Growth from spores of nonproteolytic Clostridium botulinum in heat-treated vegetable juice.
Unheated spores of nonproteolytic Clostridium botulinum were able to lead to growth in sterile deoxygenated turnip, spring green, helda bean, broccoli, or potato juice, although the probability of growth was low and the time to growth was longer than the time to growth in culture media. With all five vegetable juices tested, the probability of growth increased when spores were inoculated into the juice and then heated for 2 min in a water bath at 80 degrees C. The probability of growth was greater in bean or broccoli juice than in culture media following 10 min of heat treatment in these media. Growth was prevented by heat treatment of spores in vegetable juices or culture media at 80 degrees C for 100 min. We show for the first time that adding heat-treated vegetable juice to culture media can increase the number of heat-damaged spores of C. botulinum that can lead to colony formation. (+info)
Vaccine storage in the community: a study in central Italy.
Maintaining the vaccine cold chain is an essential part of a successful immunization programme, but in developed countries faulty procedures may occur more commonly than is generally believed. A survey was conducted in a health district in central Italy to assess the methods of vaccine transportation and storage. Of 52 primary vaccination offices inspected, 39 (76.5%) had a refrigerator for vaccine storage but only 17 (33.3%) kept records of received and stored doses. None of the seven main offices selected for monitoring had a maximum and minimum thermometer and none monitored the internal temperature of the refrigerator. Moreover, other faulty procedures, such as the storage of food and laboratory specimens in vaccine refrigerators and the storage of vaccines on refrigerator door shelves, indicated that the knowledge and practice of vaccine storage and handling were often inadequate. (+info)
Bacterial resistance of refrigerated and cryopreserved aortic allografts in an experimental virulent infection model.
PURPOSE: The bacterial resistance of refrigerated and cryopreserved aortic allografts in a highly virulent infection in a dog model was studied. METHODS: The infrarenal aorta of 12 dogs was replaced with either a cryopreserved aortic allograft (group I, n = 6) or a refrigerated aortic allograft (group II, n = 6) in infected sites. Allografts were harvested from dogs and stored for 1 week, either by cryopreservation (-140 degrees C) or refrigerated method (4 degrees C), in a preservation medium. At the time of implantation, induction of infection was achieved with an infected piece of knitted Dacron placed just beneath the allograft. The Dacron was contaminated in vitro by soaking it in a solution with Staphylococcus aureus PR209. All 12 dogs received no adjunct antibiotic or antithrombotic therapy. Four weeks after implantation, the animals were killed to recover the grafts for bacteriological and histological analyses. Bacterial results were expressed as colony-forming units (CFU)/cm2 of graft material. RESULTS: In group I, only one allograft grew bacteria at 2. 16 x 10(6 )CFU/cm2, with a blood culture positive for S aureus. In group II, one dog died at 3 weeks from a false septic aneurysm rupture, all the allografts were infected (P <.05) with a mean bacterial count of 9.41 +/- 6.8 x 10(4) CFU/cm2, and three blood cultures were positive for S aureus. The patency of the grafts was analyzed at the time of recovery. Three laminar thrombi without occlusion were present in group I; none were present in group II. A better preserved endothelium in group I was revealed by means of histologic analysis staining with factor VIII antibody before implantation. After 4 weeks of implantation in the infected site, infected allografts presented polynuclear infiltrates in the media with a high degree of inflammatory reaction, and endothelial recovery was more significant in group I, with numerous young plump cells. CONCLUSION: This study demonstrates that cryopreserved allografts implanted in infected sites in a dog model can produce greater bacterial resistance. (+info)
A predictive model that describes the effect of prolonged heating at 70 to 90 degrees C and subsequent incubation at refrigeration temperatures on growth from spores and toxigenesis by nonproteolytic Clostridium botulinum in the presence of lysozyme.
Refrigerated processed foods of extended durability such as cook-chill and sous-vide foods rely on a minimal heat treatment at 70 to 95 degrees C and then storage at a refrigeration temperature for safety and preservation. These foods are not sterile and are intended to have an extended shelf life, often up to 42 days. The principal microbiological hazard in foods of this type is growth of and toxin production by nonproteolytic Clostridium botulinum. Lysozyme has been shown to increase the measured heat resistance of nonproteolytic C. botulinum spores. However, the heat treatment guidelines for prevention of risk of botulism in these products have not taken into consideration the effect of lysozyme, which can be present in many foods. In order to assess the botulism hazard, the effect of heat treatments at 70, 75, 80, 85, and 90 degrees C combined with refrigerated storage for up to 90 days on growth from 10(6) spores of nonproteolytic C. botulinum (types B, E, and F) in an anaerobic meat medium containing 2,400 U of lysozyme per ml (50 microg per ml) was studied. Provided that the storage temperature was no higher than 8 degrees C, the following heat treatments each prevented growth and toxin production during 90 days; 70 degrees C for >/=2,545 min, 75 degrees C for >/=463 min, 80 degrees C for >/=230 min, 85 degrees C for >/=84 min, and 90 degrees C for >/=33.5 min. A factorial experimental design allowed development of a predictive model that described the incubation time required before the first sample showed growth, as a function of heating temperature (70 to 90 degrees C), period of heat treatment (up to 2,545 min), and incubation temperature (5 to 25 degrees C). Predictions from the model provided a valid description of the data used to generate the model and agreed with observations made previously. (+info)
Influence of refrigeration and formalin on the floatability of Giardia duodenalis cysts.
Giardia duodenalis cysts obtained from fresh fecal samples, fecal samples kept under refrigeration and fecal samples treated with formalin were studied as to their floatability on sucrose solutions with the following specific gravities: 1,040 kg/m3; 1,050 kg/m3; 1, 060 kg/m3; 1,070 kg/m3; 1,080 kg/m3; 1,090 kg/m3; 1,100 kgm3; 1,150 kg/m3; 1,200 kg/m3; and 1,250 kg/m3, contained within counting-chambers 0.17 mm high. Cysts that floated on and those settled down as sediments were counted, and had their percentages estimated. Sucrose solutions of 1,200 kg/m3 specific gravity (the average specific gravity of diluting liquids employed in floatation techniques) caused to float 77.7%, 78.4% and 6.6% of the G. duodenalis cysts obtained, respectively, from fresh fecal samples, fecal samples kept under refrigeration, and fecal samples treated with formalin. Cysts obtained both from fresh fecal samples and fecal samples kept under refrigeration presented similar results concerning floatability. It was observed, however, that the treatment of feces with formalin diminished the cysts floatability under the various specific gravities studied. This results should influence, the recommendations for transport and storage of fecal samples used for parasitological coproscopy. (+info)
High-resolution gas chromatographic profiles of volatile organic compounds produced by microorganisms at refrigerated temperatures.
Three different strains of bacteria isolated from spoiled, uncooked chicken were grown in pure culture on Trypticase soy agar supplemented with yeast extract. The volatile organic compounds produced by each culture were concentrated on a porous polymer precolumn and analyzed by high-resolution gas chromatographic mass spectrometry. Twenty different compounds were identified. Both qualitative and quantitative differences in the chromatographic profiles from each culture were found. (+info)
Fertility of mouse spermatozoa retrieved from cadavers and maintained at 4 degrees C.
After male animals die, the spermatozoa within the testis and epididymis eventually disintegrate. In this study, the motility, viability and fertility of mouse spermatozoa were examined after retrieval from the epididymis at various days after death. Cadavers were maintained in a refrigerator at 4 degrees C. About 30% of the spermatozoa collected 10 days after death were viable, but they had limited ability to fertilize oocytes in vitro. However, when the spermatozoa were injected into oocytes, the fertilization rate was over 80%. Normal live fetuses were even obtained using immotile spermatozoa retrieved 20 days after death. Therefore, when valuable male animals die unexpectedly and sperm cryopreservation is not possible immediately, temporal storage of cadavers (or epididymis and vas deferens) at 4 degrees C in a regular refrigerator followed by intracytoplasmic sperm injection may help to preserve the genome of individuals. This procedure could be particularly important in endangered species. (+info)
Survival of the human granulocytic ehrlichiosis agent under refrigeration conditions.
The human granulocytic ehrlichiosis (HGE) agent in infected blood specimens remained viable during refrigeration at 4 degrees C for up to 18 days. These findings suggest that blood specimens submitted for culture may withstand transportation to a remote laboratory. HGE should be added to the list of infections potentially transmitted by blood transfusion. (+info)