MFHPB-16 Detection of Clostridium botulinum and its Toxins in Suspect Foods and Clinical Specimens
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CC8916D72763483190C6FA1C91146812 |
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文件大小(MB)： |
0.04 |
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页数： |
10 |
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日期： |
2012-3-2 |
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Published on the Food Directorate (Health Canada's) website at,http://www.hc-sc.gc.ca/fn-an/res-rech/analy-meth/microbio/index_e.php,Government of Canada Gouvernement du Canada,HPB Method MFHPB-16,March 2009,HEALTH PRODUCTS AND FOOD BRANCH,OTTAWA,DETECTION OF CLOSTRIDIUM BOTULINUM AND ITS TOXINS,IN SUSPECT FOODS AND CLINICAL SPECIMENS,John W. Austin and Greg Sanders,Microbiology Research Division,Bureau of Microbial Hazards,Food Directorate,Postal locator: 2204E,Ottawa, Ontario K1A 0K9,e-mail:john_austin@hc-sc.gc.ca,1 APPLICATION,This method is applicable to the detection of botulinal toxin and viable C. botulinum in suspect foods and,clinical specimens, in accordance with Section 4 of the Food and Drugs Act. All work is to be carried out,in cooperation with the Botulism Reference Service in Ottawa. This revised method replaces MFHPB-16,dated April 1997.,2 DESCRIPTION,2.1 The method outlined below leaves some details of the procedure to the discretion of the,investigator, depending on the availability of food samples and clinical specimens, and the most,likely type of C. botulinum involved in a given outbreak. The C. botulinum strains involved in,human outbreaks fall into two distinct groups, I and II, comprising proteolytic and nonproteolytic,forms, respectively. Background information on the location of outbreaks, the suspect food, and,ethnic affiliation of the victims may suggest the involvement of one particular group and thereby,allow the procedure to be streamlined. A few characteristics relevant to the analytical procedure,are listed in Table 1.,2.2 Botulism associated with proteolytic C. botulinum strains,2.2.1 Proteolytic strains are relatively resistant to heat and preservatives, e.g., salt, acidulants,nitrite, etc. They are therefore the most likely forms involved in outbreaks from,underprocessed canned foods or from salted, pickled and otherwise cured products.,Exceptions are some dry- and brine-cured hams and pickled fish where C. botulinum may,develop before the diffusion of the main ingredients conferring safety (e.g. salt, acid) is,complete.,2.2.2 With few exceptions, infant botulism is caused by proteolytic strains of C. botulinum. In,the few exceptional cases, other clostridia (C. baratii producing type F toxin and C.,butyricum producing type E toxin) have been implicated.,- 2 - MFHPB-16,March 2009,2.3 Botulism associated with nonproteolytic C. botulinum strains,2.3.1 Type E is the prevailing form of C. botulinum in aquatic environments and the most likely,form of botulism from preserved fish. Type E is also the main cause of botulism involving,the native population of Canada and Alaska. Of 61 confirmed outbreaks among Inuits,and Amerindians recorded in Canada from 1971 to 1986, 60 were associated with type E,and one with a nonproteolytic type B.,2.3.2 Both groups, I and II, may have to be considered equally as potential causes of outbreaks,when the peccant food (i) is unknown, (ii) was temperature-abused and has little or no,protection from preservatives or (iii) is a canned product with post-process contamination.,2.4 SAFETY PRECAUTIONS,2.4.1 C. botulinum is a Bio Safety Level 2 (BSL2) organism. Procedures generating significant,quantities of toxin are stated to require BSL3 according to the Office of Laboratory,Security, PHAC.,2.4.2 All personnel engaged in handling toxic materials must be fully informed about the,hazards, and all materials to be autoclaved should be contained in stainless-steel boxes,with handles. Therapeutic antisera must be available within the province in case of,accidental intoxication.,2.4.3 Potentially toxic materials should always be contained in unbreakable, leak-proof trays or,boxes. This is particularly important in the incubation or manipulation of botulinal cultures,which may contain in excess of 105 mouse LD/mL. If toxin should be spilled, it must be,neutralized immediately with 0.1 N NaOH.,3 PRINCIPLE,3.1 The diagnosis of foodborne botulism is generally confirmed if, in addition to the clinical syndrome,botulinal toxin and/or viable C. botulinum are detected in suspect food or a clinical specimen.,Suitable specimens for toxin analysis are serum, feces, enema fluid and stomach contents. The,same specimens, except serum, are also suitable for the detection of C. botulinum.,3.2 Laboratory investigations of infant botulism are generally limited to the analysis of toxin and C.,botulinum in stools. Reported cases with detectable toxin levels in the serum are rare.,Environmental and food specimens may be tested for the presence of C. botulinum spores.,3.3 Botulinal toxin is detected by injecting serum or extracts from foods and ……
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