Microbes of Public Health Significance PDF

Republic of the Philippines CENTRAL BICOL STATE UNIVERSITY OF AGRICULTURE Calabanga | Pasacao | Pili | Sipocot FST 101 – FOOD MICROBIOLOGY MICROBES OF PUBLIC HEALTH SIGNIFICANCE...

Republic of the Philippines CENTRAL BICOL STATE UNIVERSITY OF AGRICULTURE Calabanga | Pasacao | Pili | Sipocot FST 101 – FOOD MICROBIOLOGY MICROBES OF PUBLIC HEALTH SIGNIFICANCE ALESSANDRA M. DOMANACO Assistant Professor IV Outline I. Definition of terms II. Transmission of pathogens III. Host invasion IV. Pathogenesis V. Bacterial agents of foodborne disease i. Staphylococcus ii. Clostridium iii. Listeria iv. Salmonella and Shigella v. Escherichia coli vi. Vibrio, Yersinia and Campylobacter VI. Nonbacterial agents of foodborne disease i. parasites ii. viruses iii. molds Foodborne Disease – is any illness resulting from the food spoilage of contaminated food, pathogenic bacteria, viruses, or parasites that contaminate food, as well as chemical or natural toxins. ⚫ Food intoxication – refers to food-borne illnesses caused by the presence of a bacterial toxin formed in the food. ⚫ Food infection – refers to food-borne illnesses caused by the entrance of bacteria into the body through ingestion of contaminated foods and the reaction of the body to their presence. Microbial Contamination in Foods Transmission of Pathogens 1. Transmission by person to person contact. – Measles, mumps and tuberculosis can be spread by coughing or sneezing. 2. Transmission by food – Chicken skin from a retail package contaminated with bacteria; ex. Salmonella. 3. Transmission by contaminated wastewater flowing from a pipe into a lagoon. – drinking water contaminated by human or animal feces, which may contain disease-causing microbes. 4. Insects can also transmit pathogens to food. – House flies are very good at spreading Salmonella and E.coli O157. They feed on faecal waste and transfer microbes from their feet and other body parts to food. 5. Transmission by fomites (non-living objects) such as barbed wire. – A puncture wound on the finger caused by a prick from rusted barbed wire may result in tetanus due to infection by spores of the bacterium Clostridium tetani. Stages of transmission: ⚫ Escape from the host or reservoir of infection (where the infectious agent normally lives and multiplies). ⚫ Transport to the new host. ⚫ Entry to the new host. ⚫ Escape from the new host. Bacterial Agents of Food-borne Disease: Food Intoxication A. Staphylococcal Intoxication Staphylococcal Intoxication – is caused by the ingestion of the enterotoxins of Staphyloccocus aureus. – Termed as enterotoxin because it causes gastroenteritis or inflammation of the lining of the intestinal tract. Staphylococcus aureus ✓ Gram-positive cocci ✓ occur generally in bunches ✓ nonmotile, ✓ Noncapsular ✓ Nonsporulating ✓ facultatively anaerobic Growth of Staphylococcus aureus Food requirement - Ferment carbohydrates; Cause proteolysis by extracellular proteolytic ezymes Mesophile - Temperature range of 7 to 48°C, but grows rapidly between 20 and 37°C Water activity (Aw) - 0.86 pH - 4.8 Other growth req’t - High salt and sugar (15% concentrations); presence of NO2 Habitat of Staphylococcus aureus naturally present in the nose, throat, skin, and hair (or feathers). can be present in infections, such as cuts in skin, and cuts in hands and facial-erupted acne in humans. Toxin Production of Enterotoxigenic strains of Sta. aureus - Produce 7 different enterotoxins: A, B, C1, C2, C3, D, and E - Heat stable - Optimum growth occurs between 37 to 40°C Bacterial cells of Staphylococcus aureus, which is one of the causal agents of mastitis in dairy cows. Its large capsule protects the organism from attack by the cow's immunological defenses. Disease and Symptoms Disease - Gastroenteritis Consumption - Has to consume 30 g or mL of food containing 100 to 200 ng toxins produced by 106-7 cells/g Symptom - 2 to 4 hours after consumption; can last occurrence for 1-2 days Symptoms - Salivation, nausea & vomiting, abdominal cramps, diarrhea Food Association - protein-rich foods, temperature abused foods, and foods that are handled extensively. - e.g.: ham, corned beef, salami, bacon, barbecued meat, salads, baking products containing cream, sauces, and cheeses B. Botulism Botulism - Results following consumption of food containing the potent toxin botulin of Clostridium botulinum. - The toxin botulin is a neurotoxin and produces neurological symptoms Clostridium botulinum – Gram-positive rods (occur as single cell or small chains) – Motile – Obligate anaerobes – Form single terminal spores which are highly heat resistant (killed at 115°C) Growth of Clostridium botulinum - Cells are sensitive to low pH, low Aw, and moderately high salt. - Strains can either be proteolytic or nonproteolytic Proteolytic – can grow between 10 to 48°C, optimum temp. of 35°C. Nonproteolytic – can grow between 3.3 to 45°C, optimum temp. of 30°C. Habitat of Clostridium botulinum - Spores are distributed in soil, sewage, mud and sediments. Intestinal contents of animals and fishes. - Fruits and vegetables can be contaminated with spores from soil; fishes from water and sediments. Toxin Production: Botulin - Extremely potent neurotoxin (Types A, B, E, and F) - Heat labile - Can be destroyed by high and uniform heat (such as 90°C for 15 min or boiling for 5 min. Disease and Symptoms (Botulism) - Initial stage (12 to 36 hours): gastrointestinal disorders (nausea, vomiting, diarrhea and constipation) - Neurological symptoms (1 ng/kg body weight): severe or death (blurred or double vision, difficulty swallowing, breathing and speaking; dryness of mouth; and paralysis Food Association - Canned foods - Low-acid vegetables (e.g., green bean, corn, spinach, asparagus, pepper and mushrooms - Fruits (e.g., figs and peaches) Prevention of Botulism - Use proper temperature and time in canning of low-acid products. Bacterial Agents of Food-borne Disease: Food Infection A. Salmonellosis  You can get Salmonellosis by eating food contaminated with the bacteria Salmonella. ⚫ Food contaminated during food processing or food handling. ⚫ Eating unwashed fruits and vegetables, uncooked or undercooked meat and eggs, drinking unpasteurized milk and contaminated water. ⚫ food contaminated by the unwashed hands of an infected handler. ⚫ Salmonella can also be found in the feces of some pets, especially with those with diarrhea. You can be infected if you don not wash your hands after contact.  Salmonella ⚫ Salmonella is the genus name for a large number (over 2,500) types of bacteria. ⚫ Cause disease in humans, animals and birds(especially poultry) in worldwide. ⚫ Two major types of diseases – Gastroenteritis ⚫ Non-typhoidal or Salmonella poisoning – Typhoid fever ⚫ typhoid and paratyphoid fevers) in humans Characteristics of Salmonella ⚫ rod-shaped ⚫ Gram-negative ⚫ Non-spore-forming ⚫ Facultative anaerobic ⚫ Predominantly motile enterobacteria with diameters around 0.7 to 1.5 µm Characteristics of Salmonella Mesophilic : growth range between 5 to 46°C, optimum growth between 35 and 37°C. pH : sensitive to low pH (4.5 or below) Aw : do not multiply at 0.94 Habitat of Salmonella - Natural inhabitants of the gastrointestinal tracts of animals. - Humans can also be carriers following an infection. - Also isolated from soil, water and sewage Toxins - Thermolabile enterotoxins are produced in the epithelial cells of the intestines resulting inflammatory reactions and fluid accumulation. Disease and Symptoms ⚫ Has to consume 105-6 cells ⚫ Symptoms appear generally at 24 to 36 hours, and last for 2 to 3 days. ⚫ General symptoms: abdominal cramps, diarrhea, nausea, vomiting, chills, fever and prostration Food Association ⚫ Foods of animal origin: beef , chicken, turkey, pork, eggs, milk and products made from them B. Clostridium perfringens Illness Clostridium perfringens ❖ The spores and vegetative cells of this bacterium are relatively heat-resistant, facilitating its survival in incompletely cooked foods. ❖ C. perfringens produces two toxins that are active in the human gastrointestinal (GI) tract and can thereby induce human foodborne illnesses.  