Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BACTE MIDTERMS > TOPIC 1 COAG POS GRAM POS COCCI > Flashcards

TOPIC 1 COAG POS GRAM POS COCCI Flashcards

1
Q

causes community-acquired infections

A

S. aureus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

they are known contaminants and cause
nosocomial infections

A

coagulase negative staphylococci or CONS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

S. au is a ______ that belong to the family ______

A

catalase-producing, gram(+) cocci ; Staphylococcaceae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

GENERAL CHARACTERISTICS: of Staphylococcus

A
  • Aerobic or facultative anaerobic except S. aureus subsp. Anaerobius and S. sacchrolyticus which are
    obligate aerobes
  • Nonmotile, non-spore forming
  • Spherical cells (0.5 to 1.5um) that appear singly, in
    pairs, and in clusters
  • Normal inhabitants of skin, mucous membranes, and
    intestines
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

in BAP, Staphylococcus colonies are:

A
  • medium-sized (4-8mm)
  • cream-colored, white, or rarely light gold
  • buttery-looking
  • other spp. may have gray colonies
  • some may be ß-hemolytic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Staphylococci vs Micrococci
*Bacitracin Test

A

Staphylococci: R
Micrococci: S

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Staphylococci vs Micrococci
*Furozolidone Susceptibility Test

A

Staphylococci: S
Micrococci: R

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Staphylococci vs Micrococci
*Lysostaphin Test

A

Staphylococci: S
Micrococci: R

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Staphylococci vs Micrococci
*Modified Oxidase Test /
Microdase Test

A

Staphylococci: (-)
Micrococci: (+)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Staphylococci vs Micrococci
*Growth on Furoxone Tween 80-oil Red O Agar

A

Staphylococci: (-)
Micrococci: (+)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Staphylococci vs Micrococci
*Aid in production from Glycerol (with erythromycin)

A

Staphylococci: (+)
Micrococci: (-)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Staphylococci vs Micrococci
*O/F Test

A

Staphylococci: Fermenter
Micrococci: Oxidizer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

S. au is cultivated by adding what percentage of HCl?

A

7.5-10% HCl

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q
  • Grow well on most routine media like Nutrient Agar
    (NA) and Trypticase Soy Broth (TSB)
  • on solid media,
    round, smooth, opaque and butyrous
  • on BAP, colonies
    have golden yellow color and β-haemolytic
  • True coagulase positive and most virulent species of
    staphylococci
  • Responsible for various skin, wound and deep tissue
    infection
A

S. au

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what are the virulence factors associated w/ S. au?

A
  1. Antigenic Structure
  2. Enzymes
  3. Toxins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Antigenic Structure of S. au

A
  • teichoic acid
  • peptidoglycan
  • protein a
  • clumping factor
  • capsular polysaccharide
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Contain ribitol
teichoic acid in
cell wall

A

teichoic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Together with
teichoic acid, it
protects the
bacteria from
lysis and
probably aids in
adherence

A

peptidoglycan

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q
  • Group specific
    antigen unique
    to S. aureus
  • Prevents
    antibody-
    mediated
    phagocytosis by
    PMN by
    competing for
    the Fc portion
A

protein a

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Component on
cell wall responsible for
clumping of the
whole Staphylococci in
the presence of
plasma

A

clumping factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Protects S.au from
phagocytosis

A

capsular polysaccharide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Enzymes of S.au

A
  • Coagulase (staphylocoagulase)
  • Hyaluronidase (spreading factor)
  • Staphylokinase (fibrinolysin)
  • Lipase (fat-splitting enzyme)
  • DNASE and phosphatase
  • Protease
  • Gelatinase
  • B-lactamase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q
  • Coagulates fibrinogen in the plasma
  • Promotes fibrin layer formation around the
    staphylococcal abscess protecting the bacteria from
    phagocytosis
A

coagulase (staphylocoagulase)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what are the 2 types of coagulase present in S. au?

A
  1. cell-bound coagulase or clumping factor
  2. unbound or free coagulase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what type of coagulase is bound to the cell wall and clots human, rabbit, or pig
plasma?

A

cell-bound coagulase or clumping factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what type of coagulase includes extracellular
enzymes not bound to the cell wall and cause clot
formation when bacterial cells are incubated
with plasma?

A

unbound or free coagulase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Hydrolyzes hyaluronic acid present in the intracellular
ground substance, permitting the spread of infection

A

hyaluronidase (spreading factor)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Fibrinolytic activities by dissolving fibrin clot

A

staphylokinase (fibrinolysin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q
  • Produced by both coagulase (+) and coagulase (-) staphylococci
  • Act on lipids present on the surface of the skin,
    particularly fats and oil secreted by the sebaceous
    glands
A

lipase (fat-splitting enzymes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

among the virulence factors of S. au, which is important in the formation of furuncles, carbuncles, and boils?

A

lipase (fat-splitting enzymes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q
  • o Lowers viscosity of exudates giving the pathogen more mobility
  • Destroys DNA
A

DNASE and phosphatase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

breaks down Penicillin and ß-lactam drugs

A

B-lactamase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

4 types of cytolytic toxins of S. au?

A

alpha-hemolysin
beta-hemolysin
delta-hemolysin
gamma-hemolysin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q
  • damage RBC, platelets, and macrophages and can
    cause severe tissue damage;
  • predominant hemolysin
A

alpha hemolysin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q
  • acts on sphingomyelin in the plasma membrane of
    RBC
  • aka “hot-cold” lysine : enhanced hemolytic
    activity on incubation at 37°C (heat labile) and
    subsequent exposure to cold (4°C)
  • exhibited in the Christie, Atkins, and Munch-
    Peterson (CAMP) Test
  • lethal and dermonecrotic
  • joins force with a-hemolysin
A

beta-hemolysin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q
  • less toxic to cells than either a-hemolysin or ß- hemolysin
  • produced by all S. aureus strain that cause RBC
    injury in culture and produce edematous lesions
A

delta-hemolysin ( δ-hemolysin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

what are the other Staphylococcus spp. that also produces δ-hemolysin?

A
  • S. epidermidis
  • S. haemolyticus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q
  • associated with Panton-Valentine Leukocidin
    (PVL)
A

gamma hemolysin (γ-hemolysin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q
  • exotoxin lethal to polymorphonuclear leukocytes
  • pore-forming exotoxin that suppress phagocytosis and
    associated with severe cutaneous infections and
    necrotizing pneumonia
  • associated with community-acquired staphylococcal
    infections
A

Staphylococcal Leukocidin / Panton-Valentine Leukocidin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q
  • heat-stable exotoxin: 100°C for 30 minutes
  • resistant to hydrolysis by gastric and jejunal enzymes
  • act as neurotoxins that stimulate vomiting through the vagus nerve
  • produced by 30%-50% of S. aureus isolates
A

enterotoxins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

enterotoxin associated w/ Staphylococcal food poisoning

A

Enterotoxins A, B, and D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

enterotoxins that are associated with toxic shock syndrome?

A

Enterotoxins B and C, sometimes G and I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

enterotoxin that is associated with Staphylococcal Pseudomembranous Enterocolitis?

A

Enterotoxin B

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Toxic Shock Syndrome Toxin-1 (TSST-1) is also known as>

A

Enterotoxin F or Pyrogenic Exotoxin C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q
  • Menstruating-associated TSS = TSS associated with
    tampon use
  • Chromosomal-mediated toxin
  • Superantigen that stimulates T-cell proliferation and production of a large amount of cytokines
  • Low concentrations = leakage by endothelial cells
  • Higher concentrations = cytotoxic

[include other names in answering)

A

Toxic Shock Syndrome Toxin-1 (TSST-1) or Enterotoxin F or Pyrogenic Exotoxin C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Exfoliative toxin is also known as?

A

Epidermolytic Toxin A and B or Exfoliatin serotypes A and B

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q
  • Serine protease that divides the intracellular bridges of
    the epidermis and causes excessive sloughing of the
    epidermis (stratum granulosum)
  • Causes Staphylococcal Scalded Skin Syndrome referred to as “Ritter’s Disease”
  • Implicated in Bullous Impetigo
A

Exfoliative toxin or Epidermolytic Toxin A and B
or Exfoliatin serotypes A and B

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

give the 9 related infections and diseases associated w/ S.au

A
  1. cutaneous infections
  2. toxic shock syndrome
  3. food poisoning
  4. staphylococcal bacteremia
  5. staphylococcal osteomyelitis
  6. staphylococcal pneumonia
  7. septic arthritis
  8. acute staphylococcal endocarditis
  9. uti
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

what are the cutaneous infections related to S. au?

