Infectious Diseases

Front 1

What is the causative agent of syphilis?

Back 1

Treponema pallidum, a gram-negative Spirochete

Front 2

What is the causative agent of diphtheria?

Back 2

Corynebacteria diphtheria, a gram-positive bacillus

Front 3

Which species of bacteria causes strep throat, scarlet fever, rheumatic fever, and post-streptococcal glomerulonephritis?

Back 3

Group A beta-hemolytic streptococcus (Streptococcus pyogenes)

Front 4

How long does strep throat usually last?

Back 4

5 days

Front 5

What's the scientific term for strep throat?

Back 5

Streptococcal pharyngitis

Front 6

What are the symptoms of streptococcal pharyngitis?

Back 6

Fever

Red, swollen tonsils and pharynx

Purulent exudate on tonsils

Swollen lymph nodes

Front 7

What is the causative agent of strep throat?

Back 7

Strep. pyogenes (group A beta-hemolytic streptococcus)

Front 8

What is the causative agent of scarlet fever?

Back 8

Strep. pyogenes (group A beta-hemolytic streptococcus)

Front 9

Name the toxin released by Strep. pyogenes that is responsible for scarlet fever:

Back 9

Pyrogenic toxin, also called erythrogenic toxin

Front 10

Other than staph. aureus, what other agent causes toxic shock syndrome?

Back 10

Strep. pyogenes (group A beta-hemolytic streptococcus)

Front 11

What is Sydenham's chorea? What's another name for it?

Back 11

Sydenham's chorea, historically also called St. Vitus dance after the patron saint of dance, is rapid, uncoordinated jerking movements of the face, hands, and feet that can occur during acute rheumatic fever.

Front 12

Rheumatic fever follows infection by which organism?

Back 12

Strep. pyogenes (group A beta hemolytic streptococcus), especially after pharyngitis (strep throat)

Front 13

Describe the pathophysiology of rheumatic fever:

Back 13

Antigens against strep. pyogenes cross-react with self-tissue, especially in the heart and joints.

Front 14

What are the 6 major symptoms of acute rheumatic fever?

Back 14

1) Fever
2) Arthritis
3) Myocardiits
4) Sydenham's chorea
5) Subcutaneous nodules
6) Rash

Front 15

What is ARF?

Back 15

Acute Rheumatic Fever

Front 16

Name 2 delayed-onset antigen-mediated diseases that can occur after streptococcal pharyngitis:

Back 16

1) Rheumatic fever

2) Post-streptococcal glomerulonephritis

Front 17

What's the rash that develops in rheumatic fever called?

Back 17

Erythema marginatum

Front 18

Name 2 ways in which streptococci are classified.

Back 18

1) By their ability to hemolyze red blood cells on a blood agar plate (alpha hemolytic, beta hemolytic, nonhemolytic)

2) By their Lancefield antigens (A, B, C, D, E, etc...)

Front 19

Which are the three most common pathogens associated with meningitis in infants younger than 3 months?

Back 19

Escherichia coli
Listeria monocytogenes
Group B streptococci

Front 20

Name an important complication of Strep. viridans infection:

Back 20

Subacute bacterial endocarditis with subsequent valve disease

Front 21

Where might you find Group B streptococci?

Back 21

Vaginal flora, can be passed to newborn during birth causing meningitis and septicemia

Front 22

What is the causative agent of subacute bacterial endocarditis?

Back 22

Streptococcus viridans

Front 23

What is the causative agent of acute bacterial endocarditis?

Back 23

Staphylococcus aureus

Front 24

Which group of bacteria is particularly associated with abscesses of the brain and other organs of the body?

Back 24

The so-called streptococcus milleri group, also called the Anginosus species group, which includes the species:

Streptococcus anginosus
Streptococcus intermedius
Streptococcus constellatus

Front 25

If blood culture reveals infection with a member of the angiosus species group (Streptococcus milleri group), what further workup should be completed and why?

Back 25

CT scan because species of this group (strep. angiosus, strep intermedius, strep constellatus) are highly associated with abscesses, esp. in the brain

Front 26

Who is a likely candidate for enterococcus infection?

Back 26

Weak, hospitalized patients.

Front 27

What form can enterococcus infection take?

Back 27

Variable, but infections with these members of the normal gut flora usually occur in weak, hospitalized patients.

Enterococci frequently cause a wide variety of infections, including wound infections, native and prosthetic valve endocarditis, urinary tract infections, and bacteremia and sepsis.

Front 28

If blood culture reveals infection with Streptococcus bovis, which other condition should be investigated?

Back 28

Colon cancer

Bovis in the blood, beware cancer in the bowel

Front 29

Name the most common causative agent of pneumonia in adults:

Back 29

Strep. pneumoniae ("pneumococcus")

Front 30

Name three importan infections caused by Strep. pneumoniae:

Back 30

1) Pneumonia in adults
2) Meningitis in adults
3) Otitis media in children

Front 31

How can we broadly divide the diseases caused by Staph. aureus?

Back 31

1) Disease resulting from exotoxin release

2) Disease resulting from direct tissue invasion

Front 32

Name 3 diseases caused by Staph. aureus exotoxin release:

Back 32

1) Staph. aureus gastroenteritis (enterotoxins)
2) Staphylococcal scalded skin syndrome (exfoliatins)
3) Toxic Shock Syndrome (TSST)

Front 33

What does pyrogenic mean?

Back 33

Pyrogenic means fever-inducing.

Front 34

What does TSS stand for?

Back 34

Toxic shock syndrome

Front 35

Name the exotoxin excreted by Staph aureus that can cause TSS.

Back 35

Easy:

Toxic Shock Syndrome Toxin (TSST)

Front 36

Name three exotoxins released by Staph. aureus:

Back 36

1) Exfoliatin
2) Enterotoxins
3) Toxic shock syndrome toxin (TSST)

Front 37

Describe the symptoms of Staph. aureus toxic shock syndrome:

Back 37

Fever
Nausea, vomiting
Watery diarrhea

Diffuse erythematous rash

Shock:
Low BP, acute organ failure

Front 38

Describe the pathogenesis of toxic shock syndrome (TSS):

Back 38

Exotoxins released from either Staph. aureus or Strep. pyogenes act as superantigens, binding to the MHC II molecules of APCs. The result is a massive T cell response with an outpouring of cytokines.

Front 39

Name the primary diseases that result from direct organ invasion with Staph aureus:

Back 39

Nervous system:
-Meningitis
-Brain abscesses

Respiratory system:
-Pneumonia

CVS:
-Acute bacterial endocarditis

Integumentary:
-Impetigo
-Cellulitis
-Local abscesses
Furuncles/Carbuncles
-Wound infections

MSK:
-Septic arthritis
-Osteomyelitis

Front 40

Name 3 forms that skin infection with Staph. aureus can take:

Back 40

1) Impetigo

2) Cellulitis

3) Wound infection

Front 41

Name the most frequent organism isolated from indwelling prosthetic devices:

Back 41

Staph. epidermidis

Front 42

After E. coli, what is the next leading cause of UTIs in sexually active women?

Back 42

Staph. saprophyticus

Front 43

What type of infection does Staph. saprophyticus cause?

Back 43

UTI

Front 44

Which organism causes botulism?

Back 44

Clostridium botulinum

Front 45

B. cereus causes which kind of illness?

Back 45

Food poisoning (spores often survive cooking process)

Front 46

Which antibiotic is used to treat B. cereus food poisoning?

Back 46

Trick question. The food poisoning is caused by an already-released exotoxin, so antibiotic therapy will not alter the course of the disease.

Front 47

How does botulism present in adults?

Back 47

Initial problem usually cranial nerve palsies causing diplopia or dysphagia. Later followed by general muscle weakness and paralysis that can lead to rapid respiratory paralysis and death.

Front 48

Describe the pathophysiology of botulism:

Back 48

Clostridium botulinum excretes a potent neurotoxin which inhibits the release of acetylcholine at the neuromuscular junction causing paralysis.

Front 49

Why can people get botulism from self-sealed food?

