Bacteria: Gram Positive Cocci Flashcards
(106 cards)
1
Q
Staph Aureus is _______ positive
A
- gram positive
- catalase
- coagulase
2
Q
Staph Aureus Shape
A
Cocci
3
Q
Coagulase converts
A
fibrinogen to fibrin, forming a clot in samples
4
Q
Staph Aureus are ___________ hemolytic
A
beta
5
Q
Beta hemolytic species are able to
A
completely break down hemoglobin
6
Q
Staph aureus bacteria _____ ______ mannitol
A
can ferment
7
Q
Staphylococcus aureus bacteria can ferment mannitol
A
Staphylococcus aureus bacteria can ferment mannitol, turning mannitol salt agar yellow during culture (in contrast to most non-pathogenic staphylococci, which do not ferment mannitol)
8
Q
Protein A
A
- Virulence Factor of Staph Aureus
2. Binds IgG in the Fc region, inhibiting complement activation and phagocytosis
9
Q
Staphylococcus aureus is part of the normal flora of the
A
nares and skin
10
Q
Staphylococcus aureus can cause
A
- Bacterial pneumonia
- Septic arthritis
- Impetigo
- Furuncles
- Carbuncles
- Erysipelas
- Cellulitis
- Acute Infective Endocarditis
- Rapid Onset Food Poisoning
11
Q
Staphylococcus aureus can cause bacterial pneumonia, which appears as
A
patchy infiltrates on chest X-ray (compared to lobar infiltrates in Streptococcus pneumoniae)
12
Q
Staphylococcus aureus pneumonia most commonly follows an
A
Staphylococcus aureus pneumonia most commonly follows an upper respiratory infection (especially influenza) due to weakening of the host immune system by the initial infection (known as superinfection)
13
Q
Septic Arthritis
A
which presents with a warm, swollen, tender joint and purulent aspirate
14
Q
Impetigo
A
pustules that rupture to form “honey crusted” lesions, especially on the face
15
Q
Furuncles
A
Boils
16
Q
Carbuncles
A
Communicating Furuncles
17
Q
Acute infective endocarditis presents with
A
rapid-onset of fever, chills, tachycardia, and sepsis even in previously normal heart valves
18
Q
Staphylococcus aureus is the most common cause of
A
- infective endocarditis (typically of the tricuspid valve), and is often seen with IV drug use, prosthetic valves, and previous valve damage
- osteomeyelitis
19
Q
Some strains of Staphylococcus aureus produce
A
- exfoliative toxin (a tissue protease) that causes a diffuse desquamative rash (scalded skin syndrome)
- superantigen exotoxin (which binds MHC II to cause massive inflammation), resulting in fever, a desquamative rash, and sepsis (toxic shock syndrome)
20
Q
Staphylococcus aureus is capable of producing a rapid-onset food poisoning presenting with
A
nausea and vomiting due to preformed exotoxin
21
Q
Some strains of Staphylococcus aureus bacteria are resistant to
A
- beta-lactams
2. methicillin (MRSA)
22
Q
Methicillin-resistant Staphylococcus aureus have
A
altered penicillin binding proteins, making it difficult or impossible for beta-lactams to adhere to their cell walls
23
Q
Vancomycin is effective against
A
methicillin-resistant Staphylococcus aureus
24
Q
Nafcillin (a beta-lactam) is effective against
A
non-MRSA Staphylococcus aureus
25
Staphylococcus epidermidis is _____ positive
1. gram positive
2. catalase
3. urease
26
Staphylococcus epidermidis shape
cocci
27
List the gram positive cocci
1. Staph Aureus
2. Staph Epidermidis
3. Staph Saprophyticus
4. Strep Pyogenes
5. Strep Agalacties
6. Strep Pnuemonae
7. Strep Viridans
8. Enterococcus Faecium
9. Enterococcus Faecalis
28
Staph Saprophyticus is ______ positive
1. gram
2. catalase
3. urease
29
Staphylococcus epidermidis infection is associated with
1. prosthetic joints
| 2. indwelling catheters
30
Staphylococcus epidermidis can cause
prosthetic valve endocarditis
31
Staphylococcus epidermidis produces
biofilms (extracellular polysaccharide matrix), allowing for adherence to prosthetic devices and IV catheters
32
_____ is effective against Staphylococcus epidermidis (most strains are resistant to nafcillin and methicillin due to the production of biofilms)
vancomyocin
33
Vancomycin is effective against Staphylococcus epidermidis most strains are resistant to
nafcillin and methicillin due to the production of biofilms
34
Staphylococcus epidermidis is a part of
the normal skin flora
35
Staphylococcus epidermidis is a common
blood culture contaminant
36
Staphylococcus epidermidis is susceptible to
the antibiotic novobiocin (differentiating it from Staphylococcus saprophyticus, which is novobiocin-resistant)
37
Staphylococcus saprophyticus commonly causes
uncomplicated urinary tract infections in young, sexually active females
38
Staphylococcus saprophyticus is novobiocin
resistant
39
Staphylococcus epidermidis is novobioicn
sensitive
40
Staphylococcus epidermidis and saprophyticus bacteria are _________ negative
coagulase-negative Staphylococcus species (CoNS) (differentiating them from Staphylococcus aureus, which is coagulase-positive)
41
Streptococcus pyogenes is also known as
group A strep
42
Streptococcus pyogenes is a
gram-positive coccus
43
Streptococcus pyogenes shape
coccus
44
Streptococcus pyogenes (group A strep) bacteria are _______ hemolytic
beta-hemolytic (able to completely breakdown hemoglobin)
45
Streptococcus pyogenes (group A strep) bacteria produce
a hyaluronic acid capsule
46
Streptococcus pyogenes (group A strep) can cause
1. impetigo
2. streptococcal pharyngitis (strep throat)
3.
