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1
Q

Genus Staphylococcus are grouped under

A

Order Bacillales

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2
Q

General characteristics of staphylococcus

A
  • Catalase (+)
  • Gram (+) cocci
  • Aerobic or Facultative anaerobe
  • Non-motile
  • Non-spore forming
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3
Q

S. aureus Habitat and MOT

A

HABITAT: CSPAN
MOT: Surgical wound, micro-abrasions, person-person, fomites and aerosolized

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4
Q

S.epidermidis Habitat and MOT

A

Habitat: Skin mucous membranes
MOT: implantation of medical devices (shunts, prosthetic devices) and person to person

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5
Q

S. haemolyticus and S. lugdunensis Habitat and MOT

A

Habitat: skin mucous membranes (low)
MOT: same as S. epidermidis

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6
Q

S. saphrophyticus Habitat and MOT

A

Habitat: Skin and genitourinary-tract mucosa
MOT: urinary tract notably in young sexually active females

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7
Q

Micrococcus spp. Kocuria spp. Kytococcus spp. Habitat and MOT

A

Habitat: Skin Mucosa Oropharynx
MOT: Immunocompromised hosts: brain abscess, meningitis, pneumonia, endocarditis

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8
Q

3 types of Nasal Carrier:

A

PIN
Persistent, Intermittent, Non-carriers

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9
Q

has a high prevalent nosocomial transfer from healthcare providers.

A

S. aureus

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10
Q

IMPORTANT VIRULENCE FACTORS FOR S. AUREUS: Structural components

A

Polysaccharide capsule
Peptidoglycan
Teichoic Acid
Protein A

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11
Q

MPORTANT VIRULENCE FACTORS FOR S. AUREUS: Toxins

A

Cytotoxins
Exfoliative toxins
Enterotoxins
Toxic Shock Syndrome toxin-1

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12
Q

MPORTANT VIRULENCE FACTORS FOR S. AUREUS: Enzymes

A

Coagulase
Catalase
Hyaluronidase
Fibrinolysin
Lipases
Nucleases
Penicillinases

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13
Q

Virulence Factor that inhibits phagocytosis

A

Peptidoglycan capsule

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14
Q

Virulence factor that Activates complement, IL-1, Chemotactic to PMNs

A

Peptidoglycan

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15
Q

Virulence factor that Mediate fibronectin binding

A

Teichoic Acid

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16
Q

Virulence factor that has Affinity to the Fc receptor of IgG and complement

A

Protein A

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17
Q

Virulence factor that is Toxic to RBC, WBC, Platelet & hepatocytes

A

Cytotoxin Alpha

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18
Q

Virulence factor that has Sphingomyelinase that catalyzes phospholipids

A

Cytotoxin Beta

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19
Q

Virulence factor that is Toxic to RBC and other mammalian cells

A

Cytotoxin Delta

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20
Q

Virulence factor that is Associated with Panton Valentine Leukocidin

A

Cytotoxin Gamma

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21
Q

Virulence factor that has Pre-formed toxin resulting to gastrointestinal symptoms, Food poisoning within 2-6 hrs after ingestion (pseudomembranous enterocolitis)

A

Heat Stable Enterotoxin (A-E, G-I)

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22
Q

Virulence factor that causes Exfoliative dermatitis and Ritters Disease (Scalded skin syndrome)

A

Exfoliative/Epidermolytic toxins

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23
Q

Virulence factor that causes Fever, desquamation, hypotension and toxic shock syndrome

A

Pyrogenic Exotoxin-C; Enterotoxin F (TSST-1)

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24
Q

Virulence factor that forms fibrin clot

A

Coagulase; clumping factor

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25
Virulence factor that removes fibrin clot
Fibrinolysin (Staphylokinase)
26
Virulence factor: destruction of H202
Catalase
27
Virulence factor: Degradation of hyaluronic acid Cell colonization
Hyaluronidase (spreading factor)
28
Breakdown of lipids and nucleic acids
Lipases and Nucleases
29
Virulence factor: Breakdown of B- Lactam AMR
Penicillinases
30
Virulence factor of S. epidermidis
Exopolysaccharide “slime” or biofilm; antiphagocytic Exotoxins: delta toxin
31
Common Specimens for Diagnosis
Abscess (lesion, wound, pustule, ulcer) Urine (midstream clean catch, catheter collection) Blood
32
Initial Plating Medium
5% Sheep’s Blood Agar
33
Special Plating Medium
5% Columbia Naladixic Agar
34
Incubation period for isolation from clinical specimen
35°C in carbon dioxide (CO2) or ambient air usually occurs within 24 hours of inoculation.
35
o Medium to large colonies (0.3- 1.5 um) o Pin head colonies o Pigemented creamy- yellow o Mostly B-hemolytic
S. aureus
36
o Small to medum o Grayish-white colonies o Slime producing (sticks to agar) o Non-hemolytic
S. epidermidis
37
o Large colonies o White glossy colonies o Butyrous o Non- hemolytic
S. saphrophyticus
38
o B-hemolytic
S. haemolyticus & S. lugdunensis
39
o Small to medium o Non-hemolytic o Pigmented (white, tan, yellow, orange, pink)
Micrococcus spp
40
is a basal nutrient agar that contains peptones derived from casein and meat as well as beef and yeast extracts.
Columbia Agar
41
The addition of sheep blood in Columbia Agar allows for the
Detection of hemolytic reactions
42
The selective/ inhibitory agent of CAN is the antibiotic _______ quinolone drug similar to Cipro or Levaquin.
Naladixic acid
43
used for isolation and differentiation of pathogenic staphylococci, principally Staphylococcus aureus.
Mannitol Salt Agar
44
Selective Agent for Mannital Salt Agar
7.5% Sodium Chloride (selective for Staphylococcus spp.)
45
Differential Agent for Mannitol Salt Agar
Mannitol
46
Indicator for Mannitol Salt Agar
Indicator: Phenol Red ▪ Below pH 6.4:YELLOW ▪ pH 7.4–8.4: RED ▪ Above pH 8.4:PINK
47
Incubation time for Mannitol Salt Agar
48-72 hours
48
MANNITOL SALT AGAR GROWTH: S. aureus
Yellow colonies with yellow halo
49
MANNITOL SALT AGAR GROWTH: CoNS
Pink colonies
50
What do you call S. aureus that grows in 75% NaCl or walang NaCl?
Halotolerant
51
90% of your MRSA colonies are
Mannitol Fermenters.
52
Selective and differential media for the identification of MRSA.
CHROMagar
53
These media are becoming more widely used for the direct detection of nasal colonization.
CHROMagar
54
Selective agent of CHROMagar
Cefoxitin (MRSA is resistant to this antibiotic
55
Indicator of CHROMagar
Chromogenic substrates
56
Growth (+) of CHROMagar
Mauve-coloredcolony,variety of colored colonies from white to blue to green.
57
Why should gram stain be performed on young cultures?
Gram stains should be performed on young cultures, because very old cells may lose its ability to retain crystal violet. When the cells are very old they lose their ability to maintain crystal violet, their characteristic is GRAM VARIABLE.
58
• Gram positive • Some clusters and some in tetrads (packets of 4) • Sarcinae (packets of 8) • “cube-like cocci”
Micrococcus spp.
59
• Gram positive • Cocci in clusters or in group • Grape-like structure
Staphylococcus spp.
60
BIOCHEMICAL TEST: This test differentiates catalase-positive micrococcal and staphylococcal species from catalase-negative streptococcal species.
Catalase
61
Bicohemical Test Principle: Aerobic and facultative anaerobic organisms produce two toxins during normal metabolism
hydrogen peroxide (H2O2) and superoxide radical (O22)
62
is capable of converting hydrogen peroxide to water and oxygen.
Catalase
63
(+) result of catalase
Effervescence
64
Catalase Limitation
Enterococci and Hemoglobin (from blood agar) Psudoperoxidase reacts with your hydrogen peroxide goving false positive reaction
65
Catalase quality control
o Positive: Staphylococcus aureus (ATCC 25923) o Negative: Streptococcus pyogenes (ATCC 19615)
66
This test differentiates micrococci from staphylococci
Oxidation – Fermentation Test
67
Oxidation-Fermentation Test Principle: __________will be fermented or oxidized by the isolate based on the color manifestation in the medium.
Glucose
68
Indicator of Oxidation – Fermentation Test
Bromothymol blue
69
Closed Tube: yellow Open tube: yellow Interpretation:
Fermenter (Staphylococci spp.)
70
Closed Tube: green Open tube: yellow Interpretation:
Oxidizer (Micrococcus spp.)
71
Oxidation – Fermentation Test Yellow pH Green pH
6.0 7.1
72
The microdase test is a rapid method to differentiate Staphylococcus from Micrococcus spp. by detection of the enzyme oxidase.
Microdase (Modified Oxidase) Test
73
Microdase (Modified Oxidase) Test Principle: In the presence of atmospheric oxygen, the oxidase enzyme reacts with the oxidase reagent _______to form the colored compound, indophenol).
tetramethyl-paraphylene diamine hydrochloride with dimethylsulfoxide and cytochrome C
74
Microdase (Modified Oxidase) Test (+) result (-) result
(+) Result: o Blue to Purple-Blue color (Micrococcus spp.) (-) Result: o Colorless (Staphylococcus spp.)
75
Microdase (Modified Oxidase) Test Limitation: Staphylococci should yield a negative color change, except for:
S. sciuri S. lentus S. vitulus
76
Microdase (Modified Oxidase) Test Quality Control:
o Positive: Micrococcus leteus (ATCC10240) o Negative: Staphylococcus aurerus (ATCC25923)
77
Used to distinguish: ▪ Staphylococcus aureus (+) from other Staphylococcus spp, (-), ▪ Moraxella catarrhalis (+) from Neisseria spp.
DNAse Test
78
Used to distinguish: ▪ Staphylococcus aureus (+) from other Staphylococcus spp, (-), ▪ Moraxella catarrhalis (+) from Neisseria spp.
DNAse Test
79
DNAse test principle: An enzyme catalyzes hydrolysis of DNA into small fragments (1. _______) or single nucleotide called deoxyribonuclease or 2. ______. One formulation for Dnase Agar consists of peptides from 3. _____ and 4. ________ and 5. ______. After incubation, 6._______ is added. Intact DNA will form cloudy ppt while oligonucleotide will produce clearing around the growth.
1. oligonucleotides 2. DNase 3. soybean 4. casein 5. DNA 6. 1N HCl
80
DNase Test: Result
o (+) ▪ Clearing on the medium (Staphylococcus aureus) o (-) ▪ Cloudy ppt (Staphylococcus spp.)
81
The test is used to differentiate Staphylococcus aureus (+) from coagulase-negative staphylococci (-).
Coagulase Test

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