Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

MICR 3343 > Staphylococcus and Streptococcus > Flashcards

Staphylococcus and Streptococcus Flashcards

(51 cards)

Start Studying
1
Q

Staphylococcus

A
  • one of the most opportunistic infections in hospitals
  • gram stain purple
  • grapes
  • facultative anaerobes
  • grow in high salt
  • catalase positive
  • skin, soft tissues, bones, urinary track
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Pathology depends on

A
  • production of surface proteins that mediate adherence to host tissues
  • secretion of extracellular toxins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Alpha toxin

A

genome and plasmid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

B toxin

A

shingomyelinase C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Gamma toxin

A

detergent like action

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Y toxin

A

cell lysis

-S and F pore formation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Exfoliative toxins

A

Staphylococcal scalded skin syndrome SSSS

  • mostly in young children
  • produced by 5-10% of S aureus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Enterotoxins

A
  • contaminated food

- stable to healing, gastric enzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Toxic Shock Syndrome Toxin-1 (TSS-1)

A
  • can penetrate mucosal barriers (systemic infection)

- death by hypovolemic shock (leads to multi-organ failure)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Staphylococcal enzymes

A
  • coagulase (fibrinogen) cells clump
  • Hyaluronidase (hydrolyzes connective tissue)
  • Fibrinolysin (dissolve fibrin clots)
  • Lipases (hydrolyze lipids) ensure survival of fatty tissue
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Spread

A
  • tissue-degrading enzymes (lipase) cutaneous, subcutaneous tissues
  • hyaluronidase (connective tissue)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Staphylococcal Scalded Skin Syndrome SSSS

A
  • young children
  • localized erythema (redness/inflammation) starts around mouth, covers entire body in 2 days
  • large blisters
  • skin peels
  • mortality rate is low
  • Bullous impetigo is a localized form
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Staphylococcal food poisoning

A
  • not an infection
  • food contaminated by humans
  • recovery occur within hours
  • symptoms: vomiting, nausea, diarrhea, abdominal pain
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Toxic schock syndrome

A
  • fever, hypotension, rash
  • desquamation, vomiting, diarrhea
  • organs involved: CNS, GI, hematologic, hepatic, muscles and renal
  • mortality 5%
  • high rate of occurrence
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Cutaneous infections (pyogenic)

A
  • impetigo (pus filled vesicles, dry crusted lesions)
  • folliculitis
  • furuncles (bolis)
  • carbuncles (require surgical drainage and antibiotics)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Pneumonia

A
  • aspiration of oral secretions
  • very young, elderly, chronically ill
  • patchy infiltrates, abscesses
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Osteomyelitis and septic arthritis

A
  • dissemination to bone, secondary infection, or migration from adjacent site
  • localized pain, high fever
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Septic arthritis

A

-painful, red joints, pus present on aspiration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Staphylococcus epidermis

A
  • major component of skin flora
  • opportunistic infection
  • noncomial infection
  • endocarditis - native heart valves
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Staphylococcus saprophyticus

A
  • urinary track infections (UTIs)

- coagulase-negative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Identification of S. aureus

Study These Flashcards
A

B hemolytic: sheep blood agar (rings)

  • yellow pigmented (aureus)
  • coagulase positive
  • Mannitol fermentation
22
Q

Identification of S. epidermis

Study These Flashcards
A

Non-hemolytic: sheep blood agar

  • non-pigmented
  • does not ferment mannitol
  • coagulase negative
23
Q

Antibiotic therapy

Study These Flashcards
A
  • Resistant to penicillin (penicillinase)
  • B-lactam antibiotics (often ineffective, modified penicillin binding proteins)
  • Vancomycin (current drug of choice, resistance has been observed)
24
Q

Vancomycin resistance

Study These Flashcards
A
  • Low level: thicker, more disorganized cell wall, drug may be trapped in cell wall; unable to reach membrane
  • High level uncommon: vanA gene operon from enterococci, modified peptidoglycan layer cant bind vancomycin
25
Streptococcus
- gram positive - facultative anaerobes - chains or pairs - catalase negative
26
Hemolysis on sheep blood agar *alpha*
partially hemolysis, green color
27
Hemolysis on sheep blood agar *beta*
complete clearing around the colony
28
Hemolysis on sheep blood agar *gamma*
No color change, no hemolysis
29
Hemolysis and streptococcus
- Groups A and B (beta) - Group D (alpha or gamma) - S. pneumoniae and viridans (alpha)
30
S. pyogenes
- avoids phagocytosis (hyaluronic acid capsule), inactivate complement cascade C3b, C5a - adheres to surface of host cell by 10 dff antigens - invades epithelial cells (M and F proteins)
31
S. pyogenes toxins and enzymes
- heat-labile toxins SpeA, SpeB, SpeC, SpeF - act as super antigens: TH cells enhanced release proinflamatory cytokines - Streptolysin S : B-hemolyses - Streptolysin O: oxigen labile, inhibited by cholesterol in skin infections
32
Steptokinase (A and B)
- rapid spread in tissues - cleave plasminogen to plasmid, which cleaves fibrin and fibrinogen resulting in lysis of blood clots and fibrin deposits - alpha-spreptokinase antibodies useful markers for infection
33
DNases A-D
- breakdown of free DNA in pus - reduces viscosity, facilitates spread - alpha-DNase B antibodies an important maker for skin infection
34
Pharyngitis (strep throat)
- 2-4 day after exposure - sore throat, fever, malaise, headache - red posterioir pharynx with exudate pus - Scarlet fever due to pyrogenic exotoxin
35
Pyoderma (impetigo)
- skin infection - direct contact with an infected person - enters to break in skin - blisters form, fill with pus, break, crust over - regional lymph nodes enlarge
36
Erysipels
- accute skin infection | - pain infamation, lymph nodes enlarged, systemic signs (fever, chills, leukocytosis)
37
Cellulitis
- skin and deeper subcutaneus tissues - hard to tell infected from uninfected skin - local inflamation systemic signs
38
Acute stage of eryspelas
- erythma *redness* | - bullae *blisters*
39
Necrotizing fasciitis
- deep on subcutaneus tissue - extensive destruction of muscle, fat - introduced through break in skin - toxicity multiorgan failure, death
40
Rheumatic fever
- can occur after pharyngeal strep only - inflammatory changes in heart, joints, blood vessels, subcutaneous tissue - specific class IM protein types
41
Acute glomerulonephritis
- occur after pharyngeal or pyodermal strep | - acute inflammation of renal glomeruli: edema hypertension, hematuria, protein in both blood and urine
42
Laboratory diagnosis S. pyogenes
- microscopy: Gram + cocci, pairs or chains, associated with leukocytes - Antigen detection: group specific carbohydrate in throat swab
43
culture on blood agar + antibiotics PHARYNGITIS
swab tonsils
44
culture on blood agar + antibiotics IMPETIGO
pus from a closed lesion
45
culture on blood agar + antibiotics NECROTIZING FASCIITIS
blood tissues
46
culture on blood agar + antibiotics ERYSIPELAS and CELLULITIS
not useful
47
PYR test
+: red color | -: white no color change
48
Treatment, prevention control S. pyogenes
- penicillin (oral cephalosporin if allergic to pen) - oxacillin or vancomycin id S. aureus is also present - can prevent rheumatic fever - resistant to tetracyclines, sulfonamides, erythromycin, macrolides
49
S. pneumoniae
- alpha hemolytic - pneumolysin (degrades red blood cells under aerobic conditions) - grows well on sheep blood agar - no group antogen
50
Diagnosis S. pneumoniae
- spinal fluid - direct gram stain - detection of capsular antigen - optochin sensitive
51
Treatment prevention contral S. pneumoniae
- levofloxacin or vancomycin-ceftriaxone - resistance to penicillin, erythromycin, tetracycline, cephalosporins - anticapsular vaccin prevention - 23 different capsule polysaccharies

MICR 3343 (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions