Gram Positive Cocci Flashcards
(166 cards)
0
Q
Alcohols and other solvents cause the cell wall to _____________.
A
Crenate
1
Q
Cell wall composition of gram-positive cocci
A
High concentration of peptidoglycan and a low level of lipid in the cell wall
2
Q
True or False: Alcohols and other solvents do not penetrate the gram positive cell wall
A
True
3
Q
Natural habitat of GP cocci
A
Skin and mucous membranes in humans; In dust and inanimate objects
4
Q
Mode of transmission
A
Direct contact
5
Q
Family Micrococcaceae: Four genera
A
Micrococcus, Staphylococcus, Planococcus, Stomatococcus
6
Q
Organisms that may colonize human skin but are rarely infectious
A
Micrococcus
7
Q
Organisms from the marine environment
A
Planococcus
8
Q
Organisms emerging as rare opportunistic pathogens
A
Stomatococcus
9
Q
Members of the Micrococcaceae are catalase (positive/negative)
A
Positive
10
Q
Facultative anaerobes and ferment glucose anaerobically
A
Staphylococcus
11
Q
Strict anaerobes; utilize glucose oxidatively/non-saccharolytic
A
Micrococci
12
Q
Resistant to 200 ug/ml of lysostaphin and modified oxidase positive
A
Micrococci
13
Q
Susceptible to lysostaphin and modified oxidase negative
A
Staphylococci
14
Q
A peptidase that breaks the glycine peptide linkages in the CW of Staphylococci
A
Lysostaphin
15
Q
Resistant to 0.04 units of bacitracin
A
Staphylococcus
16
Q
Susceptible to 0.04 units of bacitracin
A
Micrococcus
17
Q
Genus Staphylococcus: Catalase (positive/negative)
A
Positive
18
Q
Genus Staphylococcus: Modified Oxidase (positive/negative)
A
Negative
19
Q
Grows in 7.5-10% NaCl
A
Staphylococcus
20
Q
Easily isolated on Blood Agar, Collistin-Nalidixic Acid (CNA), or Mannitol Salt Agar (MSA)
A
Staphylococcus
21
Q
Typically arranged in pairs or chains and are pinpoint, flat, colorless colonies with wide zones of hemolysis
A
Streptococcus
22
Q
Describe the colonies of Staphylococci on blood agar
A
Medium convex, creamy, and dome shaped. Pigment varies from white to golden yellow
23
Q
Selective medium with a blood agar base that contains antibiotics collistin and nalidixic acid
A
Collistin-Nalidixic Acid (CNA)
24
Medium selective for gram-positive cocci; inhibits gram-negative bacilli
CNA
25
MSA contains ______________________.
7.5-10% NaCl, carbohydrate alcohol mannitol and phenol red indicator
26
Medium typically used to isolate Staphylococcus
MSA
27
Fermentation of alcohol is characterized by a _______________ as phenol red indicator takes up its acidic color.
Yellowing of the medium
28
Hemolytic pattern of most strains of S. aureus
Narrow zone of beta hemolysis
29
Medium to large colonies with a convex, creamy appearance
S. aureus
30
Test to differentiate S. aureus from other Staph species
Coagulase test (positive)
31
Measured in the coagulase slide test
Bound coagulase or Clumping factor
32
The appearance of white fibrin clots in the coagulase slide test (positive result) indicates the conversion of ___________.
Fibrinogen to fibrin
33
If the coagulase slide test is negativem what must be performed next?
Coagulase tube test
34
What does the coagulase tube test detect?
Free coagulase
35
An extracellular toxin which reacts in the presence of coagulase reacting factor (CRF)
Free coagulase
36
A compound normally found in plasma to form coagulase-CRF complex
CRF
37
The coagulase tube test is checked every 30 minutes since some strains of S. aureus produce this which may cause false negative results
Staphylokinase/Fibrinolysin
38
Most virulent species of staphylococci encountered
S. aureus
39
The S. aureus skin infection that involves the epidermis; Typified by the production of vesicles that rupture and
crust over
Impetigo
40
Normal flora of human anterior nares, nasopharynx, perineal area, and skin; can colonize various epithelial or mucosal surfaces
Staphylococcus aureus
41
Normal flora of human skin and mucous membranes; distributed widely, often in large numbers, over body surface
Staphylococcus epidermidis
42
Normal human flora similar to S. epidermidis but present in fewer numbers
S. haemolyticus and S. lugdunensis
43
Normal flora of human skin and mucosa of genitourinary tract
Staphylococcus saprophyticus
44
Normal flora of human skin, mucosa, and oropharynx
Micrococcus spp.
