MT 37 (LEC): Gram-positive cocci 1

0.0(0)
studied byStudied by 0 people
learnLearn
examPractice Test
spaced repetitionSpaced Repetition
heart puzzleMatch
flashcardsFlashcards
Card Sorting

1/144

encourage image

There's no tags or description

Looks like no tags are added yet.

Study Analytics
Name
Mastery
Learn
Test
Matching
Spaced

No study sessions yet.

145 Terms

1
New cards

Micrococcaceae, Staphylococcaceae

Cocci Classifications (Family)

2
New cards

MICROCOCCI

  • gram + cocci in the family: micrococcaceae

  • Normal flora: skin, mucosa, and oropharynx

  • contaminants of clinical specimens

  • rarely implicate as cause of infections in humans

3
New cards

MICROCOCCI

  • May cause brain abscess, meningitis, pneumonia, and endocarditis in immunocompromised patients

4
New cards

MICROCOCCI

Gram-positive cocci in packets of four (tetrads) or eight cocci

5
New cards

M. Flavus, M. Luteus, M. Lylae, M. Roseus, M. Dentrificans, M. Varians, M. Freudenreichii

Species from the genus Microccocus

6
New cards

M. roseus

Micrococcus Found in the dust of the air

7
New cards

M. dentrificans

Micrococcus found in soil

8
New cards

M. colpogenes

Micrococcus found in marine waters

9
New cards

M. flavus

  • Microccocus in Skin, skin glands, or skin-gland secretions of vertebrates

  • Usually found in humans

10
New cards

M. luteus, M. varians, and M. freudenreichii

  • “Milk micrococci”

  • Cause spoilage of milk

11
New cards

M. lylae

microccocus found on the skin, dust, and water

12
New cards

STAPHYLOCOCCI

  • Growth requires supplementation with various amino acids and other growth factors (Enriched Media)

  • NF: skin, mucous membrane, and intestine

13
New cards

STAPHYLOCOCCI

Facultative anaerobe & catalase (+)

14
New cards

Facultative anaerobe

  • It can thrive with or without the presence of oxygen

  • with oxygen = aerobic respiration

  • without oxygen = fermentation to produce ATP

15
New cards

Catalase

  • enzyme that detoxifies hydrogen peroxide to prevent bacterial cell wall disruption

  • Results to the “bubble” reaction if positive

  • produced by Staphylococci

16
New cards

Positive catalase reaction

  • bubble forms due to the conversion of hydrogen peroxide (H2O2) into H2O + O2

17
New cards

Staphylococci

  • Nonmotile, non-spore-former, and glucose fermenter

18
New cards

Staphylococci

Grows in 7.5% NaCl (halotolerant)

19
New cards

Staphylococci

Resistant to heat and drying, and thus can persist for long periods on fomites (inanimate objects)

20
New cards

Staphylococci

  • Species are initially differentiated by coagulase test

21
New cards

Coagulase test

  • enzyme causes coagulation by converting fibrin to fibrinogen

  • Coagulation in tube test

  • Agglutination in plasma (slide test)

22
New cards

Blood Agar Plate (BAP)

Culture media for STAPHYLOCOCCI

23
New cards

Staphylococci in BAP

  • 4-8mm colonies,

  • creamy, white to light gold,

  • “buttery-looking” (unique charact.)

  • some species are grayish & ßhemolytic

<ul><li><p>4-8mm colonies, </p></li><li><p>creamy, white to light gold, </p></li><li><p><strong>“buttery-looking” (unique charact.)</strong></p></li><li><p>some species are grayish &amp; ßhemolytic</p></li></ul><p></p>
24
New cards

Buttery-looking

Unique characteristic of staphylococcus growing in BAP

25
New cards

Alpha hemolysis, beta hemolysis, gamma (non-hemolytic)

Hemolytic Reactions in SBA

26
New cards

Alpha hemolysis

  • green zone around colony

  • Narrow or wide

  • Partial lysis of RBCs

<ul><li><p><strong>green zone</strong> around colony</p></li><li><p>Narrow or wide</p></li><li><p><strong>Partial</strong> lysis of RBCs</p></li></ul><p></p>
27
New cards

Beta hemolysis

  • clear zone around colony

  • Narrow or wide

  • Complete lysis of RBCs

<ul><li><p><strong>clear</strong> zone around colony</p></li><li><p>Narrow or wide</p></li><li><p><strong>Complete</strong> lysis of RBCs</p></li></ul><p></p>
28
New cards