A
  • foliculitis
  • furuncles
  • carbuncles
  • bullous impetigo
  • impetigo
  • scalded skin syndrome
  • toxic epidermal necrolysis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q
  • Mild inflammation of a hair follicle or oil gland; infected area is raised and
    red
A

folliculitis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

Focal suppurative lesions which has resulted from an infection (folliculitis)
that extend into subcutaneous tissue; large, raised, superficial abscesses

A

furuncles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Larger, more invasive lesions develop from multiple furuncles, which can
progress into deeper tisue; present with fever and chills, indicating systemic
infection

A

carbuncles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q
  • Larger pustules surrounded by a small zone of erythema
  • Highly contagious infection that spread by direct contact, fomites, or
    autoinoculation
A

bullous impetigo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

Superficial cutaneous infection commonly seen in newborns and young
children characterized by the formations of encrusted pustules surrounded
by red border

A

impetigo

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q
  • Bullous exfoliative dermatitis that occurs primarily in newborns and
    previously healthy young children
  • Localized skin lesion: few blisters, pemphigus neonatorum, Ritter disease
  • Generalized form: cutaneous erythema, profuse peeling of the epidermis
A

scalded skin syndrome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

Clinical manifestation with multiple causes; symptoms are due to
hypersensitivity reaction

A

toxic epidermic necrolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

Rare, but potentially fatal, multisystem disease characterized by sudden
onset of fever, chills, vomiting, diarrhea, muscle aches, and rash, which can
quickly progress to hypotension and shock

A

toxic shock syndrome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

food poisoning enterotoxin percentage

A

o Enterotoxins A (78%)
o Enterotoxin D (38%)
o Enterotoxin B (10%)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q
  • Intoxication resulting from ingestion of a toxin formed outside the body
  • Symptoms appear rapidly (2-8 hours after ingestion) and resolve within 24-
    48 hours: nausea, vomiting, abdominal pain, and severe cramping, diarrhea)
A

food poisoning

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

Leads to secondary pneumonia and endocarditis observed among IV drug
users

A

staphylococcal bacteremia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

Secondary to bacteremia

A

staphylococcal osteomyelitis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

o Secondary to influenza virus infection
o Multiple abscesses and focal lesions in the pulmonary parenchyma

A

staphylococcal pneumonia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

Frequent in children and occur in patients with a history of rheumatoid
arthritis or IV drug abuse

A

septic arthritis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

what are the bacteria present in Both adults and Neonates / Children for joined infections/septic arthritis?

A

Staphylococcus aureus
Staphylococcus agalactiae
Enterobacteriacaeae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

what are the bacteria present in Neonates / Children only for joined infections/septic arthritis?

A

Haemophilus influenzae type B
Kingella kingae

66
Q

what are the bacteria present in sexually active individuals for joined infections/septic arthritis?

A

Neisseria gonorrohoeae

67
Q

specimen of choice for lab diagnosis of S. au

A

blood, pus, urine, purulent fluids, sputum

68
Q

culture media used for purulent exudates?

A

Columbia Colistin Nalidixic Acid (CNA)

69
Q

culture media used for heavily contaminated specimens?

A

MSA and PEA

MSA: Mannitol Salt Agar
PEA: Phenylethyl Alcholol Agar

70
Q

culture media used for selective-defferential for MRSA

A

CHROM Agar

71
Q

give the 10 biochemical tests used for the laboratory diagnosis of S. au

A

a. catalase test
b. coagulase test
c. mannitol fermentation test
d. growth on tellurite glycine agar
e. polymyxin b sensitivity
f. lystostaphin sensitivity test
g. voges-proskauer test
h. dnase test
i. pyrrolidonyl arylamidase test
j. rapid methods for identification
k. molecular methods

72
Q

in the catalase test for S. au, what reagent is used? what concentration

A

3% H2O2 for aerobic catalase test
15% H2O2 for anaerobic catalase test

73
Q

result in catalase test

A

staphylococcus (+)
streptococcus (-)

74
Q

what test is the best single criterion of recognition and pathogenicity of
S. aureus?

A

coagulase test

75
Q

what are the 2 methods used in coagulase test?

A

slide method
tube method

76
Q
  • a rapid screening test
  • it detects cell-bound coagulase or clumping factor
A

slide method

77
Q

what are other spp. of Staphylococcus that is coagulase (+) ?

