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Medical Micro/Immunology > Chapter 18 > Flashcards

Chapter 18 Flashcards

1
Q

What part of the body do staphylococcus inhabit?

A

skin and mucous membranes

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2
Q

Responsible for staph infections

A

staphylococcus

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3
Q

Describe the morphology of staphylococcus

A
  • Clusters of short chains (grape racemes)
  • No spores or flagella
  • Sometimes encapsulated
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4
Q

How many species does the genus staphylococcus have? Name 3.

A

31

*S. aureus, S. epidermis, S. capitis

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5
Q

Staphylococcus are not _____________ any more.

A

harmless commensals

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6
Q

Describe the colonies of S. aureus

A

large, round, and opaque

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7
Q

What is the best temp for growth of S. aureus? and the temperature range?

A

37 degrees Celsius

10 - 46 degrees C

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8
Q

Facultative anaerobe

A

S. aureus

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9
Q

S. aureus look _____ under the microscope

A

grape-like

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10
Q

The growth of S. aureus is enhanced with ____ and ____.

A

O2 (oxygen) and CO2 (carbon dioxide)

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11
Q

S. aureus are metabolically versatile meaning…

A

They digest proteins and lipids and ferment sugars

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12
Q

Name 3 things S. aureus can resist

A
  • extremes of pH
  • extremes of temp (60 degrees C in 1 hour)
  • most current antibiotics and many disinfectants
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13
Q

Why is S. aureus a troublesome hosipital pathogen?

A

Because it is highly resistant to most disinfectants and can remain viable after months of air drying. Also highly resistant to most current antibiotics.

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14
Q

No other pathogen produces as many virulence factors as

A

S. aureus

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15
Q

Name the 6 staphylococcal enzymes

A 
Coagulase + 
Hyaluronidase
Staphylokinase
Nuclease
Lipases
Penicillinase
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16
Q

Spreading factor that digest the intercellular ‘glue’ and binds connective tissue

A

Hyaluronidase

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17
Q

intercellular “glue”

A

hyaluronic acid

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18
Q

Enzyme that digests blood clots

A

Staphylokinase

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19
Q

Enzyme that digests DNAse

A

Nuclease

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20
Q

Enzyme that help bacteria colonize oily skin and stay in sebaceous glands

A

Lipases

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21
Q

What enzymes inactivates penicillin?

A

penicillinase

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22
Q

Which enzyme must be positive in order for the bacteria to be S. aureus

A

coagulase

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23
Q

Pathogenic strains of staphylococcus produce which enzyme?

A

coagulase (coagulates plasma and blood)

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24
Q

What does coagulase do?

A

Coagulase causes fibrin to be deposited around staph cells.

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25
Fibrin stops _______ or _____________.
phagocytosis; promote adherence to tissues
26
Which enzyme is present in 97% of all isolates?
coagulase
27
Name the 5 toxins of staphylococcus?
* Hemolysins * leukocidins * enerotoxins * exfoliative toxin * toxic shock syndrome toxin
28
Which toxin will cause damage by lysing the cell membranes of neutrophils and macrophages?
Leukocidins
29
Which toxins act on the gastrointestinal tract?
enterotoxins
30
How does the exfoliative toxin cause damage?
Separates the epidermal layer from the dermis.
31
Which toxin breaks down and disrupts the cell membranes of RBC?
hemolysins
32
Hemolysins produce a zone of _______ in ___________.
hemolysis; blood agar
33
The most powerful toxin
alpha toxin
34
Alpha toxin produces
beta hemolysis
35
Alpha toxins damage the __________, ___________, __________, and ________.
leukocytes, muscles, heart, renal tissues
36
Which toxin is associated with tampons and the binding/absorption of Mg++?
Toxic shock syndrome toxin
37
Which toxin is an intimate human associate?
TSST
38
Where is TSST present?
in all environments including fomites
39
Name the circumstances that predispose a person to infection?
* poor nutrition * poor hygiene * immunodeficiency * preexisting primary infections * diabetes mellitus (people w/ no control) * tissue injury
40
Which type of infections are the 3rd most common nosocomial infection in the newborn nursery and surgical wards?
staph infections
41
________ can readily spread an epidemic pattern within and outside the hospital.
Hospital strains
42
Name the four different types of localized staph infections.
* folliculitis * furuncles * carbuncles * impetigo
43
Osteomyelitis
systemic staph infection
44
Every 20 mins bacteria _____ in population.
double
45
_____ of certain strains responsible for the most common type of food infection in the USA
Enterotoxins
46
Toxigenic strains are found in
custards, sauces, pastries, processed meats, ham... anything salty
47
Toxigenic strains are dangerous because....
toxigenic strains are not noticible in food because they do not alter the smell or taste of food.
48
Toxigenic strains are heat-stable and have in activation at ______ for ______.
100 degrees celsius for 30 mins
49
Toxigenic strains usually last how long?
one day
50
toxins act on _________ and stimulate ______.
gastrointestinal epithelium; nerves
51
Effects of toxins are.....
cramping, nausea, vomit, diarrhea
52
Staph responsible for a large % of nosocomial infections since the 1970s.
Coagulase -
53
coagulase - are _______. They infect immunocompromised people.
opportunistic
54
Name the types of staph that infect via instruments through the skin.
* S. epidermitis * S. hominis * S. capitis
55
Which type of staph infects exclusively young sexually active women?
S. saprophyticus
56
The 2nd most common cause of urinary infections in staph.
S. saprophyticus
57
How is staphylococcus identified?
* Catalase test. (Plasma clots if it is +) | * Sugar fermentation
58
All types of staph are coagulase negative except ________ which is coagulase +.
S. aureus
59
Which type of staph is novobiocin-resistant?
S. saprophyticus
60
How is S. epidermidis identified?
S. epidermidis ferments mannose
61
S. capitis lacks ________.
urease
62
Which type of staph lacks anaerobic growth?
S. hominis
63
Is there a vaccine for staph? why or why not?
No, because it mutates so much so immunization is not successful.
64
How is staph treated?
pus must be removed (pyogenic cocci)
65
What are the clinical concerns for staph?
* They are notorious for in their resistance to many drugs | * Difficult to control
66
What is the biggest concern with S. aureus?
95% of S. aureus strains have acquired genes for penicillase making them resistant to penicillin and ampicillin.
67
MRSA can only be controlled by ________?
vancomycin
68
Name 3 antibiotics that MRSA is resistant to.
Erythromycin, tetracyclins, cephalosporins
69
How can nosocomial staph infections be prevented in a hospital?
consistent practice of universal precautions by all hospital staff
70
Family of gram- cocci.
Neisseriaceae
71
Two pathogen types of Nesseria
* Neisseria gonorrhoeae | * Neisseria meningitidis
72
What is unique about the shape of Neisseriaceae
coffee bean shaped.
73
Nesseria are found in pairs or ________ with flat side touching.
diplococci
74
Neisseria gonorrehoae are also known as
gonococcus
75
What kind of incubator do Neisseria need?
Capnophylic incubator ... produces more CO2
76
How would Neisseria be identified in a lab?
Neisseria are catalase + so it should make bubbles when combined with Hydrogen peroxide *it can also be identified with cytochrome oxidase
77
Respiration of Neisseria?
aerobic or microaerophilic
78
Neisseria will survive for how long outside?
2 hours
79
What affects Neisseria?
light, temp, pH
80
Neisseria gonorrhoeae are often confused with _______________.
syphilis
81
Claudius Geller thought gonococcus was caused by ___________________.
excess flow of semen
82
Humans are the only resevoirs for
N. gonorrhoeae
83
Among the top 5 reported STD's.
Neisseria gonorrhoeae
84
How many cases of gonorreah are reported each year
400,000.
85
What type of media is N. gonorrohoea grown in?
Martin - Tayer media(chocolate agar)
86
How is neisseria gonorrhoea identified?
gram stain (stains pink bc it's negative) and oxidase test
87
special type of neisseria?
has no fimbriae
88
antibiotic formulated for control of gonorrohea?
spectinomycin
89
causes epidemic cerebrospinal meningitis
Neisseria meningitidis
90
How is Neisseria meningitidis transferred?
respitory secretion or droplets from carrier
91
Most common in US
meningococcus

Medical Micro/Immunology (8 decks)

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