Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Microbio-2 > Bugs causing diarrhea and food poisoning (Medbullets) > Flashcards

Bugs causing diarrhea and food poisoning (Medbullets) Flashcards

1
Q

Which organisms are transmitted via fecal oral? (10 total - CC GRREEANS)

A

E. coli (EHEC, EIEC, ETEC); Shigella dysenteriae, Campylobacter jejuni; Adenovirus; Norwalk virus; Reovirus; Rotavirus; Giardia lamblia; Entamoeba histolytica; Cryptosporidium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

Which organisms cause watery diarrhea? (9 total)

A

Clostriudm perfringens; E. coli (ETEC); Vibrio cholerae; Adenovirus; Norwalk virus; Rotavirus; Giardia lamblia: Entamoeba histolytica (can cause bloody diarrhea as well); Cryptosporidium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Which organisms cause bloody diarrhea? (7 total - SEECCY)

A

Clostridium difficile; E. coli (EHEC, and EIEC); Salmonella enteridis; Campylobacter jejuni (Bloody and PUS); Yersinia enterocolitica; Entamoeba histolytic (can cause watery diarrhea as well)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Transmission: Custards, mayonnaise/potato salad, canned meats, foods not kept refrigerated

  • Usually food handler
  • Gm (+) cocci, catalase and coagulase (+)
  • Growth at 7.5% NaCl, mannitol fermentation
  • Reservoir: HUMAN NOSE, skin, low levels in colon and vaginal tract
  • Heat stable - 100°C for 30 min
  • Symptoms start and end early - (
A

Staphylococcus aureus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Transmission Reheated rice/pasta, food kept warm but not hot, consumption of contaminated food with soil, cooked and kept warm

  • Gm (+) spore forming rod, aerobic
  • Patients typically present with emetic syndrome (vomiting and nausea) about 1-5 hours after ingestion or diarrheal syndrome 15-20 hours after ingestion.
  • Symptoms start and end quickly
  • Emetic: Profuse vomiting, nausea, and abdominal cramps but FEVER and DIARRHEA ABSENT
  • Diarrheal: heat labile toxin - 5 min 56°C or 30 min at 45°C - WATERY DIARRHEA, nausea, abdominal cramps, vomiting, fever absent (Assoc. with protein rich foods, such as meats, stews, gravies, vegetable dishes, puddings, vanilla sauce, milk)
  • Can cause keratitis (inflammation of cornea); endophthalmitis (inflammatory condition of intraocular cavities); or panopthalmitis (inflammation of entire eye)
A

Bacillus cereus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Transmission: Canned food, home-canned alkaline vegetables (green beans, peppers, mushrooms, smoked fish) - ingestion of preformed toxin; trauma and wound infection, ingestion of spore by infants, inhalation

  • Infants - gm (+) spore forming rods, strict ANAEROBE
  • Incubation time: 18-72 hrs after ingesting toxin
  • Causes flaccid paralysis - bilateral descending; may include abdominal pain, either diarrhea or constipation
  • Neurotoxin (8 different types): Toxin A and B assoc. with canned food variety; type E assoc. with FISH PRODUCTS
  • Neurotoxin absorbed from gut through blood stream, binds to presynaptic neuron and cleaves a protein involved in release of ACh at synapse (SNARE proteins - synaptobrevin and syntaxin) - leads to bilateral flaccid paralysis
A

Clostridium botulinum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Transmission: Reheated meat

  • Gm (+) spore forming rod, anaerobic
  • Ingestion of large number of bacteria grown on precooked and not refrigerated meat dishes
  • Meat products, poultry, gravy
  • Incubation: 8-16 hrs
  • Duration: 24 hrs or less
  • High infective dose - toxin acts on SMALL INTESTINE
  • Enterotoxin: heat labile (like B. cereus diarrhea toxin) - INC cAMP - Watery diarrhea
  • Type A strain is most infectious in humans
  • Abdominal cramps, watery diarrhea, nausea, NO FEVER OR VOMITING
  • Pig-Bel: DIARRHEA AND NECROTIZING ENTERITIS due to undercooked pig meat/sweet potatoes/malnutrition; assoc. with Type C that produce ß-toxin (cause necrotic lesions to progress to necrotizing enteritis)
  • Assoc. with eating pork with sweet potatoes which contain heat resistant trypsin inhibitor. This protects toxin from inactivation by trypsin. Common in Papua New Guinea
  • Acute abdominal pain, bloody diarrhea, vomiting, ulceration of small intestine, perforation of intestinal wall
A