Clostridium perfringens ❖ These two toxins are C. perfringens enterotoxin (CPE), the toxin responsible for the symptoms of C. perfringens type A food poisoning, and ❖ β-toxin, which is the toxin primarily responsible for the symptoms of necrotizing enteritis. ⚫ the incidence of C. perfringens is less in processed foods including meats. ⚫ Of particular concern are herbs and spices. The latter are well known for harboring bacterial spores, including C. perfringens. C. Bacillus cereus Gastroenteritis Characteristics of Bacillus cereus ⚫ Gram-positive ⚫ Facultative anaerobic ⚫ Spore-forming rods ⚫ Grows between 8 to 55°C, optimally around 28 to 35°C Disease and Symptoms ⚫ Diarrhoeal syndrome resemble those of Clostridium perfringens food poisoning. ⚫ Onset 8-16 hours after consumption, and lasts between 12 and 24 hours ⚫ Abdominal pain, profuse water diarrhea and rectal tenesmus. Food Association ⚫ Dried herbs and spices ⚫ Meat products, soups, vegetables, puddings and sauces D. Escherichia coli Infection Characteristics of E. coli ⚫ Gram-negative ⚫ Motile ⚫ Nonsporulating ⚫ Rod-shaped ⚫ Facultative anaerobic  Types of Pathogenic E.coli 1. Enteropathogenic E. coli Important in infant diarrhea, especially in places with poor sanitation. Transmitted though human carriers Needs to ingest 106-9 to develop symptoms Predominant symptom is gastroenteritis 2. Enterotoxigenic E. coli Major cause of diarrhea in travellers Heat labile and heat-stable enterotoxin Spread through human carriers Needs to ingest 108-9 to develop symptoms Predominant symptom is gastroenteritis (mild form of cholera) 3. Enteroinvasive E. coli Known to cause dysentery Spread disease through human carriers Needs to ingest 106 to develop symptoms 4. Enterohemorrhagic E. coli Cause of severe bloody diarrhea (hemorrhagic colitis) and hemorrhagic uremic syndrome (HUS) in animals. Ingestion 10 to 100 cells can produce the disease Present in intestines of animals, particularly dairy cattle. E. Shigellosis Characteristics of Shigella spp. ⚫ Gram-negative ⚫ Nonmotile ⚫ Facultative anaerobic rods ⚫ Grow between 7 and 46°C, with an optimum at 37°C. ⚫ Killed by pasteurization Habitat of Shigella spp. ⚫ Intestines of humans and some primates Disease and Symptoms Needs to ingest 101-3 to develop symptoms Symptoms occur in 12 hours to 7 days Lasts for 5-6 days Abdominal pain, diarrhea often mixed with blood, fever, chills, and headache Food Association ⚫ Present in food only through fecal contamination ⚫ Indirect contamination occurs from the use of fecal-contaminated water ⚫ Cross-contamination of ready-to-eat foods (salads) F. Yersiniosis Characterisitcs of Yersinia enterocolitica ⚫ Gram-negative short rods ⚫ Nonsporeforming ⚫ Motile below 37°C ⚫ Facultative anaerobic ⚫ Grow between 0 and 44°C, with optimum growth at 25 to 29°C Habitat ⚫ Normal inhabitant of intestines of food animals and birds, pets, wild animals and humans. Disease and Symptoms High dose of 107 is required for the disease. Severe abdominal pain, diarrhea, nausea, vomiting and fever Symptoms appear 24 to 30 hours and lasts for 2 to 3 days Can be fatal in rare cases Food Association ⚫ Isolated from raw milk, processed dairy products, raw and improperly cooked meats, fresh vegetables and improperly chlorinated water G. Vibrio spp.  VIBRIO spp. ⚫ gram-negative, curved, rod-shaped ⚫ natural inhabitants of the marine environment. – Transmission of Vibrio infections is primarily through the consumption of raw or undercooked shellfish or exposure of wounds to warm seawater. I. History ⚫ 1951 – large outbreak in Japan. “shirasu”- boiled and semidried sardines ⚫ another outbreak occurred at the National Yokohama Hospital. Salted cucumber History ⚫ 1960 –explosive epidemic occurred along the Pacific Coast of Japan. Contaminated horse mackerel ⚫ The causative agent was Vibrio parahaemolytics bacteria Nature of Disease Symptoms of Infection ⚫ Gastroenteritis ❖ Features: severe abdominal pain, diarrhea, nausea, and vomiting (also with mild fever and headache) ⚫ Symptoms occur within 12 hours ⚫ can also cause an infection of the skin when an open wound is exposed to warm seawater. Nature of Disease ⚫ Pathogenicity is associated with a thermostable haemolysin, called the Kanagawa phenomenon. Kanagawa-positive vibrios – are enteropathogenic and can cause gastroenteritis Kanagawa-negative vibrios  An individual has to consume 105 -107 cells of Kanagawa positive strains for symptoms to develop. Nature of Disease “Kanagawa-positive strains multiply rapidly