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Infectious Disease > 7322 B1 > Flashcards

7322 B1 Flashcards

1
Q

Obligate intracellular organisms

A

Cannot live outside a living cell

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2
Q

Prokaryotes

A
  • 1 chromosome
  • Circular DNA
  • Mono- or polycistronic (messenger RNA can encode for one polypeptide or many polypeptides)
  • No nucleus
  • No membrane organelles
  • 70s ribosomes (30 + 50_
  • Binary fission
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3
Q

Eukaryotes

A
  • 1 chromosome, linear DNA with histones
  • Monocistronic
  • Exon and introns
  • Nucleus
  • Membrane organelles
  • Mitosis with cytokinesis
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4
Q

Gram (+) Positive

A
  • 2 Layers
  • inner cytoplasm membrane
  • outer thick peptidoglycan layer
  • No lipid content
  • No endotoxin (LPS)
  • No periplasmic space
  • Vulnerable to lysozyme and penicillin attack
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5
Q

Gram (-) Negative

A
  • 3 Layers
  • Inner cytoplasmic layer
  • Thin peptidoglycan layer
  • Outer membrane with lipopolysaccharide (LPS)
  • High lipid content
  • Endotoxin (LPS)
  • Periplasmic space
  • Porin channel
  • Resistant to lysozyme and penicillin attack
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6
Q

Cocci

A

-Spherical

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7
Q

Bacilli

A
  • Rods

* short rods are called coccobacilli

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8
Q

Spiral Forms

A
  • Comma

- Spiral

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9
Q

Pleomorphic

A

-No distinct shape

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10
Q

Gram (+) positive

3 Cocci?

4 Bacilli?

A
  • Cocci
  • Streptococcus (chains)
  • Enterococcus (chains)
  • Staphylococcus (clusters)
  • Bacilli
  • Bacillus (spores)
  • Clostridium (spores)
  • Corynebacterium (No spores)
  • Listeria (No Spores)
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11
Q

Gram (-) negative

2 Cocci?

1 Spiral?

1 Comma?

A
  • Cocci
  • Neisseria (diplococci)
  • Moraxella (diplococci)
  • Spiral
  • Spirochetes (too small to see)
  • Comma
  • Vibrio cholerae

REMAINING GRAM NEGATIVE ARE EITHER RODS OR PLEOMORPHIC

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12
Q

Neither Gram (+) or (-)

A
  • Mycobacteria (Acid Fast)

- Mycoplasm (No cell wall)

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13
Q

Catalase?

Peroxidase?

Superoxide Dismutase?

A

Catalase - Breaks down hydrogen peroxide to water and oxygen

Peroxidase - Breaks down hydrogen peroxide to water and oxygen

Superoxide Dismutase - Breaks down superoxide radicals

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14
Q

Obligate Aerobes

A
  • Use glycolysis with oxygen as the final electron acceptor
  • Have Catalase, Peroxidase and Superoxide dismutase
  • NEED oxygen to survive
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15
Q

Facultative anaerobes

A
  • Aerobic bacteria that can grow in the absence of oxygen
  • Have catalase and superoxide dismutase
  • Can use fermentation as a source of energy, as well as glycolysis
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16
Q

Microaerophilic

A
  • Use fermentation only

- Can tolerate low amounts of oxygen due to Superoxide dismutase

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17
Q

Obligate Anaerobe

A
  • Use fermentation only

- Cannot tolerate any oxygen due to the absence of enzymes

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18
Q

Pathogenicity

A

refers to the ability of an organism to cause disease

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19
Q

Virulence

A

Often used interchangeably with pathogenicity, it refers to the degree of pathology caused by the organism

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20
Q

Avirulent

A

does not cause disease

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21
Q

Virulence factors

A

a structure, toxin, adhesion, etc… that contributes to the ability of a pathogen to cause disease

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22
Q

Adhesion factors

A
  • Involved in the binding and initial interactions between pathogen and host cells.
  • Can be proteins in cell walls or membranes, or structures such as pili/fimbriae
  • Antigenic variation can aid in the persistence of infection (evade host response - surface proteins of bacteria can alter in such a way that it is not recognized by the immune system)
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23
Q

