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Microbio > Streptococci > Flashcards

Streptococci Flashcards

1
Q

How are Streptococci categorized?

A

By Lancefield Groups based on carbohydrate types

The groups include A, B, C, D, pneumococci, and viridans.

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2
Q

What is the primary method used to type Streptococci?

A

Blood agar to determine beta or alpha hemolysis

Hemolytic patterns help in classifying the Streptococcus species.

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3
Q

What distinguishes beta-hemolytic from alpha-hemolytic Streptococci?

A

Beta-hemolytic Streptococci completely lyse red blood cells, while alpha-hemolytic Streptococci partially lyse them.

This distinction is crucial for identification and treatment.

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4
Q

What is the resistance pattern for Group A Streptococci (Streptococcus pyogenes)?

A

Bacitracin-sensitive

This feature is used in laboratory identification of Group A streptococci.

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5
Q

What is the resistance pattern for Group B and C Streptococci?

A

Bacitracin-resistant

This characteristic helps differentiate them from Group A.

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6
Q

What is the sensitivity pattern for Streptococcus pneumoniae?

A

Optochin-sensitive

This sensitivity is used to identify Streptococcus pneumoniae in clinical samples.

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7
Q

What is the resistance pattern for viridans streptococci?

A

Optochin-resistant

This helps classify them separately from Streptococcus pneumoniae.

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8
Q

Fill in the blank: Streptococcus species are named after the type of _______ they possess on their cell walls.

A

[carbohydrate]

This naming convention is essential for the classification of Streptococci.

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9
Q

What is another name for Streptococcus Pyogenes?

A

Group A strep

Group A strep is commonly known for causing throat infections and skin diseases.

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10
Q

What shape and arrangement does Streptococcus pyogenes have?

A

Cocci/ovoid and in a row

The term ‘strep’ means rows, indicating their arrangement.

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11
Q

What is the Gram status of Streptococcus pyogenes?

A

Positive

This indicates the bacteria retain the crystal violet stain used in the Gram staining procedure.

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12
Q

What structural features does Streptococcus pyogenes possess?

A

Capsules and slime layers; no endospores or flagella

These features contribute to its virulence and ability to evade the immune system.

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13
Q

How does the colony morphology of Streptococcus pyogenes vary?

A

Varies based on capsule amount — can be large and gray to small and white

The appearance of colonies can indicate different strains or growth conditions.

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14
Q

What is the optimum temperature for the growth of Streptococcus pyogenes?

A

35 - 37°C

This range is typical for human pathogens as it aligns with human body temperature.

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15
Q

What type of oxygen requirement does Streptococcus pyogenes have?

A

Facultative anaerobe

This means it can grow in both the presence and absence of oxygen.

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16
Q

Is Streptococcus pyogenes tough against environmental factors?

A

Many are sensitive to drying, heat, and disinfectants

This sensitivity can affect its survival outside a host.

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17
Q

Where is Streptococcus pyogenes commonly located in humans?

A

Throat, nasopharynx, and skin

These locations are key for transmission and infection.

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18
Q

How is Streptococcus pyogenes transmitted?

A

Contact, droplets, fomites, food

Understanding transmission routes is crucial for prevention measures.

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19
Q

Do humans carry Streptococcus pyogenes?

A

Yes, humans are the ONLY carriers

Many individuals may be asymptomatic carriers, spreading the bacteria without showing symptoms.

20
Q

Is Streptococcus pyogenes considered an opportunistic or true pathogen?

A

True pathogen

This indicates it can cause disease in healthy individuals, not just those with weakened immune systems.

21
Q

What does the word Pyogenes mean in S. pyogenes?

A

Causes Puss

22
Q

What is the function of C-carbohydrates in bacterial virulence?

A

Protects against lysozyme

C-carbohydrates are important for bacterial survival in hostile environments.

23
Q

What role does lipoteichoic acid play?

A

Allows adhesion to epithelium

Lipoteichoic acid is found on fimbriae and is crucial for establishing infections.

24
Q

What is the function of M protein in bacteria?

A

Adhesion and phagocytosis resistance

M protein helps bacteria evade the immune system and adhere to host tissues.

25
Q

What is the composition of the capsule that mimics human skin?

A

Made of hyaluronic acid

This mimicry helps decrease the immune response from the host.

26
Q

List the four virulence factors to remember.

A
  • C-carbohydrates
  • M-protein antigen
  • Lipoteichoic acid
  • Capsule made of hyaluronic acid

These factors contribute to the pathogenicity of certain bacteria.
Simple way to remember: Cell Layers Mask Camouflage

27
Q

What is lysozyme?

A

An enzyme that breaks down bacterial cell walls

Lysozyme is part of the innate immune response and targets peptidoglycan.

28
Q

What are streptolysins?

A

Beta hemolysins that also cause cell and tissue injury

Streptolysins are produced by certain strains of Streptococcus bacteria.

29
Q

What is erythrogenic toxin?

A

A superantigen that induces fever and a typical red rash

Erythrogenic toxin is associated with scarlet fever.

30
Q

What does streptokinase do?

A

Digests fibrin clots

Streptokinase is an enzyme that helps dissolve blood clots.

31
Q

Fill in the blank: The enzyme _______ is used as a medication against blood clots in people.

A

streptokinase

Streptokinase is a therapeutic agent in treating thrombotic conditions.

32
Q

What does hyaluronidase do?

A

Breaks down connective tissue

Hyaluronidase facilitates the spread of infection by degrading the extracellular matrix.

33
Q

What is the function of peroxidase in comparison to catalase?

A

Converts hydrogen peroxide into molecules other than O2, but still releases water

This highlights the different substrate handling between peroxidase and catalase.

34
Q

What are the major extracellular toxins of S. Pyogenes

A
  • Streptolysins
  • Erythrogenic toxin

These toxins play significant roles in the pathogenicity of certain bacteria.

35
Q

What are the extracellular enzymes associated with S. Pyogenes

A
  • Streptokinase
  • Hyaluronidase
  • Peroxidase

These enzymes contribute to the bacteria’s ability to invade tissues and evade the immune response.

36
Q

What is impetigo?

A

Superficial lesions that break and form highly contagious crust.

37
Q

True or False: Impetigo is not contagious.

A

False.

38
Q

Fill in the blank: Erysipelas can be -

A

superficial or become systemic.

39
Q

What factors contribute to the spread of impetigo?

A
  • Insect bites * Poor hygiene * Crowded living conditions.
40
Q

What is Erysipelas?

A

A skin infection where the pathogen enters through broken skin and spreads to the dermis (Middle skin layer) and subcutaneous (bottom layer of skin) tissues.

41
Q

What clinical condition is associated with S. pyogenes?

A

Streptococcal pharyngitis (strep throat).

42
Q

What are common symptoms of strep throat?

A

Symptoms include: * Red throat * Swollen tonsils * White patches on tonsils * Swollen lymph nodes * Petechiae.

43
Q

What serious complications can arise from untreated strep throat?

A

Pneumonia, Sepsis, Toxic shock

44
Q

Fill in the blank: Strep throat can damage the _____ of blood capillaries.

A

plasma membranes

45
Q

True or False: Scarlet fever is a complication of strep throat.

A

True

Microbio (5 decks)

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