Staphylococcus Flashcards
(97 cards)
1
Q
• ^ peptidoglycan; + v level of lipid (cell wall)
A
Gram Positive Cocci
2
Q
Gram + cocci
Lead to accumulation of neutrophils, bacterial cells, and fluids at the site
> ___________
A
Pyogenic infection
3
Q
All gram positive cocci (14)
A
- Staphylococcus
- Streptococcus
- Stomatococcus
- Salinicoccus
- Leuconostoc
- Lactococcus
- Aerococcus
- Alloiococcus
- Planococcus
- Pediococcus
- Micrococcus
- Macrococcus
- Gemella
- Rothia
4
Q
Reclassification of Gram Positive Cocci
• In 1996:
A
Bergey’s Manual of Systematic Bacteriology
• Family Micrococcaceae includes 4 genera:
• Micrococcus
• Planococcus
• Staphylococcus
• Stomatococcus
5
Q
In 1996: Bergey’s Manual of Systematic Bacteriology
• Family Micrococcaceae includes 4 genera:
A
• Micrococcus
• Planococcus
• Staphylococcus
• Stomatococcus
6
Q
• Ribosomal RNA & DNA Hybridization Analysis
• Recent Edition:
• 2 families:
A
• Family Staphylococcaceae
• Family Micrococcoceae
7
Q
Family Staphylococcaceae
• Includes :
A
• Genus Gemella
• Genus Staphylococcus
• Genus Salinicoccus
• Genus Macrococcus
8
Q
Family Micrococcaceae
• Includes:
A
• Genus Micrococcus
• Genus Arthrobacteria
• Genus Kocuria
9
Q
Stomatococcus mucilaginosus
• Only member of the Genus Stomatococcus
• Reclassified under the Genus Rothia
_____________
A
Rothia mucilaginosus
10
Q
Mucilanigosus
• [can/cannot] grow in the presence of 5% NaCl
• Weakly_____ (+),______ (-) and has a_____
• Emerging pathogen in______
A
Cannot
catalase, coagulase; capsule
immunosuppressed patients
11
Q
M vs S
Bacitracin (0.04 unit)
Micrococcus
Staphylococcus
A
Susceptible
Resistant
12
Q
M vs S
Furazolidone (100 ug/mL)
Micrococcus
Staphylococcus
A
Resistant
Susceptible
13
Q
M vs S
Lysostaphin (200 ug/mL)
Micrococcus
Staphylococcus
A
Resistant
Susceptible
14
Q
M vs S
Carbohydrate Utilization (OF Medium)
A
Oxidative
Fermentative
15
Q
M vs S
Modified Oxidase (Microdase) test
Micrococcus
Staphylococcus
A
Positive
Negative
16
Q
M vs S
Growth on Furoxone-Tween 80-oil red 0 agar
Micrococcus
Staphylococcus
A
Positive
Negative
17
Q
Staphylococcus
Significant human species: SHHEAW
A
- S. saprophyticus
- S. hominis
- S. hemolyticus
- S. epidermidis
- S. aureus
- S. warneri
18
Q
Staphylococcus: General Characteristics
Clinically Significant:
A
• S. aureus
• S. epidermidis
• S. saprophyticus
19
Q
Staphylococcus
• Catalase____
• G (+) соссі
• motile? Spore forming?
• O2 requirement???
• Modified oxidase___
• Reduces___ to ____
• Grows in ____ to ____NaCl
• Lysostaphin____
• Bacitracin____
A
(+)
Nonmotile & Non-spore forming
Facultative anaerobes
(-)
nitrates to nitrites
7.5% to 10%
sensitive
resistant
20
Q
Staphylococcus
• Transmission:
• Infections:
A
Direct contact
Fomites
poor hygiene
virulence of strain
size of inoculum
Immune status
21
Q
Staphylococcus aureus
VIRULENCE FACTORS
A
• Surface structures
• Enzymes
• Toxins
22
Q
Staphylococcus aureus
SURFACE STRUCTURES
A
- Protein A
- Capsular polysaccharide
- Peptidoglycan & Teichoic acid*
23
Q
SAU Enzymes
A
Enzymes
• Catalase
• Bound coagulase
• Staphylokinase
• Lipase
• Hyaluronidase
• DNase
• Beta lactamase
24
Q
SAU toxins
A
Toxins
• Exfoliatin
• Leukocidin
• Hemolysins
• Enterotoxins
• Superantigens
25
Staphylococcus aureus
SURFACE STRUCTURES
• binds to Fc region of IgG
• affects the immediate & delayed hypersensitivity reactions
Protein A
26
SAU surface structure
• Anti-phagocytic
•Enhance binding to host cells & prosthetics
protein A
antibody.
