Shigella species are Gram-negative rods that cause dysentery. The four main species - S. dysenteriae, S. flexneri, S. boydii, and S. sonnei - infect the large intestine and cause abdominal pain, bloody stool, and diarrhea. Shigella is transmitted through the fecal-oral route via contaminated food, water, or surfaces. It has an infectious dose of less than 100 organisms and an incubation period of 1-4 days. Treatment involves rehydration and antibiotics like ampicillin or trimethoprim-sulfamethoxazole. Proper hygiene and sanitation are important for preventing transmission.

1. LECTURE SHIGELLA SPECIES
& FOOD POISONING

2. GENERAL CHARACTERISTICS
Gram negative rods, non-lactose
fermenters ( pale colonies on Mac
Conkeys medium)
Capsule "K" and Somatic ``O`` antigen
Exotoxins:
1. Shiga toxin.
2. Entero toxin (similar to
E. coli LT)

5. 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.
Worldwide.
3. S. boydi C Worldwide.
4. S. sonnei D Most common in USA
(2-year olds)

6. DISEASES
•All four species cause
dysentery. Abdominal
pain, Bloody stool,
Diarrhea

7. DISEASES
• All four species
cause
dysentery.
Abdominal
pain, Bloody
stool, and
Diarrhea

8. EPIDEMIOLOGY:
• Reservoir: Strict human pathogen. Human
colon, food, feces, but doesn't live long
outside of host.
`` Food, fingers, flies and feces``
• Infectious dose: less than 100
organisms .
• Incubation period: 1-4 days .
• Oral >>> Stomach >>> Small Intestine
>>>large intestine >>>Feces>>>Oral

9. PATHOGENESIS:
• Invasion of colonic epithelial cells -
Reproduction (108 to 109/ml) within 12
hours in distal small bowel. In 1 to 4
days invades large intestine.
• Ulceration (purulent with PMN's)
• <<Not systemic and usually self-limiting,
lasts a few days to a month>>

11. DIAGNOSIS:
• Selective media needed for isolation.
• Stool culture for isolation.
• Plate rapidly, organisms die.
• Selective media: Mac Conkey agar,
(XLD) Xylose-Lysine-Deoxycholate agar ,
EMB
or Salmonella Shigella (SS) agar

12. TREATMENT
• Ampicillin, Trimethoprim, Sulfamethoxazole,
tetracycline, etc.
• Protection: Antibodies in blood IgG. Secretary
Ig A (short-lived).
• Herd Immunity can occur: No good
immunization available

15. Gastrointestinal Tract Infections
and Food Poisoning.
• Food borne and Water borne
diseases.
• Varieties of Microbes cause G.I.T.
infections.
• MUSHROOMS FUNGI
PARASITES BACTERIA & VIRUSES

16. • Worldwide Diarrheal
diseases second only
to Respiratory
diseases as cause of
Adult death.
• Leading cause of
child death in Asia,
Africa and South
America.
Each year 5 million
children (13,600/day)
die of Diarrheal
diseases.

17. HOW TO INVESTIGATION OF FOOD
POISONING ?
SOURCE
SYMPTOMS
INCUBATION PERIOD
MECHANISM
``TREATMENT PREVENTION AND CONTROL``

18. 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.
Symptomatic. Hygienic measures.

19. 2. Bacillus cereus gram positive rod.
Food poisoning: Bacteria or Enterotoxin in
food.
``Reheated fried rice or Chinese rice``
Heat-stable Enterotoxin …mainly vomiting.
Heat-labile Enterotoxin 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
properly.

20. 3. Clostridium perfringens gram positive rods
Spores in soil and food
Enterotoxin.
Heat-labile protein. Inhibits
glucose transport & damages int. epithelium
causes protein loss into the intestinal lumen.
Diarrhea; little or no vomiting; no fever.8-16
hours incubation
Symptomatic No antibiotics , Foods adequately
cooked.

21. 4. Clostridium botulinum gram positive rod.
Canned foods.
In newborns ingestion of honey as``
GHUTTI``
• Protein prevents release of acetylcholine at
neuro-muscular junction causing a flaccid
paralysis;
Botulism; flaccid Paralysis of muscles; ptosis
of eyelids, facial muscle paralysis.
• Heat labile toxin proper cooking will destroy.
• Trivalent Antitoxin AB&E along with respiratory
support. Proper sterilization and vacuum
packed cooked food for canning.
• Discard swollen cans.

