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COM MOD 2.2 Bacteria 1 > Chapter 1.5 Staphylococci > Flashcards

Chapter 1.5 Staphylococci Flashcards

1
Q

Where are staphylococci commonly living in normal individuals?

A

Nasopharynx and skin

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2
Q

What are the 3 major pathogenic species of staphylococci?

A

Staphylococci aureus, staphylococci epidermidis, and staphylococci saprophyticus

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3
Q

What is the shape of staphylococci?

A

They lie in grape-like clusters on Gram stain

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4
Q

What test is positive for staphylococci?

A

Catalase test

*different than streptococci which have negative catalase test

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5
Q

How can staphylococcus aureus be differentiated from beta-hemolytic streptococci?

A

Since they all are beta-hemolytic the difference is that staphylococcus aureus shows a golden pigment on sheep blood agar

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6
Q

What species of staphylococcus is an actual pathogen?

A

Staphylococcus aureus which is coagulate positive

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7
Q

What staphylococcus are present if the coagulate test is negative?

A

Staphylococcus epidermidis or staphylococcus saprophyticus

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8
Q

What proteins are present in staphylococcus aureus that disable our immune defense?

A

Protein A, coagulase, hemolysins, leukocidins, penicillin are, and novel penicillin binding protein

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9
Q

What proteins of staphylococcus aureus tunnel through tissue?

A

Hyaluronidase, staphylokinase, lipase, protease

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10
Q

What exotoxins are present in staphylococcus aureus?

A

Exfoliatin, enterotoxin, and toxic shock syndrome toxin

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11
Q

What is Exfoliatin?

A

Exotoxin of staphylococcus aureus

Causes skin to slough off (scalded skin syndrome)

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12
Q

What are enterotoxins?

A

Exotoxin of staphylococcus aureus

Cause food poisoning resulting in vomiting and diarrhea

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13
Q

What is toxic shock syndrome toxins (TSST-1)?

A

Exotoxin of staphylococcus aureus
More deadly that beta-hemolytic streptococci
Causes toxic shock syndrome
Pyrogenic toxin called a superantigen

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14
Q

What is the mechanism is Toxic shock syndrome?

A

Toxic shock syndrome toxin of staphylococcus aureus binds to the MHC Class II molecule on APC and causes massive T elk response and outpouring of cytokines causing symptoms

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15
Q

What are the symptoms of toxic shock syndrome?

A

Sudden onset of high fever, nausea, vomiting, watery diarrhea
Few days after- diffuse erythematous (red) rash
Palms and soles undergo fine peeling of the skin
Associated with septic shock

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16
Q

What diseases are caused by exotoxin release?

A

Gastroenteritis (food poisoning), toxic shock syndrome, scalded skin syndrome

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17
Q

What diseases result from direct organ invasion by staphylococcus aureus?

A

Pneumonia, meningitis, osteomyelitis, acute bacterial endocarditis, septic arthritis, skin infections, bacteremia/sepsis, urinary tract infection

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18
Q

What is the mechanism of gastroenteritis caused by staphylococcus aureus?

A

Staph. Aureus grows on food and releases exotoxin. Food is ingested and stimulates peristalsis causing nausea, vomiting, diarrhea, and abdominal pain that lasts 12-24 hours.

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19
Q

What is the mechanism of Toxic shock syndrome?

A

When tampons are left in place for a long time, Staph. Aureus is stimulated to release TSST-1. TSST-1 penetrates vaginal mucosa and stimulates TNF and IL-1
*men and nonmenstrating women can also be affected

20
Q

What can cause toxic shock syndrome that is not related to tampon-use?

A

Infected surgical wounds, cutaneous and subcutaneous infections, and infections following childbirth or abortion can be the foci for staph. aureus to release TSST-1

21
Q

What is Staphylococcal scalding skin syndrome and who does it affect?

A

Staph. aureus strain that produces exfoliatin toxin that usually affects neonates with local infection of recently severed umbilicus or older children with skin infection

22
Q

What is the clinical presentation of staphylococcal scaling skin syndrome?

A

Cleavage of epidermis with fine sheets of skin peeling off to reveal moist red skin

23
Q

What are the clinical manifestations of community-acquired bacterial pneumonia caused by staphylococcus aureus?

A

Abrupt onset of fever, chills, and lobar consolidation of the lung with rapid destruction of the lung parenchyma resulting in cavitations (holes) in the lung

24
Q

What can be found in the pleural space in pneumonia from staphylococcus aureus?

A

Effusion and empyema (pus)

25
Q

What are the clinical manifestations of patients with meningitis, celebrities, brain abscesses caused by staphylococcus aureus?

A

High fever, stiff neck, headache, obtundation, coma, and focal neurological signs

26
Q

What are the clinical manifestations of osteomyelitis from staphylococcus aureus?

A

Bone infection usually in boys under 12 y/o
Warm, swollen tissue over the bone
Systemic fever
Shakes

27
Q

What is the clinical presentation of acute endocarditis from staphylococcus aureus?

A

Sudden onset of high fever
Chills
Myalgias (bad flu)

28
Q

What is the difference between acute endocarditis found in staphylococcus aureus vs streptococcus Viridans and group D streptococci?

A

Staphylococcus aureus- sudden onset

Streptococus Viridans and group D streptococci- more gradual onset

29
Q

What is the clinical manifestation of septic arthritis caused by staphylococcus aureus?

A

Invasion of synovial membrane causes closed infection of joint cavity
Patient complains of acutely painful, red, swollen joint with decreased ROM

30
Q

What is the most common pathogen that causes septic arthritis in pediatric age and in adults over 50?

A

Staphylococcus aureus

31
Q

What would be the lab results of a patient with septic arthritis from staphylococcus aureus?

A

Synovial fluid is yellowish and turbid with huge number of neutrophils and a + gram stain

32
Q

What is the difference in skin infections from Streptococus pyogenes and staphylococcus aureus?

A

Clinically impossible to differentiate the 2

33
Q

What is the clinical manifestation of impetigo?

A

Infection occurs on face, especially around the mouth
Small vesicles lead to pustules that crust over and become honey-colored, wet and flaky
*from strep. or staph

34
Q

What is cellulitis?

A

Deeper infection of cells that is hot, red, shiny and swollen
Cause by strep and/or staph

35
Q

What is an abscess?

A

Collection of pus

36
Q

What is the clinical presentation of an infection of the hair follicle?

A

Single, pus filled crater with a red rim

*caused by staph or strep

37
Q

What is a furuncle?

A

An infection of a hair follicle that penetrates deep into the subcutaneous tissue
*skin manifestation of staph or strep

38
Q

What must a physician do if the abscess is significant?

A

Surgically drain it

39
Q

What is the clinical presentation of a blood and catheter infection caused by staph. aureus?

A

Bacteremia, sepsis, septic shock, and endocarditis

40
Q

What is MRSA?

A

Methicillin-Resistant Staphylococcus Aureus

41
Q

Where does MRSA most commonly develop?

A

In the hospital where broad spectrum antibiotics are used

42
Q

How is MRSA transferred from patient to patient?

A

By hand contact of health care workers

43
Q

What are the general characteristics of staphylococcus epidermidis?

A

Found in normal bacterial flora
Is coagulase-negative
Usually lives in skin without causing disease

44
Q

When does staphylococcus epidermidis become pathogenic?

A

In compromised hospital patients with Foley urine catheters of intravenous lines that become infected when the organism migrates from skin along the tubing

45
Q

How can staphylococcus epidermidis be harmful in prosthetics devices?

A

Cause infection by adhering to the prosthetic materials

Ex. Prosthetic joints, prosthetic heart valves, and peritoneal dialysis catheters

46
Q

What is the leading cause of urinary tract infections (after E.coli)?

A

Staphylococcus saprophytius

47
Q

Who is a staphylococcus saprophyticus infection common in?

A

Sexually active young woman

COM MOD 2.2 Bacteria 1 (12 decks)

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