47
Impetigo
a superficial skin infection often presenting with “honey-crusted” lesions usually around the nose and mouth
48
Streptococcus pyogenes (group A strep) is the most common cause of
skin infections, including cellulitis (infection of the subcutaneous tissue and skin with indistinct borders) and erysipelas (infection of the superficial dermis with sharp, indurated, raised borders)
49
one of the characteristic findings in scarlet fever is
1. strawberry tongue
| 2. diffuse desquamative “sandpaper” rash
50
Scarlet Fever is
caused by the pyrogenic exotoxin of Streptococcus pyogenes (group A strep)
51
Pharyngitis is a characteristic finding in
scarlet fever (caused by the pyrogenic exotoxin of Streptococcus pyogenes (group A strep))
52
One of the characteristic findings in scarlet fever is diffuse desquamative “sandpaper” rash which is caused by
caused by the pyrogenic exotoxin of Streptococcus pyogenes (group A strep)
53
One of the characteristic findings in scarlet fever is diffuse desquamative “sandpaper” rash that typically spares the
perioral area, palms, and soles
54
The pyrogenic exotoxin of Streptococcus pyogenes (group A strep) is a
superantigen that causes widespread T-cell activation and inflammation, resulting in streptococcal toxic shock syndrome (STSS)
55
Certain strains of Streptococcus pyogenes (group A strep) produce
pyrogenic exotoxin SpeB (a soft tissue protease) that leads to necrotizing fasciitis (a rapidly spreading infection of skin, subcutaneous tissue, and fascial planes)
56
In rheumatic fever,
the M protein of Streptococcus pyogenes (group A strep) inactivates complement, prevents phagocytosis, and causes the formation of cross-reactive antibodies (molecular mimicry), leading to pancarditis and mitral stenosis
57
The M protein of Streptococcus pyogenes (group A strep)
The M protein of Streptococcus pyogenes (group A strep) prevents phagocytosis by interfering with opsonization
58
Cross-reactive antibodies formed against the M protein of Streptococcus pyogenes can cause
rheumatic heart disease → mitral regurgitation that can progress to mitral stenosis
59
Rheumatic fever is caused by
untreated Streptococcus pyogenes (group A strep) pharyngitis (not caused by GAS soft tissue infection)
60
the JONES criteria is used for
diagnosing acute rheumatic fever ("J" - joints (migratory polyarthritis), "♡" - myocarditis, "N" - nodules (subcutaneous), "E" - erythema marginatum, "S" - Sydenham chorea)
61
Acute rheumatic fever commonly presents with
Migratory polyarthritis (usually large joints such as the elbow, knees, and ankles)
62
Acute rheumatic fever can cause
1. pancarditis affecting the pericardium, myocardium, and endocardium (valves)
2. Sydenham chorea, which presents with rapid involuntary movement affecting all muscles throughout the body (and may show up 1-8 months after infection)
63
Acute rheumatic fever can present with
1. subcutaneous nodules (which form mostly on extensor surfaces of the forearm and may show central fibrinoid necrosis)
2. a rash that consists of hive-like C-shaped areas of erythema (not to be confused with cellulitis)
64
post-streptococcal glomerulonephritis is caused by
subepithelial immune complex deposition in glomeruli → renal damage and nephritic syndrome
65
“cola-colored” urine from hemolysis is a common finding in
post-streptococcal glomerulonephritis (PSGN)
66
post-streptococcal glomerulonephritis (PSGN) leads to
a nephritic syndrome several weeks after acute infection
67
post-streptococcal glomerulonephritis can follow
Streptococcus pyogenes (group A strep) pharyngitis OR soft tissue infection
68
prompt treatment of Streptococcus pyogenes (group A strep) pharyngitis with penicillin can prevent
rheumatic fever but not post-streptococcal glomerulonephritis
69
post-streptococcal glomerulonephritis can develop after
streptococcal pharyngitis or soft tissue infection (even with treatment)
70
antibodies against streptolysin O are used to diagnose
Streptococcus pyogenes (group A strep) pharyngitis
71
streptolysin O is a
hemolytic virulence factor
72
streptokinase of Streptococcus pyogenes (a virulence factor) is a
proteolytic enzyme that activates plasminogen → plasmin (which in turn degrades fibrin, preventing development of a fibrin barrier at the site of infection)
73
antibodies against DNase (a virulence factor that liquefies purulent material) can be used to diagnose
Streptococcus pyogenes (group A strep) pharyngitis or soft tissue infection
74
DNase is a virulence factor that
liquefies purulent material
75
Streptococcus pyogenes (group A strep) is ______ sensitive
