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Disease and Defense Unit 3 > Common Bacterial Pathogens > Flashcards

Common Bacterial Pathogens Flashcards

1
Q

Gram + cocci

A 
Staph family:
Staphylococcus aureus
-SSNA "staph species, not aureus" 
Strep family:
-streptococcus pyogenes
-streptococcus pneumoniae
-"viridans" streptococci
-Enterococcus faecalis/Enterococcus faecium
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2
Q

Gram+ rods

A

Most = clostridium
Endospore forming obligate ANAEROBES

  • clostridium difficile
  • clostridium tetani
  • clostridium botulinum
  • clostridium perfringens
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3
Q

Aerobic and facultative Gram - rods

A
  • E.coli

- Pseudomonas aeruginosa

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4
Q

Gram - (diplo) cocci

A

Neisseria gonorrhoeae

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5
Q

Anaerobic bacteria (other than clostridia)

A

bacteroides fragilis

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6
Q

Obligate Intracellular Bacteria

A

Richettsia

Chlamydia trachomatis

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7
Q

Bacteria w/o cell walls

A

Mycoplasma pneumoniae

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8
Q

Staph. aureus

A

Primary pathogenic species
Gram+ cocci, clusters
Carried in anterior nares/perineum, asymptomatic in 30% of carriers.

Coagulase = virulence factor, interferes w/ phagocytosis

Alpha-toxin = cytotoxic agent

Drug resistance to penicillins, methicillin, and vancomycin.

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9
Q

Staph. aureus

cutaneous infection

A

Folliculitis, boils, wound infection.

Localized abscess

Formation of fibrinous capsule which walls of infection (associated w/ presence of foreign body)

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10
Q

Staph. aureus - toxic shock syndrome

A

Caused by superantigen toxin - non-specific T-cell antivation, massive cytokine release.

High fevel, low BP, malaise, confusion. Can progress to coma/death. Characteristic rash (will slough off 10-14 days after infection if pt survives)

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11
Q

Staph. aureus - food poisoning

A

Superantigen toxin. Ingestion of preformed toxin of contaminated food.

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12
Q

Staph. aureus - pneumonia

A

Opportunistic and common in hospital acquired pneumonia.

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13
Q

Staph. aureus - foreign body associated infections

A

Vascular catheter related infections, prosthetic joint, hardware.

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14
Q

Staph. aureus - endocarditis

A

Common cause of heart valve infection :(

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15
Q

Staph. epidermidis

A

SSNA/CNS (coagulase neg. staph)

Found in normal skin flora

Disease causing b/c produce slime, a glycocalyx which adheres to various implanted devices and allows for growth of biofilm

Resistant to methicillin. Dif. to treat b/c biofilm makes reaching these infections hella hard.

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16
Q

Streptococcus pyogenes

A

“Group A Strep”

Causes pharyngeal infection, skin and wound infection and post-strep diseases.

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17
Q

Strep. pyogenes - Pharyngeal infections

A

Strep throat!
Virulence factor: M-protein.
Spread by contact of nasal sections/droplets.

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18
Q

Strep. pyogenes - Skin and wound infections

A

Commonly cellulitis.
Produce hydrolyric enzymes that bread down tissue and kill phagocytic cells.

SO THIS SPREADS (unlike w/ staph aureus)

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19
Q

Strep. pyogenes - Glomerulonephritis

A

Post strep infection.
Immune complex disease, antigen-antibody complex gets stuck in basement membrane of kidney. Complement mediated damage to kidney results.

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20
Q

Strep. pyogenes - rheumatic fever

A

Autoimmune. Cross-reaction of host antigens with fibrin which is found on heart valves + myocardium. Antibody mediated damage to tissues.

(this is independent of bacteria)

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21
Q

Strep. pneumoniae

A

Usually in pairs (diplococci)

Normal flora in UR tract in 40% of people.

Pathogenesis associated w/ antiphagocytic polysaccharide capsule.

Resistant to penicillin (some strains)

22
Q

Strep. pneumoniae non-invasive disease examples

A

Pneumonia
Sinusitis
Otitis Media
Bronchitis

23
Q

Strep. pneumoniae, invasive disease examples

A

Meningitis
Bacteremia/septicemia
Pneumonia w/ septicemia

24
Q

Strep. pneumoniae Vaccines

A

Adult - Pneumovax, PPSV23. protection against invasive strains. Not against pneumonia. 65+ and immunocompromised adults.

Children: hepta or 13 valent, reduced overall pneumoccocal carriage. gr8 for herd immunity.

25
Q

Viridans streptococci

A

Bacterial endocarditis!!!

Can be either alpha-hemolytic or non-hemolytic.

Abundant in mouth. Associated w/ dental carries - may get access to blood w/ dental procedures.

26
Q

Viridans streptococci - Bacterial endocarditis

A

Produce dextrans which adhere to tissue/teeth.

There allow for adherence to fibrin/platelet deposits on damaged heart valves.

27
Q

Enterococcus faecalis / Enterococcus faecium

A

Common normal flora in intestines.

May cause a shit-ton of things in:
Urinary tract
Biliary tract
Endocaditis
Nosocomial infections
Surgical wounds

Often selected for w/ therapy of cephalosporins.

Biggest problem are vancomycin resistant enterococci.

28
Q

Clostridium difficile

A

hospital acquired infections
normal flora in 10%

Causes diarrhea and pseudomembranous colitis

Produces both endotoxin and cytotoxin.

Resistant to most antibiotics.

29
Q

Clostridium tetani

A

Found in soil and GI tract of animals.

Causes tetanus - lockjaw

Causes retrograde axonal transport of toxin in CNS.

Spastic paralysis due to clock of inhibitory interneurons in CNS.

Vaccine much more effective than using human immunoglobulins in ppl who already have it.

30
Q

Clostridium botulinum

A

Found in soil + GI tract of animals
Grows in contaminated food under aerobic conditions.

Produces botulinum toxin, which blocks acetylcholine at neuromuscular junctions.

Causes flaccid paralysis.

31
Q

Clostridium perfringens - wound infection

A

Such as: cellulitis, myonecrosis and gangrene.

Happens w/ crushing types of injury where oxygen cut off to tissue. Produce alpha toxin (phospholypase enzyme) which kills phagocytic cells and muscle tissue.

32
Q

Clostridium perfringens - food poisoning

A

Produces enterotoxin and bacteria sporulate in gut.

This disrupts tight junctions between endothelial cells in ilium, resulting in issues w/ electrolyte balance and fluid transport (sounds like it would cause diarrhea eh??? )

33
Q

Escheria coli

A

Aerobic and facultative
Normal flora in large intestine

Usually pretty sensitive to antibiotics, but drug resistance HAS been seen w/ acquisition of plasmids

34
Q

E. coli - GI disease

A

food/water contaminated w/ e.coli usually the cause.

Typical travelers diarrhea. This e-coli adheres to intestinal mucosa w/ pili

Uses some awesome enterotoxin to disrupt electrolyte balance

35
Q

E.coli - UTI

A

Usually from own GI tract.

Adheres to bladder epithelium, these stains are often beta hemolytic

36
Q

E. coli - Abdominal Infections

A

escape of bacteria in colon into the peritoneal cavity due to surgical wounds/trauma/colon cancer.

Often mixed, friendly w/ anaerobic bacteria (perhaps using up all the O2 so these babies can live?)

37
Q

Pseudomonas aeruginosa

A

Common environmental bacteria
Most people are resistant.

Resistant to most anti-staph drugs.

38
Q

Pseudomonal aeruginosa - Chronic Lung Infection in CF Patients

A

Nearly all CF patients get chronically infected w/ this by 15-20.

Protected from phagocytosis by thick mucus produced by patient.

Damages lungs by toxin secretion and immune system activation.

Most common cause of death in patients w/ CF.

39
Q

Pseudomonal aeruginosa - Hospital acquired infections

A

Include UTIs, pneumonia and occasionally intravascular catheter related infections

40
Q

Neisseria gonorrhoeae

A

Gram - cocci which is obvi the causative agent of the gonorrhea we know and love

THE KEY TO ITS INFECTIVENESS IS!!!! Its pilus. Required for adherence and interferes w/ bacterial killing by neutrophils.

Causes purulent discharge, local tissue invasion, eventually scarring and fibrosis (w/o treatment)

Almost always resistant to penicillin, fluroquinolone, and some resistant to cephalosporins

41
Q

Neisseria gonorrhoeae - males

A

Present as asymptomatic to urethritis.

42
Q

Neisseria gonorrhoeae - females

A

Infection of cervix, urthera. More often asymptomatic than males.

Ascending infection (up reproduction tract) may lead to fibrosis and infertility

43
Q

Neisseria gonorrhoeae - babies

A

Blindness in infants born to infected mothers (conjunctivities)

44
Q

Anaerobic bacteria

A

Usually normal flora in mouth, colon, female genitalia and skin.

Typical lesion: absess

The hallmark of anaerobic bacterial infection is MIXED infection w/ aerobic and anaerobic bacteria.

Most effective drug: metronidazole
Least effective: aminoglycosides

45
Q

Bacteriodes fragilis

A

(anaerobic bacteria)

Associated w/ 80% of intra abdominal infections

Relatively aerotolerant

Virulence factors: produces a variety of tissue destructive enzymes, ant phagocytic capsule and superoxide dismutase

46
Q

Obligate Intracellular Bacteria

A

Only grow within infected eukaryotic cells

47
Q

Rickettsia

A

Causes Rocky Mountain Fever

Has lost the ability to make own ATP and completely relies on host

48
Q

Chlamydia trachomatis - trachoma

A

Chronic infection of conjunctive, leading to scarring and blindness. Endemic in Asia and Africa.

49
Q

Chlamydia trachomatis - genital infections

A

Can present as:
Male: non-gonococcal urthritis
Female: urethritis, cervicitis, PID

Relately common STD. Co-infections w/ gonorrhea.

50
Q

Chlamydia trachomatis - Neonatal infections

A

Neonatal conjunctivitis/pneumonia

Infants born to infected mothers may become infected at birth

Lots of screening for this now tho

51
Q

Bacteria without Cell Walls

Mycoplasma pneumoniae

A

contain sterols in plasma membrane, no cell wall obvi

Doesn’t stain w/ Gram stain, so good way to rule out other infections.

Common cause of pneumonia in ages 5-20, adheres to respiratory epithelial cell. Generally mild pneumonia with fever, headache, sore throat.

Bacteria produces hydrogen peroxide and superoxide radicals.

Penicillins NOT EFFECTIVE b/c cell is highly pleomorphic

Disease and Defense Unit 3 (8 decks)

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