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(MUL) Microbiology > Terms to know > Flashcards

Terms to know Flashcards

1
Q

Tenesmus

A
  • a continual or recurrent inclination to evacuate the bowels,
  • caused by disorder of the rectum or other illnesses.
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2
Q

Gastroenteritis

A
  • known as infectious diarrhoea and gastro; inflammation of the gastrointestinal track the stomach and small intestines
  • Symptoms: diarrhea, vomiting, abdominal pai, fever, lack of energy.
  • lasts less then 2 weeks
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3
Q

Facultative Ex:

A

occuring optimally in response to circumstances rather than by nature

Ex: Facultative Anaerobe

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4
Q

Facultative anaerobe

A

an organism that makes ATP by aerobic respiration if oxygen is present, however is capable of switching to fermentation if oxygen is absent.

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5
Q

(H2S+) Hydrogen Sulfide

A
  • It is a colorless chalcogen hydride gas with the characteristic foul odor of rotten eggs. It is very poisonous, corrosive, and flammable.
  • Hydrogen sulfide is often produced from the microbial breakdown of organic matter in the absence of oxygen gas, such as in swamps and sewers; this process is commonly known as anaerobic digestion which is done by sulfate-reducing microorganisms.
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6
Q

Opportunistic Infection

A

-any infection caused by a microorganism that does not normally cause disease in humans;

occurs in persons with abnormally functioning immune systems (as AIDS patients or transplant patients receiving immunosuppressive drugs)

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7
Q

Opportunistic Pathogen

A
  • an organism that exists harmlessly as part of the normal human body environment and does not become a health threat until the body’s immune system fails
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8
Q

Major causes of Opportunistic Infection:

Provide 4 examples;

A
  1. Septicemia
  2. Pneumonia
  3. Meningitis
  4. Urinary Tract Infection
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9
Q

Examples of genera that cause “opportunistic” infections:

name 7

A
  1. Citrobacter
  2. Enterobacter
  3. Escherichia
  4. Hafnia
  5. Morganella
  6. Providencia
  7. Serratia
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10
Q

Most common Cause of Urinary tract infections

A
  1. E. coli
  2. UTI’s are ascending often from fecal containination
  3. Proteus: the organism produces a UREASE that degrades urea producing an alkaline urine
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11
Q

Define Urease

A

a naturally occurring enzyme that hydrolyzes urea into ammonium carbonate.

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12
Q

Urease Positive

(Urease Test)

A

Urease test helps for the identification of Proteus species (urease positive) and to differenitate it from other non-lactose fermenting members of the Enterobacteriaceae family.

Urease test is used for the presumptive evidence of the presence of Helicobacter pylori in tissue biopsy material

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13
Q

Opportunistic Pathogen (rev. meaning)

Provide ex: 7

A
  1. Providencia
  2. Morganella
  3. Enterobacter
  4. Srratia
  5. Proteus
  6. Klebsiella Pneumoniae (also Primary Pathogen)
    * 7. Escherichia coli (also Primary Pathogen)*
    * Organism that can only cause disease under certain condidtions or in certain hosts*
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14
Q

Primary Pathogen: Review

Example: 5

A
  1. Shigella
  2. Salmonella
  3. Yersinia
  4. Klebsiella (also opportunistic)
    * 5. Escherichia Coli (also opportunistic)*

Organism capable of causing disease in anyone

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15
Q

Characteristics shared by all Enterobacteriaceae

name all: 5

A

Gram Neg. rods

Oxidase negative

all can ferment Glucose

Facultative anaerobes

reduce nitrate to nitirite

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16
Q

Tests to Speciate

A

Lactose Fermentation

H2S production

Reactions such as: Indole/urease/motility

API Tests (Analytical Profile index) to identify diff. bacteria

17
Q

Antigenic Structure

Ex: 3 major classesof antigens are found

A

used to differentiate organisms withing a genus or species

  1. Somatic O Antigens: heat stable polysaccharide par of the LPS.
  2. Glagellar H Antigens: heat labile
  3. Envelope or capsule K antigens: overlay the surface O antigen and may block agglutination by O specific antisera. (boiling for 15 min will destroy the K antigen and unmask O antigens)

The K antigen is called the Vi (virulece) antigen in salmonella

18
Q

Virulence Factors

Endotoxin:

A

the activity of this toxin depends of the Lipid A

19
Q

Lipid A

A

Lipid A is a lipid component of an endotoxin held responsible for toxicity of Gram-negative bacteria. It is the innermost of the three regions of the lipopolysaccharide (LPS, also called endotoxin) molecule, and its hydrophobic nature allows it to anchor the LPS to the outer membrane;

toxic effects can be damaging, the sensing of lipid A by the human immune system may also be critical for the onset of immune responses to Gram-negative infection, and for the subsequent successful fight against the infection

20
Q

Escherichia Coli

A
  1. Normal inhabitant of GI tract (Produces vitamin K in the L intestines)
  2. some strains couse various forms of Gastroenteritis
    * 3. Major cause of UTI’s (acute cyctitis) - Neonetal Meningitis- Septicemia -*
    * 4. Pyelonephritis (kidney infection)*
    * 5. some strains aquired additonal “ genetic” info from lasmids, transposons and pages which allow them to be Pathogenic*
21
Q

E. Coli Antigenic structure

A

K 1 Has strong association with Virulence

(meningites in neonates)

22
Q

E. Coli Virulence factors

A

Toxins: Enterotoxins

produced by enterotoxigenic stains of E. coli (ETEC)

Cause a movement of water and ions form the tissues to the bowel resulting in watry diarrhea;

2 types of Enterotoxins: LT and ST

23
Q

Pili vs Fimbriae

A

cell surface appendages present in bacteria other than flagella. These structures are not for locomotion. Pili and fimbriae are surface appendages for attachmen

24
Q

virulence factors that protect Bacteria from host defenses:

A

Capsule protects from phagocytosis

Iron capturing ability (enterochelin)

25
Q

Enterotoxigenic (ETEC) E. Coli

A

Travelers Diarrhea (watery)

Enterotoxin that increases Cyclic AMP

No RBC or WBC in stool

attaches to inestial mucosa via colonization factors then liberates Enterotoxin

Characteristics: non-bloody diarrhea, nausea, abdominal cramps, low grade vefer for 1-5 days

no inflammation/invasion

Transmission: contaminated Food/Water

26
Q

Enteropathogenic E. coli (EPEC)

A

Bundle forming pili are involved in attachemnt to the intesinal mucosa (apical surface) flattens villi-prevents absobtion

no toxin produced

Diarrhea with large amount of mucous

no blood or pus

vomiting, malaise, low grade fever

problem: Pediatrics, hospitalized infants/in day care centers

27
Q

Enteroinvasive E. Coli (EIEC)

A

Invasive, dysintery

Clin. manifist: similar to Shigella

invades intestinal mucosa and causes necrosis and inflammation

lateral movement of the organism from one cell to adjacent cells

Sympt: Fever, severe abdominal cramps, malaise, watery diarrhea, scanty stools containing blood, mucous and pus

28
Q

Enteroaggregative E. Coli (EAEC)

A

Mucous associated Autoaglutinins cause aggregation of the bacteria at the cell surface and result in the formation of a mucous Biofilm

Attaches via pili-liberate heat-labile plasmid-encoded toxin EAST (enteroaggragative ST) Toxin

Sympt: Watery diarrhea, vomiting, dehydration, occational abdominal pain

29
Q

Enterohemorrhagic E. Coli (EHEC)

A
  • Single strain Serotype O157:H7
  • dysentery (toxin alone causes necrosis and inflammation)

Doesn’t Ferment Sorbitol (vs other E. Coli)

Hemorrhagic, Hamburger, Hemolytic-uremic syndrome (low platelet count, hemolytic anemia, and kidney failure)

-organism attaches via Pili to the intesinal mucosa liberating the Shaga-Like toxin

Symptoms: start with watery Diarrhea progress to bloody Diarrhea-without Pus/Crampy abdominal pain- No Fever or Low-grade fever

Lab: RBC in stool; Schistocytes in blood smear

TEST: must confirm that the isolate is E. coli O1547:H7 using selological Testing and confirm production of the Shiga-Like toxin prior to reporting results

30
Q

Escherichia coli

divided into 2 Serogroups based on what :

A

Escherichia coli are divided into serogroups based on the O antigen found on the lipopolysaccharide (LPS) of the cell membrane and the H antigen found on the flagella

31
Q

Thrombocytopenia

A
  • Thrombocytopenia* is a condition in which you have a low blood platelet count.
  • Platelets* (thrombocytes) are colorless blood cells that help blood clot.
32
Q

diarrheal pathogens have 2 basic machanisms by which they produce Diarrhea:

name them

A
  1. Production of Toxins called Enterotoxins-which cause physiologic changes in the intestinal epithelium that result in fluid and electrolyte secretion.
    * Vibrio Cholerae: is a classic Ex. of a diarrheal pathogen which produces A secretory diarrhea due to the action of an *Enterotoxin
  2. 2nd Mechanism is direct damage to teh intestianl epithelium caused by Cytotoxin or Organism Invation
33
Q

Antimicrobial resistance

A

Antimicrobial resistance

organisms can develop resistance encoded on transferable plasmids and exchange among species

34
Q

E. coli virulence: LT

A

LT – is heat labile and binds to specific Gm1 gangliosides on the epithelial cells of the small intestine where it ADP-ribosylates Gs which stimulates adenylate cyclase to increase production of cAMP

Increased cAMP alters the activity of sodium and chloride transporters producing an ion imbalance that results in fluid transport into the bowel.

35
Q

E. coli Virulence: ST

A

ST – is heat stable and binds to specific receptors to stimulate the production of cGMP with the same results as with LT.

Both enterotoxins are composed of five beta subunits (for binding) and 1 alpha subunit (has the toxic enzymatic activity).

36
Q

Shiga-type toxin

A

Shiga-type toxin – also called the verotoxin -produced by enterohemorrhagic strains of E. coli (EHEC) – is cytotoxic, enterotoxic, neurotoxic, and may cause diarrhea and ulceration of the G.I. tract. There are two types: shiga-like toxin 1 and shiga-like toxin 2.

37
Q

Enteroaggregative ST-like toxin

A

Enteroaggregative ST-like toxin – produced by enteroaggregative strains of E. coli (EAEC) – causes watery diarrhea.

38
Q

Hemolysins

A

Hemolysins – two different types may be found: cell bound and secreted.

They lyse RBCs and leukocytes and may help to inhibit phagocytosis when cell bound

39
Q

Adhesions

A

Adhesions – are also called colonization factors and include both pili or fimbriae and non-fimbrial factors involved in attachment.

There are at least 21 different types of adhesions. Antibodies to these may protect one from colonization.

(MUL) Microbiology (7 decks)

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