bacitracin
76
antistreptolysin O titers can be used to diagnosis
acute rheumatic fever or post-streptococcal glomerulonephritis following pharyngeal infection (streptococcal skin infections are associated with a poor ASO response, so anti-DNAse titers should be checked as well to increase sensitivity)
77
Streptococcus agalactiae
1. group B strep
2. a gram-positive coccus
3. hippurate hydrolysis positive
4. encapsulated
5. beta hemolytic
6. bacitracin resistant
78
Streptococcus agalactiae (group B strep) produces
CAMP factor, which enlarges the area of hemolysis formed by Staphylococcus aureus when plated together on blood agar
79
Streptococcus agalactiae (group B strep) is the number one cause of
neonatal meningitis
80
Streptococcus agalactiae (group B strep) is the most common cause of
neonatal sepsis
81
Streptococcus agalactiae can cause
pneumonia (primarily in infants)
82
a positive CAMP test
a positive CAMP test appears as an “arrowhead” zone of hemolysis that forms at the point of intersection between Streptococcus agalactiae and Staphylococcus aureus
83
pregnant women are screened for
Streptococcus agalactiae (group B strep) at 35-37 weeks of gestation, as GBS is the most common cause of neonatal meningitis
84
pregnant women who test positive for Streptococcus agalactiae (group B strep) on screening at 35-37 weeks of gestation are given
intrapartum penicillin intravenously
85
Streptococcus pneumoniae and viridans group streptococci are
1. gram-positive cocci
| 2. alpha-hemolytic
86
Alpha hemolytic means
able to partially breakdown hemoglobin
87
Streptococcus pneumoniae is
1. encapsulated
2. susceptible to optochin
3. lancet shaped
4. diplococci
5. bile soluble
88
Streptococcus viridans group streptococci are
1. non-encapsulated
| 2. optochin resistant
89
Optochin
a chemical used in identification of alpha-hemolytic streptococci
90
Bile soluble
no hydrolyzation of esculin → no growth in the presence of bile salts
91
Streptococcus pneumoniae can cause
lobar pneumonia (usually with unilobar consolidation) with production of “rust-colored” sputum
92
Streptococcus pneumoniae is the most common cause of
meningitis, otitis media, pneumonia, and sinusitis (MOPS)
93
the IgA protease of Streptococcus pneumoniae
cleaves IgA at the hinge region → decreased effectiveness of IgA → bacterial adherence to mucosa
94
sickle cell patients are more susceptible to infections from
encapsulated bacteria, such as Streptococcus pneumoniae
95
_______ are effective against Streptococcus pneumoniae
1. macrolides
| 2. ceftriaxone
96
The pure polysaccharide vaccine against Streptococcus pneumoniae
produces a predominantly IgM (B-cell) response and can be administered to adults; children <2 years of age must be given the protein conjugated vaccine (polysaccharide conjugated with a carrier protein) to elicit an IgG (T-cell) response
97
What kind of capsule does strep pnuemoniae have
polysaccharide capsule
98
viridans group streptococci are able to grow in the presence of
bile salts (via hydrolyzation of esculin)
99
Streptococcus mutans and sanguinis (viridans group streptococci) are
part of the normal flora of the mouth and play a role in tooth decay and the development of dental caries
100
viridans group streptococci can
1. adhere to previously damaged heart valves (most commonly the mitral valve) and establish infection, leading to subacute bacterial endocarditis
2. adhere to tooth enamel and fibrin-platelet aggregates on damaged heart valves due to their ability to produce dextrans (insoluble extracellular polysaccharides) from sucrose substrate
3. produce dextrans (insoluble extracellular polysaccharides) from sucrose substrate, which allows them to adhere to tooth enamel and fibrin-platelet aggregates on damages heart valves
101
Enterococcus faecium and faecalis bacteria are
1. gram positive cocci
2. able to grow in 6.5% hypertonic saline
3. able to grow in the presence of bile salts (via hydrolyzation of esculin)
102
Enterococcus faecium is responsible for
the minority (10-15%) of enterococcal infections
103
Enterococcus faecalis is responsible for
the majority (80-90%) of enterococcal infections
104
Enterococcus faecium and faecalis can cause
a variety of infections, including UTIs (cystitis, pyelonephritis), endocarditis, and biliary tree infection
105
some strains of Enterococcus faecium and faecalis have
developed resistance to multiple antibiotics, including vancomycin (vancomycin-resistant enterococci)
106
linezolid and tigecycine can be used to treat
vancomycin-resistant enterococcal (VRE) infection