A

S. lugdunensis
S. schleiferi

78
Q
  • a sensitive but definitive method
  • detects unbound or free coagulase
A

tube method

79
Q

what are other spp. of Staphylococci seen in animals that are coagulase (+) in tube method?

A

S. hyicus
S. intermedius
S. lutrae
S. schleiferi subsp. coagulans

80
Q

in tube method, incubate for ___ hours at _____^C?

A

1-4 hours at 35-37^C

81
Q

in tube method, if no clot forms after 4 hours, what should you do?

A

incubate for additional 20 hours at RT

82
Q

why should the result be read within 4 hours in the tube coagulase method?

A

to prevent false (-) rxn due to fibrinolysin w/c lyses the clot formed

83
Q

coagulase plasma with citrate is not suitable because?

A

it can cause false (+) result

84
Q

they use citrate
and release calcium forming clot in the absence of coagulase

A

pseudomonas and enterococci

85
Q

fill in the blanks
Mannitol Fermentation Test:
*Culture Medium:
*pH indicator:
*Result:

A

*Culture Medium: Mannitol Salt Agar (MSA)
*pH indicator: phenol red
*Result: yellow-colored colonies surrounded by a yellow halo

86
Q

what color is produced by S. au in the tellucine glycine agar test? how about for other staphylococci?

A
  • jet-black for S. au
  • growth is inhibited for other Staphylococci but if growth occurs, gray colonies are seen
87
Q

indicate the result in polymixin B sensitivity test for S.au

A

S. au - resistant
other Staphylococci - susceptible

88
Q

used to differentiate S. au from micrococci

A

lysostaphin sensitivity test

89
Q

result in lysostaphin sensitivity test

A

S. au - sensitive
Micrococci - resistant

90
Q

it is a test used to differentiate S. au from S. intermedius

A

Voges-Proskauer Test

91
Q

Voges-Proskauer Test
*Culture medium:
*Reagent:

A
  • Culture medium: VP broth w/ 5% glucose
  • Reagent: a-naphthol and KOH
92
Q

VP test result

A

S. au (+)
S. intermediums (-)

93
Q

other VP test positive Staphylococci spp.

A

S. lugdunensis
S. haemolyticus
S. schleiferi

94
Q

culture medium used in DNASE test for S. au

A

DNA-Methyl Green Agar

95
Q

DNASE test result

A

S.au - (+)

96
Q

it is a test used to differentiate coagulase (+) Staphylococci by slide methods

A

Pyrrolidonyl Arylamidase Test

97
Q

Pyrrolidonyl Arylamidase Test
*Substrate:
*Reagent:
*End product:
*Result:

A
  • Substrate: pyroglutamyl-B-naphthylamide
  • Reagent: p-dimethylaminocinnamaldehyde
  • End product: l-pyrrolidone and b-naphthylamine
  • Result: cherry red
98
Q

result in PYR test

A

PYR (-): S.au
PYR (+): S. lugdunensis, S. intermedius, S. schleiferi, S. haemolyticus

99
Q

tests used in rapid methods for identification of S.au

A
  • staphyloside
  • staphylatex
100
Q

makes use of sensitized sheep RBC

A

staphyloside

101
Q
  • Plasma-coated carrier particles (latex)
  • Plasma detects both clumping factor (w/ fibrinogen)
    and protein A in the cell wall of S. aureus (with IgG)
A

staphylatex

102
Q

a molecular method test used in identifying both MRSA and MSSA

A

Real-time PCR

103
Q
  • staphylococci from prepared smears in blood cultures
  • identification of mecA gene
A

QNAHA: Qualitative Nucleic Acid Hybridization Assay

104
Q

Molecular Method:
*Specimen:
*Advantage:

A
  • Specimen: anterior nares swabs
  • Advantage: rapid detection test for MRSA
105
Q

is responsible for adherence of S. epidermidis

A

Poly-y-DL-Glutamic Acid (PGA)

106
Q
  • Indigenous microbiota of the skin
  • Contaminant of medical instruments,
    catheters, CSF shunts, and prostheBc
    heart valve implants (implanted medical
    devices), hip prostheses
A

S. epidermidis

107
Q

what are the diseases associated with S. epidermidis?

