Bacterial Foodborne Diseases PDF

Foodborne diseases Introduction Food microbiology can be divided into three focus areas; beneficial microorganisms, spoilage microorganisms, and disease causing microorganisms (Fig. 1). 1- Beneficial microorganisms are those used in food fermentation to produce products...

Foodborne diseases Introduction Food microbiology can be divided into three focus areas; beneficial microorganisms, spoilage microorganisms, and disease causing microorganisms (Fig. 1). 1- Beneficial microorganisms are those used in food fermentation to produce products such as cheese, fermented meat (pepperoni), fermented vegetables (pickles), fermented dairy products (yogurt). In fermented products (produced by natural or control fermentation), microorganisms metabolize complex substrates to produce enzymes, flavor compounds, acids, and antimicrobial agents to improve product shelf-life and to prevent pathogens growth and to provide product attributes. Microorganisms with their enzymes also breakdown indigestible compounds to make the product more palatable and easier to digest. In addition, the beneficial microorganisms also serve as probiotics to impart direct health benefit by modulating the immune system to provide protection against chronic metabolic diseases, bacterial infection, atherosclerosis, and allergic responses. Examples of beneficial microorganisms are Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactococcus lactis, and Pediococccus acidilactici. 2- Food spoilage microorganisms are those which upon growth in a food, produce undesirable flavor (odor), texture and appearance, and make food unsuitable for human consumption. Sometimes uncontrolled growth of 1 many of the beneficial microorganisms can cause spoilage. Food spoilage is a serious issue in developing countries because of inadequate processing and refrigeration facilities. Examples of food spoilage microorganisms are Brocothrix, Lactobacillus, Bacillus, Pseudomonas spp., and some molds. The microenvironment created in a spoiled food generally discourages the growth of the pathogenic microorganisms, which are considered poor competitors. 3- Foodborne pathogenic microorganisms (Table 1) when grown in a food may not alter the quality of products and, thus may not be easy to asses the microbial safety of a product without performing multiple microbiological tests. Foodborne pathogens are responsible for food intoxication (ingestion of preformed toxin), toxicoinfection (toxin is produced inside the host after ingestion of bacteria or foodborne infection (ingestion of infective pathogen). 2  Beneficial Micro- Spoilage organisms Micro- organisms Fig. 1 Three branches of food microbiology focus areas: Beneficial and spoilage microorganisms have some Pathogenic Micro- Overlapping activity (shaded area) while pathogens make organisms a distinct group Table 1: List of foodborne pathogens involved in outbreaks from contaminated food and water Bacterial Viral Parasitic Aeromonas hydrophilia Astrovirus Cryptosporidium parvum Bacillus anthracis Hepatisis A virus Cyclospora cayatanensis Bacillus cereus/subtilis/ Hepatitis E virus Entamoeba lichniformis histolytica Brucella/abortus/melitensis/suis Nororvirus Giardia intestinalis 3  Campylobacter jejuni/coli Rotavirus Isopspora belli Clostridium botulinum Taenia solium/saginata Clostridium perfringens Toxoplasma gondii Escherichia coli Trichinella spiralis Enterobacter sakazakii Listeria monocytogenes Mycobacterium tuberculosis Salmonella enterica Shigella spp. Staphylococcus aureus Vibrio cholerae V. cholerae non-01 V. parahemolyticus V. vulnificus, V. fluvialis Food poisoning is a syndrome resulting from ingestion of contaminated food with some certain plants, fish, chemicals or some poisoning m.o. It is characterized by: - One or more person affected by eating same food at same place and/ or time. - Sudden onset. - Short incubation. - Mainly gasterointestinal disorders. 4 Type of food poisoning: 1- Poisoning by chemicals Poisoning by consumption of chemicals is rather uncommon and usually characterized by appearance of symptoms within short time after poisonous food is eaten. Antimony, arsenic, cadmium, lead and zinc, in food, have been claimed for food poisoning. Arsenic, from fruits sprayed by arsenical preparations are used in ice-cream and yoghurt production. Antimony and zinc. From the use of enameled and galvanized containers especially if increased acidity of foods. The insecticides, sodium fluoride have been accidentally added to food in place of bakery powder, flower, dry milk and/ or starch. 2- Poisonous plants and animals Gasterointestinal disturbances or even death may result from consumption of poisonous plant products. Also, some fishers in tropical water are poisonous. 3- Allergic food poisoning Some people suffer from allergy to some normal components in food. There are individuals allergic to gluten in cereals and develop digestive disorders following consumption of foods containing gluten. The same case has been shown for egg. 5 4- Microbial food poisoning Many foods, including milk and dairy products, are susceptible to the growth of food poisoning bacteria on account of their high moisture content and good nutritive value. The incidence of foodborne diseases of microbial origin is higher than all others combined. There are 4 ways in which bacteria may cause illness in human beings: 4.1- Food infection: consumption of food containing viable pathogenic m.o.: a) Living cells consumed with food b) Dose level from 10 to 100 000 viable cells/ g of food (according to pathogensity) c) Symptoms appear usually after 24 h of ingestion (longer incubation period) d) Fever with gasterointestinal disorder mainly diarrohea e) Type: Salmonella, Shigella, Listeria, pathogenic E. coli, Campylobacter, Yersinia, viruses 4.2- Food intoxication: consumption of food containing preformed microbial toxins a) Toxins produced in food b) Food may not contain viable m.o. that produced toxins c) Symptoms very early (short incubation period) as quickly as 30 minutes d) Enterotoxins with enteric symptoms (mainly vomiting) or neurotoxins with neurological symptoms 6  e) Fever usually not present f) Types: Staphylococcus, Closteridum botulinum, fungal mycotoxins (mycotoxicosis), Streptococcus. 4.3- Food toxico-infection: consumption of food containing viable m.o. and their toxins a) It is potentially happening b) Infection with high number of m.o. is present in food as Enterococc gasteroenteritis c) Sporulation occurs in intestine as Clostridum perferngens d) Colonization in intestine as enterotoxigenic E. coli e) Types: Clostridum perferngens, Bacillus cereus, Cholera, some E. coli (EHEC,ETEC) 4.4- Opportunistic food poisoning It is disease caused by m.o. in immunocompromized people like pregnant woman, young age, people that take chemotherapy and very old age. It means that may infect some people and not all. As Aeromonas hydrophila, Aer. Carvie, and Are. Sobria. 7  Fig 2: Sequence of events that lead to foodborne disease by bacteria and viruses Human reservoirs of food poisoning organisms: Skin lesions, nose infection Bowl, carrier case, water sewage S. aureus Salmonella, Shigella, Cl. perfringens Hands Hands Foods Foods Kept at room temperature to Produce sufficient toxin increase in number Food intoxication Food infection 8  I. BACTERIAL DISEASES 1- Bovine tuberculosis “ T.B ”: - It is an infectious disease of slow development. - Causative organism: is Mycobacterium tuberculosis var bovis “Mycobacterium bovis” - Lesion: is more commonly in lymph nodes, lung and liver, but less frequently in udder, bone and joints. - The severity of disease depends on: its existence in diseased cattle and the amount of raw milk or inefficient heat-treated milk consumed by population. Characters of organism: 1- It is acid fast bacilli. 2- Rod-shapes mostly occur in pairs. 3- Motile. 4- Non-capsulated non-spore forming. 5- Aerobic Gram-negative bacilli. 6- The thermal death point is 60 °C / 15-20 min. 7- Highly susceptible to sunlight and UV radiation. Sources of milk contamination: 9 Tubercle bacilli can reach milk and contaminate it through all body excretions as: 1- Directly: Consumption of contaminated raw milk or its products is the principal vehicle for the transmission of M. bovis from dairy animal to man. So, the direct contamination of milk is mainly through: - Infected udder of dairy animals as in case of ‘’tuberculous mastitis’’. - Blood as in case of ‘’generalized T.B’’ without causing any udder lesion. 