45
Produces and secretes toxins and enzymes that have a role in virulence
Staphylococcus aureus
46
Virulence factors that act on host cell membranes and mediate cell destruction (S. aureus)
Alpha, beta, gamma, and delta toxins
47
Virulence factor that mediates destruction of phagocytes (S. aureus)
Leucocidin (Panton Valentine Leucocidin)
48
Virulence factors that enhance invasion and survival in tissues (S. aureus)
Clumping factor, coagulase, and hyaluronidase
49
Production enhances organism adhesion and provides conditions refractory to antibiotic action and host defense mechanisms (S. epidermidis)
Exopolysaccharide “slime” or biofilm
50
Its propensity to acquire and disseminate antimicrobial resistance allows for survival in hospital setting.
Staphylococcus epidermidis
51
Mode of transmission: Spread of patient’s endogenous strain to normally sterile site by traumatic introduction (e.g., surgical wound or microabrasions)
Staphylococcus aureus
52
Also may be transmitted persounwashed hands of health care workers, especially in the nosocomial setting
Staphylococcus aureus
53
May be transmitted from infected skin lesion of health care worker to patient
Staphylococcus aureus
54
Spread of patient’s endogenous strain to normally sterile site, usually as a result of implantation of medical devices
Staphylococcus epidermidis
55
Person-to-person spread in hospitals can lead to patients becoming colonized and potentially infected with antibiotic-resistant strains
Staphylococcus epidermidis
56
MOT: Introduction of endogenous flora into sterile urinary tract notably in young, sexually active females
Staphylococcus saprophyticus
57
A community-acquired infection, not considered an agent of nosocomial infections
Staphylococcus saprophyticus
58
Infections generally involve intense suppuration and destruction (necrosis) of tissue.
Staphylococcus aureus
59
Ubiquitous member of normal flora makes this species the most commonly encountered in clinical specimens, usually as a contaminant
Staphylococcus epidermidis
60
The exfoliatin toxins cause extensive sloughing of epidermis to produce a burnlike effect on the patient; usually affects neonates
Scalded Skin Syndrome (SSS)
61
Toxin that has several systemic effects, including fever, desquamation, and hypotension potentially leading to shock and death.
Toxic shock syndrome toxin (TSST-1)
62
Most commonly encountered coagulase-negative staphylococci
S. epidermidis
63
Frequently found as contaminants in clinical specimens because they are ubiquitous colonizers
Coagulase-negative staphylococci
64
Medium to large; smooth, entire, slightly raised, translucent; most colonies pigmented creamy yellow; most colonies beta-hemolytic
S. aureus
65
Small to medium; translucent, gray-white colonies; most colonies nonhemolytic; slime-producing strains are
extremely sticky and adhere to the agar surface
S. epidermidis
66
Medium; smooth, butyrous and opaque; beta-hemolytic
S. haemolyticus
67
Medium to large; smooth, glossy, entire edge with slightly domed center; unpigmented or cream to yellow-orange
S. lugdunensis
68
Large; entire, very glossy, smooth, opaque, butyrous, convex; usually white but colonies can be yellow or orange
S. saprophyticus
69
True or False: Micrococcaceae will grow on 5% sheep blood and chocolate agars but not MacConkey agar
True
70
Species that may give a positive slide coagulase
| test other than S. aureus
S. lugdunensis and S. schleiferi
71
Coagulase tube test: Specimen of choice
Plasma containing EDTA; not citrate
72
Positive for both the 2-hour PYR and ornithine decarboxylase tests
S. lugdunensis
73
Can be found as part of the normal upper respiratory flora; Leading cause of bacterial pneumonia
and meningitis.
S. pneumoniae
74
May be carried in the upper respiratory tract of human but it is rarely considered as normal flora
S. pyogenes
75
Usually are only capable of causing infections in severely compromised patients
Leuconostoc spp. and Pediococcus spp
76
MOT: Person to person by direct contact with mucosa or secretions, or by contaminated droplets produced by coughs or sneezes
S. pyogenes
77
Normal flora of female genital tract and lower gastrointestinal tract; may occasionally colonize upper respiratory tract
S. agalactiae
78
MOT: Infections in fetuses and infants are acquired by person-to-person transmission from mother in utero or during delivery
S. agalactiae
79
MOT: Person-to-person spread by contact with contaminated respiratory secretions
S. pneumoniae
80
Normal flora of human oral cavity, gastrointestinal tract, and female genital tract
Viridans streptococci
81
MOT: Most notably results from dental manipulations with subsequent transient bacteremia
Viridans streptococci
82
Found in soil, food, water, and as normal flora of animals, birds, and humans
Enterococcus spp.
83
Species found in plants, vegetables, dairy products
Leuconostoc spp.
84
Found in foods and vegetation
Lactococcus spp. and Pediococcus spp.
85
Environmental; occasionally found on skin
Aerococcus spp.
