ICMSF The International Commission on Microbiological Specifications for Foods (ICMSF 2002) has revised its previous categorisation of microbiological hazards in foods. These are tabulated below.
The severity of the illness and duration should be compared with the information on p. 142-192 in the book ’The Microbiology of Safe Food’. Additionally a number of these organisms are permitted above the 0 cells in 25 gram testing specification for ready-toeat food. For details see the PHLS (UK) guidelines in Table 8.20, p.333 for ready-to-eat foods and the various EU and FDA sampling plans in Chapter 8. For more inforamtion on microbiological criteria jump to the relevant page microbiological criteria .
ICMSF microbiological hazards categorisation (p144, Table 5.2). For Cases see Table 8.1, p.301 Categorisation of common foodborne pathogens (ICMSF 1986)    Moderate, direct, limited spread, death rarely occurs B. cereus, C. jejuni, Cl. perfringens, St. aureus, Y. enterocolitica, T. saginata, T. gondii Cases 7,8,9  Moderate, direct, potentially extensive spread, death or serious sequelae can occur,. Considered severe Pathogenic E. coli, S. Enteritidis and other salmonellae other than S. Typhi and S. Paratyphi, shigellae other than Sh. dysenteriae, L. monocytogenes Cases 10,11,12  Severe, direct Cl. botulinum types A,B,E and F, hepatitis A virus. Sh. dysenteriae, S. Typhi and S. Paratyphi A, B and C, T. spiralis Cases 13, 14, 15      Up-dated categorisation (ICMSF 2002)    Food poisoning organisms causing moderate, not life-threatening, no sequelae, normally short duration, self-limiting B. cereus (including emetic toxin), Cl. perfringens type A, Norwalk-like viruses, E. coli (EPEC, ETEC), St. aureus, V. cholerae non-O1 and non-O139, V. parahaemolyticus   Serious hazard, incapacitating but not life-threatening, sequelae rare, moderate duration C. jejuni, C. coli, S. Enteritidis, S. Typhimurium, shigellae, hepatitis A, L. monocytogenes, Cryptosporidium parvum, pathogenic Y. enterocolitica, Cyclospora cayetanensis   Severe hazard for general population, life-threatenting, chronic sequelae, long duration Brucellosis, botulism, EHEC (HUS), S. Typhi, S. Paratyphi, tuberculosis, Sh. dysenteriae, aflatoxins, V. cholerae O1 and O139.   Severe hazard for restricted populations, life-threatenting, chronic sequelae, long duration C. jejuni O:19 (GBS), C. perfringens type C, hepatitis A, Crytosporidium parvum, V. vulnificus, L. monocytogenes, EPEC (infant mortality), infant botulism, Ent. sakazakki.  
Campylobacter jejuni sites  General description  WHO factsheet  FDA Bad Bug book  C. jejuni case study  Genome sequence  Guillain-Barre Syndrome (GBS)  Salmonella serovars  FDA Bad Bug book  General description  Laboratory diagnosis  Multiple antibiotic resistance, WHO factsheet  Enter-Net surveillance, EU  WHO fact sheet  Salmonella (and other causes of gastroenteritis) figures for England and Wales (2000)  Salmonella in poultry (UK)  Anatomy of an outbreak (video)  Outbreak associated with milk products  Outbreak associated with eggs  Multiple antibiotic resistance, WHO factsheet  Multi-antibiotic resistance in US  Salmonella cost estimate in USA  Severity of Salmonella (and Listeria) illnesses  Household contamination  WHO factsheet, typhoid fever  PulseNet  Salmonella genetic map  Salmonella.org; includes news on Salmonella genome sequencing  Escherichia coli sites  General aspects  Lecture  Pathogenic types  Diseases  Toxins  Lanarkshire (Scotland) outbreak summary  STEC outbreak in Wales; case study  Outbreak investigation in Japan  E. coli O111 outbreak case study  E. coli026 case in Korea - NEW  Genome sequence  E. coli O157 genome sequence  E. coli O157  HUS and HC surveillance  Pennington Group report in the the Lanarkshire outbreak  FoodNet (USA) surveillance  PulseNet  Non-O157 STEC survey, Nebraska (CDC)  Staphylococcus aureus sites  General aspects  CDC web page  Lecture  Genomic sequence  Clostridium perfringens sites  General issues  General background  General aspects  General avoidance  Outbreak  Lecture  CDC site  Listeria monocytogenessites  FDA Bad Bug book  USDA detection methods  northeastern United States outbreak  MRA fro ready-to-eat foods  Genome sequence (Entrez)  Noroviruses (formerly Norwalk-like viruses and small round structured viruses), and other enteric viruses  General backgound  General aspects  Cruise ship outbreak investigation  Foodborne viruses; emerging problem - ILSI monograph  Caliciviruses homepage  Detection method  Monitoring  Two Epidemiologic Patterns of Norovirus Outbreaks: Surveillance in England and Wales, 1992?000  Viral Gastroenteritis Outbreaks in Europe, 1995?000  UK surveillance study data  EU Scientific Committee opinion (pdf file), note this includes MRA  Enteroviruses  Emergent pathogen - Enterobacter sakazakii  The reader should note that our research group is carrying out extensive research into this emergent organism. Publications include: 
A risk profile of E. sakazakii in Trends in Food Science and Technology (November 2003).  Development of a chromogenic agar (Int J Food Microbiol - In Press) called ’DFI’ which stands for ’Druggan-Forsythe-Iversen agar’. The agar has undergone a European field trial and is being commercialised by Oxoid Ltd (UK), code CM1055.  Biofilms, growth range and thermotolerance (Lett Appl Microbiol - In Press)  Survey of ~500 food products for E. sakazakii using the chromogenic agar compared with FDA method (Food Microbiology - In Press).  Our detection method is two days shorter than the FDA method and is given here:  
I am also on various consultative panels concerning the organism. One such contribution being the FAO-WHO Geneva meeting 2-5th February (2004). The Executive summary being available at the WHO web site; Enterobacter sakazakii - FAO-WHO consultation. 
Other emergent pathogens  WHO general factsheet on foodborne diseases  WHO factsheet on medically important emerging diseases  BSE - WHO factsheet  vCJD - WHO factsheet  CJD Surveillance Unit  BSE-nvCJD  Emerging pathogens in the UK  Changes in consumer susceptibility  Investigation into vCJD outbreak in Leicestershire  multiple antibiotic resistance in Salmonella, WHO factsheet  Multi-antibiotic resistance in Salmonella (US)  Eurosurveillance (6 Number1, January 2001)  (Scientific American article)  ROAR Network  WHO factsheet on human antibiotic usage  WHO factsheet on non-human antibiotic usage  Anitbiotic abuse (Video)  Johne’s - Crohn’s disease and Mycobacterium paratuberulosis  Asssessment of surveillance and control of Johne’s disease in farm animals in GB (245 page pdf file)  Bacterial and fungal toxins  Bacterial protein proteins  Bacterial toxins; Friends or foes?  E. coli, Salmonella and Shigella cytoskeletal protein toxins  Bacterial endotoxin  Mycotoxins  There are a number of web sites which review food poisoning bacteria. One very clear one is from the University of Illinois. For more detailed information go the the FDA Bad Bug Book which is referred to below. 
Outbreaks When an outbreak occurs, it needs to be investigated in a thorough, standardised manner. For a tutorial on this topic visit the CDC web page outbreak toolkit. There are three case studies which can be downloaded (classroom based or computer based) from here. 
BSE-CJD news The Department of Health in the United Kingdom has released the latest figures (end of June 2002) on both known cases of CJD and cases of variant Creutzfeldt-Jakob disease (vCJD). By the end of June 2002, a total of 124 cases of variant Creutzfeldt-Jakob disease (vCJD) had been reported in the United Kingdom (DoH). A quarterly analyses is also available on the CJD surveillance unit website. The overall median age at death was 28 (range 14-74 years). The median number of days from onset to diagnosis was 334 days and from onset to death 411 days. Of the 124 cases, 68 (55%) were male. Although only 11 cases have been diagnosed in the first six months of 2002, it is not yet possible to conclude that the epidemic is reaching or has reached its peak. A continued exponential increase at the current underlying rate will give an estimate of approximately 32 deaths in the next 12 months. Twenty-eight cases of vCJD were reported in 2000, 15 in 1999, 18 in 1998, and 10 in 1997. Analyses shows that the underlying incidence is increasing by an estimated 18% per year based on date of symptom onset, or 20% per year based on date of death. These trends are lower than the 22% and 27% estimated last November, because only 11 cases were diagnosed in the first two quarters of 2002 (Reference: Andrews). 
The FDA Bad Bug book The Food and Drug administration (USA) have a very useful web site called Bad Bug Book which has extensive information on foodborne pathogens and toxins. You will notice that the majority of information in food microbiology is concerned with bacterial pathogens, as opposed to viruses and fungi. This is partially due to the relative ease with which bacteria can be cultivated in the laboratory. The perceived rise in viral causes in food poisoning is partially due to improved detection methods. The food poisoning statistics are dominated by Salmonella serotypes and Campylobacter jejuni. However as reviewed in foodborne illness the causative organism of a considerable number of gastroenteritis cases are not identified every year.
It should also be noted that a food microbiology in industry does not, and would not be expected to examine foods for all the possible pathogens. It would be prohibitively expensive and impractical. An additional reason for restricted microbiological analysis is that unless 100% of the food is examined then one cannot be 100% certain of the absence of pathogens or toxins in the whole batch of food. Taking known numbers of samples from a batch of food can be used to give a statistical evaluation of contamination. Hence the development of microbiological criteria. However it should be remembered that the results from a microbiological laboratory make take several days (at least if an outside accredited laboratory is used). Therefore the sampled batch of food might already have been distributed and a product recall would be expensive and deter customers from purchasing the product in the future. 
Therefore the question arises as to how can a food manufacturer produce food that is microbiologically acceptable? The answer is in the proactive approach of Hazard Analysis Critical Control Point (HACCP) . This internationally accepted means of assured safe food manufacture has already been used by large food companies for many years. However the implementation in small food outlets has been problematic due to the perceived burden of documentation. For assistance in industrial-sacle HACCP implementation see the author’s book Food Hygiene, Microbiology and HACCP.