Food borne diseases SPC method Relationship of Microorganisms

Food borne diseases SPC method

Relationship of Microorganisms and food • Pathogenic or Toxogenic: cause disease • Beneficial/ desirable( make food) – Lactobacilli bacteria in fermented food(yoghurt, pickles) – Yeast Saccharomyces in Bread and baking • Deteriorated/ undesirable – Non-pathogenic: Spoilage – Fungi, Pseudomonas, Proteus, Bacillus

Conditions for Spoilage • Water, p. H , physical structure, oxygen, temperature Water • p. H • Physical structure • Oxygen • temperature •

Spoilage of food • Organisms that cause spoilage • Pseudomonas , Proteus, Serratia, lactobacillus micrococcus, fungi such as Aspergillus, Rhizopus, yeast. • Spoilage appear as greening , moldy appearance, Rotting, discoloration, souring , bad smell.

Foodborne disease is any illness resulting from the consumption of food contaminated with one or more diseaseproducing agents( bacteria, parasites, viruses, fungi and their products toxic substances) • Two primary types – Food infection : due to presence of living organism – Food poisoning due to presence of toxins (staphylococcal, botulism, Clostridium perfringens, and Bacillus cereus food poisoning)

Food borne infections vs. intoxication Infections • Bacterial / Viral / parasite Intoxications • toxins ( natural / preformed bacterial / chemical) • No invasion or multiplication • Invade and or multiply in lining of intestine • Incubation period- hours to days • Incubation period- minutes to hours • S/s – Diarrhea , nausea, vomiting , • S/s – Vomiting , nausea, diarrhea , abdominal cramps, fever diplopia, weakness, resp. failure , numbness, sensory/motor dysfunction • Not communicable • Communicable-spreads from person to person • Factors-inadequate cooking , improper handling temperatures • Factors-inadequate cooking, cross contamination , poor personal hygiene , bare hand contact

The numbers and types of microorganisms present on a food are affected by the following factors; • The general environment which the food was originally obtained from • The microbial content of the food in the unprocessed state • The sanitary conditions during the processing • The adequacy of subsequence packaging, handling and storage conditions.

General facts • Every person is at risk of food borne illness. • No long-term health threat to average person • May be serious for very young, very old, people with long term illness • Reaction may occur in a few hours or up to several days after exposure Symptoms • Abdominal cramps, headache, vomiting, diarrhea (may be bloody), fever, death

After Ingestion of bacteria 1. Will be sick within 6 -72 hours after eating contaminated food. (NOT usually sick immediately after eating!) 2. Symptoms usually last 4 -7 days 3. Most recover without antibiotics 4. Diarrhea can be severe enough to hospitalize person (dehydration)

Sources of Pathogens in Food 1 -Food itself: soil contaminated, water irrigation Vibrio, Brucella, Salmonella 2 -Food Handlers : Cooks, workers, waiters. Staph, Salmonella, Shigella, hepatitis ironment: Food storage, sanitation of markets, utensils and benches, food transport Bacillus, Yersinia, Campylobacter

Food risky to food-borne dz. • Fermented/ pickled food • sausages, pickled vegetables, yoghurt • Raw contaminated food • Raw meat , , milk, salads, chicken • undercooked food steaks, eggs, creams, fish • Readymade food • canned, frozen , ready made sandwiches

What to do in case of food poisoning • Look for pathogenic organisms in food, patient samples, etc. • Look for toxins in food • Must take samples from 1 - Patients 2 -Handlers 3 - Food Leftovers 4 - Utensils and boards, storage places

Detection of m. o. in food • Conventional cultural techniques – Standard plate count (SPC) – Most probable number (MPN), MFT • Rapid tests biochemical, immunological – Commercial kits : MMO-MUG, Elisa • Molecular techniques – Nucleotide hybridisation – Polymerase Chain Reaction (PCR)

Comparison of detection methods • All methods must be rapid and sensitive • Methods include: – Culture techniques – may be too slow – Rapid biochemical techniques- rapid – Immunological techniques - very sensitive – Molecular techniques – new, sensitive and specific

Evaluating the sanitary quality of foods • It is impractical to analyze all food for presence of pathogens • Use of indicator organisms • If present in greater than allowable No’s, it indicates that food is not of acceptable sanity quality. If absent food is almost safe • SPC method can be used to test different organisms.

Standard plate count(SPC) The process of using standard plate count is to dilute samples of the material to be tested with the agar medium, after 48 hours of incubation at 35 c visible colonies are counted Homogenise food sample(50 g of food+450 ml of S. saline) Make ten fold serial dilutions from mixed sample Plate on suitable selective media Incubate at 35 o. C, for 24 h. Colony count

Analysis of food using ATP photometry • Breakdown non microbial cells in food ( somatic cells)to release their ATP • Remove the non microbial ATP using the enzyme ATPase • Release the bacterial ATP from bacterial cells • Assay the amount of bacterial ATP by the addition of firefly luciferin/ luciferase • Record the amount of light emitted using ATP photometer • Using a correlation curve to convert relative light units to colony forming units (cfu's)/ml

Rapid tests • Commercial kits: many • Faster than conventional method – e. g. the MMO-MUG method for Coliform testing Negative Positive E. coli Negative Positive Total Coliform

Pathogens of Most Concern on Fresh Produce • • Salmonella Shigella Escherichia coli Campylobacter Yersinia enterocolitica Staphylococcus aureus Clostridium species Bacillus cereus Vibrio species Viruses (Hepatitis A, Norwalk) Parasites/Protozoa- (Giardia, Entamoeba, Toxoplasma, Sarccystis, Isopora, Cryptosporidium, Eimeria, Cyclospora)

General Control of food borne disease • Food inspection • Check Handlers health • Education and training for food handlers and public • Market sanitation • Proper transport and storage methods

Food control In the Home • Drink pasteurized milk and juices • Wash hands carefully and frequently – After using the bathroom, Changing infant’s diapers, Cleaning up animal feces • Wash hands before preparing food • Wash raw fruits and vegetables before eating • After contact with raw meat or poultry – Wash hands, utensils and kitchen surfaces with hot soapy water

In the Home • Cook beef/beef products thoroughly – Internal temperature of 70 o C • Cook poultry and eggs thoroughly – Internal temperature of 80 o. C • Eat cooked food promptly • Defrost meats in the refrigerator • Refrigerate leftovers within 2 hours after cooking • Store in shallow containers so that the contents gets cooled evenly throughout

Five keys to Safer food 1. Keep Clean – Wash hands before handling food and often during preparation Wash hands after going to toilet Wash n sanitize all surfaces n equipment for food preparationprotect kitchen from insects , pets 2. Separate raw and cooked food. Separate raw meat , poultry n seafood from other foods Use separate utensils for handling raw foods Store food in containers to avoid contact between raw and cooked foods 3. Cook Thoroughly – esp. Meat , poultry , eggs and Seafood Bring soups n stews to boiling (ensure>70 degree temp) Reheat cooked food thoroughly

Five Keys to Safer Food 4. Keep food at safe temperature Don't leave cooked food at room temp. >2 hours Prompt refrigeration of cooked n perishable food Keep cooked food piping hot(>60 de. ) prior to serving Don’t store food too long even in refrigerator Don’t thaw frozen food at room temperature 5. Use safe water and raw materials- • Use safe water or treat to make it safe • Select fresh and wholesome fruits • Choose foods processed for safety - pasteurized milk • Wash fruits n vegetables if eaten raw • Don’t use food beyond expiry date

Prevention of Food Borne diseases WHO ‘ten golden rules v v v v v Food processed for safety Thoroughly cook Eat immediately Store carefully Reheat thoroughly No contact between raw & cooked Wash hands Keep food preparation surfaces clean Protect from pests Use potable water

CONCLUSIONS • 1. It is important to realize that with any of the method of analysis for pathogen or indicator, there is no absolute guarantee of success. • 2. The organisms under test can be missed completely (false negative) or other organisms can mimic positive results giving rise to false positives. • 3. Developing and improving methods of analysis for pathogens and indicators is an area of intensive and continuing research. • 4. This is particularly the case where `new’ pathogens are concerned and a widely accepted method needs to be established. • 5. Even when techniques are well established, research continues to try and improve sensitivity, eliminate false positive and reduce the time taken to obtain results .