Capsular polysaccharide
27
SAU
• Chemoattractant for neutrophils; Activates complement
• Elicits production of IL-1 & opsonic Abs by monocytes
• mediates adhesion by binding to tissue fibronectin*
Peptidoglycan & Teichoic acid*
28
Staphylococcus aureus
DISEASE PROCESS
• SAU → invades tissues & produce toxins
• Organism spread (site of carriage) → site of infection (breaks on the skin)
• Organism → blood → lungs, bones, liver, brain, or heart
29
Staphylococcus aureus
DISEASES
Types of Staphylococcal Diseases:
• Local Abscesses
• Focal Suppuration
• Diseases caused by toxin elaboration
30
SAU
LOCAL ABSCESSES
• Folliculitis
• Furuncles (Boils)
• Carbuncles
• Sty
31
SAU
FOCAL SUPPURATION
• Osteomyelitis
• Pneumonia
• Meningitis
• Empyema
• Endocarditis
• Sepsis
• Impetigo / Pyoderma
32
EXOTOXIN ELABORATION
• Enterotoxins A & B
Nausea, vomiting & abdominal pain
• FOOD POISONING
33
EXOTOXIN ELABORATION
• Enterotoxins A & B
Nausea, vomiting & abdominal pain
• FOOD POISONING
34
EXOTOXIN ELABORATION
Epidermolytic toxin/ exfoliatin = Exfoliation
• SCALDED SKIN SYNDROME
35
EXOTOXIN ELABORATION
• multisystemic disease
• TSST-1 producing strains of SAU
• TOXIC SHOCK SYNDROME
36
GENERAL CHARACTERISTICS
• Normal flora of skin & mucous membranes
• G (+) cocci in clusters
Staphylococcus epidermidis
37
Staphylococcus epidermidis
GENERAL CHARACTERISTICS
• Virulence factor
• Biofilm production
• cell surface & extracellular compounds
• promote adherence of bacteria to surfaces of prosthetic devices.
38
Staphylococcus epidermidis
•______ growth on BAP
•____ growth on CNA
• _______on MSA
• Coagulase___
• DNase___
•____ to Novobiocin
White creamy non-hemolytic
+
Can grow but lacks fermentation
(-)
Susceptible
(-)
39
Staphylococcus epidermidis
DISEASES
catheters
prosthetic heart valve implantation
prosthetic devices: CNS shunts, intravascular catheters vimmunosuppression
HOSPITAL ACQUIRED
40
GENERAL CHARACTERISTICS
• Contaminant
• important cause of UTI among sexually active females
• Catheter-associated UTI
Staphylococcus saprophyticus
41
Staphylococcus saprophyticus
• Catalase___
• Coagulase___
• DNase___
• ___on BAP
• MSA____
•____ to 5 ug NOVOBIOCIN
(+)
(-)
(-)
Non-hemolytic
fermentation variable
Resistant
42
• Strains of SAU that are resistant to beta lactams
Methicillin Resistant
Staphylococcus aureus (MRSA)
43
• Many SAU strains produce______ and are _____
B-lactamase & are penicillin-resistant
44
• Significant nosocomial infection (HA-MRSA)
• CA-MRSA
Methicillin Resistant
Staphylococcus aureus (MRSA)
45
Methicillin Resistant
Staphylococcus aureus (MRSA)
Antibiotics
Oxacillin, cloxacillin & methicillin
46
Staphylococcus
Specimen Collection & Processing
Specimens:
+ NOTED
• Wound
• Blood
• Sputum
• Urine
• Do direct gram stain from specimen
• Gram (+) cocci & neutrophils are noted
47
Staphylococcus: Culture Medium
Sheep's Blood Agar Plate
Colistin Nalidixic Acid Agar (CNA)
Growth on MSA
Chromogenic Agar (Hardy Chrome Staph aureus agar)
48
