LEC MOD 4: UNIT 1 Flashcards by Leanne Grace Fernandez | Brainscape

Q

Staphylococcus species are classified in the family

A

Staphylococcaceae

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Q

How many species and subspecies are within the genus staphylococci

A

45 species and 21 subspecies

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Q

what type of staphylococci are seen frequently in human infections

A

the coagulase-positive Staphylococcus aureus

- two coagulase-negative species, S. epidermidis and S. saprophyticus

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Q

causes an infectious dermatitis in swine

A

S. hyicus

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Q

causes infections in swine, cattle, and goat

A

S. chromogenes

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Q

has been isolated from several types of infections in dogs.

A

S. intermedius

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Q

cause infectious processes in dolphins, domesticated cats, dogs, and sea otters, respectively

A

S. delphini, S. felis, S. schleiferi subsp. coagulans, and S. lutrae

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Q

cause external otitis in dogs

A

S. schleiferi subsp coagulans

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Q

Most staphylococci are not environmental. T or F

A

False

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Q

Gram-positive cocci

A

general characteristic of the staphylococci

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Q

0.5 - 1.5 um in diameter, and typically in grape-like clusters.

A

general characteristic of the staphylococci

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Q

non-motile

A

general characteristic of the staphylococci

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Q

non-spore-forming

A

general characteristic of the staphylococci

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Q

facultative anaerobes

A

general characteristic of the staphylococci

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Q

Grow most rapidly at 37°C

A

general characteristic of the staphylococci

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Q

halotolerant

A

general characteristic of the staphylococci

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Q

catalase (+)

A

general characteristic of the staphylococci

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Q

fermentative

A

general characteristic of the staphylococci

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Q

Nitrate reduction(+)

A

general characteristic of the staphylococci

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Q

Coagulase(+)
DNase(+)
Mannitol fermenter

A

Staphylococcus aureus

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Q

habitat of staphylococcus aureus

A

human nose and skin

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Q

found in the anterior nares of 20% to 40% of adults

A

S. aureus

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Q

S. aureus is carried by healthy individuals chronically rather than intermittently. T or F

A

False. intermittently rather than chronically

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Q

Other sites of colonization of S. aureus

A

nasopharynx, perineum, the axillae, and the vagina

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Q

S. aureus on the skin are believed to be contaminants from the nose. T or F

A

True

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Q

Transmission of S. aureus

A

via contaminated hands

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Q

Staphylococcal infections are most commonly acquired endogenously from

A

colonized anterior nares

- by direct contact with someone carrying S. aureus.

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Q

how do staphylococcal infections transmit via nasal site

A

-the bacteria are shed to the exposed skin and clothing of the carrier and others with whom they are in direct
contact
-Spread is augmented by touching the face and, of course, nose
picking

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Q

Factors which may predispose an individual to serious S. aureus infections

A

-breaks in the continuity and integrity of mucosal and cutaneous surfaces.
-presence of foreign bodies or implants (e.g., sutures, intravenous lines,
prosthetic devices).
-prior infection with other agents, particularly viruses (e.g., influenza).
-underlying diseases with defects in cellular or humoral immunity, either
congenital or acquired, (e.g. defects in leukocyte chemotaxis, defects in
opsonization by antibodies, hypogammaglobulinemias or complement
component deficiencies and/or defects).
-chronic underlying diseases such as malignancy, alcoholism, and heart
disease.
-therapeutic or prophylactic antimicrobial administration

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Q

how do staphylococcal infections occur on the skin

A

through:

wounds
follicles
skin glands

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Q

characteristics of Staphylococcal infections of the skin

A

pyogenic (pus-forming)

- often presents as an inflamed, fibrous lesion enclosing a core of pus called an abscess

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Q

a mild inflammation of the superficial dermis that is restricted to ostia
(opening) of the hair follicles

A

folliculitis

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Q

characterized by the presence of small, reddish, painful lesions and the absence of systemic symptoms.

A

folliculitis

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Q

If folliculitis occurs in the eyelid, it is referred to as

A

stye / sty

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Q

Hidradenitis suppurativa is a chronic or relapsing inflammatory disease of the skin, involving

A

apocrine gland-bearing areas

axillae
groin
perinea (perineum - an area between the thighs)
perianal regions

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Q

This condition is characterized by presence of multiple lesions
associated with blocked and infected apocrine sweat glands

A

Hidradenitis suppurativa

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Q

In Hidradenitis suppurativa, local pain, swelling and erythema are absent, while systemic symptoms such as fever is usually present. T or F

A

False. local pain, swelling and erythema are present, systemic symptoms
such as fever is usually absent.

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Q

a deeper-seated infection of the hair follicles

A

furuncle or boil

latin term = furunculus - little thief

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Q

It results when the inflammation of single hair
follicle or sebaceous gland progresses into a
large, red, extremely tender abscess or pustule.

A

furuncle

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Q

furuncle in clusters

A

furunculosis

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Q

where do furuncles often appear in clusters

A

buttock
breasts
axillae
back of the neck where skin rubs other skin or clothing

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Q

a larger and deeper lesion created by aggregation and interconnection of a cluster of furuncles

A

carbuncle

-latin term = carbunculus - little coal

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Q

They are extremely painful and can even be fatal in elderly patients when they give rise to systemic disease

A

carbuncle

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Q

carbuncle is usually found in areas of which thin skin such as on the
back of the neck. T or F

A

False. Thick skin

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Q

a staphylococcal skin infection that is not

confined to follicles and skin glands.

A

impetigo

-latin term = impetus - to attack

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Q

is characterized by bubble-like epidermal sweeping that can break and peel away like a localized form of scalded skin syndrome

A

impetigo

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Q

impetigo occurs in two forms:

A

non-bullous and bullous

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Q

furuncle is usually present on exposed areas,
especially the face, and may spread to surrounding areas by
autoinoculation. T or F

A

False. impetigo

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Q

a type of transmission wherein the infected person himself infects other sites of his body

A

autoinoculation

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Q

begins as a single red macule (patch) or papule that quickly becomes a vesicle.

A

non-bullous impetigo

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Q

in non-bullous impetigo, the vesicle rupture and
forms an erosion, and the lesion and its
contents dry to form a characteristic
honey-colored crusts with erythematous
(reddish) margins that may be pruritic
(itchy). T or F

A

True

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Q

a localized form of staphylococcal scalded skin syndrome that
commonly affects neonates but can also occur in older children and adults

A

bullous impetigo

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Q

a localized form of staphylococcal scalded skin syndrome that
common affects neonates but can also occur in older children and adults

A

bullous impetigo

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Q

Bullous impetigo is usually found in moist,
intertriginous areas (e.g., the diaper area,
axillae, neck folds). T or F

A

True

Q

in bullous impetigo, superficial vesicles progress to enlarging bullae (singular; bulla plural; vesicle or blister) with sharp margins with no surrounding erythema. T or F

A

True

Q

What form of impetigo is characterized by honey-colored crusts?

A

non-bullous impetigo

Q

what form of impetigo is characterized by yellow crust?

A

bullous impetigo

Q

S. aureus can present itself as a _________ and cause toxigenic diseases

A

toxemia

-due to the production of toxins

Q

a gastrointestinal illness caused by eating foods contaminated with toxins produced by the S. aureus

A

Staphylococcal food poisoning

Q

staphylococcal food poisoning is considered a food-borne infection rather than a food intoxication. T or F

A

False. It is considered as a food intoxication because the food is not the cause of food poisoning, it is due to the fact that the food is contaminated with toxins

Q

Staphylococcal food poisoning is characterized by acute symptoms that appear in ___________

A

2 to 6 hours after ingestion of the toxin-contaminated food

Q

Recovery from staphylococcal food poisoning is usually _____

A

within 24 hrs

Q

Symptoms of staphylococcal food poisoning

A

emesis (vomiting), often projectile

- diarrhea is less frequent

Q

Staphylococcal food poisoning is due to the ingestion of viable S. aureus cells. T or F

A

False

Q

Staphylococcal food poisoning is associated with eating foods such as

A

custards, sauces, cream pastries, processed meats, chicken salad, or ham that have been contaminated by handling and then left unrefrigerated for a few hours.

Q

S. aureus has high salt tolerance. T or F

A

True

Q

Also known as Ritter’s Disease

A

Staphylococcal Scalded Skin Syndrome (SSSS)

Q

Ritter’s disease or SSSS is usually seen in __________

A

neonates (newborns/children less than 1 month old)

- infants less than 5 years

Q

characterized by

widespread erythema
appearance of bullous lesions over large areas of the body
subsequent sloughing of the superficial skin layers

A

Ritter’s disease or Staphylococcal Scalded Skin Syndrome

Q

Ritter’s disease is similar to ______________. However, their only difference is that the latter is localized.

A

Bullous impetigo

Q

Ritter’s disease leads to the exposure of large areas of

denuded ( stripped off surface layers) and raw skin. T or F

A

True

Q

In ritter’s disease, desquamation occurs and symptoms wane over _____

A

5-7 days

Q

initially a flu-like illness characterized by fever, hypotension, and rash on the skin that resembles a sunburn

A

Staphylococcal Toxic Shock Syndrome (TSS)

Q

Staphylococcal Toxic Shock Syndrome only involves certain regions of the body. T or F

A

False. It can involve any region of the body (lips, mouth, eyes, palms, and soles)

Q

In patients who survive the initial phase of the infection (TSS), the rash is
followed by desquamation _______________ after onset

A

1-2 weeks

Q

Staphylococcal Toxic Shock Syndrome (TSS) involves only 1 organ system. T or F

A

False.
There is the involvement of multiple (three or more) organ systems with varying symptoms of vomiting, diarrhea, renal failure, headache, chills, sore throat and conjunctivitis

Q

TSS was noted most frequently in men. T or F

A

False.
-the disease was noted most frequently in women, with onset mainly occurring during menstruation (use of high-absorbancy tampons)

Q

non-menstrual-associated TSS is reported in males and females as _________

A

complication of staphylococcal abscesses or systemic infections

Q

Most systemic staphylococcal infections have an irregular pattern. T or F

A

False.
Most systemic staphylococcal infections have a focal pattern,
spreading from a local cutaneous infection to other sites.

Q

Example of miscellaneous systemic infections

A

osteomyelitis (bone infection)
pneumonia (usually occurs after influenza viral infection)
bacteremia (with consequences such as endocarditis, arthritis, and meningitis)

Q

Virulence Factors of S. aureus

A

Protein A
Microcapsule
Catalase
Coagulase
DNase
Hyaluronidase
Lipase
Staphylokinase
B-lactamase
Leukocidin
Hemolysins
Exfoliative toxin
TSS toxin
Enterotoxin A-E

Q

Microcapsule among most S. aureus strains of clinical importance consists of _______

A

polysaccharides

Q

This has been called microcapsule because ______

A

it can be visualized only by electron microscopy unlike the true capsules of some bacteria which are readily visualized by light microscopy

Q

It mediates the attachment of S. aureus to host cells or tissues

A

microcapsule

Q

It inhibits phagocytosis by polymorphonuclear leukocytes

unless specific antibodies are present

A

microcapsule

Q

How many serotypes of microcapsules have been identified

A

11

- types 5 and 8 responsible for the majority of infections

Q

How many serotypes of microcapsules have been identified

A

11

- types 5 and 8 responsible for the majority of infections

Q

a bacterial surface protein in some S. aureus strains

A

Protein A

Q

Protein A binds to the _____ portion of _____

A

Fc; IgG

Q

protein A binds to the Fc portion of IgG,
leaving the IgG no longer capable of binding to Fc
receptor on phagocytes, thus preventing

A

opsonization

Q

protein A also blocks

A

complement fixation

Q

inactivates toxic hydrogen peroxide and free radicals formed by the
myloperoxidase system within the phagocytic cells

A

catalase

Q

the primary killing mechanisms within the phagolysosome.

A

myloperoxidase system

Q

promotes conversion of fibrinogen to fibrin causing plasma to clot

A

coagulase

Q

function of fibrin

A

fibrin protects bacterial cells from PHAGOCYTOSIS and IMMUNE RESPONSE by hiding their antigenic surface

Q

hydrolyze DNA

A

Deoxyribonuclease (DNase)

Q

This facilitates the spread of bacteria by liquefying and decreasing the viscosity of abscess materials.

A

Deoxyribonuclease (DNase)

Q

spreading factor

A

Hyaluronidase

Q

hydrolyzes the intercellular matrix of acid mucopolysaccharides (hyaluronic acid) in tissue

A

hyaluronidase

Q

hydrolyzes lipids and help the spread of the organism in cutaneous and
subcutaneous tissues

A

lipase

Q

plasminogen activator

A

staphylokinase

Q

This factor dissolves fibrin clot (a

fibrinolysin).

A

staphylokinase

Q

affects tissues of the host making

them more susceptible to damage and destruction during complement activation

A

Phosphatidylinositol-specific phospholipase C

Q

under plasmid-control transmitted by transduction and perhaps
also by conjugation

A

B-lactamase

Q

provides resistance to β-lactam antibiotics such as

penicillin, penicillin derivatives, and cephalosporins

A

B-lactamase

Q

penicillin derivatives

A

penams

Q

penicillin, penicillin derivatives, and cephalosporins all have a common element in their molecular structure

A

four-atom ring known as (B-lactam)

Q

the β-lactamase breaks the β-lactam ring

open, deactivating the molecule’s antibacterial properties through

A

hydrolysis

Q

a specific type of β-lactamase, showing specificity for penicillins

A

penicillinase

Q

These lyse red blood cells by disrupting their cell membranes.

A

Hemolysins

Q

these damage cell membranes of neutrophils and macrophages, causing
them to lyse

A

Leukocidins

Q

what are the two blood cell toxins

A

hemolysins leukocidins

Q

This toxins probably help incapacitate the host’s phagocytic line of
defense

A

Blood Cell toxins

Q

heterogeneous protein that facilitates formation

of pores on the target eukaryotic cell membrane

A

a-hemolysin

Q

a-hemolyisin facilitates formation of pores on the target eukaryotic cell membrane through which monovalent cations can pass, leading to

A

osmotic swelling and rupture of the cell

Q

effects of a-hemolysin

A

-lyses red blood cells
-damages:
>monocytes
>macrophages
>lymphocytes
>skeletal muscle
>heart
>renal tissue

Q

a-hemolysin may contribute to ____________ during S. aureus bacteremia

A

septic thrombotic events

Q

a sphingomyelinase that degrades sphingomyelin in the cell membrane and therefore is toxic for many kinds of cells

A

B-hemolysin

Q

a protein exotoxin described as a “hot-cold” hemolysin

A

B-hemolysin

Q

what bacteria encodes B-hemolysin toxin

A

lysogenic bacteriophage

Q

B-hemolysin hemolytic properties are enhanced by

A

subsequent exposure to red blood cells to low temperatures.

Q

B-hemolysin is cytotoxic to

A

human erythrocytes and monocytes

Q

B-hemolysin is inactive against

A

granulocytes
lymphocytes
fibroblasts

Q

cell death caused by B-hemolysin results from

A

disruption of host cell

plasma membrane fluidity

Q

a small peptide that acts primarily as a

surfactant or a detergent-like molecule

A

delta-hemolysin

Q

interacts with cell membranes and forms channels resulting in slow leakage of cellular contents. It may have a role in S. aureus diarrheal diseases.

A

delta-hemolysin

Q

a leukocidin that lyses white blood cells and is

composed of two proteins

A

gamma-hemolysin

Q

two proteins of gamma-hemolysin

A

S and F

Q

It is capable of efficiently lysing white blood cells by causing pore formation in the cellular membranes that increase cation permeability.

A

gamma-hemolysin

Q

the cells affected by gamma-hemolysin undergo

A

degranulation of cytoplasm
cell swelling
lysis

Q

gamma-hemolysin causes massive release of inflammatory mediators which are responsible for necrosis and severe inflammation

A

True

Q

produced by lysogenized strains of S. aureus

A

Panton-Valentine Leukocidin (PVL)

Q

This pore-forming toxin is active against neutrophils and

causes tissue necrosis

A

Panton-Valentine Leukocidin (PVL)