Bacterial GI disease 2, Lect 6

Question 1

Shigellosis invade and multiply where in body

Answer 1

Invade and multiply in colon epithelial cells

Question 2

which bacteria is a Facultative intracellular enteric bacilli causing an inflammatory disease of the large bowel

Answer 2

Shigellosis

Question 3

Describe Shigella

• gram status
• does it need oxygen?
• can it form a spore?
• motile?

Answer 3

• Gram negative rod
• Nonspore-former
• Facultative anaerobe
• Nonmotile (usually)

Question 4

clinical presentation: classic

1. initial symptoms: fever, cramps, vomiting, watery diarrhea
2. progresses to dysentery - blood, mucous and Granulocytes (PMN) in stools

Answer 4

Shigellosis

• suspect shigellosis in any patient with fever and diarrheal disease
  
  • blood and mucus in feces + acute onset

Question 5

shigellosis is unable to ferment which sugar

Answer 5

nonlactose fermenting

Question 6

treatment of shigellosis

Answer 6

• self limiting disease
• fluid replacement
• effective Abx therapy may shorten course
  
  • many are multiple Abx resistant

Question 7

complications of Shigellosis infection

Answer 7

• Reiter’s syndrome (urethritis, polyarthritis, conjunctivitis): strong association with HLA-B27
• hemolytic uremic syndrome
• acute renal failure with poor prognosis
• **same complication that is linked to E-coli O157:H7
  
  • Shiga toxin and Shiga like toxin are biochemically identical

Question 8

reservoir for shigellosis

Answer 8

• humans are sole reservoir
  
  • person to person transmission
  • highly infectious

Question 9

highest incidence of shigellosis is in which patient population

Answer 9

children 1-4 yo

• all ages susceptible

Question 10

What are the four species of Shigellosis? Which is most severe

Answer 10

• ### Group A - S. dysenteriae : most severe
• ### Group B - S. flexneri
• ### Group C - S. boydii
• ### Group D - S. sonnei: least severe
• **bold: most prevalent in U.S.

Question 11

prevention of Shigellosis

Answer 11

handwashing is the single most important control measure

Question 12

Reservoir of salmonellae

Answer 12

• ### these microbes are the normal gut flora of many birds and animals and infect humans through food contamination
  • High frequency of infection with this species in domestic herd/flock animals
• reservoirs:
  
  • ​eggs
  • beef products
  • pigs and pork products
  • dogs, cats, pet reptiles

Question 13

clinical presentation

• sudden onset of disease
  
  • fever, chills, cramps, diarrhea, vomiting
  • 2-3 duration in normal host, more severe in infants and eldery

Answer 13

Salmonellosis

Question 14

Describe salmonellae

• gram status?
• can it form a spore?
• does it need O2?
• motile?

Answer 14

• gram negative
• nonspore former
• facultative anaerobe
• motile

Question 15

which sugar is salmonellae unable to ferment

Answer 15

nonlactose fermenting

Question 16

how is salmonellae diagnosed

Answer 16

• Microscopic: fecal leukocytes present
  
  • more macrophages than PMNs
• culture: sample food and water and fecal matter
• unable to ferment lactose
• Fluorescent antibody (FA) tests

Question 17

treatment of Salmonellae

Answer 17

• ## Supportive therapy for patients of otherwise normal good health
  • ## Maintain fluid and electrolytes
• ### Antibiotics not required if disease is not systemic
  • ### AIDS patients require special care

Question 18

Salmonellosis transmission

Answer 18

• contaminated food and water
• High dose microbe

Question 19

Salmonellosis is most prevenalent at what times of year

Answer 19

• Infection has a strong seasonal trend – sharp increases are evident in summer and fall

Question 20

highest incidence of salmonellosis is in which patient age group

Answer 20

• infants and children 6 months to 5 yrs.

Question 21

Clostridium difficile is associated with which antibiotic induced disease

Answer 21

Pseudomembranous colitis

Question 22

Describe Clostridium difficile

• gram status
• does it require O2?
• can it form spores?

Answer 22

• gram positive
• rod shaped
• anaerobic
• subterminal spore former

Question 23

It can be difficult to distinguish pseudomembranous colitis from ulcerative colitis, crohn’s disease, and chronic inflammatory bowel disease. What are three types of disease resulting from C. difficile

Answer 23

1. diarrhea with lower abd cramping: no systemic symptoms
2. severe colitis without pseudomembrane
   
   1. diarrhea, fever, nausea
3. classic PMC

Question 24

presentation of classic pseudomembranous colitis

Answer 24

• #### same symptoms as severe colitis +
• #### Elevated yellowish plaques 2-10 mm diameter over inflamed regions of mucosa
  • #### The pseudomembrane is a fibrin mesh of necrotic cells, PMNs, monocytes and RBCs.

Question 25

how is pseudomembranous colitis diagnosed

Answer 25

* Detection of toxin in feces * Gram stain of stool will reveal Gram positive rods with subterminal spores * Culture * Many hospitals screen all antibiotic-associated diarrhea patients for toxin

Question 26

PMC treatment

Answer 26

* fluid and electrolyte replacement * discontinue original Abx therapy * administer new Abx

Question 27

what is a predisposing factor to becoming infected with PMC

Answer 27

* disruption of normal gut flora * subsequent colonization by C. diff and release of toxins * 10% carry this bacterium as normal flora without problem

Question 28

reservoir of PMC

Answer 28

* asymptomatic patients * noncomial outbreaks in hospitals and nursing homes

Question 29

describe Clostridium perfringens type A * gram status * motile? * require O2? * can it form spores?

Answer 29

* gram positive rod * nonmotile * aerotolerant anaerobe * spore former

Question 30

clinical presentation * Short incubation period * Moderate severe diarrhea, abdominal cramping * **Complete recovery in a day**

Answer 30

Clostridium perfringens

Question 31

how do people become infected with Clostridium perfringens

Answer 31

* This organism is a common member of gut flora of humans and animals * **Consumption of grossly contaminated meat, poultry** * **Cooking is not adequate to destroy spores** * If **food is allowed to stand**, spores will germinate

Question 32

is Clostridium perfringens a high or low dose organism

Answer 32

high dose organism = one must receive a large number of cells to get disease

Question 33

how is Clostridium perfringens diagnosed

Answer 33

* must isolate **large numbers of microbe in food and feces**

Question 34

describe Baceillus cereus * gram status * require O2? * does it form spores? * motile?

Answer 34

* gram positive * rod shaped * aerobic * spore former * motile

Question 35

Two forms of Baceillus cereus

Answer 35

1. Emetic form 2. Diarrheal form

Question 36

Clinical presentation * upper GI symptoms **1-5 hours** after ingestion of contaminated food * vomiting, cramps, diarrhea

Answer 36

* Emetic form of B. cereus * preformed toxin

Question 37

clinical presentation * abdominal pain, profuse watery diarrhea **1-17 hours** after ingestion of contaminated food

Answer 37

* Diarrheal form of B. cereus * ingestion of large numbers of vegetative cells that produce toxin

Question 38

How is B. cereus diagnosed

Answer 38

* Afebrile disease * high index of suspicion if upper GI illness is evident 1-5 hours after eating or lower GI illness 5-17 hours after eating * Isolate more than 10⁵ B. cereus per gram of food or feces

Question 39

where is B. cereus commonly found

Answer 39

* spores are commonly found on grains and vegetables * **especially rice** * prevention: Prompt refrigeration of all grain foods after cooking

Question 40

which bacteria is caused by **consumption of heat stable preformed toxin** in foods * Under the proper set of conditions, it is possible to **have disease without colonization or infection of the host with this agent**

Answer 40

Staphylococcal Food Borne Disease

Question 41

clinical presentation * **Short incubation period of 1-6 hours** after food consumption * Nausea, vomiting, diarrhea, cramps, acute salivation * Self-limiting – complete recovery in 1-4 days

Answer 41

Staphylococcal Food Borne Disease

Question 42

what is the virulence factor in Staphylococcal Food Borne Disease that causes symptoms

Answer 42

* Enterotoxin A * water soluble and heat stable (can withstand boiling for 30 min) * Emetic response is elicited by this toxin – absorbed in gut, stimulus reaches CNS and sends impulse to the vomiting center * Diarrheal effects – enhanced fluid transmucosal movement into lumen coupled with decreased water absorption

Question 43

reservoir of Staphylococcal Food Borne Disease

Answer 43

* human * toxin is undetectable in foods * Toxin produced quickly in warm conditions (just a few hours)

Question 44

How is staphylococcal disease diagnosed

Answer 44

* ## Afebrile disease, **not directly communicable** * ## High index of suspicion with **short time** between eating and symptoms eruption * ### **Custard filled baked goods**, canned foods, processed meats, potato salad * Enterotoxin tests are available and reliable

Question 45

treatment of staphylococcal disease

Answer 45

* symptomatic relief * this is an intoxication, Abx are of no help * disease course is fast, toxin is not synthesized to any great extent in GI tract

Question 46

What do staphylococcus, B. Cererus, and C. perfringens have in common

Answer 46

* foodborne toxin disease * Abx are NOT useful * not transmissible in direct person to person fasion * toxemias * common factors: inadequate cooking, reheating or refrigeration of foods