22. 5. Vibrio cholera gram negative
curved rod Ingestion with
contaminated water or
food.(shellfish, shrimp, oysters)
Contaminated water supplies, Lack of
septic tanks springs, wells become
infected during floods.
Cholera; Severe Diarrhea; Rice
water stools;
Massive IV fluids required. Strict
Public health measures, Boiled or
chlorinated water in epidemics.
Cholera Pots. Tetracyclines shorten
exertion of bacteria. Rehydration.

24. 6. Enterotoxigenic (ETEC) E. coli
contaminated water or cells. Traveler's
Diarrhea; watery, self limited
diarrhea, vomiting, cramps, nausea,
low-grade fever, 1-3 days duration. Also
known as Turista Antibiotics not
advocated. 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
nonbloody diarrhea.
Treatment Same

25. 9. Enteroaggregative (EAggEC) E. coli
Ingestion contaminated water. Persistent
watery diarrhea with vomiting. and dehydration
in Infants. Can lead to bloody stools. Treatment
same
10. Enteroinvasive (EIEC) same
11. Enterohemmorhagic (EHEC) E. coli
(hemolytic uremic syndrome) [HUS]).

26. 12. E. coli strain O157:H7, which is infamous for
causing widespread outbreaks. which is infamous
for causing widespread
`` Jack-in-the-Box outbreak ``

28. 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
Pseudomembranous colitis.
Causative agent should be withdrawn esp.
Clindamycin.
Treatment with Vancomycin Fluid replacement

29. 14. Vibrio parahemolyticus slightly curved
gram negative rod.
Ingestion of contaminated undercooked or raw
seafood. Organisms grow in gut and invade
epithelium Most common cause of diarrhea
in Japan. Pseudo membranous colitis.
Self limiting Avoid undercooked or
contaminated sea food.

30. 14. Rotavirus fecal-oral contamination
No toxins Winter diarrhea-fever, abdominal
pain and Vomiting (mostly in Infants.)
Fluid replacement, Prevent infection from
spreading in nurseries.
15. Norwalk Agent fecal-oral contamination.
No toxins. Summer diarrhea- fever,
abdominal pain, diarrhea, and vomiting.
Rehydration

31. 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,
Flatulence(gas) ,
Metronidazole 10 gms in 10 days
Secondal short treatment 4 tabs,
Symptomatic.

32. 17. Shigella S.sonnei S. flexneri S. boydii,
S. dysenteriae . Transmitted by the 4-F's;``
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

33. 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
discomfort,
constipation bloody feces nausea,
vomiting, Diarrhea
Antibiotics like Amoxil, Chloramphenicol
Quinolones etc. Soft diet. Fluids

34. 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 replacement.

35. 20 . Campylobacter jejuni coma or seagull-shaped
gram negative rod. Animal to human transmission,
contaminated water, raw milk and food especially
poultry.
Verotoxin - similar to the Shigella toxin .2-10 days
bloody diarrhea. Self limiting, usually recovers in 5-10
days.
Erythromycin in severe cases

36. 21.Yersinia enterocolitica and Yersinia
pseudotuberculosis.
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

37. 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,
Hepatosplenomegaly Usually no vomiting or
Diarrhea. Myalgias Streptomycin.
Symptomatic treatment

38. 23 . Helicobacter pylori curved rod,
fecal oral spread
Peptic ulcer, Gastritis results in dyspepsia,
Cramps, nausea, vomiting and Flatulence.
• Triple drug therapy, Antacids Bismuth
sulphate.

39. 24. Entamoeba histolytica parasite protozoa
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.

40. 25. Listeria
monocytogenes
present all around in the
environment. It has also
been found in low
numbers in many foods.
In certain foods, such as
cheeses and pâtés, it
may be present in higher
numbers.
Eating foods containing
high levels of Listeria
monocytogenes is
generally the cause of
illness

41. Prevention:
``Hand washing is the most
effective means of preventing
diarrheal 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 mouth.
Children should wash their hands frequently,
especially after using the toilet and before eating.
• Clean bathroom surfaces .

42. 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 poultry.
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.

43. 5. When traveling, never drink from streams,
springs.
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
operations.
8. Pets, especially reptiles, can spread
germs if their feeding areas are not separate
from family eating areas.

44. THANK YOU FOR YOUR PATIENCE
.