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Microbiology - Bacteria > Chapter 4: Gram-positive Bacteria: Streptococcus > Flashcards

Chapter 4: Gram-positive Bacteria: Streptococcus Flashcards

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0
Q

Streptococcus - morphology?

A

chains (strips) of cocci

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1
Q

Streptococci - Gram stain?

A

Gram-positive

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2
Q

Streptococcus - catalase?

A

catalase-negative

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3
Q

Group A streptococci - taxonomic name?

A

Streptococcus pyogenes

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4
Q

S. pyogenes - Lancefield antigen?

A

Group A streptococcus

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5
Q

Group A strep (S. pyogenes) displays what kind of hemolysis on blood agar?

A

beta (complete) hemolysis

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6
Q

Group A strep (S. pyogenes) can be differentiated from Group B strep (S. agalactiae) based on sensitivity to what?

A

bacitracin

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7
Q

Group A strep (S. pyogenes) is (sensitive, resistant) to bacitracin.

A

sensitive

“B-BRAS”

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8
Q

Group A strep (S. pyogenes) causes what 3 categories of diseases?

A

1) pyogenic
2) toxigenic
3) immunologic

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9
Q

Group A strep (S. pyogenes) causes what pyogenic diseases? (2)

A

1) pharyngitis

2) skin infections - cellulitis, impetigo, folliculitis, erysipelas, pyoderma

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10
Q

Group A strep (S. pyogenes) causes what toxigenic diseases? (3)

A

1) scarlet fever
2) toxic shock-like syndrome
3) necrotizing fasciitis

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11
Q

Group A strep causes what immunologic (antibody-mediated) diseases? (2)

A

1) rheumatic fever

2) acute glomerulonephritis

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12
Q

What is the major virulence factor for Group A streptococci (S. pyogenes)?

A

Protein M

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13
Q

What is M protein and which microbe expresses it?

A

M protein is a major virulence factor for Group A streptococci (S. pyogenes).
It inhibits the activation of complement and protects the organism from phagocytosis.

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14
Q

What test can be used to detect recent Group A strep (S. pyogenes) infection? How does it work?

A

ASO titer. Following infection, anti-streptolysin O antibodies develop.

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15
Q

ASO titer is used to detect infection by what microbe?

A

Group A streptococci (S. pyogenes)

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16
Q

What is streptolysin O?

A

an enzyme that destroys red and white blood cells, and is the reason for the beta-hemolytic ability of Group A streptococci (S. pyogenes). It is oxygen labile (inactivated by oxygen). It is antigenic (ASO antibodies)

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17
Q

What is streptolysin S?

A

an enzyme that destroys red and white blood cells, and is responsible (with streptolysin O) for the beta-hemolytic ability of Group A streptococci (S. pyogenes). It is oxygen stable. It is not antigenic.

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18
Q

A throat swab rapid antigen detection test (RADT) can be used to specifically diagnose infection with what microbe?

A

Group A streptococcus (S. pyogenes)

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19
Q

What specific test can be used to quickly diagnose Group A streptococcus (S. pyogenes) infection?

A

throat swab rapid antigen detection test (RADT), immunologically detects group A Lancefield carbohydrate antigen

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20
Q

What toxins are produced by Group A streptococcus (S. pyogenes), and what diseases do they cause? (2)

A

1) pyrogenic toxin –> Scarlet fever

2) Exotoxin A (toxic shock syndrome toxin) (different from staphylococcus toxin TSST-1) –> Toxic shock-like syndrome

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21
Q

Pyrogenic toxin produced by Group A streptococcus (S. pyogenes) leads to what disease?

A

Scarlet fever

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22
Q

Exotoxin A is produced by what microbe?

A

Streptococcus pyogenes (Group A Strep)

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23
Q

Exotoxin A produces what disease?

A

Toxic shock-like syndrome (S. pyogenes)

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24
Q

How does streptococcus pyrogenic toxin released by Group A strep (S. pyogenes) lead to scarlet fever?

A

activates the endogenous mediators of sepsis, such as the cytokine IL-1

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25
Q

Scarlet fever results from what bacterial toxin?

