A collaborative study was conducted in 15 laboratories to evaluate 2 different techniques for enumerating Bacillus cereus in foods. A direct plating technique using mannitol-egg yolk-polymyxin agar and a most probable number (MPN) technique using trypticase-soy-polymyxin broth were compared for the enumeration of high and low populations of B. cereus in mashed potatoes. The collaborative results showed that the overall mean recovery obtained with the low population level was essentially the same by both techniques. However, the overall mean recovery was significantly higher by the direct plating technique at the high population level. A statistical evaluation of the data also showed that the direct plating technique had better repeatability and reproducibility than did the MFN technique at both the high and low population levels. These results suggest that the MPN technique is suitable for examining foods containing low populations of B. cereus, but that the direct plating technique is preferable for foods that contain a high population of this organism. The confirmatory technique used in the proposed method is reliable for presumptive identification of isolates as B. cereus. The method has been adopted as official first action.
Bacterial recovery by a portable Reuter centrifugal air sampler and a standard Mattson-Garvin slit-to-agar air sampler was compared in a series of experiments. Microbial air quality was monitored in seven typical laboratory locations. Tests showed that the Reuter centrifugal air sampler yielded significantly higher recoveries than did the slit-to-agar unit.
Health Care Workers are exposed to numerous biological hazards in the work place. This can occur in hospitals, care centers, laundry facilities, laboratories and other units dealing with the various aspects of health care. Some of these biological hazards can lead to death and the economic and emotional impact can be costly. This burden falls not only on the health care worker and individuals receiving these services but also on industry and government.
There is a need to develop methods appropriate for evaluating protective wear against microbial as well as viral hazards. These hazards not only occur through fluid contamination like blood, serum but also through aerosol transmission.
A method has been developed to evaluate the biobarrier properties of materials using either a bacterial spore or a bacteriophage. The indicator organism was aerosolized in an acrylic chamber. Filtration cups containing the testing material were exposed to the indicator organism consisting of B. subtilis var. niger spores. The materials were ranked by comparing the number of organisms that penetrated the material to the initial number exposed.
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