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Microbiology Exam 2 > Bacteriology 8: Streptococcus/Enterococcus > Flashcards

Bacteriology 8: Streptococcus/Enterococcus Flashcards

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1
Q

Streptococcus morphology

A

Gram (+)
Cocci
Most arranged in chains (except S.pneumomiae)

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2
Q

Most members of the Streptococcus family commonly are found where?

A

As a normal flora of the mouth and gut EXCEPT S.pyogenes

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3
Q

lol

A
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4
Q

How does streptococcus differentiate from staphylococcus with the catalase test and salt test

A

Staphylococci = all of them are catalase (+) therefore must do a coagulase test to exclude S.aureus. All of them are also salt tolerant in the mannitol-salt test.

Streptococci = all of them are catalase (-) and not salt tolerant

Therefore we can distinguish staph and strep with a catalase test and a mannitol-salt test

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5
Q

How are most streptococci classified in the lancefield group

A

Based on a carboyhydrate antigen found on the cell wall

Group A Streptococci (GAS): Includes Streptococcus pyogenes, which causes strep throat, scarlet fever, and rheumatic fever.

Group B Streptococci (GBS): Includes Streptococcus agalactiae, which is a major cause of neonatal infections

Cell wall = peptidoglycan layer
Not all streptococci can be classified by this system, though; for example, Streptococcus pneumoniae don’t fit into the Lancefield groups.

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6
Q

Alpha-hemolytic streptococcus species

A

Can be further classified with optochin-sensitive vs. optochin-resistant

optochin-sensitive
-streptococcus pneumoniae

optochin-resistant
-Group D and viridans streptococci

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7
Q

Beta-hemolytic streptococcus species

A

Can be further classified b/w bacitracin-sensitive and bacitracin-resistant

bacitracin-sensitive
-group A streptococci (Streptococci Pyogenes)

bacitracin-resistant
-group B, C streptococci

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8
Q

Virulence factors- surface antigens for GAS
M-protein

A

More than 100 stereotypes of M protein = pathogenic
The more pathogenic forms can cause serious sequelae of strep throat like rheumatic fever (b/c autoimmune rxn)

M-protein
-inhibit phagocytosis
-inactivates the complement system
-Antigenic

sticking out of the capsule in bacteria like Protein F, protein G and the M protein and lipoteichoic acid (b/c gram (+))

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9
Q

Virulence factors- surface antigens for GAS
Protein G

A

Binds to the Fc portion of antibodies, thereby interfering with/ opsonization

sticking out of the capsule in bacteria like Protein F, protein G and the M protein and lipoteichoic acid (b/c gram (+))

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10
Q

Virulence factors- surface antigens for GAS
protein F

A

Responsible for attachment to host cells

sticking out of the capsule in bacteria like Protein F, protein G and the M protein and lipoteichoic acid (b/c gram (+))

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11
Q

Virulence factors- surface antigens for GAS
Hyaluronic acid capsule

A

Inhibits phagocytosis
(We know this… capsule = virulence factor)

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12
Q

Virulence factors- surface antigens (GAS)
Group A carbohydrate

A

Protection against lysozyme

(We know that the lysozyme is an enzyme that will cleave the peptidoglycan cell wall- specifically the glycosidic bond b/w NAG-NAM carbohydrate backbone)

Therefore group A carbohydrate surface antigen must be imbedded w/n the cell wall to protect against lysozymes.
It anchors on top of the the cytoplasmic membrane (inner membrane)

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13
Q

Which surface antigens (virulence factors) are found outside the capsule for possible antibody interaction on GAS?

A

Protein G
Protein F
M protein

The hyaluronic acid = capsule
Group A carbohydrate = from outer surface of inner membrane to top layer of cell wall (peptidoglycan layer)

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14
Q

Virulence factors - toxins (GAS)
Streptococcal pyrogenic exotoxins (SPE)

A

Erythrogenic toxins b/c they cause the skin to redden

-they cause the red rash that isass. w/ scarlet fever
-superantigen ass. w/ toxic shock syndrome**

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15
Q

Virulence factors - toxins (GAS)
Streptolysin O

A

Causes lysis of RBCs, leukocytes, and platelets but only under anaerobic conditions

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16
Q

Virulence factors - toxins (GAS)
Streptolysin S

A

Causes lysis of RBCs, leukocytes, and platelets but under both under anaerobic conditions and aerobic

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17
Q

Virulence factors - enzymes (GAS)
-streptokinase

A

Dissolves blood clots
(We know this… kinases will dissolve the blood clots created by a coagulase enzyme for virulence factor)

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18
Q

Virulence factors - enzymes (GAS)
C5a peptidase

A

Degrades C5a from the complement cascade and prevents the recruitment of neutrophils

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19
Q

Virulence factors - enzymes (GAS)
-hyaluronidase

A

The primary function of hyaluronidase is to degrade hyaluronic acid, a key component of the extracellular matrix, particularly in connective tissues.

Hyaluronidase is an enzyme produced by several types of bacteria, including Streptococcus, Staphylococcus, and Clostridium species, as well as some other organisms.

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20
Q

Name all the virulence factors describes as toxins, enzymes, and surface antigens under a streptococcus bacteria (GAS)

A

Surface antigens
-M protein
-Protein G
-Protein F
-Hyaluronic acid capsule
-Group A carbohydrate

toxins
-SPE
-streptolysin O
-Streptolysin S

enzymes
-streptokinase
-C5a peptidase
-hyaluronidase

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21
Q

URS infection caused by streptococcus group A (GAS)

A

Strep. Pharyngitis

GAS = S.pyogenes

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22
Q

Skin infection caused by streptococcus group A (GAS)

A

Impetigo

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23
Q

Soft tissue infections caused by streptococcus group A (GAS)

A

Skin trauma/infection spreads into surrounding lymph nodes and tissues

Erysipelas
-involves the epidermis and upper dermis
cellulitis
-involves both the superficial and deep layers of the skin (dermis and subcutaneous fat)

can progress to deeper tissues or sepsis in the very young, very old, and immunocompromised

Necrotizing Fasciitis
-“flesh-eating disease”
-necrotizing fasciitis is a severe and rapidly progressing soft tissue infection. It primarily affects the fascia, which is a layer of connective tissue that surrounds muscles, nerves, and blood vessels.
-starts as a minor infection or break in the skin, then progresses rapidly in the fascia, resulting in the destruction of muscle/fat tissue due to a variety of enzymes and toxins.
therefore it invades the CT and muscle

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24
Q

Streptocococcal toxic shock syndrome (STSS)

A

Can begin at the site of any S.pyogenes infection, often ass. w/ necrotizing fasciitis.
-this is a systemic condition that spreads rapidly leading to septic shock (patients die often w/n 2-3 days) if you survive = multiple amputations
-caused by superantigen

25
Q

Toxic shock syndrome can be caused by what bacteria and what virulence factors

A

-streptococcal pyogenes (GAS)
- staphlylococcus aureus

=superantigen
=hypotension, fever, rash, desquamation of skin (palms and soles) multiple organ failure = TSS

S.aureus
-TSST-1 is a toxin = (virulence factor) that is produced by 15% of S.aureus bacteria.
-TSST-1 = superantigen. Bacteria stays local while toxin goes to bloodstream = systemic
-use of tampons, nasal surgery

streptococcal pyogenes (GAS)
-streptococcal pyrogenic exotoxins (SPE) = virulence factor that is produced by S.pyogenes
-SPE = superantigen.

26
Q

Group B of streptococcus (GBS)

A

S.agalactiae

27
Q

General characteristic of GBS
-found where
-commonly causes
-capsule made of vs. in GAS
-can it cause homlysin? What about GAS?
-resistant or sensitive ?
-enzyme?

A

-normal flora of the GI tract and vagina
-serous neonatal diseases - newborns
-Sialic acid capsule vs. Hyaluronic acid capsule (both inhibit phagocytosis b/c that’s the effect of having a capsule as a virulence factor)
-both GAS/GBS are ass. w/ Beta-hemolytic.
-Bacitracin resistant
-Hyaluronidase = degrade hyaluronic acid = a key component of the ECM, particularly in CT.

28
Q

Diseases caused by GBS
-neonates
-infants
-pregoo
-men/non-pregoo

A

neonates
-bacteremia —> sepsis —> meningitis

infants
-bacteremia —> meningitis

preggo women
-UTI

Men/non-preggo
-bacteria —> pneumonia, bone/joint infections

29
Q

S.pneumonia
-lancefield group?

A

Streptococcus pneumoniae, also known as the pneumococcus, does not belong to any of the Lancefield groups (A, B, C, etc.), as it lacks the specific carbohydrate antigens used in the Lancefield classification system. Instead, it is classified based on its biochemical properties and capsular serotypes.

30
Q

S.pneumoniae (pneumococcus)
-hemolytic?
-shape?
-found?
-transmission?

A

-Alpha-hemolytic
-diplococci
-normal flora
-person-to-person (40% infections)
-endogenous (healthcare-ass.)

31
Q

S.pneumoniae virulence factor
-capsule

A

Inhibits phagocytosis

32
Q

S.pneumoniae virulence factor
-Phosphocholine

A

Part of the cell wall that facilitates entry into respiratory cells and into the bloodstream

Therefore part of the peptidoglycan cell call of bacteria

33
Q

S.pneumoniae virulence factor
-Pneumolysin

A

Pore-forming toxin that lyses pulmonary cells which facilitates the movement of bacteria into alveoli therefore disrupting cilia of the respiratory tract

34
Q

S.pneumoniae virulence factor
-IgA protease

A

Cleaves IgA

35
Q

Lobar pneumonia
-bacteria
-organ affecting
-clinical manifestations

A

-S.pneumoniae
-fast onset
-affects one/more lobes of the lungs
-fever, chills, congestion, productive cough, chest pain, short/rapid breathing, blood in sputum

36
Q

Vaccine for Streptococcus

A

S.pneumoniae

-prevnar (13 valent)
Infants
-pneumovax (23 valent)
Young adults who smoke cigarettes
adults >65

37
Q

S.pneumoniae infections

A

URS
-sinusitis
-Ottis media

nervous system
-bacteremia —> meningitis

CVS
-acute endocarditis

38
Q

Viridans streptococci

A

four groups
-S.mutans
-S.salivarius
-S.mitis
-S.anginosus

39
Q

General characteristic of viridans streptococci
-hemolytic?
-shape
-lancefield?
-catalase?
-found?

A

-alpha hemolytic
-short and long chains
-no lancefield
-catalase (-) = ALL STREPTOCOCCUS
-oral microbiota
some are opportunistic pathogens causing subacute infective endocarditis

40
Q

Which Streptococci bacteria is found mainly in dental plaque and is one of the main causative agents of enamel and root surface caries?

A

S.mutans group

Dental plaque found in tooth decay or w/ caries

(Viridans streptococci)

41
Q

Which Streptococci contributes to biofilm formation in the oral cavity and how?

A

S.mutans
Scavenge dietary sugars efficiently and convert them into acids (lactate)
Make extracellular soluble and insoluble polysaccharides from sucrose
This contributes to biofilm formation

42
Q

S.sobrinus

A

Ass. w/ human dental caries

43
Q

S.salivarius

A

Preferentially colonize mucosal surfaces, especially the tongue. Produces large quantities of an unusual extracellular fructan from sucrose

44
Q

S.vestibularis

A

Part of the S.salivarius group

Isolated from vestibular mucosa of the mouth
DOES NOT produce extracellular polysaccharides from sucrose like the S.mutans group (S.mutans/S.sobrinus)
Instead they have urease to generate ammonia and raise the local pH.
H2O2: stop the growth of competing bacteria

45
Q

S.mitis group

A

S.sanguinis
S.gordonii
S.mitis
S.oralis

46
Q

What are the 2 most common streptococcal species in the mouth?

A

S.oralis
S.mitis

Some but not all strains produce extracellular glucan from sucrose

47
Q

Which Streptococci removes sialic acid from oligosaccharide side chains of salivary mucins?

A

S.oralis (part of the S.mitis group = viridans strep)

S.oralis produce Neuraminidase and IgA protease potentially promoting bacterial adhesion and colonization in the mouth.

Salivary mucins are glycoproteins found in saliva that play an important role in maintaining oral health.
Sialic acid is often the terminal sugar on glycoproteins like mucins. By removing it, Streptococci can access underlying carbohydrates, which they can then metabolize for energy.
This process is important for the bacteria’s ability to colonize and persist in the oral cavity, as it allows them to utilize components of saliva as a nutrient source.

48
Q

Which streptococci does not produce extracellular polysaccharides from sucrose?

A

-S.vestibularis (from S.salivarius group)
-S.anginosus
-S.constellatus (from S.anginosus group)
-S.intermedius (from S.anginosus group)

49
Q

Which streptococci produces extracellular polysaccharides from sucrose?

A

-S.mutans group (S.mutans and S.sobrinus)

S. salivarius does produce extracellular polysaccharides, but it is less known for this compared to S. mutans and S. sobrinus. Its polysaccharides are typically less involved in caries formation. They produce large quantities of fructan from sucrose

Some species within the S. mitis group, such as Streptococcus oralis, are known to produce extracellular polysaccharides from sucrose. These polysaccharides can contribute to plaque formation but are generally less cariogenic compared to those produced by Streptococcus mutans and Streptococcus sobrinus.

50
Q

Which streptococci is the causative agents of serious, purulent diseases and abscesses of internal organs?

A

S.anginosus group (S.anginosus, S.constellatus, S.intermedius)

DO NOT** produce extracellular polysaccharides from sucrose instead they are the causative agents of purulent diseases and abscesses of internal organs

51
Q

Enterococcus morphology
-gram +/-
-shape
-enzyme
-catalase
-anaerobic/aerobic
-found in

A

Gram (+)
Short chains/diplococci
Gelatinase: allows adhesion to dentin
Catalase negative But yet SALT TOLERANT
ONLY GRAM (+) BACTERIA THAT IS SALT TOLERANT
Catalase (-) like all Streptococci
-Faculative anaerobic
-normal microbiota of intestinal tract, urethra, female genital tract
*can also grow in low and high pH)

s.pneumoniae is also Diplococci

52
Q

Which is the only gram (+) bacteria that is catalase (-) and salt tolerant?

A

Enterococcus = only gram (+) bacteria that grows in salt

All streptococcus are catalase (-)
All staphylococcus are catalase (+) only these are salt tolerant
All of them are gram (+)

53
Q

Which bacteria are the most common for being catalase (-) and gram (+)

A

Enterococcus and streptococcus

54
Q

Where are enterococcus bacteria commonly isolated from

A

Patients in ICUs
Enterococcus bacteria is a major cause of infection in hospitals
Ass. w/ abdominal surgery, catheters, peritoneal dialysis and nosocomial UTIs, bacteremia, soft tissue, and intra-abdominal infections

55
Q

Which bacteria is a common nosocomial infection?

A

Enterococcus

major cause of infection in hospitals

56
Q

Enterococcal infections

A

-opportunistic UTI
-Bacteremia
-secondary endodontic infections (E.faecalis can invade dentinal tubules)

57
Q

Which bacteria is common found in infected root canals, periodontal pockets that fail to respond to therapy and can invade dentinal tubules?

A

Enterococcus

58
Q

Which enterococcus bacteria is most frequently isolated in low numbers from different oral sites?

A

Enterococcus

Microbiology Exam 2 (12 decks)

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