Gram-Positive Cocci (Staphylococcus) Flashcards

1
Q

Bacteria that are circular in shape

A

Cocci

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2
Q

Three in general of cocci which has medical importance or pathogenic to human

A
  • Genus staphylococcus
  • genus Streptococcus
  • Genus Neisseria
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3
Q

what is color for gram positive bacteria

A

Purple or blue

Note: gram positive, meaning they take up their primary stain which is your crystal violet

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4
Q

A key diagnostic tool in micro laboratory

A

Gram Staining

Note: the principle behind is based on cell wall differences
GRAM POSITIVE: thicker peptidoglycan and take up more stain
GRAM NEGATIVE: thin peptidoglycan

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5
Q

What is the color of gram NEGATIVE bacteria

A

Pink or Red

Note: crystal violet will absorb but when you do decolorizer the outer membrane portion will be washed out leaving the organism to be colorless, once it will be stained by the secondary stain it will take up the color pink or red which is the color of safranin the secondary stain.

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6
Q

What test should you perform to differentiate staphylococcus, streptococcus and micrococcus

A

Catalase test

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7
Q

Catalase POSITIVE reaction

A
  • micrococcus
  • staphylococcus

Note: MICROCOCCUS form regular pockets of four or tetrads while STAPHLOCOCCUS are groups clusters.

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8
Q

Catalase NEGATIVE reaction

A

Streptococcus

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9
Q

To differentiate micrococcus and staphylococcus you need to perform

A

Glucose degradation or oxidation fermentation test

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10
Q

Oxidation reaction positive

A

Micrococcus

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11
Q

Fermentation positive

A

Staphylococcus

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12
Q

Test that is used to determine class and bacteria, if the bacteria metabolize carbohydrate oxidatively by fermentation or non-saccharolytic and therefore have no ability to use carbohydrates in te media

A

Glucose degradation test or oxidative fermented test

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13
Q

Used to detect the presence of cytochrome oxidase enzyme

-the principle behind is because of the main reagent here is Hydrogen peroxide or agua oxinada you add this to the small amount of bacterial growth from your culture medium if the reaction is bubbling or effervescence then that is positive because of the release of oxygen and if the reaction is just normal suspension without bubbles then that is negative

A

Catalase test

note: they will employ this test after doing gram staining. The main purpose is to differentiate the members of the family micrococci, streptococcus and staphylococcus

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14
Q

What is the main reagent for Catalase test

A

Hydrogen peroxide or agua oxinada

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15
Q

What is the difference between Micrococci and Staphylococci

A

Micrococci are either oxidative or inert, while Staphylococci are fermentative, they ferment glucose

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16
Q

Positive reaction for this one is color blue

A

Microbase (modified oxidase)

17
Q

A gram positive cocci and spherical in shape comes from a greek word staphyl which means a bunch of grapes since it is arrange in clusters, also seen in pairs, tetrads and chains.

A

Staphylococcus

  • All staphy are catalase POSITIVE
  • aerobic
  • non motile, non spore forming
18
Q

Staphylococcus species

A
  • Staphylococcus aureus
  • Staphylococcus epidermis
  • Staphylococcus saprophyticus
  • Staphylococcus hemolyticus
  • Staphylococcus lugdenensis
19
Q

What is the most pathogenic, among the five species of staphylococcus

A

Staphylococcus Aureus

20
Q

source of infection for Staphylococcus

A
  1. Shedding from human lesions
  2. fomites
  3. contaminated lesion esp. respiratory tract and skin
  4. Asymptomatic carriers among hospital staff & patients
21
Q

Mode of transmission

A
  1. Spread of patient’s endogenous strain to normally sterile site by traumatic induction
  2. person to person transmission
  3. Transmitted from infected skin
22
Q

Most virulent spp of Staphylococci encountered, responsible for 80% suppurative infection in human

A

Staphylococcus aureus