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Micro & Pathology > Micro Lab Exam 2 > Flashcards

Micro Lab Exam 2 Flashcards

1
Q

3 layers of skin

A

epidermis, dermis, subcutaneous tissue

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2
Q

Subcutaneous tissue

A

barrier to infection for deeper tissues, rich in fat, contains hair follicles and sweat glands

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3
Q

Dermis

A

dense connective tissue rich in blood and nerve supply

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4
Q

how does bacteria attack the skin??

A

Toxin production and initiating blood clots

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5
Q

What are the defense mechanisms of the skin?

A

maintenance of body temperature, maintenance of pH, presence of normal flora and excretion of water and salts

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6
Q

Which virus is associated with toxic shock syndrome and how?

A

Staph aureus; It produces and secretes several toxins and enzymes that act on the host’s immune system to mediate cell destruction

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7
Q

What are the test results of S. auerus?

A

It is catalase positive, rapid staph latex positive and coagulase positive

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8
Q

What is MRSA resistant to?

A

Methicillin

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9
Q

What areas of the body does MRSA colonize on?

A

nares, groin, and axilla

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10
Q

What tests are used for MRSA and what body parts are they for?

A

PCR - Nares
Culture - nares, groin, axilla

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11
Q

Pathogenicity

A

is a combination of the organism’s ability to cause disease as well as the human’s ability to prevent infection.

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12
Q

How we protect respiratory tract from infection?

A

nasal hairs, convoluted passages, mucous linings of the nasal turbinates, secretory IgA, nonspecific antibacterial substances like lysozomes, cilia and mucous lining of trachea, and reflexes like coughing, sneezing, and swallowing

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13
Q

How pathogens cause disease in respiratory tract?

A

adherence to host tissue cells, toxin production, bacterial possession of a polysaccharide capsule

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14
Q

Predisposing factors for infection

A

viral infections, mechanical ventilation, age, immune state

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15
Q

Appropriate culture sources

A

throat, sputum

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16
Q

Bordatella pertussis

A

Whooping cough

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17
Q

How to test for whooping cough

A

PCR

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18
Q

H. influenzae

A

a small gram negative coccobacilli that will grow primarily on chocolate agar.

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19
Q

Moraxella catarrhalis morphology

A

gram negative diplococci

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20
Q

Mycoplasma pneumoniae

A

organism associated with walking pneumonia.

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21
Q

Klebsiella pneumoniae

A

gram negative rod. It is sometimes found in alcoholics. Klebsiella pneumonia also has a capsule.

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22
Q

Organisms with capsules

A

Klebsiella pneumoniae and Streptococcus pneumoniae

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23
Q

ColumbiaCNA vs MAC agar

A

selects for growth of gram + organism while the other selects gram - organisms

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24
Q

Organisms showing alpha or green hemolysis include

A

Viridans strep
Streptococcus pnemoniae Streptococcus mutans Aerococcus viridans Aerococcus urinae Enterococcus faecium

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25
Q

What kinds of strep can cause endocarditis?

A

Alpha strep or Viridans Strep (gram positive cocci in chains)

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26
Q

Streptococcus pneumoniae

A

(gram positive arrow heads or lancets) – can cause pneumonia, meningitis, and otitis media (ear infections)

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27
Q

How to identify Streptococcus pneumoniae?

A

taxo P or optochin disk. Measure area of killing (no bacteria)

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28
Q

Which bacteria is the major cause of tooth decay?

A

Streptococcus mutans

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29
Q

What is the newly found pathogen in urine that is alpha hemolytic?

A

Aerococcus viridans or urinae

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30
Q

Which bacteria has a large percentage of resistance to vancomycin (about 40%)?

A

Enterococcus faecium

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31
Q

Beta strep group A can cause…

A

cause of strep throat and scarlett fever. Also known as Streptococcus pyogenes

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32
Q

Beta strep group B causes…

A

causes sepsis and meningitis in newborns. Also known as Streptococcus agalactiae.

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33
Q

Examples of beta strep groups

A

Beta strep Group A, Beta strep Group B, Beta strep Group C, Beta strep Group F and Beta strep Group G

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34
Q

Antigen testing is used to identify what primarily?

A

beta streps but also Group D Strep and nonhemolytic Group B Strep

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35
Q

example of a bacteria with Gamma hemolysis

A

Enterococcus faecalis – (gram positive cocci in chains)- can cause urinary tract infection (UTI)

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36
Q

What organisms does Mannitol Salt Agar grow?

A

Staphs and Vibrios because of the high concentration of salt

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37
Q

What does Mannitol agar contain?

A

agar contains mannitol and pH indicator phenol red

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38
Q

Pathogenic staph in mannitol agar plate lookes like…

A

yellow since mannitol fermented and pH dropped

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39
Q

Catalase test

A

Grind/rub bacteria into slide to break cell wall. Add 1 drop of 3% Hydrogen peroxide. A positive test produces bubbles while a negative test does not

40
Q

catalase negative bacteria

A

Streptococci and Enterococci

41
Q

Catalase positive cocci

A

Staph aureus, Staph epidermidis, Staph saprophyticus and Micrococcus luteus.

42
Q

Staph vs micrococcus appearance

A

Micrococcus is larger gram positive cocci in tetrads (units of 4)

43
Q

Staph saprophyticus “Honeymoon cytitis”

A

Common cause of uncomplicated UTIs in women and can cause prostatitis in men

44
Q

What is Staph saprophyticus resistant to?

A

Novobiocin

45
Q

Test results of S. auerus

A

Catalase +
Mannitol = yellow growth
Coagulation +
Rapid staph latex +(agglutination)
Novobisocin = sensitive
Disease state = skin, blood, bone, fluids, surgical wounds

46
Q

Test results of Staph epidermis

A

Catalase +
Mannitol = red growth
Coagulation -
Rapid staph latex -
Novobisocin = sensitive
Disease state = biofilms

47
Q

Test results of Staph saprophyticus

A

Catalase +
Mannitol = red growth
Coagulation -
Rapid staph latex -
Novobisocin = RESITANT
Disease state: Urines in sexually active in females; prostatitis in men

48
Q

Test results for Micrococcus luteus

A

Catalase +
Mannitol = red growth
Coagulation -
Rapid staph latex -
Novobisocin = sensitive
Disease state: opportunistic in the immunocompromised

49
Q

Which tests should only be for staph

A

Rapid staph and coagulate test

50
Q

What group is Strep pyogenes and what are their test results?

A

BETA STREP GROUP A
Hemolysis =Large Beta
Catalase -
Antigens A+, B-, D-
Taxo A +
Taxo P-
Salt -
Capsule = no
Disease state = strep throat, scarlett fever, destroy tissue

51
Q

What group is strep agalactiae and what are its test results?

A

BETA STREP GROUP B
Hemolysis=small beta
Catalase -
Antigens A-, B+, D-
Taxo A -
Taxo P -
Salt -
Capsule = no
Disease state = sepsis and meningitis in newborns; transmitted sexually

52
Q

Test results for Enterococcus Faecalis

A

Hemolysis = none
Catalase -
Antigens A-, B-, D+
Taxo A -
Taxo P -
Salt +
Capsule = no
Disease state= found in GI tract as normal flora, common in UTI

53
Q

Test results for Streptococcus pneumoniae

A

Hemolysis = Alpha/ green
Catalase -
Antigens A-, B-, D-
Taxo A -
Taxo P +
Salt-
Capsule = yes
Disease state = pneumonia

54
Q

What are the advantages a capsule provides for a bacterium?

A

protection, adherence, virulence (capable to cause disease), biofilms

55
Q

What does it mean for a bacterium to have adherence?

A

protein molecules that enable the bacteria to attach to surfaces such as host tissues or medical devices.

56
Q

Septicemia

A

systemic bacteremia with clinical signs and symptoms (fever, chills, hypothermia, vomiting, hyperventilation, and septic shock

57
Q

Risk factors for sepsis

A

Hospitalization, Recent surgery, Hemodialysis, IV and immune therapy and IV drug abuse.

58
Q

Describe the two ways blood cultures are evaluated in the lab

A

1st - blood culture contamination rate to be beneath 3%
2nd - appropriate volume of blood in the bottle

59
Q

3 types of blood culture machines

A

Bactec, BactiAlert, and Trek.

60
Q

three basic bottle types

A

aerobic,and anaerobic: 8-10 ml
pediatric: 1-4 ml

61
Q

Which bottle has a 95% of organisms covered?

A

Aerobic bottle

62
Q

How does the blood culture machines test the bottles?

A

They test the bottles every 10 minutes and then the pH is measured based on the CO2 given off by the bacteria. The bottle is positive when there is a 4 fold increase in gas. The machine will alarm and flash and the bottle is taken out of the machine and gram stained

63
Q

How long should a critical value be reported?