A
  • stitch disease
  • healthcare-acquired UTI
  • endocarditis
  • bacteremia
108
Q

secondary to E. coli in causing UTI

A

S. saprophyticus

109
Q

what type of UTI is caused by S. saprophyticus?

A

COMMUNITY-ACQUIRED UTI

110
Q
  • Present on the normal skin and in the
    periurethral and urethral flora
  • Adheres effectively to the epithelial cells
    lining the urogenital tract
  • it is the common cause of UTI in young, sexually active women
A

S. saprophyticus

111
Q

what amount of CFU is considered significant in the urine culture of S. saprophyticus?

A

<10,000 CFU/ml

112
Q

what gene codes for oxacillin resistance?

A

mecA gene

113
Q
  • Clumping factor (+), tube coagulase (-)
  • Contains mecA gene that encodes oxacillin resistance
  • More aggressive than other CoNS in infectivity
A

S. lugdunensis

114
Q

what are the diseases caused by S. lugdunensis

A

infective endocarditis, septicemia, skin and soft tissue infections, meningitis, UTIs, and septic shock

115
Q

in BAP, they appear gray to white, opaque, small to
medium-sized pin-heads and non-hemolytic colonies

A

S. epidermidis

116
Q

biochemical test for S. epidermidis

A
  • Coagulase test: (-)
  • CNA: (+)
  • DNASE: (-)
  • Mannitol Fermentation: (-)
117
Q

noviobiocin susceptibility of S. epidermidis

A

novobiocin susceptible (5ug susceptible)

118
Q

in BAP, they appear white, opaque, slightly larger than pin-heads, non-hemolytic colonies although
some strains produce yellow pigments

A

S. saprophyticus

119
Q

biochemical test for S. saprophyticus

A
  • Coagulase (-)
  • DNASE (-)
  • Mannitol fermentation (-)
120
Q

noviobiocin susceptibility of S. saprophyticus

A
  • novobiocin resistant
121
Q

absence of phosphatase production
a. S. epidermidis
b. S. saprophyticus

A

b. S. saprophyticus

122
Q
  • causes wounds, bacteremia, endocarditis, and UTIs
  • Medium-sized colonies, with moderate or weak hemolysis and variable pigment production
A

S. haemolyticus

123
Q

NOVOBIOCIN SUSCEPTIBLE CoNS

A

S. epidermidis
S. capitis
S. haemolyticus
S. hominis subsp. hominis
S. lugdunensis
S. saccharolyticus
S. warneri

124
Q

NOVOBIOCIN RESISTANT CoNS

A

S. saprophyticus
S. cohnii
S. kloosii
S. xylosus

125
Q
  • a class of enzyme inactivating genes
  • codes for the methylation of 23s rRNA
  • results in resistance to erythromycin
  • inducible/constitutive resistance to clindamycin
A

ERM Gene: Erythromycin Ribosomal Methylase Gene

126
Q

ERM gene confers cross resistance to _____ and _____

A

macrolides (erythromycin) and streptogramins (quinupristin)

127
Q
  • codes for efflux mechanism: resistance to erythromycin but susceptibility to clindamycin
A

MSR Gene: Methionine Sulfoxide Reductase Gene

128
Q

give the resistant genes produced by Staphylococci

A
  • Erythromycin Ribosomal Methylase Gene
  • Methionine Sulfoxide Reductase Gene
129
Q
  • Type of S. aureus that is resistant to methicillin,
    nafcillin, and oxacillin
  • Acquired after prolonged stay in the hospital, close
    contact with carriers, effects of broad spectrum
    antibiotic treatments and exposure to nasal secretions
A
  • MRSA: Methicillin-Resistant S. au
130
Q

treatment of choice for MRSA

A

Vancomycin

131
Q

what are the 3 types or MRSA?