Clostridium perfringens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Transmission: Endogenous/nosocomial (NOT food poisoning) - think hospital setting

  • Bloody diarrhea
  • Antibiotic associated diarrhea (AAD)
  • Gm (+) rod, SPORE FORMER
  • Pseudomembranous colitis
  • Onset: 4-10 days after start of antibiotic, up to 2 weeks after termination
A

Clostridium difficile

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Transmission: Undercooked meat, contaminated food, fecal-oral

  • Gm (-), lactose fermenter, indole (+)
  • Watery diarrhea followed by Bloody diarrhea
A

E. coli (EHEC - no invasion, no WBCs; EIEC - invasion + WBCs)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the different types of E. coli and what are their distinguishing factors? (I.e. invasive or not, etc)

A

EHEC (enterohemorrhagic)- no invasion, no WBCs

-EIEC (enteroinvasive) - invasion, and WBCs present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the different types of E. coli and what are their distinguishing factors? (I.e. invasive or not, etc)

A

EHEC (enterohemorrhagic)- no invasion, no WBCs, no fever

-EIEC (enteroinvasive) - invasion, and WBCs present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Transmission: Chicken products (eggs, raw chicken)

  • Bloody diarrhea
  • Incubation time: 6-48 hrs after consumption
  • Lasts 2-7 days, spontaneously resolve
  • Dx: Hektoen enteric agar - blue green colonies (non-lactose fermenter); black deposits in center of colonies (Hydrogen sulfide H2S producer)
  • H2S (+)
  • May enter blood stream and cause septicemia, invade brain, bone, lungs, causing meningitis, pneumonia, osteomyelitis (especially in sickle cell patients since their monocyte/macrophage are overextended in cleaning up red cell debris from the sickle disease and can’t fight the infection and contain it to the GI tract).
A

Salmonella enteridis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Transmission: Poultry, unpasteurized milk, fecal-oral

  • Bloody diarrhea WITH PUS
  • Gm (-), curved rod, motile, microaerophilic
  • Grows best at 42°C
A

Campylobacter jejuni

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Transmission: Fecal-oral

  • Profuse watery diarrhea after 48 hrs followed by Bloody diarrhea
  • Incubation period: 36-72 hrs
  • Lasts 2-7 days, spontaneously resolves
  • Gm (-) rod, non-lactose fermenter, non-motile, H2S negative
  • 4 F’s: Fingers, Food, Flies, Feces
  • Primarily pediatric disease (
A

Shigella dysenteriae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Transmission: Poultry, unpasteurized milk, fecal-oral

  • Bloody diarrhea WITH PUS
  • Watery diarrhea followed by FOUL SMELLING BLOODY DIARRHEA
  • Intense abdominal pain, FEVER, vomiting, mimic acute appendicitis
  • Gm (-), curved rod, motile, microaerophilic
  • Grows best at 42°C and microaerophilic
  • Toxin production, invasion of epithelial cells, survival in monocytes like salmonella
  • Enterotoxin: electrolyte movement - watery diarrhea followed by inflammatory diarrhea due to invasion of epithelial cells - leads to ulcers in bowel mucosa and induces acute inflammatory response
  • Self-limiting
  • Guillain-barre syndrome and Reactive arthritis
  • Campy-BAP or Skirrow media contain antibiotics, vancomycin, polymyxin B and trimethoprim that reduce growth of other enteric microorganisms
A

Campylobacter jejuni

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Transmission: Seafood, sushi (leading cause of diarrhea in Japan)

A

Vibrio parahaemolyticus/vulnificus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Transmission: contaminated milk, pork, pet feces

  • Bloody diarrhea
  • Grows best at 25/22°C
  • Gm (-) rod, non-lactose fermenter
A

Yersinia enterocolitica

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Transmission: contaminated milk, pork, pet feces

  • Bloody diarrhea - may last 1-2 weeks
  • Grows best at 25/22°C - motile at these temps
  • Gm (-) rod, non-lactose fermenter
  • Enterotoxin and invasion of mucosa. Inflammation and ulceration, may extend to MESENTERIC LYMPH NODES
  • Complications: Reiter’s syndrome (reactive arthritis) or peripheral joints/HLA-B27
A

Yersinia enterocolitica

18
Q

Transmission: Fecal-oral

  • Watery diarrhea
  • Pediatric
A

Adenovirus and Norwalk virus

19
Q

Transmission: Fecal-oral

  • Watery diarrhea
  • Infant mortalit
A

Rotavirus

20
Q

Transmission: Fecal-oral

  • Watery diarrhea
  • Associated with campers/hikers
A

Giardia lamblia

21
Q

Transmission: Fecal-oral

-Watery OR Bloody diarrhea

A

Entamoeba histolytica

22
Q

Transmission: Fecal-oral

-Diarrhea in AIDs

A

Cryptosporidium

23
Q

What patients are at risk of developing systemic infections from salmonella spp.? (5)

A
  • Neonates,
  • persons over 50 yrs
  • immunocompromised patients
  • patients with sickle cell
  • patients with prosthetic valves or vascular grafts.
24
Q

What is the incubation period and infective dose required for EIEC? (Enteroinvasive E. coli). What are some of the resulting symptoms (4). Where is it primarily seen?

A
  • Incubation period: 12-72 hrs
  • Infective dose: 10 organisms
  • Fever, cramping, watery diarrhea may progress to dysentery
  • Primarily seen in under-developed countries, rare in the US
25
Q

What are the virulence factors associated with EHEC? (2)

A

1) Bundle forming pili (Bfp) like EPEC, attaching-effacing - wiping out of microvilli
2) Shiga-like toxin (verotoxin): inhibit protein synthesis and kills epithelial cells and endothelial cells (strain is known as STEC)
- Infective dose as small as 100 cells

26
Q

What are the clinical symptoms of EHEC?

A

Children present with HUS following an acute diarrheal illness

  • Acute onset of diarrhea, can mimic ulcerative colitis, various enteric infections or appendicitis
  • Diarrhea becomes hemorrhagic (70% of cases) within 1-2 days of onset of diarrhea
  • Neurologic symptoms are observed in 33% of patients and may include irritability, seizures or altered mental status
27
Q

Pathogen of E. coli that cause intestinal disease: Tight adhesion and destruction of microvilli. Formation of filamentous actin pedestals or cup like structure

  • Attaching and effacing - wiping out of microvilli, pedestal formation
  • Bundle forming pili (Bfp); intimin
A

EPEC - enteropathogenic - small intestine - infant diarrhea

28
Q

Pathogen of E. coli that cause intestinal disease: Involves 3 stages: (adherence (stacked bricks, ST toxin, cytolysin))

1) Adherence to mucosa
2) Enhanced mucus production that encases bacteria forming a biofilm
3) Followed by elaboration of a cytotoxin which damages the intestinal cells. Have the ability to colonize both small and large intestine.
- AAF/GVVPQ fimbriae

A

Enteroaggregative E. coli (EAEC) - infant diarrhea in developing countries

29
Q
  • Pathogen of E. coli that cause intestinal disease: Colonize the small intestine and produce a cholera-like (heat-labile, LT) toxin and a heat stable toxin (ST). Both toxins ultimately stimulate secretion of chloride by the host cells resulting in a watery diarrhea
  • Type 1 pili; colonization factor antigens (CFA) and (LT)
  • ST (heat stabile toxin) binds to and activates membrane guanylate cyclase receptor on epithelial cells - results in excess cGMP - blocks ion transport into cells so water moves into lumen
A

ETEC - enterotoxigenic - small intestine - traveler’s diarrhea

30
Q

Pathogen of E. coli that cause intestinal disease: Invasive like Shigella

A

EIEC - enteroinvasive - large intestine - Shigellosis-like disease in developing countries

31
Q

Pathogen of E. coli that cause intestinal disease: Shiga like toxin + like EPEC
-Intimin

A

EHEC - enterohemorrhagic - large intestine - Hemmorrhagic colitis can lead to HUS

32
Q
  • Gm (-) rod, non lactose fermenter, H2S producer

- Colonization of gallbladder for up to one yr of infected persons

A

Salmonella typhi/paratyphi

33
Q

What is the clinical disease of enteric fever/typhoid fever?