Back 49

The organism that causes botulism, Clostridium botulinum, is anaerobic. When placed in such an environment, such as a sealed food container, the spores germinate and toxins are released. If someone eats the contaminated food they become sick.

Front 50

What is risus sardonicus?

What is the etymology?

Back 50

Risus sardonicus refers the grin-like facial expression caused by muscle spasms. It is most commonly seen in tetanus.

Risus sardonicus means Sardinian smile. In pre-Roman Sardinia, a neurotoxic plant was used for ritual killing of elderly people, producing the "Sardonic smile."

Front 51

What is the causative agent of tetanus and how can it be classified?

Back 51

Clostridium tetani, an anaerobic Gram-positive bacillus

Front 52

How does C. tetani lead to muscle spasm?

Back 52

The exotoxin excreted, tetanospasmin, prevents inhibitory neurons from releasing GABA, thereby allowing motor neurons to fire at will.

Front 53

What is the scientific name for gas gangrene?

What is the causative agent?

Back 53

Gas gangrene is clostridial myonecrosis. The causative agent is C. perfringens

Front 54

Clostridial myonecrosis is also known as what?

Back 54

Gas gangrene

Front 55

On palpation, tissue infected with C. perfringens may produce what finding?

Why?

Back 55

Crepitus

C. perfringens, though anaerobic, produces gas.

Front 56

Which organism is responsible for pseudomembranous colitis?

Back 56

Clostridium dificile

Front 57

How is C. dificile infection confirmed?

Back 57

Stool samples. There will be toxins in the stool.

Front 58

If a patient develops diarrhea within a month of being on antibiotics or while on antibiotics, what organism may they be infected with?

Back 58

C. dificile

Front 59

In what situations do C. dif. infections occur?

Back 59

C. dif. is an opportunistic pathogen and can only cause infectious disease if other gut flora have been cleared by broad-spectrum antibiotics.

Front 60

What are the "psuedomembranes" seen by colonoscopy is pseudomembranous colitis?

Back 60

White exudate overtop of red inflamed mucosa.

Front 61

What's the pharmacotheraphy for pseudomembranous colitis caused by C. dificile?

Back 61

1) Metronidazole
2) Oral vancomycin
3) Terminate use of responsible antibiotic

Front 62

What illness does B. cereus cause?

Back 62

Food poisoning:

Nausea/vomiting
Diarrhea

Front 63

Which organism causes diphtheria? How can this organism be classified?

Back 63

Corynebacterium diphtheriae

Gram positive bacillus, not spore-forming.

Front 64

How does diphtheria present clinically?

Back 64

Initial mild fever with sore throat

Dark pseudomembranous exudate forms on pharynx

Front 65

What three treatments are employed in the management of diphtheria?

Back 65

1) Diphtheria antitoxin
2) Appropriate antibiotic (penicillin or erythromycin)
3) DPT vaccine

Front 66

Which tests are ordered to confirm a diagnosis of diphtheria?

Back 66

Culture:
-Potassium tellurite agar
-Loeffler's medium

Front 67

Which groups are most susceptible to infection with Listeria monocytogenes?

Back 67

1) Pregnant women in the third semester

2) Fetus/neonate

3) Elderly/otherwise immunocompromised?

Front 68

Which three species of bacteria cause almost almost all cases of meningitis in neonates (<3 months of age)?

Back 68

L. monocytogenes

E. coli

Group B streptococci (S. galactiae)

Front 69

Why is infection with L. monocytogenes particularly dangerous to those with impaired cell-mediated immunity?

Back 69

This is a facultative intracellular oganism, so it can hide out in cells to avoid humoral immunity. If cell-mediated immunity is defective (as it is in pregnant women, fetuses, neonates, the elderly, and HIV positive) then there can be trouble...

Front 70

What's the antibiotic of choice to cover Listeria monocytogenes?

Back 70

Ampicillin

Front 71

What kind of bacteria are responsible for the overwhelming majority of localized abscesses within the cranium, thorax, peritoneum, liver, and female genital tract?

Back 71

Anaerobes!

Bacteroides, Fusobacterium, and peptostreptococci.