A
  • Community-Associated MRSA (CA-MRSA)
  • Healthcare-Associated Community Onset MRSA (HACO-MRSA)
  • Hospital-Associated MRSA (HA-MRSA)
132
Q
  • used to screen for MRSA in clinical samples
  • differentiate MRSA from hyperproducers of ß-
    lactamase, or Borderline Oxacillin-Resistant
    Staphylococcus aureus (BORSA)
A

Oxacillin-Salt Agar Plate

133
Q

codes for the altered Penicillin-Binding Protein
(PBP) = PBP2a or PBP2’

A

mecA gene

134
Q

Chromogenic Selective Differential Media in Chromogenic Test

A
  • MRSA Select
  • Spectra MRSA
  • CHROM Agar
135
Q

inhibit non-MRSA

A

Cefoxitin

136
Q

result of chromogenic test

A

changes in color of MRSA colonies within 24-48
hours using CHROM Agar against colonies of non-MRSA
(mauve-colored colonies)

137
Q
  • detect altered PBPs
  • Alternative method for testing and confirmation of
    oxacillin resistance
  • Performed on both CoNS and S. aureus
A

latex agglutination

138
Q

gold standard for MRSA detection

A

Molecular Nucleic Acid Probes or PCR Amplification

139
Q

screening for Vancomycin-Resistant Staphylococci

A

Vancomycin Agar Plate

140
Q

discrepant macrolide test results (erythromycin
resistant and clindamycin susceptible)

A

Modified Double Disk Diffusion Test (D-zone test)

141
Q

what are the tests utilize in the laboratory diagnosis for MRSA

A
  • Oxacillin-Salt Agar Plate
  • Chromogenic Test
  • Latex Agglutination
  • Molecular Nucleic Acid Probes or PCR Amplification
142
Q

what are the different types of tests in the beta-lactamase tests?

A
  • Cephalosporinase test
  • Acidimetric Method
  • Iodometric Method
143
Q

Uses cephalosporin or cefinase disk

A

cephalosporinase test

144
Q

substrate for cephalosporinase test

A

nitrocefin

145
Q

(+) Result of Cephalosporinase Test

A

deep pink or red color within 10 minutes (60 minutes for Staphylococci)

146
Q

Acidimetric method
*Reagent:
*pH indicator:
*(+) Result:

A
  • Reagent: citrate-buffered penicillin
  • pH indicator: phenol red
  • (+) Result: yellow
147
Q

Iodometric Method
*Reagent:
*(+) Result:
*(-) Result:

A
  • Reagent: citrate-buffered penicillin and starch iodine complex
  • (+) Result: colorless solution (penicilloic acid reduces iodine and prevents it to combine with starch)
  • (-) Result: purple (no color change)
148
Q

treatment used for cutaneous infections

A
  • oral oxacillin or dicloxacillin
  • if allergic, erythromycin can be substituted
149
Q

treatment used for systemic infections

A
  • parenteral nafcillin or oxacillin
  • if allergic, vancomycin or cephalosporin may be used
150
Q

Screening Test for MRSA

A
  • oxacillin screen plate
  • cefoxitin disk diffusion
  • macro e test
  • vancomycin agar screen plate
151
Q

Oxacillin Screen Plate
*Culture media:
*Microdilution testing:

A
  • Culture Media: MHA with 4% NaCl and 6ug/ml oxacillin
  • Microdilution testing: oxacillin in cation-supplemented MH Broth containing 2% NaCl
152
Q

Oxacillin Screen Plate
*Result:

A

resistant: growth of more than one colony
susceptible: no growth on the agar plate

153
Q

Oxacillin Screen Plate
*CoNS (resistant or susceptible)

A

R: 24 mm ZOI
S: >25mm ZOI

154
Q

disadvantage of oxacillin screen plate?

A

does not reliably detect oxacillin-resistant CoNS

155
Q
  • it is the preferred method for detection of oxacillin-resistance
    for both S. aureus and S. lugdunensis
  • improves detection of MRSA
  • serves to induce greater PB2a in mecA-containing
    strains
A

Cefoxitin Disk Diffusion

156
Q

Cefoxitin Disk Diffusion
*Interpretation

A
  • Resistant: <21mm
  • SuscepBble: >22mm
157
Q

Detection of heteroresistant VISA because the test uses
a higher concentration of organisms (1x10^8 bacteria/ml)

A

Macro E Test

158
Q
  • Best method for detection of either Vancomycin-
    resistant S. aureus (VRSA) or VISA
  • Broth microdilution test
A

Vancomycin Agar Screen Plate

159
Q

in Vancomycin Agar Screen Plate, what should be the result?

A

any growth or colony

159
Q

in Vancomycin Agar Screen Plate, S. au should be screened with _______ ?

A

6ug/ml vancomycin
incorporated into BHIA

160
Q

Colony test for oxacillin resistance

A

broth dilution and E-test

BACTE MIDTERMS (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions