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Vet prep bacteriology > Bacteria > Flashcards

Bacteria Flashcards

1
Q

Opportunistic pathogen

A

Organisms that do not cause disease in a host that has a healthy immune system

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2
Q

True Pathogen

A

Equipped w/ virulence genes for adherence, invasion and evasion from the immune system and toxins

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3
Q

Nosocomial infection

A

Hospital acquired infections
ex. MRSA
Diarrhea

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4
Q

Staphylococcus

A

Gram Positive
-s. aureus
-Commensals on the skin and mucus membranes
-Pyogenic bacteria
-Abscesses, suppurative infections. post surgical
Virulence Factors
-Enterotoxins A-E (food poisoning)
-Exfoliation- Skin, scaled skin syndrome (infants)
-Porcine exudative epidermitis
-Eipidermolytic toxins-Skin
-Haemolysins
-Leukocidins
-Protein A-Present as surface component on most strains of virulent S. aureus (antiphagocytic and can bind to IgG)

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5
Q

Botryomycosis

A 
Bacterial pseudomycosis
Infrequent, chronic pyogramulmatus
-Supportive wound infections and septicemia
-Pyoderma
-Pyemia
-Lameness
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6
Q

Streptococcus

A 
Gram Positive
-Large group ( more than 68 species)
-Occurs in nature and normal flora
-Facultatively anaerobic
S. pyogenes-Mostly human (scarlet fever)
Mastitis, arthritis, meningitis
S. equi equi- Stangles
-Pyogenic
-Hemolysis
-Capsule interferes w/ phagocytosis
S. pneumoniae-Pneumonia
S. mutans
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7
Q

Bacillus

A 
Gram Positive Rod
-Bacillus anthacis- anthrax
Virulence factors
-Endospores
-capsule
-exotoxins- 3 heat libel protein components- work together as a complex
Lethal factor-A part
Edema Factor- A part
Protective antigen- Binding part
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8
Q

Clostridium

A 
Gram positive rod
Histotoxic
-Invasive clostridium
C. chauvoel (black leg)
C. perfringens (gas gangrene)
Neurotoxic
C. tetani
C. botulinum
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9
Q

Clostridium tetani

A

Tetanus
Endotoxin (AB toxin)
-spastic paralysis
-trauma, surgical wounds, puncture, puncture wounds

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10
Q

Clostridium botulinum

A

BoNT- Flaccid paralysis

  • *Intoxication not infection**
  • Food borne
  • Infant botulism
  • Wound botulism
  • Botox related
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11
Q

BoNT and TeNT

A
  • Same mode of action
  • Multiplies in dead carcuss and produce toxin
  • Eating spoiled foods in which toxins have been produced under anaerobic conditions
  • Different types of toxins depending on species
  • Neurotoxin is heat labile
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12
Q

Facultative intracellular Bacteria

A

-Invades host cells when its advantageous
-Bacteria that can enter and survive in cells are shielded from humoral antibodies
-Can only be eliminated by a cellular immune response
-Must posses specialized mechanisms to protect them from the harsh environment of the lysosomal enzymes encountered within cells
Ex. Listeria monocytogenes
-Neisseria spp
-Brucells spp

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13
Q

Obligate intracellular Bacteria

A

-Cannot live outside the cell
-Need the host cell to supply then with ATP or other intermediates
Ex. Rikettsia spp

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14
Q

To cause disease a pathogen must…

A
  1. Gain access to the host
  2. Adhere to the host tissues
  3. Penetrate or evade host defenses
  4. Damage the host
    - Directly
    - Accumulation of microbial wastes
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15
Q

Preferred portals of entry

A

Mucus membranes

  • Respiratory tract
  • GI tract
  • Urogenital tract
  • Conjunctiva
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16
Q

Skin as a portal of entry

A
  • Some pathogens infect follicles and sweat glands

- Unless broke, skin is usually an impermeable barrier to microbes

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17
Q

Parental Route

A
  • Trauma
  • Arthropods
  • Injections
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18
Q

Numbers of invading microbes

A
  • minimum infective dose
  • likelihood of disease increases as the number of invading pathogens increases
  • ID50= number of microbes required to produce infection in 50% of the population
    • Different for each pathogen
    • Different for different portals of entry
  • LD50 (lethal dose)
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19
Q

Adhesions

A

Surface projections on pathogen, mostly made of glycoproteins or lipoproteins
-adhere to complementary receptors on the host cell
-can be part of the
-glycocalix
Ex. Streprococcus mutants
-Fimbrea- also pili and flagella
Ex. E.coli
Host cell receptors are most commonly sugars

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20
Q

Biofilms

A

Provide attatchment and resistance to antimicrobial agents

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21
Q

Capsules

overcoming host defenses

A

Inhibition or prevention of engulfment (by phagocytosis)

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22
Q

Cell wall components

overcoming host defenses

A
  • Techoic acid
  • Mycolic acid
  • LPS
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23
Q 
Antigenic Variation 
(overcoming host defenses)
A

-Avoidance of host immune response

Ex. Trypanosoma neisseria

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24
Q

Penetration in the host cell cytoskeleton

overcoming host defenses

A

Ex. salmonella
E.coli
-Produce invasins

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25
Q

Invasins

A

Protein that cause the actin of the host cells cytoskeleton to form a base that carries the bacteria into the cell

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26
Q

Production of enzymes

overcoming host defenses

A

Digest tissues

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27
Q

Intracellular Bacteria survival following phagocytosis

overcoming host defenses

A
  • escape from phagocytic vacuoles into cytosol
  • prevention of lysosomal fusion to phagosomes
  • resistance to hydrolytic enzymes
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28
Q

Cogulase

A

promotes blood clotting
fibrinogent-fibrin
walls of bacteria from phagocytosis

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29
Q

Kinase

A

Breaks down fibrin

blood clot dissolve

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30
Q

hyaluronidase

A

spreading factor
digestion of intracellular cement
tissue penetration

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31
Q

Collagensase

A

Collagen hydrolysis

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32
Q

IgA protease

A

IgA destruction

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33
Q

Hemolysins

A

Lyse blood cells

34
Q

Leukocidins

A

Lyse neutrophils and macrophages

35
Q

Direct host cell damage

A
  • Growth and replication in host cells results in host cell lysis
  • penetration through host cells causes damage
  • lysis of host cells to obtain nutrients
36
Q

Using the hosts nutrients to damage the host

A

Iron
-required from all cells
-host cell usually does not have free iron
Pathogens can produce siderophores
-compounds secreted by bacteria capable of binding iron from host proteins
Ex. enterobactin (gram - bacteria such as E.coli and salmonella)

37
Q

Siderophores

A

iron chelators

-iron complex is absorbed by bacteria

38
Q

Bacteria factors that disturb host functions

A

-Protein exotoxins with specific target receptors
Ex. Gram - and Gram +
-Hydrolytic Enzymes
-Broad substrate specificities
Ex. nucleases, proteases, lipases
Products that evoke aberrent host response
-Cross creative antigens (autoimmunity)
-superantigens
Endotoxins
-gram - only LPS, Lipid A part, release upon cell death due to vigorous inflammation
-massive release (endotoxic shock)

39
Q

Exotoxins

A

-proteins produced inside pathogenic bacteria
-most commonly gram + as part of their grown and metabolism
Exotoxins are then excreted into surround medium following lysis

40
Q

Endotoxins

A
  • Lipid portions of LPS that are part of the outermsmbrane of the cell wall of gram negative bacteria
  • Lipid A
  • Endotoxins are liberated when the bacteria die and cell wall breaks apart.
41
Q

Toxemia

A

Presence of toxins in the blood

42
Q

Toxigenicity

A

ability to produce toxins

43
Q

Antitoxins

A

antibodies produced against exotoxins

44
Q

Type l exotoxin

A 
Superantigens
-bacterial proteins that non specifically stimulate t-cells
-Cause intense immune response due to cytokines from host cell
-excessive cytokines can cause
-fever
-nausea
-vomiting
-diarrhea
-shock
-death (septic shock)
Ex. Toxic shock syndrome (staphylococcus)
staphylococcal food poisoning
45
Q

Type ll exotoxin

A

Membrane disrupting toxins
-disrupt host cell plasma membranes
-leads to ion imbalance and uncontrolled entry of water from surrounding tissues into the cells- cell swells and bursts
Ex. Leukocidins- kills WBCs
-Hemolysins- Kills erythrocytes
Streptolysins- Hemolysins produced by streptococci

46
Q

Type lll exotoxins

A

A-B toxins
-MOST EXOTOXINS
-consists of two polypeptides
A part-enzyme
B part- Binding component
-Bacterium produces and releases exotoxin
-B component attaches to host cell receptor
-A-B exotoxin enters host cell by endocytosis
-A-B exotoxin enclosed in pinched off portion of plasma membrane during pinocytosis
-A-B components separate
-A part alters cell function by inhibiting protein synthesis
-B part is released from host cell
Ex. Botulinum and tetanus toxins

47
Q

Neurotoxins

A

Interfere with neurological signal transmission

48
Q

Leukotoxins

A

Destroy leukocytes

49
Q

Enterotoxins

A

Effect the intestinal tract

50
Q

Cytotoxins

A

Kills host cells

51
Q

Endotoxins

A

-Release of endotoxins by
-Cell death
-antibiotics
-Antibodies
Cause
-fever
-shock
-Tumor necrosis factor allows bacteria to cross the blood brain barrier
-LAL assay detects endoroxins

52
Q

Quorum sensing

A
  • Bacteria appear relativity innocuous as they quietly grow in numbers
  • When population reaches a certain level, behavior, appearance, metabolism are altered
  • these changes cumulate in an infection that can ambush and overwhelm immune system
53
Q

How can bacteria acquire virulence factors?

A
  • Encoded in DNA
  • Encoded on- bacteriophage DNA
    - Plasmid DNA
    - Transposons
  • lysogenic conversion
  • transduction
  • conjugation
  • transformation
54
Q

Bacteriophages

A

Virus particles which attack bacteria

-phage can be transmitted to non-pathogenic strains making them virulent

55
Q

Lysogenic conversion with bacteriophages

A

-Can result in bacteria with virulence factors such as toxins, fimbriae or capsules

56
Q

Transduction

A

-The process by which DNA is transferred from 1 bacterium to another by phage
-Mediated conjugation
-transfer of genetic material from a donor cell to a recipient cell by cell to cell contact
–Plasmids may carry genes for antibiotic resistance and or virulence factors between bacteria, allowing new bacteria to become pathogenic
Ex. tetanus neruotoxin
staphylococcus enterotoxins (superantigen)
Hemorrhagic E. coli (fimbriae and shiga toxin)

57
Q

Plasmids

A

Circular DNA present in bacteria

58
Q

Conjugation

A

-The process by which on bacterium (w. fertility factor) transfers genetic material to another through direct contact

59
Q

Transformation

A

-The genetic alteration of a cell, resulting from the direct uptake and incorporation of exogenous genetic material from its surroundings and taken up though the cell membrane

60
Q

Listeria monocytogenes

A 
Gram positive rod
non sporulating
-Septicemia, abortion, meimgeoenephalitis
-Food bourne->pathogen
-(milk, cheese, ready to eat meals)
-Neural form- circling disease
     -gets into eyes and mm while eating
     -effects neural system 
     -milk producing animals
     -cillage eating animals
-Visceral form
     -ingestion
Virulence factors
-invasins
61
Q

Mycobacterium

A
  • Acid fast positive
  • Intracellularl (facultatively obligate)??
  • M. tuberculosis- humans
  • M. bovine- induces granulomas
  • M. avium- avian
  • M. avium sbsp. paraturburculosis- Johne’s disease
    • chronic granulomatus enteritis**
62
Q

enterobacteriaceae

A 
Gram negative rods
Facultative anearobe
-Escherichia 
-Salmonella
-Yersinia
63
Q

Gram (-) oxidase negative rods

A
  • Ferment glucose
  • Motile
  • many non pathogenic species*
  • present in water, soil environment and the GI tract of humans and animals
  • Coliform bacteria
64
Q

Coliform bacteria

A
  • E.coli
  • Klebsiella
  • Enterobactor
  • Faecal streptococcus and Enterococcus (human)
  • *Indicators**
65
Q

E. coli

A

gram (-) bacteria

66
Q

Enterotosigenic E. coli

A 
Diarrhea
neonatal colisepticemia in cows and pigs
First 6 weeks of life in piglets (lose receptors as they age)
K88 (F4)- Pigs
K99 (F5)- Calves
**adhesions**
Exotoxins
67
Q

Enterohemorrhagic E. coli

A 
Shiga toxin producing (verotoxins)
Causes edema disease in piglets
0157H7 in humans
    -Hemmorrhagic enteritis
    - Hemolytic uremic syndrome and irreversible kidney failure
68
Q

Salmonella

A 
gram negative
Salmonella enterica
animals- septicemia, acute, subacute and chronic enteritis
**some are host specific**
S. dublin- cattle
S. typhi- humans
S. enteritidis- chickens and humans
69
Q

Typhoid

A

only cause systemic disease in humans resulting from material invasion of the blood stream

70
Q

Yersinia

A

gram (-) bacteria

71
Q

Yersinia enterocolitica

A

pathogen of humans and animals

-causes gastroenteritis and other infections

72
Q

Yersinia pseudotuberculosis

A

Mainly animals
acute enteric disease
gastrointestinal tract of domestic and wild animals and birds
transmission by ingestion of contaminated food and water

73
Q

Yersinia pestis

A

causes plague in humans, rodents and cats

74
Q

Gram negative rods and cocci

A

Non-fermenting, aerobic/microaerophilic
psuedomonas
P. aeruginosa (environmental microorganism)
-opportunistic
-high antimicrobial resistance (can form biofilms)
-all animals
-wound infections, absesses diarrhea, ear and urogenital infections. nosocomial infections
-Dogs-> ear and urinary tract infections

75
Q

Spiral shaped

A 
Campylobacter
-pathogenic (animals and humans)
C. jejuni- GI diseases in goats, dogs, cats, sheep, calves
Leptospira
spirochete->endoflagella
gram (-)
L. interrogans- leptospirosis
-spread in urine
-natural hosts- swine, rodents, dogs
-can live in water for days
-direct or indirect infection
76
Q

Class molicutes

A

-no cell wall
-no peptidoglycan
Mycoplasmas
M. pneumonia- walking pneumonia
M. bovis-pneumonia and arthritis in cattle
fried egg colonies

77
Q

Obligate intracellular pathogens

A

Chlamydia
-gram (-) pleomorhpic
-do not generate ATP needs hosts ATP
-C. psittaci- psittacosis in humans and avians
chlamydosis in avians and bovine abortion
-zoonotic
-infect mucus membranes of respiratory and GI tracts of normal animals

78
Q

Rikettsia

A 
Gram (-) cocobacilli
-obligate intracellular
R. rikettsia
-rocky mountain spotted fever
-humans and dogs
-ticks as vectors
79
Q

Enterotoxigenic Clostridium

A

C. preferingens (enterotoxemia)

C. deficile (pseudomembenous colitis in humans and enterocolitis in lab animals)

80
Q

Atypical Clostridium

A

C. piliforme-obligate intracellular pathogen

  • ONLY GRAM NEGATIVE CLOSTRIDIUM
  • Tyzzers disease, necrotising hepatitis, ileitis, typhlitis and colitis
  • laboratory rodents, rabbits and horses

Vet prep bacteriology (2 decks)

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