• Medium, convex, creamy, dome shaped
• Pigment: white to golden yellow
Sheep's Blood Agar Plate
49
• Selective medium for growth of G(+) bacteria
• The medium is blood agar base with Antibiotics
Colistin Nalidixic Acid Agar (CNA)
50
• Selective & differential medium
• 1 salt (7.5%) = selective
• Mannitol & phenol red
Growth on MSA
51
Chromogenic Agar (Hardy Chrome Staph aureus agar)
______ appears deep pink to fuchsia colonies
______partially or completely inhibited
______appears turquoise colonies
• SAU
• S. epidermidis
• S. saprophyticus
52
Staphylococcus aureus
MACROSCOPIC CHARACTERISTICS
COLONIES
• Medium to large smooth, butyrous, creamy
• Margin is entire
• Staphyloxanthin (yellow pigment)
• Narrow zone of B-hemolysis (SBA
53
Test for Differentiation: Catalase Test
• Differentiate Staphylococcus from Streptococcus
54
Test for Differentiation: Coagulase Test
• Differentiate Staphylococcus aureus from CoNS
55
• Latex agglutination
• Latex particle (coated with human plasma fibrinogen & IgG) → reacts with clumping factor & protein A of
SAU
Rapid Detection of Coagulase Activity
56
Ex. BBL Staphyloslide Latex Test
• _____________→ cross-linking → agglutination w/ latex particle
Blue Latex reagent + SAU colonies
57
Test for Differentiation:
Modified Oxidase Test
• Differentiate Micrococcus from Staphylococcus
58
Modified oxidase test reagent
Reagent:
• 6% tetramethyl-p-phenylenediamine dihydrochloride in dimethyl sulfoxide
59
Modified Oxidase Test
Result:
• (+) =
• (-) =
dark blue - purple color
(Cytochrome C)
no change in color
60
Test for Differentiation:
Bacitracin Susceptibility Test
• Differentiate_______ _____ and ______
Micrococcus & Rothia
from Staphylococcus
61
Test for Differentiation:
Bacitracin Susceptibility Test
• Differentiate _____ and _____ to _____
•____ u Bacitracin disk
• Interpretation:
•_____ = Susceptible
• _____= Resistant
Micrococcus & Rothia from Staphylococcus
0.04
Zones > 10 mm
Zones < 10 mm or no zone of inhibition
62
Test for Differentiation:
Bacitracin____
• Differentiate Micrococcus & Rothia
from Staphylococcus
• 0.04 u Bacitracin disk
• Interpretation:
• Zones > 10 mm = Susceptible
• Zones < 10 mm or no zone of inhibition = Resistant
Susceptibility Test
63
Test for Differentiation:
Bacitracin Susceptibility Test
Micrococcus & Rothia :
Staphylococcus :
S
R
64
MOT
Result:
(Cytochrome C)
• (+) = dark blue - purple color
65
Test for Differentiation:
Novobiocin Susceptibility Test
• Differentiate S. saprophyticus from other CoNS
66
Test for Differentiation:
Novobiocin Susceptibility Test
• S. saprophyticus:_____
• other CoNS :_____
• Place____ of Novobiocin
Resistant
Sensitive
5ug
67
Novobiocin Susceptibility Test
Interpretation:
• Susceptible = zone > than 16 mm
• Resistant = zone < or = to 16 mm
68
Test for Differentiation:
• For the presumptive identification of S. aureus and differentiates it from CoNS.
• Methyl Green:
• Toluidine Blue O:
• Detection of thermostable nuclease
DNAse Test
colorless
bright pink color.
69
Detection of Antibiotic Resistant SAU
MRSA
1. Cefoxitin Disk Screen Test
2. Latex agglutination for PBP2a
3. MH agar with NaCl & 6 ug/mL of
Oxacillin
4. Chromogenic Agar
5. Detection of mecA gene or its product PBP2a
70
Treatment and Prevention
• Handwashing; local antisepsis
• Drainage of pus
• Surgical drainage, removal of tissue
-For S. aureus:
71
SAU
Antimicrobial Therapy:
• Methicillin, nafcillin, cloxacillin
• Vancomycin
• Tetracyclines
72
For
• Difficult to treat. Removal of the prosthetics may be done.
• 40% of CoNS are resistant to B-lactamase resistant antibiotics
S. epidermidis:
73
S. epidermidis:
• Treatment:
• Penicillin G
• semisynthetic penicillinase-resistant penicillins
• cephalosporins
• Vancomycin
74
• The majority of _______infections can be adequately treated with antibiotics.
• Untreated → progress to pyelonephritis.
S. saprophyticus
75
S. saprophyticus
• The antibiotic of choice: v Nitrofurantoin (Macrobid)
~ Trimethoprim-sulfamethoxazole (TMP-SMX)
• The antibiotic of choice: v Nitrofurantoin (Macrobid)
~ Trimethoprim-sulfamethoxazole (TMP-SMX)
76
will break down Hydrogen peroxide into water and oxygen (Bubble formation)
***Hydrogen peroxide*** is needed by the immune cells to function properly - no H202 means no immune action - no opsonization,
Catalase
77
will convert Fibrinogen into Fibrin which will result in a clot.
A clot in the body is toxic to the immune cells
Coagulase
78
Clotting factor
Bound Coagulase
79
TWO TYPES OF COAGULASE
(Clotting Factor)
(Tube Coagulase)
1. Bound coagulase
2. Free coagulase
80
Enzyme that dissolves the clot.
The clot becomes small particles - these STILL become toxic for the immune cells
Spreads infection throughout the body
Staphylokinase
81
Hydrolyze lipids in the skin / if ever the lipids have been hydrolyzed, this manifests
SKIN INFECTIONS caused by the Staphylococcus
boils, carbuncles, furuncles
Lipase
82
Hydrolyzes hyaluronic acid - it is responsible for the spread infection
Hyaluronidase
83
Also known as Penicillinase
Breaks down B-lactam rings in which these are found in antibiotics, specifically in penicillin making penicillin ineffective for Staphylococcus aureus
Beta lactamase
84
Cleave stratum granulosum of the skin
Excessive peeling of skin
Associated with Staphylococcal Scalded Skin Syndrome
Exfoliatin
85
Toxin responsible for continuously puncturing holes in the immune cells rendering them dead and inhibit phagocytosis
Leukocidin
86
Toxin responsible for continuously puncturing holes in the immune cells rendering them dead and inhibit phagocytosis
Hemolysins
87
Among the seven heat stable, only two are very common that can cause food poisoning → ***A and B***
Enterotoxins
88
Responsible for making cytokines in the body - too much cytokines will let them accumulate, and increased cytokines will cause havoc
Superantigens
89
→ Inflammation of hair follicles - where it is supposed to grow
→ Back, arms, buttocks
Folliculitis
90
→ Presence of pus → a.k.a Abscess
Furuncles (Boils)
91
→ Collection of boils left untreated
→ Common at the region of the nape
Carbuncles
92
→ Skin is affected, then the bone is inflamed next
→ Left untreated, will require amputation
→ Common in patients with diabetes
Osteomyelitis
93
→ Presence of pus in the lungs
Empyema
94
→ Common in toddlers/infants that are yet to develop immunity
Impetigo/ Pyoderma
95
• Medium-large in size, convex, creamy, dome shaped
Beta-hemolytic, some Staphylococcus spp. have no hemolysis
Pigment: white to golden yellow
Sheep's Blood Agar Plate
96
Selective medium for growth of G(+) bacteria
The medium is blood agar base with Antibiotics
Columbia Colistin Nalidixic Acid Agar (CNA)
97
Selective & differential medium
1 salt (7.5%) = selective
Mannitol and phenol red
Growth on MSA