A

Severe multi-systemic illness characterized by classic prolonged fever - potentially fatal if untreated
-First week: stepwise fever that becomes sustained (that is, the temperature does not return to the baseline), often with relativebradycardiaand usually with positive blood cultures.
Second week: abdominal pain, often (but < 50% of cases) with a rash consisting of faint salmon-colored macules on the trunk and abdomen (rose spots).
Third week:hepatosplenomegalywith, in severe cases, intestinal bleeding and/or perforation caused by erosions of Peyer’s patches. Complications include shock, stupor, delirium, seizures, psychosis, myelitis, and pneumonia.

34
Q

What are the pathological changes in typhoid fever? (5)

A

1) Perforation wall of intestine
2) Fatty degernation of fat in cells resulting in enlarged spleen and liver, mesenteric glands, kidney, heart
3) Inflammation of gall bladder
4) Skin - ROSE SPOTS
5) DIC: thrombophlebitis - vein inflammation related to a blood clot

35
Q

How would you diagnose typhoidal salmonella spp.? (3)

How would you treat it?

A

Dx:

1) Specimen: blood, bone marrow, urine, stool (chronic)
2) Culture: selective and differential media - Hektoen enteric agar
3) Serology/Widal test: test tube agglutination - detect antibody against specific O and H antigen in patient sera
tx: multi-drug resistance common: broad spectrum, fluoroquinolones, ciprofloxacin or ceftriaxone

36
Q

Are there vaccines for typhoid? If so, how many and what are their characteristics?

A
  • 2 types:
    1) Capsular vaccine: Vi antigen
    2) Live attenuated vaccine (Ty21a strain)
  • Taken orally can reduce risk of disease for travelers in endemic areas, but vaccine not 100% protective
37
Q

What type of media are MacConkey and Eosin methylene blue (EMB)?

A
  • Selective: only gram negatives grow

- Differential: differentiates lactose fermenters (colored colonies) from nonlactose fermenters (gray/white colonies)

38
Q

What are general characteristics of Enterobacteriaceae? (8)

A
  • All are gm (-) non spore forming bacilli (rods)
  • Are facultative anaerobes and can ferment glucose
  • Are OXIDASE NEGATIVE and REDUCE NITRATES to NITRITES
  • Classification based on biochemical tests and antigenic properties of O antigen (LPS), capsular, and flagellar antigen
  • Share common enterobacterial antigen - core saccharides of O antigen
  • Biochemical differentiation is based on carbohydrate fermentation and activity of amino acid decarboxylases
  • Culture on differential media that contain special dyes may alow rapid presumptive identification
  • Ability to ferment lactose can be detected on media like MacConkey and Eosin methylene blue agar (EMB)
39
Q

How do you interpret a triple sugar iron agar? (TSI)

A

Interpretation:

  • If lactose and or sucrose is fermented, large amount of acid is produced/ both butt and slant become yellow
  • If glucose is fermented, less acid produced and turns the color (yellow) only in the butt
  • If none of them is fermented, no acid is produced (meaning the organism is strict aerobe)
40
Q

How do you serotype enterobacteriaceae? Give an example

A

Three antigens are important in serotyping this group: O, K, H antigens

1) They all possess LPS as a prominent toxin - the terminal sugars of LPS, O somatic antigen is useful in id
2) Some species possess a K (CAPSULAR) or Vi (virulence) antigen
3) If motile, the flagellar or H antigens
ex: A strain of E. coli with O55:k9:H6
- somatic O55
- Capsular K9
- Flagella H6

41
Q

What are some properties that differentiate E. coli from other lactose fermenters? (4)

A

1) Production of indole from tryptophan
2) Decarboxylates lysine
3) Use of acetate as sole carbon source
4) It is motile

42
Q

What are the E. coli strains that cause noninflammatory diarrhea (in small intestines - remains lumenal) (3)
-Lactose fermenter, gm (-), most common anaerobe in GI tract

A

1) Enterotoxigenic E. coli (ETEC) - travelers and infant diarrhea in developing countries
2) Enteropathogenic E. coli (EPEC)
3) Enteroaggregative E. coli (EAEC)

43
Q

What are the E. coli strains that cause INFLAMMATORY diarrhea? (2)

A

1) Enterohaemorrhagic E. coli (EHEC)

2) Enteroinvasive E. coli (EIEC)

Microbio-2 (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions