Biomedical subjects
A H Hauschild
Publications and source records attributed to A H Hauschild.
Botulism from chopped garlic: delayed recognition of a major outbreak.
Diagnosis of botulism in two teenaged sisters in Montreal led to the identification of 36 previously unrecognized cases of type B botulism in persons who had eaten at a restaurant in Vancouver, British Columbia, during the preceding 6 weeks. A case-control study implicated a new vehicle for botulism, commercial chopped garlic in soybean oil (P less than 10(-4)). Relatively mild and slowly progressive illness, dispersion of patients over at least eight provinces and states in three countries, and a previously unsuspected vehicle had contributed to prolonged misdiagnoses, including myasthenia gravis (six patients), psychiatric disorders (four), stroke (three), and others. Ethnic background influenced severity of illness: 60% of Chinese patients but only 4% of others needed mechanical ventilation (P less than 10(-3]. Trypsinization of serum was needed to show toxemia in one patient. Electromyography results with high-frequency repetitive stimulation corroborated the diagnosis of botulism up to 2 months after onset. Although botulism is a life-threatening disease, misdiagnosis may be common and large outbreaks can escape recognition completely.
Food-borne botulism in Canada, 1971-84.
Sixty-one outbreaks of food-borne botulism involving a total of 122 cases, of which 21 were fatal, were recorded from 1971 to 1984 in Canada. Most occurred in northern Quebec, the Northwest Territories or British Columbia. Of the 122 victims 113 were native people, mostly Inuit. Most of the outbreaks (59%) were caused by raw, parboiled or "fermented" meats from marine mammals; fermented salmon eggs or fish accounted for 23% of the outbreaks. Three outbreaks were attributed to home-preserved foods, and one outbreak was attributed to a commercial product. The causative Clostridium botulinum type was determined in 58 of the outbreaks: the predominant type was E (in 52 outbreaks), followed by B (in 4) and A (in 2). Renewed educational efforts combined with a comprehensive immunization program would significantly improve the control of botulism in high-risk populations.
Inhibitory effect of cocoa powder on the growth of a variety of bacteria in different media.
The inhibitory effect of cocoa powder on 102 organisms belonging to 13 genera was determined. All organisms tested were inhibited by 5% cocoa. Shigella, Staphylococcus, Micrococcus, and Bacillus were the most sensitive. The degree of inhibition depended on the organism, temperature of incubation, and the medium in which the cocoa powder was suspended. Of six media tested, lactose broth and nutrient broth were the most inhibitory, while non-fat dry milk was the least inhibitory. Supplementing NB with tryptone or casein reduced the toxicity of cocoa.
ICMSF methods studies. XII. Comparative study for the enumeration of Clostridium perfringens in feces.
As the second phase of an international comparative study for the enumeration of Clostridium perfringens, four methods were compared for "total" and spore counts of C. perfringens in fecal specimens: the SFP (Shahidi-Ferguson perfringens) agar (A), TSC (tryptose-sulfite-cycloserine) agar (B), SC (sulfite-cycloserine) agar (C), and neomycin blood agar (D) methods. In both the total and spore count procedures, the confirmed C. perfringens counts in method D were lower than in methods A, B, and C. Little differences among methods were found in the percentages of presumptive colonies confirmed as C. perfringens. The nonspecific counts in methods A and D were generally greater than in B and C, but nonspecific microorganisms did not interfere in the enumeration of C. perfringens spores by any of the four methods. In overall performance, methods B and C were superior to A and D. The mean C. perfringens spore count was only 0.17 log lower than the mean total count. Spore counts alone are, therefore, adequate in investigations of C. perfringens outbreaks.
A modified pork plasma agar for the enumeration of Staphylococcus aureus in foods.
The coagulase reaction of Staphylococcus aureus on the PPSA (pork plasma for S. aureus) agar of Devoyod et al. was found to be fibrinogen-deficient. By including bovine fibrinogen (BFG) in the medium, the fibrin halos around S. aureus colonies became more distinct, preparations of pork plasma previously unacceptable for inclusion in the original PPSA agar were performing well, and the amount of pork plasma required in PPSA agar could be reduced by nearly 90%. In the modified medium, designated PPF (pork plasma fibrinogen) agar, the agar base (Baird-Parker agar without egg yolk) was unchanged. After surface plating, the base was covered with 8 mL of a modified overpour agar: 2.5% pork plasma, 0.38% BFG, and 0.0015% soy trypsin inhibitor in 0.7% Bacto agar. Most S. aureus strains could be enumerated after 24 h of incubation at 35 degrees C; the others required 44 h. Without soy trypsin inhibitor, a number of strains showed considerable fibrinolysis between 24 and 44 h of growth; this activity was neutralized by the inhibitor. The S. aureus counts of 27 food samples on PPF agar were essentially the same as the confirmed S. aureus counts obtained by the Baird-Parker method.
