FOODBORNE DISEASES BACTERIAL FOODBORNE DISEASES A Bacteria are

FOODBORNE DISEASES

BACTERIAL FOODBORNE DISEASES A- Bacteria are by far the most common contaminants with food and cause many different foodborne diseases w Most diarrhea (1/2 to 1/3) caused by foodborne bacteria w Symptoms of foodborne diseases can range from mild to severe w Some people asymptomatic but can transmit the disease B- Definition of foodborne disease Eating food that contains a sufficient quantity of either pathogenic microorganism or their toxins to cause

BACTERIAL FOODBORNE DISEASES - Therefore, the presence of bacteria is not important but the number of bacteria ingested. - The dose required to cause illness can vary markedly for different microorganism For examples: w Salmonella requires 100, 000 bacterial cells inorder to produce symptoms w Staphyllococcus required 500, 000 microorganisms in order to produce illness

PATHWAYS OF FOODBORNE INFECTION CAUSED BY MICROORGANISM 1 -Ingested pathogenic microorganism then *The microrganism penetrates the intestinal mucosa and colonize the GIT - Examples: Shigella, Salmonella 2 –Microorganism travels from GIT to other tissues Then it stay in this tissues for examples: - Hepatitis A virus goes to the liver 3 - The toxins are released as the infecting microorganism multiplies or lyses in the intestinal tract Examples Vibro cholerae, Clostridium perfringens and E. coli

THE MOST COMMON FOODBORNE MICROORGANISMS A- BACTERIAL 1 -Salmonellae species 2 - Pathogenic E. coli 3 - Clostridium botuli 4 - Staphyllococcus aureus 5 - Shigella specie B- PARASITES C- Viruses

SALMONELLAE SPECIES w Salmonellae species are gram negative bacilli belongs to family enterbacteriacea w Salmonellae has three species - Salmonellae typhi - Salmonella enteritidis - Salmonellae choleraesuis w The main reservoir for Salmonellae is - intestinal tract of animals - poultry products such as eggs - meat

CHARACTERISTICS OF SALMONELLAE w Salmonellae grows in aerobic & anaerobic conditions Salmonellae is sensitive to lower PH that explains it requires large number of bacterial cells to induce symptoms w Most strains are heat sensitive but some are heat resistant w Drying or freezing does not kill it

SOURCES OF SALMONELLAE w Most common sources of salmonellae are EGGS & poultry products w Utensils such as cutting boards and cutting utensils used for uncooked meat and poultry may serve to inoculate other foods w Raw milk and its product such as chedder cheese made from raw milk w Contaminated water

SYMPTOMS OF SALMONELLOSIS w Usually occur 12 -24 hours after eating and subside in 24 -48 hours w SYMPTOMS - Diarrhea resolve within 1 -5 days - Cramps - Nausea and vomiting - Chills and fever which resolve within two weeks in Typhi species) - Stool may contains mucous or blood

Salmonella enteritidis q. Motile gram-negative q. Killed by high temperatures q. These organisms are common pathogens in animals and poultry. q Food poisoning occurs after ingesting: Improperly cooked meat of infected animals. Eggs of infected birds. Food contaminated with rat excreta. .

Salmonella enteritidis Common Symptoms In most cases poultry eggs are the culprit. Illness lasts 4 to 7 days, most persons recover without antibiotic treatment. In some cases, diarrhea can be very severe enough to require hospitalization. The elderly, infants, and those with impaired immune systems may be affected severely. In these patients, the infection may spread from the intestines to the blood stream, and then to other body sites and can cause death unless the person is treated immediately with antibiotics. Symptoms are usually fever, abdominal cramps, and diarrhea beginning 12 to 72 hours after consuming a contaminated food or beverage.

Pathogenesis Mode of infection q. Oral route through contaminated food or drinks. q The bacteria multiply in mesenteric lymph nodes then pass to the blood stream causing primary bacteremia for 1 - 2 weeks (incubation period). q The bacteria then enter the phagocytic cells and pass to the liver, gall bladder, spleen, kidney and bone marrow. q From these organs, the bacteria pass again to the blood causing secondary bacteremia leading to FEVER. q The patient may recover or become CARRIER of salmonella either in the gall bladder or in the urinary tract. q If the organism is carried in the gall bladder, it will be excreted in the stool intermittently. q If the organism is carried in the urinary tract, it will be excreted in urine.

Botulism toxin w Toxin produced by the bacterium Clostridium botulinum w Anaerobic, gram positive, rod-shaped bacteria w Spore-forming w Create spores that can remain dormant for 30 years or more w Spores extremely resistant to environmental stressors, such as heat and UV light C. botulinum

Microbiology w C. Botulinum spores Soil l Airborne dust l Surfaces of raw fruits and vegetables l Seafood l

Categories of Botulism w Foodborne botulism n caused by eating foods that contain botulism toxin w Intestinal botulism (infant and child/adult) n caused by ingesting spores of the bacteria which germinate and produce toxin in the intestines w Wound botulism n C. botulinum spores germinate in the wound w Inhalation botulism n Aerosolized toxin is inhaled n does not occur naturally and may be indicative of bioterrorism

Clostridium Botulinum w Destroyed by n boiling >120 degrees for >20 min w Botulinum toxin n Very powerful l n 0. 5 nanograms (lethal) Heat sensitive l 80 degrees for 30 min

Botulism Pathogenesis w Incubation period n ingestion: unknown n foodborne: 6 hours-8 days n wound: 4 -14 days n inhalation: (estimated) 24 -36 hours

Toxins w Botulinum toxin is synthesized as a single polypeptide chain ( low potency). w The toxin is nicked by a bacterial protease (or by gastric proteases) to produce two chains : § a light chain (the A fragment) § a heavy chain (the B fragment) connected by a disulfide bond. w The A fragment of the nicked toxin, becomes the most potent toxin found in nature

Active Toxin

Mode of action w Toxin enters bloodstream from mucosal surface or wound w Binds to peripheral cholinergic nerve endings w Inhibits release of acetylcholine, preventing muscles from contracting w Symmetrical, descending paralysis occurs beginning with cranial nerves and progressing downward

w Can result from airway obstruction or paralysis of respiratory muscles w Secondary complications related to prolonged ventilatory support and intensive care

Symptoms of botulism poisoning w Classic symptoms of botulism poisoning include: n double vision n muscle weakness n drooping eyelids n slurred speech n difficulty swallowing w Infants with botulism will present with: n weak cry n poor feeding n constipation n poor muscle tone, “floppy” baby syndrome

Symptoms of botulism poisoning cont. w With disease progression n descending paralysis respiratory weakness respiratory failure w Death usually caused by respiratory failure w w Partial paralysis may persist for 6 -8 weeks

Staphylococcus aureus w Enterotoxins w Gram-positive cocci, nonmotile, anaerobic w found n protein rich foods l n ham, poultry, fish, milk and other dairy improper food handling

Toxins w Staphylococcus aureus produces toxins 1. Cytolytic toxins n n Disrupts the cytoplasmic membrane of a variety of cells Leukocidin can lyse leukocytes specifically 2. Exfoliative toxins l Causes the patient’s skin cells to separate from each other and slough off the body

Toxins (cont. ) 3. Toxic-shock-syndrome toxin n Causes toxic shock syndrome 4. Enterotoxins n Stimulate the intestinal muscle contractions, nausea, and intense vomiting associated with staphylococcal food poisoning

Staphylococcus w Mechanism n n n entrotoxin acts as a superantigen stimulates intense cytokine production toxic shock like syndrome w Signs and Symptoms n n n 2 -6 hrs abdominal pain N/V/D

Marine toxins o Very fast acting GI and neurological Symptoms Ø Saxitoxin § Paralytic shellfish poisoning § Sodium channel blocker Ø Ciguatoxin § Most common non-bacterial finfish foodborne illness § Reef fish including grouper ﺍﻟﻬﺎﻣﻮﺭ and mackerel § GI, itching ﺍﻟﺤﻜﺔ , cardiovascular disorder, CNS dysfunction

Ø Conotoxin q. Paralytic poison of Pacific cone snail q Blocks nerve impulse from nerve to muscle Ø Scombroid poisoning q. Most common form of fish poisoning in USTuna, sardines and anchovies q GI and neurological-flushing and rash

Tetrodotoxins TTX Starfish, parrotfish-produced by associated bacteria q. Neurotoxin (sodium channel blocker)

Poison w A single milligram of pure TTX can kill an adult (size of a pin head) w No antidote w 10, 000 times as lethal as cyanide in mice w Three stages n n n Numbness in lips and tongue Increasing paralysis Death can occur in 3 -6 hours Photo from: http: //en. wikipedia. org/wiki/Pufferfish