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BL and DD Unit 3 > Bacterial Pathogens > Flashcards

Bacterial Pathogens Flashcards

1
Q

Staphylococcus aureus

A
  • gram+ cocci (in clusters)
  • anterior nares and perineum
  • cutaneous infections
  • toxin-mediated disease (superantigens) (staphylococcocal toxic shock syndrome)
  • hospital acquired pneumonia
  • foreign body infections
  • bacteremia/endocarditis
  • resistant to penicillin, methicillin, and soon vancomycin
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2
Q

What bacteria is involved in toxic shock syndrome?

A

Staphylococcus aureus

superantigen toxin –> activation of T-cells –> systemic manifestations

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3
Q

What bacteria is involved in hospital acquired pneumonia?

A

Staphylococcus aureus

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4
Q

What bacteria is involved in cutaneous infections creating a local abscess?

A

Staphylococcus aureus

fibrinous capsule that prevents attack by phagocytes

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5
Q

Staphylococcus epidermidis

A
  • gram+ cocci
  • prototypical SSNA
  • produces slime/glycocalyx
  • allows adherence to foreign bodies
  • requires removal of device
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6
Q

Streptococcus pyogenes (Group A Strep)

A
  • gram+ cocci (usually in chains or pairs)
  • pharyngitis
  • skin/wound infections (cellulitis)
  • post-strep diseases (glomeruloephritis, rheumatic fever)
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7
Q

How does pharyngitis occur?

A
  • M protein expressed by strep pyogenes adheres bacteria to epithelial cells and prevents phagocytosis
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8
Q

How does post-strep glomerulonephritis occur?

A
  • immune complex formation of strep antigen-antibody complexes deposit in kidneys (BM)
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9
Q

How does post-strep rheumatic fever occur?

A
  • self-reactive antibodies in response to pharyngeal infection of group a strep
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10
Q

Streptococcus pneumoniae

A
  • gram+ cocci in pairs
  • noninvasive pneumonia, sinusitis, otitis media, bronchitis
  • invasive meningitis, bacteremia, septicemia
  • antiphagocytic capsule
  • young/old, alcoholics, respiratory viral infection
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11
Q

Viridans streptococci

A
  • infective endocarditis
  • abundant in mouth
  • deposit on damaged heart valves using dextrans for adherence
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12
Q

What causes infective endocarditis?

A

Viridans streptococci

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13
Q

Enterococcus faecalis/faecium

A
  • gram+ cocci
  • enterococcal infections of urinary tract, surgical wounds, biliary tract, endocarditis
  • acquired resistance, especially to vancomycin
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14
Q

What are common causes of UTIs?

A

Enterococcus faecalis/faecium and E. coli

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15
Q

What are the most common gram+ rods?

A

Clostridium:

  • strict anaerobes
  • form endospores
  • hospital acquired diarrhea/colitis (c diff)
  • tetanus (c tetani)
  • botulism (c botulinum)
  • gangrene (c perfrignens)
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16
Q

Clostridium difficile

A
  • gram+ rods
  • most common hospital acquired
  • diarrhea and colitis
  • antibiotics can cause, esp clindamycin
  • produce enterotoxin and cytotoxin
  • res to a lot of antibiotics
17
Q

Clostridium tetani

A
  • gram+ rods
  • found in soil
  • anaerobic local infection and toxin prod
  • block of inhibitory neurons in CNS –> constant constriction
18
Q

Clostridium botulinum

A
  • gram+ rods
  • found in soil
  • ingested in anaerobic conditions (canned, undercooked food)
  • toxin is preformed
  • toxin blocks Ach transmission –> paralysis
19
Q

What causes spastic paralysis?

A

Clostridium tetani

20
Q

What causes flaccid paralysis?

A

Clostridium botulinum

21
Q

Clostridium perfringens

A
  • gram+ rods
  • wound infections; dec blood flow and low oxygen environments –> produces alpha toxin to kill phagocytic cells and muscle (causes cellulitis, gangrene)
  • food poisoning from enterotoxin –> dysregulation of fluid transport
22
Q

Escherichia coli

A
  • gram- rods
  • most common to acquire resistance through plasmids
  • GI: diarrhea from adherence to intestinal mucosa and toxins that mess up electrolyte balance
  • UTI: adherence to bladder epithelium; hemolytic
  • Abdominal: colon to peritoneal cavity; (wounds, colon cancer)
23
Q

Pseudomonas aeruginosa

A
  • gram- rods
  • really resistant
  • wounds, esp burns
  • lung infection w/ CF: stasis of fluids in lungs get infected
  • hospital acq infections: UTIs, pneumonia, catheter-related
24
Q

Neisseria gonorrhea

A
  • gram- diplococci
  • gonorrhea and conjunctivitis
  • pilus-mediated: adherence and inhibits neutrophil attack
  • inflammation of mucosal surface
  • res to penicillin and FQ
25
Q

Bacteroides fragilis

A
  • anaerobic bacteria
  • typically in abscess
  • mixed infection (aerobic bacteria metabolize o2 to make anaerobic more habitable)
  • tissue-destructive enzymes, anti-phagocytic capsule, prod of superoxide dismutase
26
Q

Chlamydia trachomatis

A
  • obligate intracellular
  • trachoma: chronic conjuctivitis
  • genital infections
  • neonatal infections
27
Q

Mycoplasma pneumoniae

A
  • lacks a cell wall
  • causes pneumonia
  • penicillins not effective (since no cell wall)
  • adheres to respiratory epithelial cells and produces h2o2 and superoxide dismutase –> damage tissue
28
Q

Gram+ cocci

A
  • Staphylococcus aureus
  • Staphylococcus epidermidis (SSNA, CNS)
  • Streptococcus pyogenes
  • Streptococcus pneumoniae
  • “Viridans” Streptococci
  • Enterococccus faecalis,
  • Enterococcus faecium
29
Q

Gram+ rods

A
  • Clostridium difficile
  • Clostridium tetani
  • Clostridium botulinum
  • Clostridium perfringens
30
Q

Gram- rods

A
  • Escherichia coli

- Pseudomonas aeruginosa

31
Q

Gram- cocci

A
  • Neisseria gonorrhoeae
32
Q

Anaerobic bacteria

A
  • Bacteroides fragilis

- all Clostridium

33
Q

Obligate intracellular bacteria

A
  • Rickettsia

- Chlamydia trachomatis

34
Q

Lacks a cell wall

A
  • Mycoplasma pneumoniae
35
Q

What are ways that bacteria can produce toxins?

A
  • secrete outside of cell
  • inject with needle like apparatus
  • lysis of bacteria
  • LPS
36
Q

What are mechanisms of action of toxins?

A
  • break down ECM or degrade debris in necrotic tissue
  • insert into membranes and create pores –> lysis
  • superantigens: activate T cells and lots of cytokine prod
  • inhibit protein synth
  • modify intracellular signaling
  • inhibit neurotransmitter release
37
Q

What are ways for toxins to enter cells?

A
  • act extracellularly

- cross PM using membrane parts as receptors or being endocytosed

BL and DD Unit 3 (11 decks)

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