in the intestine that is essential for enteropathogenicity.” (Sakazaki et al., 1974) Habitat ⚫ can be isolated from sediment, plankton, sea fish, crustaceans, and shellfish in coastal and estuarine environments, especially in warmer countries. Characteristics of Agent Vibrio parahaemolyticus gram-negative, nonsporulating, motile, curved rods. Facultatively anaerobic, halophilic bacterium. Characteristics of Agent Minimum / Factors Optimum Maximum Medium 1-8% NaCl 2-4% NaCl Temperature 42˚C 30˚ to 35˚C pH 5.6 to 9.6 7.6 to 8.6 Characteristics of Agent Vibrio parahaemolyticus colonies: – Moist, smooth, circular, and opaque – 2-3 mm colony size (24 hours) – broth media: dense homogenous turbidity, pellicle formation Characteristics of Agent Persistence and Survival killed by heat at 60˚C for 15 minutes or less and is easily destroyed by drying. survive refrigeration and freezing may be killed in vinegar within 1 hour and in 0.5% acetic acid within a few minutes.  Prevention and Control ⚫ The control methods should include the following: no consumptions of raw seafoods proper heat treatment of seafoods proper sanitation to avoid cross-contamination of heated foods proper refrigeration of raw and heated products consumption of food within a reasonable period of time  History ⚫ endemic in the delta of the Ganges and Bramhaphutra rivers in eastern India and Bangladesh. ⚫ 1st - occurred in the Bengal region of India (1817 -1824).  Nature of Disease Symptoms: -profuse, painless diarrhea (rice-water) and vomiting of clear fluid which can lead to rapid dehydration and electrolyte imbalance, and death in some cases. Nature of Disease Symptoms of Dehydration: ❖ The cheeks and eyes are sunken ❖ the skin is cold ❖ the pulse is rapid and barely palpable. ⚫ occur within 5-12hrs of the onset of diarrhea and if untreated, patients often die within 24hrs. ⚫ Incubation period: 1-5 days  Nature of Disease ⚫ cells (106 viable cells) colonize the small intestine and multiply rapidly and produce toxins. When the cells die and lyse, the toxins are released into the intestine.  Characteristics of Agent Vibrio cholerae – Gram negative, straight or slightly curved rod – Single polar flagellum – Facultatively anaerobic – Optimal pH:7.6 and 8.6 – Optimal temperature: 30˚-35˚C. Characteristics of Agent Persistence and Survival sensitive to antibiotics: streptomycin, tetracycline, chloramphenicol, kanamycin, and novobiocin. killed by heat at 55˚C for 15 minutes and is sensitive to drying. Can survive in feces for a few weeks at 1˚C but is killed within a day or two at room temperature. Prevention and Control ⚫ adopting proper hygienic measures: ▪ provision for properly heated municipal water ▪ decontamination of other water by boiling or chemical treatment ▪ proper disposal of sewage Prevention and Control ⚫ Seafoods should not be eaten raw. ⚫ The time-temperature of heat treatment of suspected food should be enough to kill the pathogen. ⚫ Food processing and places in which foods are sold should be subjected to strict supervision. Viral Infections - food-borne infection caused by ingestion of food containing viruses that can survive in the gut and attack the intestinal flora (the case of bacteriophages), or cells from humans (in the case of animal viruses).  Food Borne Viruses ⚫ most common pathogens transmitted via food ⚫ small acellular microorganisms ⚫ (15 to 400 nm diameter) ⚫ contains only 1 type of nucleic acid ⚫ described as obligate, ww.cdc.gov intracellular parasites  Food Borne Viruses ⚫ during transmission: is a small, inert particle with a transitory ability to cause infection ⚫ during infection: a portion of the virus passively serves as the template upon which more virus is produced by the host ⚫ Viruses can only replicate in living cells (host organism) ⚫ “Cannot replicate in food  FB Virus Transmission -transmitted via oral-fecal route -examples – Aerosol, water – Subjects soiled with human or animal feces or vomit – Contact with blood of infected persons – Contact with diseased animals – Vectors such as gnats or ticks that can transmit arboviruses ⚫ Infectious hepatitis Hepatitis virus enters a person through the oral route normally as a result of fecal contamination of water or