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Bacteria > Gram (+) Cocci > Flashcards

Gram (+) Cocci Flashcards

1
Q

Pharyngitis from GAS

A

Strep throat

red, erythematous, inflamed throat

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2
Q

Rash from scarlett fever

A

spares the face

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3
Q

Scarlett Fever

A

one of the SPE (A, C) caused infections from strep pyogenes.

reddening, swelling of tongue (strawberry tongue)
Pharyngitis
widespread rash that SPARES THE FACE

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4
Q

Pneumonia in staph aureus

A

XR shows patchy infiltrate

Normally it’s a post-viral bacterial pneumonia. It happens after immune system has been weakened by viral infection.

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5
Q

Scaled skin syndrome

A

Result of staph aureus

skin peels off

Mediated by exfoliative toxin (a protease)

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6
Q

Post-streptococcal Glomerulonephritis (PSGN)

A

Damage caused by own immune system after strep pyogenes infection - Type 3 hypersensitivity

Damage is from circulating antigen-antibody immune complexes that deposit in glomerulus

Symptoms: Dark brown, cola colored urine
Facial swelling, puffiness from erythema

Happens 2 weeks after initial strep infection

RF occurs after pharyngitis, but PSGN can happen after pharyngitis OR skin infection like impetigo

Early dx/tx of strep throat does NOT prevent PSGN

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7
Q

What disease process is Strep Sanguines associated with most?

A

A type of Strep Veridans

Causes subacute endocarditis in damaged heart valves.

Only infects damaged heart valves.

Mitral is most common, bc it’s the most likely to be damaged already (MVP, RF)

After teeth cleaning in person with a damaged valve, the bacteria enter the blood and can adhere to any fibrin-platelet aggregates of damages tissue by creating dextrans.

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8
Q

Staph food poisoning

A

Toxin-mediated disease of staph aureus

rapid onset from a preformed toxin (1-8 hrs)

More associated with vomit than diarrhea (!!!)

Meats and cream-based food (mayo,custard) left out too long

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9
Q

Describe Staph Aureus appearance on blood agar

A

Colonies have yellow/gold look on blood agar

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10
Q

Prevention for strep pneumo

A

2 vaccines:

Adults: 23-valent polysaccharide vaccine (IgM)

No protein so the immune system generates T-cell-independent response and only generates IgM (no long-lasting protection)

Kids: 7-valent, but it’s conjugated to protein (IgG)

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11
Q

Tx for enterococci

A

Linezolid or Tigecycline

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12
Q

How do Strep viridans adhere to platelets?

A

Dextrans - it creates this adherent from glucose

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13
Q

How do you prevent GBS infection in newborns?

A

At 35 wks, mom’s vagina and rectum are swabbed to checl for colonies.

If she is colonized give mom penicillin during delivery (intrapartum)

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14
Q

Heart issue caused by Staph aureus

A

Acute bacterial endocarditis. This has a fast onset and happens more in IV drug users (this makes it right sided)

Valve most affected = tricuspid

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15
Q

Diseases caused by staph aureus

A

Inflammatory (Pneumonia, Septic arthritis, Abscesses, Acute bacterial endocarditis, skin issues [impetigo, cellulitis, foruncles, carbuncles, abscesses], osteomyelitis)

Toxin-mediated (Scalded skin syndrome, TSS, food poisoning)

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16
Q

Which Strep species is CAMP (+)?

A

Agalactiae - when it is plated with S.aureus you see an increased zone of hemolysis

Arrowhead zone of hemolysis

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17
Q

Streptolysin O

A

Another strep pyogenes virulence factor

Allows GAS to lyse RBCs and be B-hemolytic

We generate antibodies to it. Anti-streptolysin O antibodies (ASO titer) tells us if we have been recently infected by GAS (helpful in diagnosing acute RF or PSGN)

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18
Q

Protein A mechanism

A

It binds Fc portion of immunoglobulins. This prevents complement from binding that region and prevents opsonization/phagocytosis.

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19
Q

What are the 3 major illnesses caused by enterococcus?

A

UTI, Endocarditis, Biliary Tree infections

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20
Q

Describe the appearance of Strep species?