Gamma (non-hemolytic)

  • no zone of hemolysis

  • No lysis

<ul><li><p>no zone of hemolysis</p></li><li><p>No lysis</p></li></ul><p></p>
29
New cards

Staphylococcus aureus

  • Normal flora: Anterior nares, nasopharynx, perineal area, skin, and colonizer of mucosa

30
New cards

Staphylococcus aureus

  • Endogenous strain: sterile site by traumatic introduction

  • Direct contact: person-to-person, fomites

  • Indirect contact: aerosolized

31
New cards

Staphylococcus epidermidis

  • Normal flora: Skin, mucous membranes

32
New cards

Endogenous strain, Direct Contct

MOT of Staphylococcus epidermidis, S. haemolyticus, S. lugdunensis

33
New cards

Staphylococcus saprophyticus

Normal flora: skin, genitourinary tract, mucosa

34
New cards

Staphylococcus saprophyticus

  • Endogenous strain: sterile urinary tract, notably in young, sexually active females

  • Common cause UTI

35
New cards

Staphylococcus haemolyticus, Staphylococcus lugdunensis

  • Normal flora: skin, mucous membranes (low numbers)

36
New cards

Staphylococcus aureus

  • Most clinically significant species of staphylococci

  • the most virulent species of staphylococcus

37
New cards

False, true-coagulase positive

S. aureus is true coagulase-negative (TRUE/FALSE)

38
New cards

Facultatively anaerobic

What type of anaerobe is S. aureus?

39
New cards

False, it is non-motile and non-spore-forming

S. aureus is motile, spore-forming (TRUE/FALSE)

40
New cards

Positive; negative

S. aureus is catalase ___ and oxidase ___

41
New cards

7.5%

S. aureus: Tolerance to ____ sodium chloride

42
New cards

Mannitol

What does S. aureus ferments what sugar alcohol?

43
New cards

Hyaluronidase

What enzyme does S. Aureus produce?

44
New cards

Capsule, slime layer, peptidoglycan, techoic acid, Protein A

Enumerate the VIRULENCE FACTORS

45
New cards

Virulence factors

  • Helps the bacteria evade the immune system

46
New cards

Capsule

  • Inhibits chemotaxis and phagocytosis;

  • inhibits proliferation of mononuclear cells

47
New cards

Neutrophils, Macrophages, Phagocytes

Wbcs that perform phagocytosis

48
New cards

Biofilm

a thin, slimy film of bacteria that adheres to a surface.

49
New cards

Slime layer

  • Facilitates adherence to foreign bodies;

  • inhibits phagocytosis

  • Prevents penetration of antibiotics

50
New cards

Slime layer

  • Prevents penetration of antibiotics

51
New cards

Peptidoglycan

  • Provides osmotic stability;

  • inhibits phagocytosis

52
New cards

Peptidoglycan

  • leukocyte chemoattractant (abscess formation);

53
New cards

Peptidoglycan

  • stimulates production of endogenous pyrogen (endotoxin-like activity);

54
New cards

Abscess formation

  • difficult to treat with antibiotics due to failure to penetrate

  • Made by S. aureus

  • can be removed through drainage (if deep within tissue)

55
New cards

Boils, furuncles, carbuncles

Examples of abscess formations due to S. aureus

56
New cards

Peptidoglycan

  • thick layer in the cell wall in S. aureus

  • What contains the crystal violet within the cell wall

57
New cards

Teichoic acid

  • for adherence

  • Binds to fibronectin

58
New cards

Protein A

  • Inhibits antibody-mediated clearance by binding IgG, IgG2, and IgG4 Fc receptors;

  • anti-complementary by creating a pore in the cell wall or cell-membrane

59
New cards

Protein A

  • leukocyte chemoattractant;

60
New cards

Staphylocoagulase/Coagulase, Hyaluronidase, Lipase, DNAse and phosphatase, β-lactamase

Virulence factors: Enzymes and toxins produced by S. aureus

61
New cards

Staphylocoagulase/Coagulase

  • Coagulates fibrinogen in plasma (causes abnormal clotting)

  • Promotes the formation of a fibrin layer around the staphylococcal abscess thereby protecting the bacteria from phagocytosis

62
New cards

Cell-bound coagulase or clumping factor, Unbound or free coagulase

2 types of coagulase

63
New cards

Cell-bound coagulase or clumping factor

  • Bound to the cell wall and clots human, rabbit, or pig plasma by directly converting fibrinogen into fibrin