2- Indirectly: - Tubercle bacilli can reach milk through various animal body excretions (feces, sputum, urine & uterine discharges). - Manure is the very common source that can contaminate animal coat, bedding, udder especially insufficient cleaned and sanitized milking or milk utensils “tuberculous enteritis & tuberculous hepatitis”. - Sputum of infected animal as in case of “Pulmonary T.B’’ in which M. bovis bacteria comes from the lung of tuberculous animal and as the animal swallowed the sputum not expectorate it then it reaches the GIT causing tuberculous ulcer in GIT and then can discharge the organism in feces. - Infected uterus by uterine discharges as in case of tuberculous metritis “Uterine T.B” - Urine as in case of “Tuberculus nephritis’’. 10 Symptoms: 1- Fever. 2- Coughing accompanied with blood y sputum. 3- Severe respiratory disturbance. 4- Emaciation and loss of appetite. 5- Death in late stage. Control of disease: 1- In milk: By Proper pasteurization of milk and discarded milk from infected animal. 2- Between animals: - By detection of diseased animals in the dairy farm or quarantine on newly purchased animals before join to the herd by application of “tuberculin test” by S/C or I/D injection -------- swelling at the site of injection. - Periodical examination of dairy animals at farm level. 11  All animals Tuberculin test TttttubercTuber ulin test Positive reactors Negative reactors Clinical examination Apparently Clinically recognized healthy animals animals Slaughtering -Isolation from the herd -Heat-treatment of milk -Breeding and separation of their calves and feeding them on T.B free milk. -After weaning (6 months) Join to herd Tuberculin test Positive reactors 12  3- Between dairy men: By detection of diseased person using tuberculin test “Manotoux test” or rontogenographic screen. 2- Brucellosis “Bang’s disease or contagious abortion or storm abortion” It is an occupational bacterial disease. Causative Animal Man organism Brucella Contagious abortion Undulant fever abortus in bovine or Bang’s Mediterranean disease sea fever Brucella Contagious Malta fever melitensis abortion in sheep and goat Brucella suis Pork and cattle Brucellosis Character of organism: 1- Gram negative cocco bacilli. 2- Non motile. 3- Non sporulated. 4- Micro-aerophilic or need O2 and 10% CO2. 13 5- It is able to grow intracellular and tend to localize in lymphatic tissue, liver, spleen, bone marrow and other parts of reticuloendothelial system. 6- Thermal death point is 60 ºC/ 10 min. 7- It survives natural acidity and milk processing. 8- It may persist in dust and soil for 2 or 3 months. 9- It rarely causes clinical mastitis. 10- All species can infect man and excrete in milk of dairy animals. Sources of milk contamination: 1- The organism is transmitted to milk through uterine discharge from infected genitalia due to predilection sites for brucella in non pregnant animal are udder and supra-mammary lymph nodes. 2- The organism infected pregnant animal from different sources, circulating with blood and reach udder. The organism is secreted in milk with small number. 3- Abortion of pregnant animals are commonly occurred and infect large number of pregnant dairy animals, so it is called “Storm abortion’’ organism presented in high number in aborted fetus, placenta and uterine discharge which contaminate dust (dust-borne infection), water supply, utensils and udder. After abortion the organism may localized in udder and secreted in high number in milk (direct infection). 4- From contaminated feces and urine from uterine discharge. 5- Indirect infection is mainly through dairy men, contaminated utensils with flies and from uterine discharge. Sources of transmission to human: 14  1- Direct contact with infected animals or their discharges. 2- Inhalation of dust contaminated with brucella organism. 3- Ingestion of infected milk or un-pasteurized dairy products. Symptoms: 1- Undulant fever “Malta fever” occurs which is accompanied with fluctuation of body temperature 37 ºC then 39 C then 36 ºC then 40 ºC. 2- Observed loss of weight. 3- Abortion in pregnant animals. 4- Orchitis in male. 5- Weakness. 6- Localized pain in back, neck, joint and abdomen. Control and preventive measures: 1- Adequate heat treatment of milk with prevention post-pasteurization contamination. 2- Eradication of diseased animals. 3- Routine exam of dairy animals at farm level by application ABRT for bulk milk (not more than 10 animals). The positive one has been confirmed by serum agglutination test to detect individual cases. 