Preenrichment procedure for detection of Salmonella in gelatin.
Trypticase soy broth was superior to nutrient and lactose broths as a preenrichment medium for the detection of Salmonella in artificially and naturally contaiminated gelatin. The detection rate for Salmonella were further enhanced when homogenization of the gelatin-broth mixture was accomplished by the use of gelatinase rather than by heating of 45 degrees C. Detection rats were also increased by adjusting the pH of the gelatin-broth mixture of 7.0, optimum pH for gelatinase (EC 3.4.23.2) activity.
Enumeration of Clostridium botulinum spores in meats by a pour-plate procedure.
Colonies of Clostridium botulinum could be easily distinguished from meat particles by supplementing Wynne agar with 0.4% egg yolk. The pour-plate method was suitable for enumeration of C. botulinum, provided the medium was covered with a layer of agar containing 0.01% dithiothreitol. Viable counts of heat-treated spores were consistently higher in Wynne agar supplemented with egg yolk (Wynne-EY agar) than in Wynne agar alone.
ICMSF methods studies. VIII. Comparative study for the enumeration of Clostridium perfringens in foods.
Four methods were compared in an international comparative study for the enumeration of Clostridium perfringens: the SFP (Shahidi-Ferguson perfringens) agar (A), TSC (tryptose-sulfite-cycloserin) agar (B), SC (sulfite-cycloserine) agar (C), and neomycin blood agar (D) methods. The confirmed C. perfringens counts were slightly lower for D than for A-C. The percentages of presumptive colonies confirmed as C. perfringens were essentially the same in each method. The relative numbers of nonspecific colonies were the lowest in C, followed by B, D, and A. The methods were also compared for simplicity and for aspects associated with the recognition and selection of presumptive colonies.
Evaluation and modifications of media for enumeration of Clostridium perfringens.
The suitability of the Shahidi-Ferguson perfringens, TSC (tryptose-sulfite-cycloserine), and oleandomycin-polymyxin-sulfadiazine perfringens agars for presumptive enumeration of Clostridium perfringens was tested. Of these, the TSC agar was the most satisfactory. The TSC agar method was improved by eliminating the egg yolk and using pour plates. The modified method allowed quantitative recoveries of each of 71 C. perfringens strains tested and is recommended. For confirmation of C. perfringens, the nitrite test in nitrate motility agar was unreliable, particularly after storage of the medium for a few days. In contrast, positive nitrite reactions were obtained consistently when nitrate motility agar was supplemented with glycerol and galactose.
Enumeration of food-borne Clostridium perfringens in egg yolk-free tryptose-sulfite-cycloserine agar.
The SFP (Shahidi-Ferguson perfringens), TSC (tryptose-sulfite-cycloserine), EY (egg yolk)-free TSC, and OPSP (oleandomycin-polymyxin-sulfadiazine perfringens) agars have been tested for their suitability to enumerate Clostridium perfringens in naturally contaminated foods. Complete recoveries of C. perfringens were obtained in each of the four media, but only the TSC and EY-free TSC agars were sufficiently selective to ensure subsequent confirmatory tests without interference from facultative anaerobes. Because of some disadvantages associated with the use of egg yolk, EY-free TSC agar is recommended for enumeration of C. perfringens in foods. Several conditions for convenient shipment of foods and C. perfringens isolates with minimum loss of viability have been tested. The highest viable counts were preserved when foods were mixed 1:1 (wt/vol) with 20% glycerol and kept in a container with dry ice. Isolated C. perfringens strains remained viable for at least 2 weeks at ambient temperatures on blood agar slopes with a 2% agar overlay in screw-cap culture tubes.
Enumeration of fecal Clostridium perfringens spores in egg yolk-free tryptose-sulfite-cycloserine agar.
The Shahidi-Ferguson perfringens, tryptose-sulfite-cycloserine (TSC), and egg yolk-free TSC agars have been tested for their suitability to enumerate fecal spores of Clostridium perfringens. When these spores comprised at least 20% of the total anaerobe spores, equally accurate counts were obtained in the three media. With lower ratios of C. perfringens spores, the most accurate counts were obtained in egg yolk-free TSC agar. The median C. perfringens spore count of 60 normal fecal specimens was log 3.4/g. A nonmotile, sulfite- and nitrate-reducing Clostridium, not identifiable with any known clostridial species, was isolated from 14 out of 60 fecal specimans. It was not differentiated from C. perfringens in the nitrite motility test, but could be distinguished by its inability to liquefy gelatin.
Purification of Clostridium perfringens type C theta toxin.
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Improved purification and further characterization of Clostridium perfringens type A enterotoxin.
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Immunization of sheep against experimental Clostridium perfringens type A enteritis.
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The role of enterotoxin in Clostridium perfringens type A enteritis.
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