Multi-layer of endospores

A
  1. Cell membrane
  2. Thick peptidoglycan layer
  3. Another cell membrane
  4. Wall of keratin-like protein
  5. Outer layer called exosporium
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24
Q

Facultative intracellular organism

A

Like to live in the host cell

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25
Q

Endotoxins

A

-Part of outer membrane
-Part of LPS of Gram (-) bacteria
*Listeria monocytogenes, only gram (+) with endotoxin
NOTE:
Sometimes treating patients with gram-negative infection can worsen disease as bacteria are lysed.

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26
Q

Endotoxins act on…

A
  • Some act outside the host cell (TSST)
  • Some act on cell membrane
  • Some act inside the cell
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27
Q

Bacteremia

A

bacteria in the blood

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28
Q

Sepsis

A

refers to bacteremia that causes systemic immune response to infection

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29
Q

Septic shock

A

caused by gram (-) and gram (+) bacteria
High mortality (40%)
Drop in blood pressure
TNF triggers coagulation causing vasodilation

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30
Q

What type of gene transfer are naked DNA fragments are taken up?

A

Transformation

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31
Q

Two types of Phage dependant gene transfer are?

A

Generalized and Specialized

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32
Q

What type of gene transfer involves a sex pilus and plasmid?

A

Conjugation

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33
Q

What are mobile genetic elements that insert into chromosome?

A

Transposons (Jumping genes)

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34
Q

Naked DNA from a lysed bacterium is picked up by another bacterium

A

Transformation

Recipient bacteria must be competent (able to bind and internalize DNA)

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35
Q

Bacterial Benefits of Capsule

A
  • Both Gram (+) and (-) have them
  • Interferes with phagocytosis
  • Impairs complement killing
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36
Q

Defense against Capsules

A

-Vaccines target capsule
-Illicit IgG antibody response which helps macrophage kill bacteria
NOTE
Some vaccines are comprised of serotypes of capsular polysaccharides

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37
Q

Facultative intracellular organisms often inhibit phagosome-lysosome fusion in macrophages. They also avoid effects of the host cell’s release of superoxide and hydrogen peroxide. What are some organisms in this class?

A
  • Listeria monocytogenes
  • Solmonella typhi
  • Yersinia
  • Francisella tularensis
  • Brucella
  • Legionella
  • Mycobacteria
  • Noardia
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38
Q

Flagella

A
  • Spin and cause the bacteria to move

- Provides strong motility, enables penetration of mucus layer

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39
Q

Pilli (Fimbrae)

A
  • Straight filaments arising from the cell wall
  • short
  • Can serve as adherence factors
  • specialized pili (sex) are involved in gene transfer
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40
Q

What are the two major types of toxins?

A

Endotoxin

Exotoxin

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41
Q

Exotoxins are:

A

Proteins released by bacteria

  • Some act on inside the cell
  • Binding unit (B or H)
  • translocating unit (A or L)
  • Some act outside the host cell
  • Some act on cell membrane
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42
Q

Endotoxins are:

A

Part of the outer membrane

  • part of lipopolysaccharide (LPS) of gram (-) bacteria
  • The lipid A portion of LPS is the toxic component
  • Sometimes treating patients with antibiotics who have gram (-) infections can worsen the disease as lysed bacteria release large amounts of endotoxin
  • ONLY GRAM (+) WITH ENDOTOXIN IS
  • Listeria monocytogenes*
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43
Q

Bacteremia

A

bacteria in the blood

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44
Q

Sepsis

A

refers to bacteremia that causes a systemic immune response to infection

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45
Q

Septic shock

A

Caused by gram (-) and gram (+) bacteria

  • Endotoxin (LPS) is often the stimulus of septic shock
  • Dangerous drop in blood pressure and multi-organ failure
  • High mortality (about 40%)
46
Q

Transformation

A

Naked DNA from lysed bacteria is picked up by another bacteria

  • recipient bacteria must be competent (able to bind and internalize)
  • internalized DNA is incorporated into bacterial genome (must have homology)
47
Q

Associated with burns, diabetic lesions, lungs in CF patients and also Catheters and artificial hips.

A

BioFilms

-an extracellular polysaccharide network that protects bacteria from antibiotics and immune response.

48
Q

Streptococci are gram (+) and…

A

-Found in chains and catalase negative (cannot breakdown hydrogen peroxide to oxygen and water)
-Can be classified by their ability to hemolyze RBC
and antigenic characteristics of carbs in cell wall
*Letter given to different Lancefield antigens

49
Q

Staphylococci are gram (+) and …

A

-Found in clusters (Grapes) and are catalase positive

50
Q

Lancefield antigen A

-Group A streptococci

A

Streptococcus Pyogenes

  • Cause
  • Strep throat
  • Scarlet fever
  • Skin infections
  • Streptococcal toxic shock syndrome
  • Streptococcal glomerulonephritis
51
Q

Non-Lancefield type

Lancet shaped Gram (+) cocci found in pairs (diplococci)

A

Streptococcus pneumoniae

  • The major cause of pneumonia and meningitis
  • otitis media (middle ear infection) in children
  • The major virulence factor is the polysaccharide capsule
  • Vaccines are created to target capsule
52
Q

Group B Streptococci

Streptococcus agalactiae cause…

A

neonatal meningitis
neonatal pneumonia
neonatal sepsis
sepsis om pregnant

53
Q

Cause endocarditis (inflammation of the heart), dental infections and abscesses?

A

Viridans group streptococci

54
Q

What are the three staphylococci that can cause disease in humans?

A

aureus
epidermidis
saprophyticus

55
Q

Staphylococcus aureus is coagulase ______

A

positive (can cause blood clot)

56
Q

Gram positive cocci, chains
-catalase negative
-how they are classified:
=By their ability to hemolyze RBC’s in agar plate
=By antigenic characteristics of carbohydrate in cell wall (Lancefield antigens)
-Letters given for different Lancefield antigens (A, B, C, D, E, through S)
=5 are significant human pathogens. 3 are A, B, and D, while other two do not have Lancefield antigens

A

Streptococci

57
Q

Gram-positive, catalase negative
-Group A streptococci
=Lancefield antigen “A”
=Carbohydrate found in cell wall
-Virulence factors
=M protein – inhibits complement activation and phagocytosis
=Antibodies against M protein aids in destroying organism
=Streptolysin O and Streptolysin S
=O is oxygen labile, S is oxygen stable
=Lysis red and white cells, responsible for beta hemolysis
-Diseases caused by include: Strep throat, scarlet fever, skin infections, Streptococcal toxic shock syndrome, rheumatic fever, post-streptococcal glomerulonephritis, and others

A

Streptococci pyogenes

58
Q

Lancet-shaped gram positive cocci found in pairs (diplococci)
-No Lancefield type
-Major cause of bacterial pneumonia and meningitis in adults
-Otitis media(middle ear infection) in children
-Major virulence factor is its polysaccharide capsule
=Protects from phagocytosis
=Antibody against capsular polysaccharides are protective, Vaccines target these. Unfortunately, many serotypes of capsular antigens (antigenically different), thus vaccines target most common ones.

A

Streptococcus pneumoniae (also known as pneumococcus)

59
Q
  • Group B streptococci
  • Neonatal meningitis, neonatal pneumonia, neonatal sepsis
  • Sepsis in pregnant women
A

Streptococcus agalactiae

60
Q

Cause endocarditis, dental infections, and abscesses

A

Viridans group streptococci

61
Q
  • Fever, myocarditis, migratory arthritis, rash, etc.
  • Immune responses against M protein can cross react with heart tissue (molecular mimicry)
  • Can cause permanent damage to heart valves
  • Strep throat usually treated to prevent this complication, as most people will quickly recover from strep throat without treatment.
A

Rheumatic fever caused by antibody-mediated complications

62
Q
  • Occurs about 1 wk after pharyngeal or skin infections by nephritogenic strains of beta-hemolytic GAS.
  • Ab-Ag complexes in circulation deposit in kidneys, result in damage due to complement and PMN.
  • Generally, does not cause long term kidney damage
A

Acute post-streptococcal glomerulonephritis caused by antibody-mediated complications

63
Q

Gram positive cocci, found in clusters like graps

Catalase positive

A

Staphylococci

64
Q

-Coagulase positive (causes blood clot)
-Member of normal flora of nose and skin in many people problem in hospital
=Causes skin infections, pneumonia, osteomyelitis, endocarditis, etc
-Has proteins that disable defenses, tunnel through tissues, exotoxins
=Lots of virulence factors that contribute to it being a successful pathogen, Examples:
==Coagulase positive (distinguishes from other staphylococcal species)
==Fibrin formation around bacteria, preventing phagocytosis
==Hemolysins that destroy RBC’s, neutrophils and macrophages
==Protein A in cell wall – binds Fc portion of IgG antibody to prevent complement activation
==Toxins
**Enterotoxin – heat stable toxin that causes food poisoning (preformed toxin in food) E.g. potato salad and other food
**Toxic shock syndrome toxin (TSST-1) – superantigen that causes massive T cell activation with cytokine production, resulting in multiple symptoms including shock

A

Staphylococcus aureus

65
Q

Multiple strains that can be found outside of the hospital. Tends to be sensitive to several oral antibiotics, e.g. clindamycin and trimethoprim-sulfamethoxazole

A

Community-acquired MRSA (CA-MRSA)

66
Q

Multi-drug resistant, even against methicillin and Naficillin

  • Vancomycin can be effective
  • Vancomycin resistant strains (VRSA) are reported
A

Methicillin-resistant S. aureus (MRSA)

67
Q
  • Coagulase negative
  • Normal flora of skin
  • Nosocomial infections, including biofilms associated with prosthetic devices
  • Resistant to antibiotics
A

Staphylococcus epidermidis

68
Q
  • Coagulase negative

- Urinary tract infections in sexually active women

A

Staphyloccus saprophyticus

69
Q

Are aerobic (likes oxygen)
-Only bacteria with capsule composed of protein
=Prevents phagocytosis
-Anthrax – primarily affects herbivores, but can cause disease in humans
=Skin, gastrointestinal and pulmonary forms of disease
-Toxin composed of 3 proteins that are non toxic alone, but together produce the effects of anthrax
=Edema factor – impairs neutrophil function and causes edema
=Protective antigen – promotes entry of edema factor into cells
=Lethal factor – stimulates macrophages to release TNF and IL-1, contributing to death
-Rapid identification critical in treatment

A

Bacillus anthracis

70
Q

Are anaerobic (cannot grow in oxygen)
-Pseudomembranous enterocolitis
-Gram (+) spore-forming rods
-Diarrhea following broad spectrum antibiotics
=Antibiotics wipe out normal flora, allowing pathogenic C. difficile to superinfect colon
-Toxins
=Toxins A and B damages mucosal cells so extensively that they no longer control water movement
=Toxin B is more cytotoxic than toxin A.
=Strains with new toxin: binary toxin CDT
-Treatment for C. difficile
=Metronidazole – mild disease
=Vancomycin – severe disease
=Spores resistant to antibiotics, and therefore relapse can occur (10-25%).
*Fidazomicin shown superior to vancomycin in treating recurrences

A

Clostridium difficile

71
Q

Are anaerobic (cannot grow in oxygen)
-Lethal neurotoxin that causes a rapidly fatal food poisoning
-Exotoxin (neurotoxin) blocks the release of acetylcholine in nerve terminals, causing flaccid muscle paralysis.
-Spores found in smoked fish, home-canned vegetables
=If not cooked thoroughly, and then placed in anaerobic environment.
*Spores germinate, and bacteria grow and release toxin

A

Clostridium botulinum – botulism

72
Q

Are anaerobic (cannot grow in oxygen)

  • Spores commonly found in soil, enter skin through trauma
  • Produces tetanus toxin, causing sustained contraction of skeletal muscles.
  • “Lockjaw”
  • Vaccine is against the toxin
A

Clostridium tetani – tetanus

73
Q

Are anaerobic (cannot grow in oxygen)

  • Spores found in soil, contaminates wounds
  • Deep wounds with dead tissue, anaerobic environment.
  • Bacteria grows and releases exotoxin enzymes
A

Clostridium perfringens – gaseous gangrene

74
Q

Non-spore forming gram positive rods

  • Causes diphtheria
  • Pseudomembrane of fibrin, leukocytes, dead epithelial cells and bacteria in pharynx
  • Exotoxin mediated
  • Vaccine is against toxin
A

Corynebacterium diphtheriae

75
Q

Non-spore forming gram positive rods

  • Septicemia in pregnant women
  • Neonatal meningitis and meningitis in immunosuppressed patients
A

Listeria monocytogenes

76
Q

-Cause of leprosy, also called Hansen’s Disease
-WHO estimates about 2 million people infected with this organisms in the world
=Most in India, Brazil, Burma, Indonesia, Madagascar and Nepal
=In U.S., over 100 newly diagnosed cases per year.
• Usually in immigrants
-Impossible to grow this bacteria on artificial media
-Clinical manifestations are dependent upon 2 phenomenon:
=Severity dependent on host’s cell-mediated immune response
• Similar to that described for TB
=Bacteria appear to grow better in cooler body temperatures closer to skin surface
• Damages skin, superficial nerves, eyes, nose and testes

A

Mycobacterium leprae

77
Q

o Smallest free-living organisms capable of self replication
o Lack cell wall (no peptidoglycan, etc)
o Cannot be gram-stained
o Only protective layer is a cell membrane
o Lipid bilayer packed with sterols (like cholesterol)
o Pleomorphic – many shapes but no defined shape
o Antibiotics against cell walls are ineffective, e.g. penicillin, cephalosporin
o Two major pathogenic species
=Mycoplasma pneumoniae
=Ureaplasma urealyticum

A

Mycoplasmatacea

78
Q

o Number one cause of pneumonia in teenagers and young adults
 More frequent in college dorms and military barracks
o Causes atypical pneumoniae (walking pneumonia)
 Most often mild bronchitis and pneumonia, but there are cases of fatal pneumonia.
• Clinically these patients do not feel very sick
o Gradual onset of fever, sore throat, malaise and persistent dry hacking cough
 After treatment, many symptoms disappear but the cough may last up to 2 months.
o Major virulence factor is P1 adhesion protein
 Attaches to respiratory epithelium, causing ciliostasis and damage
o Diagnostic tests are available, but most times not used
 Patients are treated with broad spectrum antibiotics that treat common causes of disease
• Another cause of atypical pneumonia is Chlamydia pneumoniae

A

Mycoplasma pneumoniae

79
Q

o Also known as T-strain mycoplasma (T for tiny because of colony size on artificial media)
o Produces urease, which metabolizes urea into ammonia and CO2
o Part of normal flora of 60% if healthy women and commonly infects the lower urinary tract, causing urethritis
o Neisseria gonorrhoeae and Chlamydia trachomatis are the other 2 bacteria that cause urethritis
o Can cause pneumonia in neonates and play a role in infertility

A

Ureaplasma urealyticum

80
Q

o Only pathogenic gram-negative cocci
o Found in pairs, e.g. diplococci
 Each coccus shaped like kidney bean and the pair of cocci stick together with concave surfaces facing each other.