4- Calving and lambing sheds should be away from dairy. 5- Vaccination of calves by strain 19 vaccine (calf hood vaccination). 3- Anthrax: It is rare to occur as before reach to udder, the animal will die (feverish condition) and milk secretion is nearly stopped. 15  It caused by Bacillus anthracis. This bacterium is non-motile, spore forming bacilli. The vegetative form of organism is susceptible to pasteurization, while spore form can survive it for 24 hrs. But it destroyed by heating at 95 °C / 45 min or 100 °C/ 10 min. Sources of milk contamination: 1- Blood (main source) as there is bleeding from all body openings that the blood carries the bacilli can contaminate animal bedding and coat. 2- The bacilli spores can persist for many years in the dust (Dust-borne disease). 4- Listeriosis: It caused by Listeria monocytogenes which characterized by: 1- It is one of psychrotrophic bacteria which can grow at refrigerated temperature. 2- It is widely distributed in soil, manure, water and improper fermented silage. 3- It is sensitive to heat. 4- It is excreted in milk from infected animals. Sources of transmission to human: 1- Infected udder of dairy animals (mastitis). 2- Contaminated dairy utensils (soil and water). 3- Polluted water with animal manure. Associated Foods: L. monocytogenes has been associated with such foods as raw milk, supposedly pasteurized fluid milk, cheeses (particularly soft-ripened 16  varieties), ice cream, raw vegetables, fermented raw- meat sausages, raw and cooked poultry, raw meats (all types), and raw and smoked fish. Its ability to grow at temperatures as low as 3oC permits multiplication in refrigerated foods. **Once the bacterium enters the host's monocytes, macrophages, or polymorphonuclear leukocytes, it is bloodborne (septicemic) and can grow. Its presence intracellularly in phagocytic cells also permits access to the brain and probably transplacental migration to the fetus in pregnant women. The pathogenesis of L. monocytogenes centers on its ability to survive and multiply in phagocytic host cells. Symptoms: A) In animal: 1- Bovine mastitis. 2- Abortion in cattle. 3- Circling disease in sheep. B) In man: 1- It is an immuno-comprimized disease that can attack people of low immunity as newly borne infants, diseased human, pregnant women and old ages people. 2- Influenza-like symptoms. 3- Septicemia. 4- Nervous symptoms (brain abscess, meningitis and encephalitis). 17 5- Abortion of pregnant woman with still birth or death of infants soon after birth. 6- Surviving infants usually develop meningitis which may be fetal or result in permanent mental retardation. Complications: Most healthy persons probably show no symptoms. The "complications" are the usual clinical expressions of the disease. When listeric meningitis occurs, the overall mortality may be as high as 70%; from septicemia 50%, from perinatal/neonatal infections greater than 80%. In infections during pregnancy, the mother usually survives. Successful treatment with parenteral penicillin or ampicillin has been reported. Trimethoprim-sulfamethoxazole has been shown effective in patients allergic to penicillin. Target Populations: The main target populations for listeriosis are: pregnant women/fetus - perinatal and neonatal infections; persons immunocompromised by corticosteroids, anticancer drugs, AIDS; cancer patients - leukemic patients particularly; less frequently reported - diabetic, cirrhotic, asthmatic, and ulcerative colitis patients; the elderly; normal people. A listerosis outbreak in Switzerland involving cheese suggested that healthy uncompromised 18  individuals could develop the disease, particularly if the foodstuff was heavily contaminated with the organism. Control: Heat treatment of milk at temperature higher than 61.7 ºC/33 min. 5-Campylobacteriosis: It caused by C. jejuni and C. faetus (bacteria). Campylobacter jejuni is a Gram-negative slender, curved, and motile rod. It is a microaerophilic organism, which means it has a requirement for reduced levels of oxygen. It is relatively fragile, and sensitive to environmental stresses (e.g., 21% oxygen, drying, heating, disinfectants, acidic conditions). Because of its microaerophilic characteristics the organism requires 3 to 5% oxygen and 2 to 10% carbon dioxide for optimal growth conditions. This bacterium is now recognized as an important enteric pathogen. Source of infection is mainly through ingestion of faecally contaminated milk. Symptoms: Foul smell and/ or bile-stained diarrhea and can contain blood (usually occult) and fecal leukocytes (white cells), abdominal cramps, headache, fever, nausea and muscle pain. The illness usually occurs 2-5 days after ingestion of the contaminated food or water. Illness generally lasts 7-10 days. Associated Foods: C. jejuni frequently contaminates raw chicken. Surveys show that 20 to 100% of retail chickens are contaminated. Raw milk is also a source of infections. 