INACTIVATION OF THE RADIATION-RESISTANT SPOILAGE BACTERIUM MICROCOCCUS RADIODURANS. II. RADIATION INACTIVATION RATES AS INFLUENCED BY MENSTRUUM TEMPERATURE, PREIRRADIATION HEAT TREATMENT, AND CERTAIN REDUCING AGENTS.
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The R(1) strain of Micrococcus radiodurans, previously determined to be more resistant than three other strains exposed to gamma radiation, was studied further to determine the influence of certain environmental factors on resistance to radiation inactivation. The frozen state offered insignificant protection to the organisms irradiated in raw pureed beef. Resistance was reduced by higher menstruum temperatures (40 and 50 C) during irradiation. Preirradiation heat treatment was found to lower resistance to subsequent irradiation. When the cells were irradiated in buffer at pH 5, 7, or 9, no differences in resistance were noted. Cell suspensions in buffer were protected to some extent by cysteine but not by thioglycolate. Ascorbate enhanced radiation inactivation. (+info)
BACTERIOLOGY OF SPOILAGE OF FISH MUSCLE. II. INCIDENCE OF SPOILERS DURING SPOILAGE.
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A test medium consisting of a sterile raw press juice from fish muscle was used to determine the incidence of spoilage bacteria on stored fillets of English sole (Parophrys vetulus). The initial load of spoilers was shown to be consistently below 10%. This percentage rose but slightly toward the middle of the spoilage runs, and actually declined when spoilage was most apparent both organoleptically and chemically. Further evidence implicating the Pseudomonas and Achromobacter groups in the spoilage of fresh fish is presented. (+info)
LIQUID NITROGEN FREEZING IN MICROBIOLOGICAL ASSAY SYSTEMS. I. PRESERVATION OF LACTOBACILLUS LEICHMANNII FOR DIRECT USE IN THE VITAMIN B12 ASSAY.
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Suspensions of Lactobacillus leichmannii were stored in liquid nitrogen and were used as direct inocula in vitamin B(12) assays. Complete recovery of viable cells was obtained when the suspensions in basal B(12) medium were rapidly frozen by direct immersion into liquid nitrogen and rapidly thawed by agitating the suspensions in a water bath at 40 C. Greater than 90% destruction occurred when the suspensions were in saline. However, both suspensions were usable in the B(12) assay system. Assay results on a number of test materials indicated good correlation between freshly prepared suspensions and frozen suspensions in basal medium stored 3 months. Suspensions in saline stored for 1 year in liquid nitrogen showed no detectable difference from the first day after freezing. Suspensions frozen slowly at the rate of 1 degree per min from 4 to -40 C and subsequently immersed in liquid nitrogen had a longer lag period of growth and were not usable in the 18-hr assay incubation system. A major advantage of a stored inoculum for direct use in a microbiological assay is the reduced day-to-day variation in the inoculum. (+info)
PRESERVATION OF T2 BACTERIOPHAGE WITH LIQUID NITROGEN.
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There have been few reports on the preservation of viruses at the temperature of liquid nitrogen (-196 C). In this study, factors affecting the survival of phage were observed. Phage lysates in broth did not lose titer after a storage period of 4 weeks in liquid nitrogen. The rate of freezing was not critical, but freezing in nitrogen vapor was not satisfactory. When the virus was partially purified and suspended in buffered saline solution, it rapidly lost titer. Of seven protective agents recommended in the literature, only gum acacia seemed to demonstrate significant protection of purified virus against loss of viability. The temperature of thawing of phage suspended in broth did not affect its titer after freezing and storing in liquid nitrogen. (+info)
Stability of ethanol in postmortem blood and vitreous humor in long-term refrigerated storage.
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Ethanol concentrations in postmortem blood and vitreous humor samples collected at the Miami-Dade Medical Examiner Department over 5-6 years ago were reexamined to assess whether vitreous humor is a more reliable specimen for the analysis of ethanol in samples stored long term. The average change in 50-mL polypropylene tubes containing blood was 0.06 gm/dL (35% loss). On the other hand, vitreous humor samples collected in 10-mL gray-top Vacutainer tubes yielded an average change of 0.01 gm/dL (6.1% loss). This study demonstrates that vitreous humor may be a reliable matrix for ethanol analysis following prolonged refrigerated storage of the samples. (+info)
The refrigeration treatment of chronic osteomyelitis.
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Systemic penicillin therapy plus refrigeration at the site of the lesion, with operation if necessary, was used in the treatment of chronic osteomyelitis. Nine patients with disease of long standing were treated. For three, bed rest, chemotherapy and refrigeration were sufficient. Surgical treatment in addition was carried out in six cases. Operations consisted of unroofing the abscess cavity, multiple drilling for sievelike perforation of the abscessed bone, and primary suture of the incision. Solutions of penicillin, 500 to 1,000 units per cubic centimeter, were used for local irrigation at the time of closure. In all cases the lesions healed and there was no recurrence within a period of two years. The period of hospitalization did not exceed 14 days in any case.Refrigeration of the infected area before and after operation reduced pain, swelling, infection and toxemia. (+info)
Predicting the growth of Salmonella typhimurium on beef by using the temperature function integration technique.
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Lag and generation times for the growth of Salmonella typhimurium on sterile lean beef were modeled as functions of cooling time under various carcass-chilling scenarios. Gompertz growth models were fit to the log10 colony counts over time at each of six temperatures in the range of 15 to 40 degrees C. Lag and generation times were defined as the points at which the second and first derivatives, respectively, of each growth curve attained a maximum. Generation time and lag time parameters were modeled as functions of temperature by use of exponential-decay models. The models were applied to typical beef carcass-cooling scenarios to predict the potential growth of S. typhimurium during the cooling of beef. Validation studies indicated no significant difference between the observed and predicted bacterial populations on inoculated lean and fatty beef tissues cooled at either 6 or 9 degrees C/h. (+info)
A review of outbreaks of foodborne disease associated with passenger ships: evidence for risk management.
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OBJECTIVE: Foodborne disease outbreaks on ships are of concern because of their potentially serious health consequences for passengers and crew and high costs to the industry. The authors conducted a review of outbreaks of foodborne diseases associated with passenger ships in the framework of a World Health Organization project on setting guidelines for ship sanitation. METHODS: The authors reviewed data on 50 outbreaks of foodborne disease associated with passenger ships. For each outbreak, data on pathogens/toxins, type of ship, factors contributing to outbreaks, mortality and morbidity, and food vehicles were collected. RESULTS: The findings of this review show that the majority of reported outbreaks were associated with cruise ships and that almost 10,000 people were affected. Salmonella spp were most frequently associated with outbreaks. Foodborne outbreaks due to enterotoxigenic E. coli spp, Shigella spp, noroviruses (formally called Norwalk-like viruses), Vibrio spp, Staphylococcus aureus, Clostridium perfringens, Cyclospora sp, and Trichinella sp also occurred on ships. Factors associated with the outbreaks reviewed include inadequate temperature control, infected food handlers, contaminated raw ingredients, cross-contamination, inadequate heat treatment, and onshore excursions. Seafood was the most common food vehicle implicated in outbreaks. CONCLUSIONS: Many ship-associated outbreaks could have been prevented if measures had been taken to ensure adequate temperature control, avoidance of cross-contamination, reliable food sources, adequate heat treatment, and exclusion of infected food handlers from work. (+info)