  • Detected by slide method

64
New cards

Slide method

  • Detects Cell-bound coagulase or clumping factor

  • Faster method compared to tube method

65
New cards

Unbound or free coagulase

  • An extracellular enzyme that is not bound to the cell wall;

  • Performed by tube method because it requires incubation

66
New cards

Tube method

  • Detects Unbound or free coagulase

  • Requires incubation (18-24 hours)

67
New cards

Unbound or free coagulase

  • causes clot formation when bacterial cells are incubated with plasma

68
New cards

Hyaluronidase

  • Spreading factor enzyme

  • Helps the bacteria reach more places to infect

  • Enhances invasion and survival of S. aureus in the tissue and skin

69
New cards

Hyaluronidase

Breaks down hyaluronic acid that is present in the intracellular ground substance of connective tissues, resulting in the spread of bacteria

70
New cards

fibrinolysin

Staphylokinase Is Also known as?

71
New cards

Staphylokinase

  • Causes fibrinolytic activities by dissolving fibrin clots

  • Proteolytic enzyme

  • Helps S. aureus establish skin infections

72
New cards

Staphylokinase, Hyaluronidase

Enzymes that Help S. aureus establish skin infections

73
New cards

Lipase

  • Produced by both coagulase-negative and coagulase-positive staphylococci

74
New cards

Fat-splitting enzyme

Lipase Is aka?

75
New cards

Lipase

  • Essential for bacterial survival in the sebaceous areas of the body

  • Found in armpits, hair follicles, and other areas that are rich in oil and fats

76
New cards

Lipase

Important in the formation of furuncles, carbuncles, and boils

77
New cards

DNAse and phosphatase

  • Lower the viscosity of exudates giving the pathogen more mobility

78
New cards

Exudates

  • mass of cells in fluid (nana)

  • Viscous

79
New cards

DNAse and phosphatase

Destroys DNA

80
New cards

β-lactamase

  • produced in response to antibiotics

  • Breaks down penicillin and other β-lactam drugs

81
New cards

β- lactam drugs

  • Inhibits cell wall synthesis like hindering peptidoglycan synthesis

82
New cards

Enterotoxins, Leukocidin, Exfoliatin serotypes A and B or Epidermolytic toxins A and B, Hemolysin, Toxic Shock Syndrome Toxin-1 (TSST-1)

VIRULENCE FACTORS: Toxins produced by S. aureus

83
New cards

Enterotoxins

  • heat-stable at 100°C for 30 minutes

84
New cards

30 minutes

Enteroxins are heat-stable at 100°C for?

85
New cards

30% to 50%

Enterotoxins are Produced by ___% to ___% of S. aureus isolates

86
New cards

Enterotoxins

Resistant to hydrolysis by gastric and jejunal enzymes

87
New cards

Enterotoxins A, B, and D

  • Enterotoxins responsible for food poisoning with A being the most common cause

88
New cards

Enterotoxins B, C, G, and I

  • Enterotoxins associated with TSS (Toxic shock syndrome)

89
New cards

Enterotoxin B

  • enterotoxin associated with pseudomembranous enterocolitis and is often found in contaminated milk products

90
New cards

Pseudomembranous enterocolitis

  • mainly cause by Clostridium difficile and sometimes by S. aureus

91
New cards

Enterotoxin

  • Neurotoxin

  • stimulates the vagus nerve (a nerve responsible for nusea center of brain)

  • if ingested by host, host keeps vomiting

92
New cards

Leukocidin

  • Attacks and kills white blood cells (PMN, macrophage, and monocytes)

93
New cards

Panton-Valentine Leukocidin (Cytolytic toxin)

Leukocidin is aka?

94
New cards

Leukocidin

Pore-forming exotoxin that suppresses phagocytosis

95
New cards

Leukocidin

Responsible for severe cutaneous infections and necrotizing pneumonia

96
New cards

Exfoliatin serotypes A and B (superantigens)

  • aka Epidermolytic toxins A and B

97
New cards

Exfoliatin serotypes A and B (superantigens)

  • Divides the intracellular bridges of the epidermis resulting to extensive sloughing to produce burn-like effect

98
New cards

Superantigens

  • overstimulates the immune system

  • Causes the host to Excessively produce cytokines

  • Eventually results to organ failure

99
New cards

Stratum granulosum

Exfoliatin serotypes A and B (superantigens) destroys what layer of the skin/

100
New cards

Bullous impetigo

Exfoliatin serotypes A and B (superantigens) Has been implicated in What disese?