19  The bacteria are often carried by healthy cattle and by flies on farms. Non- chlorinated water may also be a source of infections. However, properly cooking chicken, pasteurizing milk, and chlorinating drinking water will kill the bacteria. Complications: Complications are relatively rare, but infections have been associated with reactive arthritis, hemolytic uremic syndrome, and following septicemia, infections of nearly any organ. The estimated case/fatality ratio for all C. jejuni infections is 0.1, meaning one death per 1,000 cases. Target Populations: Although anyone can have a C. jejuni infection, children under 5 years and young adults (15-29) are more frequently afflicted than other age groups. 6- Actinomycosis (lumpy jaw) : It caused by Actinomyces bovis. This bacterium commonly found in and around the mouth of healthy cattle, Upper respiratory tract and skin. The organism enters the body through wound and reaches milk. Source of infection of milk is mainly udder lesions. Symptoms: A) In Animal: 20  Abscess formation with capsulation in jaw, tongue, udder and internal organs. B) In man: When organism found in udder, it caused pus formation and secret enterotoxin in milk. Consumption of such milk leads to diarrhea, abscess in the injured intestinal tract. Control: 1. Efficient heat treatment of milk. 2. Milk from diseased animal must be discarded. 7- Leptospirosis (Weil’s disease or Mud fever or Swamp fever or Swineherd’s disease): It is a febrile bacterial disease (fever) and goes by different names in different regions. It caused by L. interrogans. About 20 serogroups are subdivided to 180 serovars as L. Pomona, L. canicola, L. icterohaemorrhagae. It causes mastitis in cattle and goat. The organism is very labile and easily destroyed by slight acidity. It persists in milk stored at 4°C/ 2 months and survives pasteurization at 80 °C/5 min but it destroyed by boiling. 21 Source of infection is mainly through consumption of raw milk especially of goat and cattle suffering from mastitis. The most common animals that spread the disease are rodents. Signs and symptoms can range from none to mild such as headaches, muscle pains; to sever with bleeding from lungs or meningitis. If the infection causes the person to turn yellow with liver damage (causing jaundice), has kidney failure and bleeding, it is then known as Weil’s disease. As it affects people who take care of pig or occupied in the slaughtering or processing of pork, it is also called Swineherd’s disease. It characterized by aches, pains throughout the body, fever, dizziness and nausea. 8. Queery fever (Q-Fever) It is the most rickettsial disease transmitted through consumption of milk It caused by Coxiella burnetti (obligate Gram-negative intracellular bacterium, not multiply except inside living cell). It is widespread among cattle, sheep and goat. It is relatively resistant to heat, pasteurization and freezing. It is extremely resistant to chemical agents as formalin (0.5%) and phenol for 24 h. The organism is rod shape or coccoid cells and presents in large quantities in placental tissue and fluids. The organism grows in the vacuoles of host cells (ticks) which responsible for the transmission of disease. Sources of milk contamination: 22  Ticks are responsible for transmission microorganism among animals and the organism circulate in blood which then reaches to milk (tick-borne disease). Infected cattle continue to secret Coxiella burnetti in their milk for long period (up to 200 days) with variable amount. Sources of transmission to human: 1- Inhalation of infected matter (dust) contaminated from amniotic fluid and fetal membrane of infected animals. 2- Consumption of infected raw milk or its products. Symptoms: - In animal: general weaknes - In man: 1- They resemble to influenza (acute febrile influenza like disease), weakness, and headache may be pneumonia. 