A

They form long chains or pairs instead of clusters

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21
Q

Impetigo from GAS

A

Skin infection that looks honey crusted

Can also be caused by Staph aureus

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22
Q

What does strep pneumo look like?

A

Lancet-shaped gram (+) diplococci

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23
Q

Which staph species are urease (+)?

A

Staph epidermidis and staph saprophyticus

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24
Q

In what population does Strep Agalactiae (GBS) cause the most serious infections?

A

newborns

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25
Q

What is the #1 cause of meningitis in neonates?

A

Strep agalactiae (GBS)

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26
Q

What are the 3 infections caused by streptococcal pyrogenic exotoxin (SPE)

A 
Scarlett Fever (SPE A, C)
Toxic Shock Like Syndrome (SPE A, C)
Necrotizing Fasciitis (SPE B)
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27
Q

Describe the appearance of Staph

A

Look like bundles of grapes

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28
Q

What is the most common cause of endocarditis affecting artificial heart valves?

A

Staph epidermidis

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29
Q

MRSA

A

It becomes resistant to methicillin by altering its penicillin binding proteins (PBPs)

PBPs help build cell walls.

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30
Q

Describe the pneumonia of strep pneumo

A

1 cause of community acquired pneumonia in adults

Lobar pneumonia that infiltrates lower lobes

Leads to production of rust-colored sputum

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31
Q

How do you differentiate staph epi from staph sapro?

A

Novobiacin sensitive = epidermidis

Novobiacin resistent = saprophyticus

32
Q

What do you do if you see staph epi on culture?

A

NOTHING! It’s normal skin flora. It contaminates a lot of cultures (blood cultures too)

33
Q

What does staph sapro like to cause?

A

UTIs in sexually active women.

34
Q

How do you treat staph epi caused endocarditis?

A

vancomycin

35
Q

DNase

A

Another strep pyogenes virulence factor

Depolymerizes DNA

36
Q

List the gram (+) cocci (8)

A 
Staph Aureus
Staph Epidermidis
Staph Saprophyticus
Strep Pyogenes
Strep Agalactiae
Strep Pneumoniae
Strep Viridans
Enterococcus
37
Q

Tx for strep pneumo

A

erythromycin (Macrolide)

OR Ceftriaxone (3rd gen cephalosporin)

38
Q

In Staph vs Strep, which is catalase (+)?

A

Staph

39
Q

How do you tell the difference between Strep Pneumoniae and Strep Viridans?

A

Strep pneumo = Optochin sensitive, bile soluble (cannot grow in bile)

Strep viridans = Optochin resistant, bile resistant/insoluble

40
Q

What are the 2 subspecies of Strep Veridans?

A

Strep Mutans and Strep Sanguines

41
Q

Cellulitis from GAS

A

erythema of skin

Also Erysipelas: very superficial cellulitis with well-demarcated borders. GAS is most common cause.

42
Q

What does staph epidermidis commonly infect?

A

artificial joints and implanted hardware (the enemy of orthopedic surgeons!)

Also indwelling catheters and lines (it covers our skin… when you penetrate the skin, it is ready to enter)

43
Q

What makes staph epi so good at sticking to sleek metal/plastic surfaces?

A

It produces a lot of adherent biofilms

Biofilms are a bunch of polysaccharides that help it stick and form coatings to protect against antibiotics and immune cells.

Since staph epi produces a lot of biofilms, it is resistant to a lot of antibiotics

44
Q

What disease process is Strep Mutans associated with most?

A

A type of Strep Veridans

Causes dental carries

45
Q

M Protein

A

Main virulence factor in Rheumatic Fever

Highly antigenic protein in strep pyogenes cell wall. Causes Type 2 hypersensitivity.

Interferes with opsonization (anti-phagocytic) and is extremely antigenic. It elicits strong humoral response. There is a very high chance that you will make antibodies against a very similar self-antigen (the myosin in cardiac muscle) in a process called molecular mimicry

Mitral valve is most affected leading to mitral stenosis

46
Q

Why is a splenectomy relevant?

A

Pts who have no spleen or who have sickle cell disease are at higher risk of infection from encapsulated organisms.

47
Q

Tx for strep throat

A

penicillin

48
Q

Which Strep species is Hippurate (+)?

A

Agalactiae - It hydrolyzes sodium hippurate

49
Q

Where does staph aureus like to colonize?

A

nares

50
Q

Tx for staph aureus

A

MRSA = vancomycin

MSSA = nafcillin (use a penicillin bc it’s more effective than vancomycin)

51
Q

Septic arthritis and Staph Aureus

A

Staph aureus is #1 cause in adults

52
Q

What is the Strep pyogenes capsule made out of?

A

Hyaluronic acid

We have hyaluronic acid in our own joints, therefore the capsule is not immunogenic

53
Q

Which Staph species is coagulase (+)?

A

Staph aureus only. Coagulase converts fibrinogen to fibrin.

54
Q

Strep Pneumo and Strep Viridans hemolysis

A

Alpha-hemolytic (partial hemolysis so surrounding zone of hemolysis is a green hue - green from oxidation of hemoglobin)

55
Q

Staph aureus on Mannitol salt agar

A

Staph aureus ferments mannitol - turns agar yellow

If organism does not ferment mannitol - it stays pink

56
Q

Rheumatic Fever course

A

Starts after strep pharyngitis, but NOT SKIN INFECTIONS and also NOT if the strep throat has been treated right away.

See RF mostly in young children without access to healthcare

57
Q

Staph aureus hemolysis

A

B-hemolytic

58
Q

Main virulence factor of staph aureus

A

Protein A

59
Q

Symptoms of Rheumatic Fever

A

JONES criteria

J = Joints (polyarthritis)
O = Heart issues (valvular damage leading to new murmurs, myocarditis, pericarditis)
N = Nodules (subQ nodules on extensor surfaces of forearms or elbows/knees)
E = Erythema marginarum (rash with thick, red borders)
S = Sydenham's chorea (rapid involuntary movements, esp of the hands and face)
60
Q

Toxic Shock Syndrome

A

Toxin-mediated disease of staph aureus

Toxin = TSST (toxic shock syndrome toxin)

From leaving foreign packing in too long (tampons, gauze after rhinoplasty)

Non specific binding of MHC II and T cell receptors leads to overactivation and eventual cytokine storm

Could be fatal

61
Q

Toxic Shock Like Syndrome (TSLS)

A

one of the SPE (A, C) caused infections from strep pyogenes

superantigen mediated

62
Q

What makes E. faecium Tx so hard?

A

It is resistant to a lot of things, even vancomycin

Vancomycin Resistent Enterococcus (VRE)

63
Q

What are the 2 virulence factors of strep pneumo?

A

1) It’s capsule

2) IgA Protease - cleaves IgA which lets it colonize and invade our mucosa

64
Q

Necrotizing Fasciitis

A

one of the SPE (B) caused infections from strep pyogenes

invades fascia and spreads fast

surgical emergency with amputation possible

65
Q

What is the #1 cause of osteomyelitis in adults?

A

staph aureus

66
Q

What diseases can GBS cause in neonates?

A

meningitis, sepsis, pneumonia

67
Q

How do you treat an infected prosthesis?

A

Prob have to replace it

68
Q

How can you differentiate GAS from GBS?

A 
GAS = bacitracin sensitive 
GBS = bacitracin resistant
69
Q

Special general features about enterococci

A

Formerly called Group D Strep

Infects the intestinal tract

E. faecalis is most common

E. faecium is less common, but worse.

Bile resistant (can grow in bile)

Can both grow in mediums up to 65% NaCl

70
Q

What are the 3 main pyrogenic infections caused by Group A Strep (pyogenes)?

A

Impetigo, Pharyngitis, and Cellulitis

71
Q

How does a baby get GBS?

A

As it passes through vaginal canal during delivery

72
Q

Strep pyogenes (GAS) hemolysis

A

B-hemolytic (due to streptolysin-O)

73
Q

What is the function of catalase?

A

It converts H2O2 to water.

74
Q

Streptokinase

A

Another strep pyogenes virulence factor

Converts plasminogen to plasmin

Plasmin is fibrinolytic. We can actually give streptokinase during MI/stroke to lyse clots.

75
Q

What are the 4 diseases that Strep pneumo is the #1 bacterial cause of?

A

MOPS

M = Meningitis 
O = Otitis media
P = Pneumonia 
S = Sinusitis

Bacteria (11 decks)

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