A

A positive blood culture (a critical value) should be reported within 1 hour of finding it

64
Q

Verigene or Biofire

A

rapid methods of identifying bacteria along with markers directly from blood and results take 1-2 hours (this saves lives and work)

65
Q

How long does it take for culture results?

A

48 hours

66
Q

What are blood culture bottles with resin used for?

A

When antibiotics are being given before a blood draw, this would be the best bottle to give because the resin will bind the antibiotic and allow any bacteria that is present to grow

67
Q

Sheep Blood agar plate:

A

5% sheep blood. It medium is red in color, it is enriched, nonselective, differential for hemolysis

68
Q

Chocolate Agar Plate

A

Solid medium with peptone base and lysed sheep red blood cells. , brown, enriched, nonselective

69
Q

What species of bacteria does the chocolate agar plate support the growth of?

A

Haemophilus and Neisseria species

70
Q

Mannitol Salt Agar

A

This is a solid medium with peptone base that contains 7.5% salt, mannitol and a phenol red indicator. It is selective for Staphylococcus and vibrios, not enriched, differential for mannitol fermentation of gram positive bacteria

71
Q

MacConkey Agar Plate

A

This is a solid medium with a peptone base to which bile salts and lactose have been added, selective for gram negative rods, neutral red is pH indicator, not enriched, differential for lactose fermentation, pink = +

72
Q

Rapid tests can be done to identify what group of streps?

A

Group A

73
Q

Tell me about rapid tests

A

Less sensitive than PCR, includes internal controls that give the result (one line = -, two lines = +)

74
Q

What happens in a strep latex test?

A

bacteria are mixed with a liquid extraction reagent to release the antigens from the cell wall

Agglutination happens when the antigen from a bacterial cell wall attaches to a specific antibody that is attached to latex particles

75
Q

Which bacteria has large, unique, complex carb antigens in their cell wall?

A

The beta-hemolytic streptococci

76
Q

Colonization

A

is the presence of microorganisms that do not cause disease in a particular setting

77
Q

Pathogenicity

A

a combination of the organism’s ability to cause disease as well as the human’s ability to prevent infection

78
Q

Bromthymol blue

A

the indicator in (oxidation/fermentation) OF tubes

79
Q

OF tubes

A

a semi-solid medium with a single carbohydrate like glucose and bromthymol blue pH indicator, nonselective and differential, oil is placed on one of the tubes to show fermentation result

80
Q

OF tube results

A

The tube is yellow below pH6.0 (acid), green between 6.0 and 7.6; (intermediate); blue above pH 7.6 (alkaline)

81
Q

What bacteria resulrs as a nonfermenter that is oxidase positive?

A

Pseudomonas aeruginosa

82
Q

The first basic test used to differentiate fermenters from nonfermenters ?

A

Oxidase

83
Q

What bacteria are Lactose fermenters and how do they appear in tests?

A

Klebsiella pneumoniae, E. coli, and Enterobacter aerogenes

appear pink on Mac and are oxidase negative

84
Q

Organisms that ferment lactose on MacConkey agar?

A

E. coli and Klebsiella pneumoniae

85
Q

How can you get a false positive on an oxidase test?

A

sometimes triggered by a metal loop or false negatives with older cultures.

86
Q

Clean voided urines are planted using what kind of loop vs bladder urines?

A

1:1000 loop vs 1:100 loop

87
Q

How to calculate how many colonies for clean voided urine?

A

Each colony that grows on a plate planted using a 1:1000 loop is multiplied by 1000

88
Q

UTI colony results?

A

have greater than 100,000 org/mL

89
Q

Pyelonephritis

A

kidney infection

90
Q

Cystoscopic urine

A

Collected with a cystocope which passed through the urethra into the bladder

91
Q

Pathogen found most commonly in urinary tract infection

A

E. coli

92
Q

Urinalysis

A

a procedure that combines a dipstick and microscopic analysis

93
Q

Urine culture is a culture for

A

isolation, identification and susceptibility testing of pathogen

94
Q

Dipstick urinalysis is used to detect

A

white blood cells, protein and nitrate

95
Q

Predisposing factors that will lead to a urinary tract infection

A

kidney stones, urine catheters that are left in for more than 24 hours, chronic conditions like diabetes, short urethra in women, hormonal changes, sexual activity, pregnancy, enlarged prostate in men.

96
Q

1 nosocomial acquired infection

A

UTI

Micro & Pathology (7 decks)

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