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Gram (+) Cocci Flashcards

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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
What is the #1 cause of meningitis in neonates?
Strep agalactiae (GBS)
26
What are the 3 infections caused by streptococcal pyrogenic exotoxin (SPE)
``` Scarlett Fever (SPE A, C) Toxic Shock Like Syndrome (SPE A, C) Necrotizing Fasciitis (SPE B) ```
27
Describe the appearance of Staph
Look like bundles of grapes
28
What is the most common cause of endocarditis affecting artificial heart valves?
Staph epidermidis
29
MRSA
It becomes resistant to methicillin by altering its penicillin binding proteins (PBPs) PBPs help build cell walls.
30
Describe the pneumonia of strep pneumo
#1 cause of community acquired pneumonia in adults Lobar pneumonia that infiltrates lower lobes Leads to production of rust-colored sputum
31
How do you differentiate staph epi from staph sapro?
Novobiacin sensitive = epidermidis | Novobiacin resistent = saprophyticus
32
What do you do if you see staph epi on culture?
NOTHING! It's normal skin flora. It contaminates a lot of cultures (blood cultures too)
33
What does staph sapro like to cause?
UTIs in sexually active women.
34
How do you treat staph epi caused endocarditis?
vancomycin
35
DNase
Another strep pyogenes virulence factor Depolymerizes DNA
36
List the gram (+) cocci (8)
``` Staph Aureus Staph Epidermidis Staph Saprophyticus Strep Pyogenes Strep Agalactiae Strep Pneumoniae Strep Viridans Enterococcus ```
37
Tx for strep pneumo
erythromycin (Macrolide) OR Ceftriaxone (3rd gen cephalosporin)
38
In Staph vs Strep, which is catalase (+)?
Staph
39
How do you tell the difference between Strep Pneumoniae and Strep Viridans?
Strep pneumo = Optochin sensitive, bile soluble (cannot grow in bile) Strep viridans = Optochin resistant, bile resistant/insoluble
40
What are the 2 subspecies of Strep Veridans?
Strep Mutans and Strep Sanguines
41
Cellulitis from GAS
erythema of skin Also Erysipelas: very superficial cellulitis with well-demarcated borders. GAS is most common cause.
42
What does staph epidermidis commonly infect?
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
What makes staph epi so good at sticking to sleek metal/plastic surfaces?
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
What disease process is Strep Mutans associated with most?
A type of Strep Veridans Causes dental carries
45
M Protein
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
Why is a splenectomy relevant?
Pts who have no spleen or who have sickle cell disease are at higher risk of infection from encapsulated organisms.
47
Tx for strep throat
penicillin
48
Which Strep species is Hippurate (+)?
Agalactiae - It hydrolyzes sodium hippurate
49
Where does staph aureus like to colonize?
nares
50
Tx for staph aureus
MRSA = vancomycin MSSA = nafcillin (use a penicillin bc it's more effective than vancomycin)
51
Septic arthritis and Staph Aureus
Staph aureus is #1 cause in adults
52
What is the Strep pyogenes capsule made out of?
Hyaluronic acid We have hyaluronic acid in our own joints, therefore the capsule is not immunogenic
53
Which Staph species is coagulase (+)?
Staph aureus only. Coagulase converts fibrinogen to fibrin.
54
Strep Pneumo and Strep Viridans hemolysis
Alpha-hemolytic (partial hemolysis so surrounding zone of hemolysis is a green hue - green from oxidation of hemoglobin)
55
Staph aureus on Mannitol salt agar
Staph aureus ferments mannitol - turns agar yellow | If organism does not ferment mannitol - it stays pink
56
Rheumatic Fever course
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
Staph aureus hemolysis
B-hemolytic
58
Main virulence factor of staph aureus
Protein A
59
Symptoms of Rheumatic Fever
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
Toxic Shock Syndrome
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
Toxic Shock Like Syndrome (TSLS)
one of the SPE (A, C) caused infections from strep pyogenes superantigen mediated
62
What makes E. faecium Tx so hard?
It is resistant to a lot of things, even vancomycin Vancomycin Resistent Enterococcus (VRE)
63
What are the 2 virulence factors of strep pneumo?
1) It's capsule | 2) IgA Protease - cleaves IgA which lets it colonize and invade our mucosa
64
Necrotizing Fasciitis
one of the SPE (B) caused infections from strep pyogenes invades fascia and spreads fast surgical emergency with amputation possible
65
What is the #1 cause of osteomyelitis in adults?
staph aureus
66
What diseases can GBS cause in neonates?
meningitis, sepsis, pneumonia
67
How do you treat an infected prosthesis?
Prob have to replace it
68
How can you differentiate GAS from GBS?
``` GAS = bacitracin sensitive GBS = bacitracin resistant ```
69
Special general features about enterococci
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
What are the 3 main pyrogenic infections caused by Group A Strep (pyogenes)?
Impetigo, Pharyngitis, and Cellulitis
71
How does a baby get GBS?
As it passes through vaginal canal during delivery
72
Strep pyogenes (GAS) hemolysis
B-hemolytic (due to streptolysin-O)
73
What is the function of catalase?
It converts H2O2 to water.
74
Streptokinase
Another strep pyogenes virulence factor Converts plasminogen to plasmin Plasmin is fibrinolytic. We can actually give streptokinase during MI/stroke to lyse clots.
75
What are the 4 diseases that Strep pneumo is the #1 bacterial cause of?
MOPS ``` M = Meningitis O = Otitis media P = Pneumonia S = Sinusitis ```

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