A

Neisseria

81
Q

o Causes second most common sexually transmitted disease (STD)
o Urethral, rectal, eye, pharyngeal, joint (arthritis) infections
o In women, genital tract infections are clinically silent and can progress to pelvic inflammatory disease
 Sterility, ectopic pregnancy, etc
o Urethral swabs will show gram-negative diplococcus within WBC

A

Neisseria gonorrhea (Gonococcus

82
Q

o Pili
 Attachment and prevent phagocytosis
 Antigenic variation – Complex genes that undergo multiple recombinations, resulting in pili with hypervariable amino acid sequences
• Shift in antigenic type protects from existing antibodies
o Invasins - invasion into epithelial cells
 Outer membrane protein porins (PorA, PorB)
 Opa proteins (results in opaque colonies)
o Endotoxin (LPS) - promote inflammation.
o No capsule

A

N. gonorrhea: Virulence factors

83
Q

o Pili (antigenic variation)
o LPS
• Has a capsule (gonococcus does not)
o Inhibits phagocytosis, unless antibody binds to it
o Different polysaccharides, at least 13 serogroups
 caused by serogroups A, B, C
 Vaccines are available

A

Neisseria meningitidis

84
Q

o 5% population carry in nasal passages
o High risk groups for disease: Infants (6 mo to 2 yr), Army recruits and College freshmen
o Spread by respiratory route
o Diseases:
 Rash consistent with invasive meningococcal infection
 Endotoxin release is responsible, causing vascular necrosis, inflammatory reaction in skin
 Meningitis (#1 cause) – common form of disease
• Often striking infants < 1 year of age
 Bacteremia – severe cases could result in septic shock
o Diagnosis: Gram stain and culture of blood, spinal fluid or rash
o Treatment:
 Patient: Penicillin G or Ceftriaxone
 Close contacts: Rifampin or ciprofloxin

A

Meningococcal disease

85
Q

carbohydrate portion of LPS

A

O antigen

86
Q

capsule that covers O antigen

A

K antigen

87
Q

subunit of flagella (if positive, motile bacteria)

A

H antigen

88
Q

 Enterobacteriacea
 Vibrionacea
 Pseudomonadaceae
 Bacteroidaceae

A

Enterics

89
Q 
o	Gram-negative rods
o	Many produce enterotoxins: all have endotoxin (LPS)
o	Transmission
	Fecal-oral
	Migration up the urethra
	Colonization of catheters in hospitalized patients
o	Many acquired antibiotic resistance
o	Pathogenic species
	Escherichia coli
	Klebseilla pneumonia
	Proteus mirabilis
	Shigella dysenteriae
	Salmonella typhi
	Yersinia enterocolitica
A

• Enterobacteriaceae

90
Q

 Heat labile toxin (LT) similar to cholera toxin

 Heat stable toxin (ST)

A

o Enterotoxigenic E. coli (ETEC)

91
Q

 Shiga-like toxin (verotoxin) – similar action to Shigella toxin
 Attach with pili and toxin leads to intestinal epithelial cell death
 Bloody (hemorrhagic) diarrhea
 E. coli strain O157:H7 is part of this group

A

o Enterohemorrhagic E. coli (EHEC)

92
Q

 Invades into epithelial cells, like Shigella

 Bloody diarrhea

A

o Enteroinvasive E. coli (EIEC)

93
Q 
o	Pneumonia (commonly in alcoholics or those with underlying lung disease)
o	Hospital acquired urinary tract infections and sepsis
A

• Klebsiella pneumoniae

94
Q

o Dysentery – BLOODY diarrhea

o Shiga toxin – kills intestinal epithelial cells

A

• Shigella dysenteriae

95
Q

o Fecal-oral transmission
o Carrier state – “Typhoid Mary”
o Invades cells, including epithelial cells and macrophages
o Can survive intracellularly in macrophages/monocytes
o Spread to lymph nodes and finally other organs

A

• Salmonella typhi

96
Q

Cholera

A

o Vibrio cholera

97
Q

Diarrhea due to eating raw seafood

A

o Vibrio parahaemolyticus

98
Q

Bloody diarrhea due to zoonotic infection

A

o Campylobacter jejuni

99
Q

Peptic ulcers

A

o Helicobacter pylori

100
Q

Anaerobic gut bacteria causing infections due to surgical or trauma damage to intestines

A

o Bacteroides fragilis

101
Q

• Hospital-acquired gram-negatives
o Often arise from endotracheal tubes, foley catheters, i.v. catheters and surgical incisions.
o Most common group is the Enterobacteriacae family of gram-negative bacteria

A

 E. coli, Klebsiella and Enterobacter

102
Q

o Healthy people are typically resistant to disease due to this organism
o Can cause:
 Pneumonia, e.g. cystic fibrosis and cancer patients
 Osteomyelitis, e.g. diabetic patients, i.v. drug users
 Burn-wound infections
 Sepsis (high mortality rate)
 UTI and pyelonephritis
 Endocarditis (common cause of endocarditis, along with S. aureus, with i.v. drug users)

A

• Pseudomonas aeruginosa

103
Q

o Can survive on environmental surfaces, increasing chances of transmission
o Pneumonia, bacteremia, UTI, burn/wound infections and eye infections
 Very common infection in soldiers with wounds
o Can be mistaken for Neisseria
 Coccobacillus and on solid media can form diplococci
 Sometimes could look gram-positive as well
o Challenge to treat due to multidrug resistance

A

• Acinetobacter baumannii

104
Q

o Small gram-negative rod (coccobacillus)
 Cause of sinusitis, otitis media, meningitis, pneumonia mostly in children
o Polysaccharide capsule – multiple serotypes
 Type b serotype more invasive than others
 Anti-capsule antibody confers protection
• Maternal antibodies protect baby for first 6 months
• Between 6 months to 3-5 years old children are lacking these antibodies (Type b most important)
• Vaccine is available

A

• Haemophilus influenza

105
Q

o Meningitis
 Main cause of meningitis in children (6 months to 3 yrs) until vaccine was introduced
 Potentially fatal infection or development of neurologic deficits.
 Following inhalation the organism reaches blood stream allowing penetration into brain
o Acute epiglottitis
o Septic arthritis
o Sepsis

A

• H. influenzae type b Diseases

106
Q

o Usually limited to upper airways
o Increased lymphocytes often seen in these patients
o Exotoxins
 Pertussis toxin (AB toxin) – activates adenylate cyclase (precise role unknown)
 Extracytoplasmic adenylate cyclase – impairs the function of inflammatory cells
 Tracheal cytotoxin – destroys ciliated epithelial cells. May be responsible for violent (whooping) cough

A

• Bordetella pertussis – Whooping cough

107
Q

o Cause of Pontiac fever and Legionaires’ disease
o Aerosolized contaminated water is inhaled
 Form biofilms in water towers, air conditioning systems, whirlpools, etc.
o Intracellular pathogen
 Lives in amoebas in water
 Lives inside macrophages by inhibiting phagosome-lysosome fusion

A

• Legionella pneumophila

108
Q

o Can only survive by establishing residence inside animal cells
o Need host’s ATP as an energy source

A

Obligate intracellular bacteria
o Chlamydia
 C. trachomatis – Eye infections, non-gonococcal urethritis, etc
 C. pneumoniae – Atypical pneumonia
o Rickettsia
 Tend to be zoonotic or vector borne, e.g. from animals or insects
 Example: R. rickettsia – Rocky mountain spotted fever (Tick borne)

109
Q

o Tiny gram-negative bacteria that look like corkscrews
 Motile with axial filaments winding around organism
• Contraction causes spinning motion

A

• Spirochetes

110
Q

 Primary stage – Painless chancre (ulcer)
 Secondary stage – Rash on palms and soles, painless wart like lesion, almost any organ can be infected
 Tertiary stage – can develop over 6-40 years
• Slow inflammatory damage to organ tissue, small blood vessels or nerve cells
 Latent – secondary syphilis has resolved but relapses can occur
 Congenital – Acquired in utero with high mortality rate

A

o Treponema pallidum – syphilis (STD)

111
Q 
Lyme disease (tick-borne)
•	Rash, neurologic infections, cardiac infection, arthritis
A

Borrelia burgdorferi

Infectious Disease (56 decks)

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