food. May result in liver complications. ⚫ Poliomyelitis Polio Infectious hepatitis Polio virus Parasite Infections Parasites Organisms that obtain their food from other living creatures Well-adapted parasites does not kill its host Usually smaller than their food source Toxoplasmosis Etiologic agent Caused by protozoan Toxoplasma gondii (intracellular coccidian parasite) Definitive hosts: felids including domestic cat (Felis catus) & wild Felidae Intermediate hosts: Various warm-blooded animals  Toxoplasmosis Sporulated Unsporulat oocyst ed oocyst - sporulate - are shed in outside in cat cat feces feces w/in 1 or more days Toxoplasmosis Etiologic agent Ingestion of tissue cysts in undercooked meat or oocysts in food contaminated w/ cat feces congenital T. gondii infections are frequent in humans, sheeps and goats can cause parasitemia in the mother and lead to infection of the fetus Toxoplasmosis Baby with congenital Toxoplasmosis Sarcocystosis Etiologic agent coccidian parasites; implies parasites in muscle, & refers to sarcocysts found in striated muscles of mammals, birds and poikilothermic animals  Sarcocystosis Sarcocystis sp. Sarcocyst in the Sarcocystis sp. A sarcocyst (blue muscle of a cow. This cyst contains arrows, note the internal septum in the many bradyzoites which, when eaten center of the cyst of this species) in the by the definitive host, will initiate the muscle of a rodent. Note the Trichinella infection. spiralislarva (red arrow) in the adjacent muscle cell. Trichinellosis Etiologic agent Infection by a parasite worm of the Phylum Nematoda belonging to the genus Trichinella. T. spiralis –cause of human trichinellosis; derived from domestic pork Trichinellosis Trichinella spiralis Trichinellosis Etiologic agent fertilized female trichinae burrow into the intestinal wall and release larvae. The larvae are transported by the bloodstream to all parts of the body. The worm grows within muscle tissue (16 days to mature). A cyst develops around the larva's body. Trichinellosis Etiologic agent Photomicrograph of cysts of Trichinella spiralis embedded in muscle tissue. Taeniasis/cysticercosis Etiologic agent cysticercosis & taeniasis refer to infections w/ larval & adult tapeworms larvae are meatborne (beef or pork) and the adult stages develop only in the intestines of humans (obligate host) Taenia saginata (‘beef tapeworm’) and T. solium (‘pork tapeworm’) Taeniasis/cysticercosis Taenia saginata Taeniasis/cysticercosis Taenia saginata Taeniasis/cysticercosis Scolex (head) of the tapeworm Taenia solium. The hooks of the scolex enable the tapeworm to attach to the intestinal wall. Fishborne Helminths Nematodes Capillaria philipiensis nematode first reported in the Philippines Parasite is small, and the adult have rows of cells (stichocytes) that surround the esophagus at the anterior half of the worm. The worms reside in the small intestines, and eggs produced by females pass in the feces and reach freshwater. Nematodes C. philipiensis female worm (left) and egg (right) Nematodes Gnathostoma spp. Cats and dogs – definitive hosts for G. spinigerum Pigs – definitive host for G. hispidium Nematodes Gnathostoma spp. Nematodes Anisakis simplex infection w/ the larval stages of anisakid nematodes. parasites of marine mammals found in the stomachs of cetaceans and pinepeds. Whales, dolphins & porpoises – definitive hosts for Anisakis simplex Seals, sea lions & walruses – definitive hosts for Pseudoterranova decipiens Nematodes Anisakis simplex Nematodes Anisakid nematodes/ Anisakis simplex Mycotoxins – Are fungal metabolites. 1. Aflatoxin Are produced by certain strains of Aspergillus flavus and A. parasiticus. Aflatoxin B1 is the most toxic of the aflatoxins. Peanuts, cottonseeds, and corn. 2. Patulin Originally isolated as an antibiotic. Exhibits strong fungistatic activity and is toxic to seeds and seedlings of higher plants including sugar beets, corn, wheat, peas, tomato, cucumber and flax. 3. Ochratoxin A toxic metabolite isolated from Aspergillus ochraceus. Ochratoxin A is toxic to ducklings, rats, chicks and trout. 4. Luteoskyrin Penicllium islandicum produces two metabolites, luteoskyrin and cyclochlorotine. No known acute human intoxications. THANK YOU!