1 - Water and microbiology

• Food Microbiology and Food Related Pathogens are topics discussed in Lecture 1 by Dr Marwan Albuhtori.
• The various roles of microbes in food, common methods used to ensure food safety, the burden of microbes within the food industry, and major food-borne pathogens and their threat to human health are topics discussed in Lecture 1.
• Types of food borne disease include infection, bacterial, fungal, eukaryotic parasites, viruses, intoxication, bacterial and fungal toxins, shellfish toxins, metals, chemicals, and allergies.
• The causative agent must be in the environment in which the food is produced, processed, or prepared for food-borne infection.
• Transmission of the agent from the source to a food is a crucial step in the causative chain of food-borne infection.
• Food must be kept in conditions that allow the agent to survive/thrive/ grow for food-borne infection.
• Salmonella is a major pathogen found in the intestinal tract of birds and other animals, and human contamination occurs through consumption of contaminated animals, animal products or water.
• Food preservation can involve extrinsic treatment actions such as heat treatment, low temperature storage, growth inhibition, modified atmosphere packaging, and radiation.
• The incubation period for Salmonella infections is 8 – 48 hours, with a morbidity period of 3 – 6 days and an infection type of superficial infection of the gut.
• Hurdle Technology involves combining several preservation factors to improve food safety, enhance organoleptic properties, and can be more effective than individual processing methods.
• Infection with Salmonella can result in gastroenteritis or typhoid fever depending on the type of Salmonella encountered.
• About 8,500 laboratory confirmed cases of Salmonella infections occur in the UK each year, although this is believed to be a large underestimation.
• Various NaCl solutions of different concentrations have different effects on water activity, with higher salt concentration decreasing water activity and being protective.
• Symptoms of Salmonella infections can include occasional vomiting, severe diarrhoea, mild fever, muscle aches, and are rarely fatal.
• Water availability affects the rate of growth of different microorganisms.
• Food-borne diseases can be caused by major pathogens such as Clostridium perfingens, Bacillus cereus, Escherichia coli, Aeromonas hydrophila, Plesimonas shigelloides, Shigella sp., Streptococcus sp., Norovirus, Salmonella sp., Clostridium botulinum, Staphylococcus aureus, Campylobacter jejuni, Yersinia enterocolitica, Listeria monocytogenes, Vibrio cholerae, V parahaemolyticus, Vibrio vulnificus.
• Transmission/contact took place on food/surface that supports the growth of the microorganism is a step in the causative chain of food-borne infection.
• The susceptible host eats/consumes the contaminated food/drink is a crucial step in the causative chain of food-borne infection.
• A long chain and all links needed in to get infection must be present for food-borne infection.
• Break any link and you won’t have food-borne infection.
• Beneficial bacteria, such as Lactobacillus acidophilus, can enhance foods like cheese, meat, wine and beer, and are used in food additives, food safety and stability, probiotics, and food preservation.
• The treatment of food-borne infection can involve water activity, pH, food acidity, antimicrobial chemicals, biological agents, and competitive microflora.
• Growth inhibition can be achieved through water activity, pH, food acidity, antimicrobial chemicals, and biological agents.
• Listeriosis can result in mild non-invasive infection or potentially life-threatening invasive syndromes such as septicaemia and infection of the CNS.
• Listeria monocytogenes has a low incidence (<200 cases per year, UK) but an extremely high mortality rate (>25%).
• The symptoms of E. coli infection include severe stomach cramps, vomiting, diarrhoea, possible fever, and occasional vomiting.
• Listeriosis is the disease caused by Listeria.
• Listeria sp. is a member of the Listeriaceae family and the species Listeria monocytogenes is the primary human pathogen within the genus.
• Campylobacteriosis is the disease caused by Campylobacter.
• Escherichia coli 0157-H7 (STEC) is a member of the Enterobacteriaceae family and the species Escherichia coli is the primary human pathogen within the genus.
• Campylobacter sp. is a member of the Campylobacteraceae family and the species Campylobacter jejuni is the primary human pathogen within the genus.
• Campylobacter commonly inhabits the GI tract of animals and is commonly found in poultry, red meat, and untreated water.
• E. coli infection can lead to Enterohemorrhagic or Enterotoxigenic disease.
• Elderly, young newborns, and immuno-compromised individuals are at increased risk of complications from E. coli infection, such as the development of Haemolytic Uremic Syndrome (HUS).
• Listeria is a Gram positive, rod-shaped bacteria which is found commonly in the environment due to its resilient nature.
• Epidemiology of STEC 0157 E. coli PHE (2016)
• Listeria contains 7 species, only one of which is a significant human pathogen, Listeria monocytogenes.
• Campylobacteriosis can be prevented by sufficient cooking, good hygiene, and correct processing by food/water providers.