A

Streptococcus pyrogenic toxin by Group A streptococcus (S. pyogenes)

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26
Q

How do strains of Group A streptococci (S. pyogenes) obtain streptococcus pyrogenic toxin leading to scarlet fever?

A

obtain exotoxin from a temperate bacteriophage by lysogenic conversion

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27
Q

streptokinase - function

A

activates plasminogen to plasmin to lyse fibrin clots. expressed by Group A strep (S. pyogenes)

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28
Q

What enzyme activates plasminogen to plasmin to lyse fibrin clots, and is expressed by Group A strep (S. pyogenes)?

A

streptokinase

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29
Q

What virulence factors does Group A streptococcus (S. pyogenes) express? (6)

A

1) M protein
2) Streptolysin O, streptolysin S
3) streptokinase
4) hyaluronidase
5) DNAse
6) anti-C5a peptidase

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30
Q

What enzyme breaks down proteoglycans of extracellular matrix, and is expressed by Group A strep (S. pyogenes) and S. aureus?

A

hyaluronidase

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31
Q

hyaluronidase - function

A

breaks down proteoglycans of extracellular matrix. Expressed by Group A strep (S. pyogenes) and S. aureus

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32
Q

What enzymes are responsible for the beta-hemolytic ability of Group A streptococcus (S. pyogenes)? Which are antigenic?

A

streptolysin O, streptolysin S

Streptolysin O is antigenic (ASO titer)

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33
Q

What microbe causes pharyngitis, skin infections, scarlet fever, toxic shock-like syndrome, necrotizing fasciitis, rheumatic fever, and acute glomerulonephritis?

A

Group A streptococcus (S. pyogenes)

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34
Q

The pyogenic diseases of pharyngitis and skin infection are caused by what microbe?

A

Group A streptococcus (S. pyogenes)

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35
Q

The toxigenic diseases of scarlet fever, toxic shock like syndrome, and necrotizing fasciitis are caused by what microbe?

A

Group A streptococcus (S. pyogenes)

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36
Q

The immunologic diseases of rheumatic fever and acute glomerulonephritis are caused by what microbe?

A

Group A streptococcus (S. pyogenes)

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37
Q

What skin infections can result from Group A streptococci (S. pyogenes)? (5) Define them.

A

1) Folliculitis - infection of hair follicle
2) Impetigo - vesicular blistered eruption that becomes crusty and flaky, frequently found around the mouth
3) Cellulitis - deep infection of the skin cells, producing red, swollen skin which is hot to the touch
4) Erysipelas - superficial infection of skin cells (dermis). Specific appearance of raised (erythematous) bright red rash with a sharp border
5) Pyoderma - pustule, usually on the extremity of the face, that breaks down after 4-6 days to form a thick crust, healing slowly to leave a depigmented area

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38
Q

Erysipelas are more common caused by (S. pyogenes; S. aureus)

A 
Streptococcus pyogenes (Group A strep)
Rarely caused by staphylococcus aureus
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39
Q

Define folliculitis.

A

infection of hair follicle

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40
Q

What is infection of the hair follicle called?

A

folliculitis

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41
Q

Define impetigo.

A

vesicular blistered eruption that becomes crusty and flaky, frequently found around the mouth

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42
Q

What is the term for vesicular blistered eruption that becomes crusty and flaky, frequently found around the mouth?

A

impetigo

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43
Q

Define cellulitis.

A

deep infection of the skin cells, producing red, swollen skin which is hot to the touch

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44
Q

What is the term for deep infection of the skin cells, producing red, swollen skin which is hot to the touch?

A

cellulitis

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45
Q

Define erysipelas.

A

superficial infection of skin cells (dermis). Specific appearance of raised (erythematous) bright red rash with a sharp border

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46
Q

What is the term for a superficial infection of skin cells (dermis), with a specific appearance of raised (erythematous) bright red rash with a sharp border?

A

erysipelas

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47
Q

Define pyoderma.

A

pustule, usually on the extremity of the face, that breaks down after 4-6 days to form a thick crust, healing slowly to leave a depigmented area

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48
Q

What is the term for a pustule, usually on the extremity of the face, that breaks down after 4-6 days to form a thick crust, healing slowly to leave a depigmented area?

A

pyoderma

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49
Q

Streptococcal pharyngitis - characteristics (4)

A

1) red, swollen tons and pharynx
2) purulent exudate on tonsils
3) fever
4) swollen lymph nodes

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50
Q

What is the clinical syndrome described by the following:

1) red, swollen tons and pharynx
2) purulent exudate on tonsils
3) fever
4) swollen lymph nodes

A

pharyngitis

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51
Q

scarlet fever - characteristics? (4)

A

1) fever
2) scarlet red rash: confluent erythematous sandpaper-like (fine, blanching) rash
3) circumoral pallor
4) strawberry tongue

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52
Q

What syndrome has these features?

1) fever
2) scarlet red rash: confluent erythematous sandpaper-like (fine, blanching) rash
3) circumoral pallor
4) strawberry tongue

A

scarlet fever

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53
Q

Describe the red rash caused by scarlet fever (texture, location, timing of onset and fading)

A

1) sand-paper like red rash (fine and rough-textured)
2) blanches upon pressure
3) appears 12–72 hours after the fever starts
4) generally begins on the chest and armpits and behind the ears. It may also appear in the groin
5) on the face, often shows as red cheeks with a characteristic pale area around the mouth (circumoral pallor)
6) is worse in the skin folds (so-called Pastia lines, where the rash runs together in the armpits and groin, appear and can persist after the rash is gone)
7) begins to fade three to four days after onset and desquamation (peeling) begins. “This phase begins with flakes peeling from the face. Peeling from the palms and around the fingers occurs about a week later.” Peeling also occurs in the axilla, the groin, and the tips of fingers and toes.

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54
Q

How do strains of streptococcus pyogenes (Group A strep) lead to necrotizing fasciitis?

A

Certain strains express M proteins that block phagocytosis, allowing the bacteria to move rapidly through tissue. S. pyogenes enter a break in the skin and follow a path along the fascia (between the subcutaneous tissue and muscle).

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55
Q

How is S. pyogenes (Group A strep) transmitted? (3)

A
  • respiratory droplets
  • food
  • direct inoculation to the skin
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56
Q

Rheumatic fever is caused by what bacterium? What mechanism?

A

S. pyogenes (Group A strep)

antibody-mediated

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57
Q

What are the major manifestations of rheumatic fever (other than fever)? (5)

A

JONES

1) Joints - migratory polyarthritis
2) Carditis (O for heart) - endocarditis, myocarditis, or pericarditis
3) Nodules - subcutaneous (rubbery nodules just under the skin) on extensor surfaces (wrist, elbow, knee)
4) Erythema marginatum rash - rash with a red margin that spreads out from its center
5) Sydenham’s chorea - uncontrolled dance-like movements of the extremities, usually begins 2-3 weeks after pharyngitis

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58
Q

What syndrome is characterized by these major criteria?

1) migratory polyarthritis
2) carditis
3) subcutaneous nodules on extensor surfaces
4) Erythema marginatum rash
5) chorea 2-3 weeks after pharyngitis

A

Rheumatic Fever

JONES criteria:

1) Joints - migratory polyarthritis
2) Carditis (O for heart) - endocarditis, myocarditis, or pericarditis
3) Nodules - subcutaneous (rubbery nodules just under the skin) on extensor surfaces (wrist, elbow, knee)
4) Erythema marginatum rash - rash with a red margin that spreads out from its center
5) Sydenham’s chorea - uncontrolled dance-like movements of the extremities, usually begins 2-3 weeks after pharyngitis

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59
Q

What is the cause of carditis in rheumatic fever?

A

There are antigens in the heart that are similar to the antigens of Group A strep (S. pyogenes). The antibodies that form to fight S. pyogenes infection cross-react with self-antigens in the heart.

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60
Q

After 10-20 years of recurrent infections with Group A strep (S. pyogenes), what can happen to the heart? specific site?

A

Initial myocarditis, followed by valvular heart disease (most frequently the mitral valve, followed by the aortic valve)

61
Q

How does Group A strep (S. pyogenes) cause acute glomerulonephritis?

A

A few strains of S. pyogenes are nephritogenic: Antigens from these bacteria induce an antibody response. The resulting antigen-antibody complexes travel to and are deposited in the glomerular basement membrane, where they activate the complement cascade, leading to local glomerular destruction in the kidney.

62
Q

How does acute post-streptococcal glomerulonephritis typically present? (4)

A

1) puffy face, caused by retention of fluid from damaged kidney
2) tea or coca-cola colored urine, due to hematuria
3) high blood pressure, from hypervolemia secondary to fluid retention
4) sore throat or skin infection ~1 week prior (impetigo more commonly precedes glomerulonephritis than pharyngitis)

63
Q

What is the differential diagnosis for a child presenting with:

1) puffy face
2) tea or coca-cola colored urine
3) high blood pressure
4) sore throat or skin infection ~1 week prior

A

acute glomerulonephritis caused by Group A strep (S. pyogenes) infection

64
Q

What are treatment options for Group A streptococcus (S. pyogenes) infection? (3+2)

A

1) Penicillin G - inhibits transpeptidase
2) Penicillin V (oral form - covers all organisms that penicillin G does)
3) erythromycin - macrolide, binds to 50S ribosomal subunit to inhibit protein synthesis
4) penicillinase-resistant penicillin for skin infections where staphylococcus could be the responsible organism
5) add clindamycin for invasive S. pyogenes infections such as necrotizing fasciitis or toxic shock like syndrome (lincomycin derivative, binds to 50S ribosomal subunit to inhibit protein synthesis)

65
Q

What is the treatment for Group A strep (S. pyogenes) skin infection where stapylococcus could also be the responsible organism?

A

penicillinase-resistant penicillin

66
Q

What is the treatment for invasive S. pyogenes infection (such as necrotizing fasciitis or toxic shock like syndrome)?

A

penicillin G (or V), plus clindamycin

67
Q

Group B streptococci - taxonomic name?

A

Streptococcus agalactiae

68
Q

S. agalactiae - Lancefield antigen?

A

Group B streptococcus

69
Q

Group B strep (S. agalactiae) displays what kind of hemolysis on blood agar?

A

beta (complete) hemolysis

70
Q

Group B strep (S. agalactiae) can be differentiated from Group A strep (S. pyogenes) based on resistance to what?

A

bacitracin

71
Q

Group B strep (S. agalactiae) is (sensitive, resistant) to bacitracin.

A

resistant

“B-BRAS”

72
Q

Where is Group B streptococci (S. agalactiae) commonly found?

A

25% of women carry these bugs vaginally, and a baby can acquire these bacteria during delivery

73
Q

What microbe is commonly carried vaginally and transmitted to the baby upon delivery, causing neonatal (<3 mos) meningitis, pneumonia, and sepsis?

A

Group B streptococcus (S. agalactiae)

74
Q

What diseases does Group B strep (S. agalactiae) cause? (3)

A

1) neonatal meningitis
2) neonatal pharyngitis
3) neonatal sepsis

75
Q

What factor produced by Group B streptococcus enlarges the area of beta hemolysis by Staph aureus on blood agar?

A

CAMP factor

formation of arrowhead when GBS streak meets S. aureus streak

76
Q

What microbe can the CAMP test identify? How?

A

Group B strep (S. agalactiae).
GBS is not strongly beta hemolytic on its own, but it produces CAMP, which enlarges the area of beta-hemolysis formed by Staph aureus, forming an arrowhead when streaked on blood agar.

77
Q

A positive hippurate test indicates the presence of which bacterium?

A

Group B streptococcus (S. agalactiae)

78
Q

How is the hippurate test used to detect Group B strep (S. agalactiae)?

A

Group B strep can hydrolyze hippurate to produce glycine and benzoate. Upon addition of the oxidizing agent ninhydrin, the glycine gets deaminated, and the ninhydrin gets reduced, forming a precipitate and becoming purple/brown (if no glycine is present, the solution stays clear)

79
Q

What is the treatment for Group B streptococcus (S. agalactiae) infection?

A

Penicillin G

80
Q

A pregnant woman is screened at 35-37 weeks, and is positive for Group B streptococcus (S. agalactiae) colonization. Should she be treated?

A

Yes - with intrapartum ampicillin prophylaxis
(Group B strep in pregnant women can cause bacteremia and sepsis, and secondary infection of the fetus resulting in stillbirth or spontaneous abortion in 30% of cases)

81
Q

What bacteria can cause neonatal meningitis (<3 mos)? (3)

A

1) Group B streptococcus (S. agalactiae)
2) E. coli
3) Listeria monocytogenes

82
Q

Group B strep, E. coli, and Listeria monocytogenes are the common causes of what disease?

A

neonatal meningitis

83
Q

What bacteria cause meningitis in older children (<5yo, after maternal antibodies wane but before new antibodies develop)? (2)

A

1) Neisseria meningitides

2) Haemophilus influenzae

84
Q

Neisseria meningitides and Haemophilus influenzae are the common causes of what disease?

A

Meningitis in older children (<5 yo)

85
Q

Enterococci and Non-enterococci - Lancefield antigen?

A

Group D

86
Q

Group D streptococci can be divided into 2 subcategories:

A

Enterococci and Non-enterics

87
Q

E. faecalis and E. faecium are species in what category of bacteria?

A

Group D streptococci - enterococci

88
Q

Group D streptococci (enterococci and non-enterococci) exhibit what type of hemolysis when grown on blood agar?

A

gamma (non) hemolytic

89
Q

E. faecalis exhibits what pattern of hemolysis when grown on blood agar?

A

Gamma (non) hemolytic

E. faecalis is Group D streptococcus / Enterococci

90
Q

E. faecium displays what pattern of hemolysis when grown on blood agar?

A

Gamma (non) hemolytic

E. faecium is Group D streptococcus / Enterococci

91
Q

S. bovis displays what pattern of hemolysis when grown on blood agar?

A

Gamma (non) hemolytic

S. bovis is Group D streptococcus, non-enterococci

92
Q

Major example species of Enterococci (2)

A

E. faecalis

E. faecium

93
Q

Major examples of non-enterococci Group D strep (2)

A

Streptococcus bovus

Streptococcus equinus

94
Q

Group D streptococci are commonly found in the gut. Are all Group D streptococci part of normal gut flora?

A

No: Enterococci (E. faecalis and E. faecum) are part of normal gut flora. Non-enterococci (S. bovis) is not part of normal gut flora.

95
Q

Where can Group D streptococcus (enterococci and non-enterococci) be found?

A

in the gut

Enterococci are part of normal gut flora, but S. bovis is not part of normal gut flora

96
Q

What diseases do Group D strep (enterococci such as E. faecalis and E. faecium; non-enterococci such as S. bovis and S. equinus) commonly cause? (3)

A

1) UTI
2) biliary tract infection
3) subacute bacterial endocarditis (SBE) (following GI/GU procedures)
(4) bacteremia and sepsis

97
Q

What special lab media conditions can enterococcus grow in?

A

40% bile

6.5% NaCl

98
Q

What special lab media can S. bovis grow in?

A

40% bile (but not 6.5% NaCl, unlike enterococci; not as hardy)

99
Q

These bacteria can grow in 40% bile or in 6.5% NaCl

A

Enterococci (group D strep): E. faecalis and E. faecium

100
Q

These bacteria can grown in 40% bile, but not in 6.5% NaCl

A

Non-enterococci (group D strep): S. bovis, S. equinus

101
Q

How can enterococci and non-enterococci Group D streptococci be differentiated based on growth in special media?

A

Enterococci can grow in both 40% bile and 6.5% NaCl.

Non-enterococci (S. bovis) can grow in 40% bile, but not in 6.5% NaCl.

102
Q

What are treatment options for non-resistant strains of enterococci? (2)

A

1) ampicillin with aminoglycoside (synergistic)
2) vancomycin with aminoglycoside (synergistic)
* Note, Group D strep are resistant to penicillin G

103
Q

Which streptococcus group is resistant to penicillin G?

A

Enterococci: E. faecalis, E. faecium

104
Q

What are treatment options for vancomycin-resistant enterococci (VRE)? (3)

A

1) linezolid - kills Gram+ bugs by blocking the 50S ribosomal subunit
2) daptomycin - a cyclic lipopeptide that kills Gram+ bugs by altering the microbe cell membrane electrical charge and transport
3) nitrofurantoin

105
Q

S. bovis infection is strongly correlated with what disease?

A

colon cancer (colorectal neoplasms)

“Bovis in the Blood: Cancer in the Colon”

106
Q

Infection with which microbe is strongly correlated with colon cancer (colorectal neoplasms)?

A

Stretococcus bovis

“Bovis in the Blood, Cancer in the Colon”

107
Q

What microbe commonly causes the following diseases:

1) UTI
2) biliary tract infection
3) subacute bacterial endocarditis (SBE) (following GI/GU procedures)

A

Group D streptococci:
Enterococci: E. faecalis, E. faecium
Non-enterococci: S. bovis, S. equinus

108
Q

S. viridans displays what pattern of hemolysis when grown on blood agar?

A

alpha (partial, green) hemolysis

109
Q

Which streptococci species are alpha hemolytic?

A

S. viridans

S. pneumoniae

110
Q

How can the alpha hemolytic streptococci species be differentiated? (3)

A

1) capsule - S.pneumoniae has a capsule; S. viridans does not
2) optochin - S.pneumoniae is susceptible; S. viridans is resistant (OVRPS)
3) bile - S. pneumoniae is bile soluble; S. viridans is bile insoluble

111
Q

Where are S. viridans found?

A

normal GI flora, frequently found in the nasopharynx and gingival crevices
(Viridans group strep live in the mouth because they are not afraid of-the-chin (op-to-chin resistant))

112
Q

Viridans group streptococci can cause which 3 main types of infections?

A

1) dental caries (S. mutans)
2) subacute bacterial endocarditis at damaged heart valve (such as from old rheumatic fever from S. pyogenes, congenital heart defect, or mitral valve prolapse) (S. sanguinis)
3) abscesses in brain or liver (S. intermedius)

113
Q

Which species of streptococcus bacterium is responsible for causing dental caries?

A

S. mutans of the viridans group streptococci

114
Q

S. mutans of the viridans group streptococci causes what disease? Mechanism?

A

dental caries. S. mutans can bind to teeth and ferment sugar, which produces acid and dental caries.

115
Q

Which species of viridans group streptococci causes subacute bacterial endocarditis?

A

S. sanguinis

116
Q

Which streptococcal species can cause subacute endocarditis? (2)

A

enterococcus (Group D strep)

S. sanguinis of viridans group streptococci

117
Q

Enterococci (Group D strep) and the viridans group of streptococci (S. sanguinis) can both cause what disease?

A

subacute (slow onset) endocarditis

118
Q

Enterococci (Group D strep) and S. viridans (S. sanguinis) express what molecule to cause subacute bacterial endocarditis (SBE)?

A

extracellular dextran helps them bind to fibrin-platelet aggregates on damaged heart valves

119
Q

Dextran is expressed by which bacterial species?

A

Enterococci (Group D. strep) and S. viridans (S. sanguinis)

120
Q

Extracellular expression of dextran by enterococci (Group D strep) and S. viridans (S. sanguinis) causes what disease?

A

subacute bacterial endocarditis. Extracellular dextran helps them bind to heart valves

121
Q

Which streptococcal species can cause brain and liver abscesses?

A

S. intermedius (anginosis)

“Streptococcus InterMeDius an AnginoSus - IMmeDiately Assess for ABSCESS”

122
Q

S. sanguinis of the viridans group of streptococci cause what disease?

A

subacute bacterial endocarditis (SBE)

123
Q

S. intermedius / S. anginosus can cause what disease?

A

abscess in the brain or liver

If find in the blood “Streptococcus InterMeDius and AnginoSus, IMmeDiately ASSess for ABSCESS”

124
Q

Abscesses in the brain or liver is associated with what streptococcal species?

A

S. intermedius / S. anginosus of the viridans group streptococci

125
Q

What is the treatment for infection with viridans group streptococci (S. mutans, S. sanguinis, S. intermedius/anginosus)?

A

penicillin G

126
Q

Appearance of streptococcus pneumoniae? (3)

A

lancet-shaped
Gram-positive cocci
diplococci (arranged in pairs)
encapsulated

127
Q

What Gram-positive cocci is lancet-shaped and arranged in pairs (diplococci)?

A

Streptococcus pneumoniae

128
Q

S. pneumoniae displays what pattern of hemolysis when grown on blood agar?

A

alpha (partial, green) hemolysis

129
Q

S. pneumoniae is optochin (sensitive, resistant)

A

sensitive

130
Q

S. pneumoniae is bile (soluble, insoluble)

A

soluble (lysed by bile)

131
Q

What is the major virulence factor of pneumococcus (S. pneumo)?

A

polysaccharide capsule, which protects the organism from phagocytosis
-no virulence without capsule

(also IgA protease)

132
Q

Other than its polysaccharide capsule, what is another major virulence factor of S. pneumoniae?

A

IgA protease

133
Q

Is the S. pneumoniae polysaccharide capsule antigenic?

A

Yes, but there are 84 different capsule serotypes, so surviving an infection with one strain only provides immunity to 1 out of 83 possible capsule types

134
Q

What is the most common cause of pneumonia in adults?

A

Streptococcus pneumoniae

135
Q

S. pneumoniae is the most common cause of what diseases? (4)

A

1) meningitis
2) otitis media (in childreN)
3) pneumonia
4) sinusitis

MOPS are Most Optochin Sensitive (and remember OVRPS)

136
Q

What is the most common cause of bacterial meningitis in adults?

A

Streptococcus pneumoniae

137
Q

What is the most common cause of otitis media (middle ear infection) in children?

A

Streptococcus pneumoniae

138
Q

How does pneumococcal (S.pneumoniae) pneumonia present on physical exam? (5)

A

1) sudden onset
2) shaking chills (rigors)
3) fever
4) chest pain with respirations
5) shortness of breath

-Get a CXR and sputum culture

139
Q

How does pneumococcal (S.pneumoniae) pneumonia appear on chest X-ray?

A

white consolidated lobe: the alveoli of one or more lung lobes fill up with white blood cels (pus), bacteria, and exudatae

140
Q

How does pneumococcal (S.pneumoniae) pneumonia present on sputum culture?

A

the patient will cough up yellow-green phlegm (“rusty sputum” from hemoptysis caused by coughing) that on Grm stain reveals gram-positive lancet-shaped diplococci

141
Q

How does meningitis in neonates (Group B strep) differ from meningitis in adults (S. pneumoniae)?

A 
Nuchal rigidity (stiff neck), the classic sign of meningitis, is usually present in an adult with meningitis.
Nenoates with meningitis don't usually present with stiff neck, but display nonspecific signs such as fever, vomiting, poor feeding, and irritability.
142
Q

What bacterium is commonly associated with the following diseases?

1) meningitis (in adults)
2) otitis media (in children)
3) pneumonia (in adults)
4) sinusitis

A

Streptococcus pneumoniae

143
Q

S. pneumoniae is associated with sepsis in what patient populations?

A

asplenecis/splenectomy

sickle cell anemia (functionally asplenic)

144
Q

Is there a vaccine for pneumoniae? What is it made of and who is it given to?

A
  • Pneumovax has 23 of the most common capsular polysaccharide antigens against Streptococcus pneumoniae.
  • Given to asplenics, or with HIV disease who are unable to defend themselves against encapsulated bacteria.
  • Prevnar (13 valent conjugated vaccine) can also reduce cases of otitis media in children
145
Q

S. pneumoniae is (positive, negative) for the Quellung test.

A

positive - it has a polysaccharide capsule that swells when tested against antiserum containing anti-capsular antibodies

146
Q

How is S. pneumoniae transmitted?

A

respiratory droplets

147
Q

What are Pneumovax and Prevnar? Who are the target populations?

A

Both are S. pneumococcus vaccines.
Pneumovax contains 23 of the most common capsular polysaccharide antigens. Given to asplenic, immunocompromised, elderly.
Prevnar is a 13-valent conjugte vaccine. Given to children <5 to prevent pneumonia and otitis media.

148
Q

What is the treatment for S. pneumoniae infection? (3)

A

1) penicillin (high-dose intramuscular (IM))
2) erythromycin
3) ceftriaxone (third generation cephalosporin)

149
Q

Enterococci - morphology?

A

Gram-positive cocci in pairs

Microbiology - Bacteria (15 decks)

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