administered to two intervention groups, one also received a plastic container with a tap to assist these activities. Indicators of compliance were the direct observation of soaking dishes and the presence of faecal streptococci from fingertip-rinses; the main outcome indicator was Escherichia coli contamination of stored water. The intervention group receiving the container was significantly better than the control for indicators of compliance (P less than 0.001 and P less than 0.01) and its stored water was significantly less contaminated (P less than 0.001). There was no significant improvement to the other intervention group, although some features of the intervention had clearly been made available to the control group. Humidity was significantly correlated with fingertip contamination (r = 0.2; P less than 0.001) and with the peak of reported diarrhoea around the beginning of the rainy season.

Bacterial Infections↗
PubMed2005

Multiple enzyme activities of Escherichia coli MutT protein for sanitization of DNA and RNA precursor pools.

8-OxoGua (8-oxo-7,8-dihydroguanine) is produced in nucleic acids as well as in nucleotide pools of cells, by reactive oxygen species normally formed during cellular metabolic processes. MutT protein of Escherichia coli specifically degrades 8-oxoGua-containing deoxyribo- and ribonucleoside triphosphates to corresponding nucleoside monophosphates, thereby preventing misincorporation of 8-oxoGua into DNA and RNA, which would cause mutation and phenotypic suppression, respectively. Here, we report that the MutT protein has additional activities for cleaning up the nucleotide pools to ensure accurate DNA replication and transcription. It hydrolyzes 8-oxo-dGDP to 8-oxo-dGMP with a K(m) of 0.058 microM, a value considerably lower than that for its normal counterpart, dGDP (170 microM). Furthermore, the MutT possesses an activity to degrade 8-oxo-GDP to the related nucleoside monophosphate, with a K(m) value 8000 times lower than that for GDP. These multiple enzyme activities of the MutT protein would facilitate the high fidelity of DNA and RNA syntheses.

DNA Replication↗
PubMed1992

Hydrolytic elimination of a mutagenic nucleotide, 8-oxodGTP, by human 18-kilodalton protein: sanitization of nucleotide pool.

8-Oxoguanine nucleotide can pair with cytosine and adenine nucleotides at almost equal efficiencies. Once 8-oxodGTP is formed in the cellular nucleotide pool, this mutagenic nucleotide is incorporated into DNA and would cause transversion mutations. The MutT protein of Escherichia coli possesses enzyme activity to hydrolyze 8-oxodGTP to the corresponding nucleoside monophosphate and thus may be responsible for preventing the occurrence of such mutations. Here we show that the human cell has an enzyme specifically hydrolyzing 8-oxodGTP in a fashion similar to that seen with MutT protein. The human 8-oxodGTPase has been found in cell-free extracts from Jurkat cells and purified > 400-fold. Analyses by gel filtration and gel electrophoresis revealed that the molecular mass of the native form of human 8-oxodGTPase is 18 kDa. Mg2+ ion is required for the enzyme action and the optimum pH for the reaction is pH 8.0. The enzyme hydrolyzes 8-oxodGTP to 8-oxodGMP with a Km value of 12.5 microM. dGTP and dATP are also degraded to dGMP and dAMP, respectively, with Km values 70 times greater than that for 8-oxodGTP. dTTP and dCTP are not hydrolyzed. These properties of the human 8-oxodGTPase are similar to those observed with the E. coli MutT protein, suggesting that the function of protecting the genetic information from the threat of endogenous oxygen radicals is widely distributed in organisms.

Chromatography, Affinity↗