Gram negative rods, non-lactose
fermenters ( pale colonies on Mac
Capsule "K" and Somatic ``O``
1. Shiga toxin.
2. Entero toxin (similar to
1. S. dysenteriae A
Type 1 (Asia, Japan, Central America)
May go systemic.
Type 2 (Europe) Less severe form
2. S. flexneri B Most common.
3. S. boydi C Worldwide.
4. S. sonnei D Most common in USA (2-
Reservoir: Strict human pathogen.
Human colon, food, feces, but doesn't
live long outside of host.
`` Food, fingers, flies and
Infectious dose: less than 100
Incubation period: 1-4 days .
Oral >>> Stomach >>> Small
Intestine >>>large intestine
Invasion of colonic epithelial cells -
Reproduction (108 to 109/ml)
within 12 hours in distal small
bowel. In 1 to 4 days invades
Ulceration (purulent with PMN's)
<<Not systemic and usually self-
limiting, lasts a few days to a
Selective media needed for isolation.
Stool culture for isolation.
Plate rapidly, organisms die.
Mac Conkey agar
Salmonella Shigella (SS) agar
Sulfamethoxazole, tetracycline, etc.
Protection: Antibodies in blood IgG.
Secretary Ig A (short-lived).
Herd Immunity can occur: No good
Infections and Food
Food borne and Water borne
Varieties of Microbes cause G.I.T.
PARASITES BACTERIA & VIRUSES
second only to
diseases as cause
of Adult death.
Leading cause of
child death in
Asia, Africa and
Each year 5
HOW TO INVESTIGATION OF FOOD
``TREATMENT PREVENTION AND
1. Staph. aureus gram positive coccus
Dairy & bakery products like,
mayonnaise, sauces pastries ice
creams, processed meat etc. Salads
also common source. Heat stable
Rapid onset with short duration1-8
hours to 24 hours. Vomiting, little or
no diarrhea, no fever.
2. Bacillus cereus
gram positive rod.
Food poisoning: Bacteria or Enterotoxin in
``Reheated fried rice or Chinese
Heat-stable Enterotoxin …mainly vomiting.
mainly diarrhea by stimulation of
adenylate cyclase. (increases cAMP).
Incubation period 2-16 hours. Vomiting or
Diarrhea; no fever.
Symptomatic: Rice should not be reheated.
Sauces creams prepared and stored
3. Clostridium perfringens
gram positive rods
Spores in soil and food
Inhibits glucose transport & damages int.
epithelium causes protein loss into the
Diarrhea; little or no vomiting; no fever.8-16
Symptomatic No antibiotics , Foods
4. Clostridium botulinum gram positive rod.
In newborns ingestion of honey as``
Protein prevents release of acetylcholine at
neuro-muscular junction causing flaccid
Botulism; flaccid Paralysis
of muscles; ptosis of eyelids, facial muscle
Heat labile toxin:destroyed by proper
Trivalent Antitoxin AB&E along with
respiratory support. Proper sterilization and
vacuum packed cooked food for canning.
Discard swollen cans.
5. Vibrio cholera gram negative
curved rod .
Ingestion with contaminated water
Contaminated water supplies,
Lack of septic tanks springs, wells
become infected during floods.
Cholera; Severe Diarrhea; Rice
Massive IV fluids.
Strict Public health measures,
Boiled or chlorinated water in
Tetracyclines shorten exertion of
6. Enterotoxigenic (ETEC) E. coli
contaminated water or cells.
Traveler's Diarrhea; watery, self limited
low-grade fever, 1-3 days duration.
Also known as Turista Antibiotics not
Septran can shorten illness. Rehydration.
7. Enteropathogenic. (EPEC) E.coli
(EPEC) Ingestion of contaminated water or
food. No toxins24-48 hours Infant
diarrhea with fever, nausea, vomiting
9. Enteroaggregative (EAggEC)
E. coli Ingestion contaminated water.
Persistent watery diarrhea with
vomiting. and dehydration in Infants.
Can lead to bloody stools.
10. Enteroinvasive (EIEC) same
11. Enterohemmorhagic (EHEC) E. coli
(hemolytic uremic syndrome)
12. E. coli strain O157:H7, which is infamous for
causing widespread outbreaks. which is
infamous for causing widespread
`` Jack-in-the-Box outbreakJack-in-the-Box outbreak ``
13, Clostridium difficile gram positive rod.
Treatment of a patient with antibiotics
loss of normal flora allowing
Cl. difficile to
overgrow. Especially after Abdominal
surgery, abrupt onset of bloody
diarrhea fever and abdominal pain.
Antibiotic associated or
Causative agent should be withdrawn
Treatment with Vancomycin. Fluid
14. Vibrio parahemolyticus
slightly curved gram negative rod.
Ingestion of contaminated undercooked
or raw seafood.
Organisms grow in gut and invade
Most common cause of diarrhea in
Japan. Pseudo membranous colitis.
Self limiting Avoid undercooked or
contaminated sea food.
14. Rotavirus fecal-oral contamination
No toxins Winter diarrhea-fever,
abdominal pain and Vomiting (mostly
Fluid replacement, Prevent infection from
spreading in nurseries.
15. Norwalk Agent fecal-oral
contamination. No toxins. Summer
diarrhea- fever, abdominal pain,
diarrhea, and vomiting.
16 . Giardia lamblia Intestinal parasite
Ingestion of Contaminated water or food.
Tooth brushes .
``Upper part of intestine `` Duodenum
Attach to microvillus of small intestine
Giardiasis- fatty, foul smelling diarrhea,
Metronidazole 10 gms in 10 days
Secondal short treatment 4 tabs,
17. Shigella S.sonnei S. flexneri S.
boydii, S. dysenteriae . Transmitted by
food, fingers, feces, and flies.``
Fever and cramping Abdominal pain is
Prominent. Diarrhea usually appears after
48hours, with dysentery supervening about
2 days later.
Amoxil and Septran in severe cases.
Electrolyte and fluid replacement
18 . Salmonella typhi, Salmonella
paratyphi A, B, and C, Salmonella
cholerasuis : Ingestion of fecally
contaminated food or water. Able to
survive in neutrophils. Typhoid fever,
paratyphoid or enteric fever.
abdominal pain and
constipation bloody feces nausea,
Antibiotics like Amoxil, Chloramphenicol
Quinolones etc. Soft diet. Fluids
19. Salmonella enteriditis 1500 serotypes
gram negative rod Fecal-oral
transmission contaminated water,
Food (poultry, eggs, or dairy
products). Nausea vomiting Diahorrea
Antibiotics not indicated
except in infants
Fluid and electrolyte
20 . Campylobacter jejuni coma or seagull-
shaped gram negative rod. Animal to
human transmission, contaminated
raw milk and food especially poultry.
Verotoxin - similar to the Shigella toxin.
bloody diarrhea. Self limiting,
usually recovers in 5-10 days.
Erythromycin in severe cases
21.Yersinia enterocolitica and Yersinia
Spread via contaminated meat or milk.
Ingestion of uncooked or undercooked
meat invasins allows entry in cells in the
Payer’s patches, diarrhea, fever,
abdominal pain ,
If severe treat with Gentacin.
Fluid and electrolyte replacement
22. Francisella tularensis
Ingestion of uncooked or under cooked
mammals. Tularemia a zoonosis disease,
of bird fanciers.
Present in bird droppings. No toxins.
Continuous fever (without chills or sweating
(muscle pains), Severe headaches,
Usually no vomiting or Diarrhea.
23 . Helicobacter pylori
fecal oral spread
Peptic ulcer, Gastritis results in dyspepsia,
Cramps, nausea, vomiting and Flatulence.
Triple drug therapy, Antacids Bismuth
24. Entamoeba histolytica parasite
Transmitted by the
4-F's; food, fingers, feces, and flies
dysentery= bloody Mucoid diarrhea,
flask shaped ulcers in the Colon.
Can cause Liver Abscess.
Metronidazole Surgery may be required.
present all around in the
It has also been found in
low numbers in many
In certain foods, such as
cheeses and pâtés, it
may be present in
containing high levels
generally the cause
``Hand washing is the most
effective means of
infections that are passed
from person to person. ``
Dirty hands carry infectious germs into
the body when a child bites his nails or
puts any part of his hands into his
Children should wash their hands
frequently, especially after using the
toilet and before eating.
Clean bathroom surfaces .
Food and water also can carry
infectious germs: 08 tips
1. Be sure to wash fruits and
vegetables thoroughly before eating.
2. Wash kitchen counters and cooking
utensils after they have been in
contact with raw meat, especially
3. Refrigerate meats as soon as
possible after bringing them home
from the supermarket, and cook them
until they are no longer pink.
4. After meals, refrigerate cooked
leftovers as soon as possible.
5. When traveling, never drink from
6. In our country , it may be safer to drink
only bottled water and drinks rather than
water from a tap.
7. Exercise caution when buying prepared
foods from street vendors, especially if no
local health agency oversees their
8. Pets, especially reptiles, can spread
germs if their feeding areas are not
separate from family eating areas.