2- It has effect on CNS. Control: 1- Separation the diseased animals 2- Heat treatment of milk 9- Udder infection (Mastitis): 2- Streptococcus pyogenes is the principal cause of mastitis in animals and tonsillitis and scarlet fever in human. 3- Staphylococcus aureus causes of mastitis in animals and food poisoning in human. 4- E.coli (EPEC) causes of mastitis in animals and GIT disorder in human. 23 10- Aeromonas hydrophila 1. Name of the Organism: Aeromonas hydrophila, Aeromonas caviae, Aeromonas sobria & (Aeromonas veronii). Aeromonas hydrophila is a species of bacterium that is present in all freshwater environments and in brackish water. Some strains of A. hydrophila are capable of causing illness in fish and amphibians as well as in humans who may acquire infections through open wounds or by ingestion of a sufficient number of the organisms in food or water. Not as much is known about the other Aeromonas spp., but they too are aquatic microorganisms and have been implicated in human disease. 2. Name of Acute Disease: A. hydrophila may cause gastroenteritis in healthy individuals or septicemia in individuals with impaired immune systems or various malignancies. A. caviae and A. sobria also may cause enteritis in anyone or septicemia in immunocompromised persons or those with malignancies. 3.Nature of Disease: 24  hydrophila is a cause of human gastroenteritis. Its presence in the stools of individuals with diarrhea, in the absence of other known enteric pathogens, suggests that it has some role in disease. Likewise, A. caviae and A. sobria are considered by many as "putative pathogens," associated with diarrheal disease. Two distinct types of gastroenteritis have been associated with A. hydrophila: - a cholera-like illness with a watery (rice and water) diarrhea. - dysenteric illness characterized by loose stools containing blood and mucus. The infectious dose of this organism is unknown, but ingestion of small amounts of water can cause illness, and A. hydrophila has isolated from stools. A general infection in which the organisms spread throughout the body has been observed in individuals with underlying illness (septicemia). 4. Associated Foods: A. hydrophila has frequently been found in fish and shellfish. It has also been found in market samples of red meats (beef, pork, lamb) and poultry. 5. Usual Course of Disease and Some Complications: On rare occasions the dysentery-like syndrome is severe and may last for several weeks. 25  A. hydrophila may spread throughout the body and cause a general infection in persons with impaired immune systems. Those at risk are individuals suffering from leukemia, carcinoma, and cirrhosis and those treated with immunosuppressive drugs or who are undergoing cancer chemotherapy. 6. Target Populations: All people are believed to be susceptible to gastroenteritis, although it is most frequently observed in very young children. People with mpaired immune systems or underlying malignancy are susceptible to the more severe infections. Epidemic diseases 11- Septic sore-throat: It caused by Streptococcus pyogenes (bacteria). Source of infection: 1- Cough spray of infected persons ‘’ droplet infection”. 2- Contaminated hands from udder lesions (mastitis). Symptoms: 1- Cough, fever. 2- Sever inflammation of throat and tonsillitis. 3- Formation of abscess around the tonsil and in cervical lymph nodes. 12- Scarlet fever: 26  - It caused by Streptococcus scarletina. -This bacterium produces erythrogenic toxin that lysis RBCs and leads to skin rash. - Source of infection: as in septic sore-throat. 13- Diphtheria: It caused by Corynebacterium diphtheria (bacteria). Source of infection: 1- Cough spray (direct droplet infection). 2- Contaminated hands of diseased persons. 3- Udder lesions from human sources. Control measures: 1- Sanitary disposal of animal and human faeces. 2- Control of flies at plant level. 3- Ensure that milkers are healthy and free from pathogen. 14- Cholera: - It caused by Vibrio cholerae (bacteria) - It is easily destroyed by developed acid in milk. Source of infection: 1- Active or carrier cases especially their soiled hands. 2- Contaminated water used in dairy purposes. 3- Flies. 27 Symptoms: Acute watery diarrhea with severe dehydration. This can lead to death if left untreated. 28