86
Not only contribute to virulence but are also responsible for the beta-hemolytic pattern of S. pyogenes on blood agar plates
Streptolysin O and Streptolysin S
87
Virulence Factor (S. pyogenes): Mediates epithelial cell attachment
Protein F
89
Virulence Factor (S. pyogenes): Antiphagocytic
M protein
90
S. pyogenes produces enzymes and hemolysins that contribute to tissue invasion and destruction (Give the 5)
Streptolysin O/S, streptokinase, DNase, Hyaluronidase
91
Mediate production of rash (i.e., scarlet fever)
Streptococcal pyrogenic exotoxins
92
Cross-reactions of antibodies produced against streptococcal antigens and human heart tissue (disease)
Rheumatic fever
93
Deposition of antibody-streptococcal antigen complexes in kidney results in damage to glomeruli (disease)
Acute, poststreptococcal glomerulonephritis
94
Causes Rheumatic fever
S. pyogenes
95
Causes acute, poststreptococcal glomerulonephritis
S. pyogenes
96
Causes acute pharyngitis, impetigo, erysipelas, necrotizing fasciitis, myositis, and bacteremia
S. pyogenes
97
Causes pneumonia and scarlet fever
S. pyogenes
98
Its capsular material interferes with phagocytic activity and complement cascade activation
S. agalactiae
99
Infections most commonly involve neonates and infants, often preceded by premature rupture of mother’s membranes
S. agalactiae
100
Infections of this organism may be classified as early or late onset
S. agalactiae
101
Infections caused by this Strep group occur in patients with underlying malignancies
Group G streptococci
102
Occasionally have been associated with acute pharyngitis (Strep group)
Group C streptococci
103
Inhibits phagocytosis; Primary virulence factor of S. pneumoniae
Polysaccharide capsule
104
Leading cause of meningitis and pneumonia with or without meningitis; sinusitis, otitis media
S. pneumoniae
105
Virulence factor of Viridans streptococci that enhances attachment to host cell surfaces
Production of extracellular complex polysaccharides
106
Plays a key role in the development of dental caries
S. mutans (Viridans streptococci)
107
Generally considered to be of low virulence (Strep)
Viridans streptococci
108
Adhesion, cytolysins, and other metabolic capabilities may allow these organisms to proliferate as nosocomial pathogens
Enterococus spp.
109
Most common cause of acute pharyngitis, impetigo and erysipelas
S. pyogenes
110
“Flesh-eating bacteria”
S. pyogenes
111
Causes scarlet fever (exotoxin and organism involved)
Streptococcal pyrogenic exotoxins (SPE); S. pyogenes
112
Typified by multisystem involvement that includes renal
| and respiratory failure, rash, and diarrhea (dse, org and toxin)
Streptococcal TSS caused by SPE (S. pyogenes)
113
Manifested by fever, carditis (inflammation of
| heart muscle), subcutaneous nodules, and polyarthritis
Rheumatic fever
114
Characterized by edema, hypertension, hematuria, and proteinuria
Acute Glomerulonephritis
115
Mediated by antigen-antibody complexes that deposit in glomeruli, where they (S. pyogenes) initiate damage.
Acute Glomerulonephritis
116
Infections usually are associated with neonates and are acquired before or during the birthing process (organism)
S. agalactiae
117
Greening streptococci
Viridans
118
Formal name of Abiotrophia spp.
Nutritionally variant streptococci
119
Grow on 5% sheep blood and chocolate agars but not MacConkey agar
Micrococcaceae
120
Grow in the presence of salt and ferment mannitol produce colonies surrounded by a yellow halo
S. aureus
121
Visible growth on 5% sheep blood and chocolate agars incubated at 35C in CO2 or ambient air occurs within _____ of inoculation (Micrococcaceae)
24 hours
122
Incubation time required before growth is detected in MSA and other selective media
48-72 hours
123
May also ferment mannitol resembling S. aureus in MSA
S. saprophyticus
124
Not lysed with lysostaphin
Micrococcus spp and other related genera
125
Resistant to furazolidone
Micrococcus spp and other related genera
126
Susceptible to bacitracin
Micrococcus spp and other related genera
127
Microdase positive
Micrococcus spp and other related genera
128
Lysed with lysostaphin
Staphylococci
129
Bacitracin resistant
Staphylococcu
130
Furazolidone resistant
Staphylococci
131
Microdase negative
Staphylococci
132
Staphylococci are: (a) anaerobic (b) aerobic (c) facultatively anaerobic
(C) Facultatively anaerobic
133
Important agent of dogbite wound infections and may be misidentified as S. aureus if only coagulase testing is performed
S. intermedius
134
Positive for both the 2-hour PYR and ornithine decarboxylase tests
S. lugdunensis
135
Intrinsically more resistant to the antimicrobial agents commonly used in hospitals and is especially resistant to all currently available cephalosporins and aminoglycosides (genus)
Enterococci
136
Capable of acquiring and exchanging genes that encode resistance to antimicrobial agents (genus)
Enterococci
137
First clinically relevant group of grampositive cocci to acquire and disseminate resistance to vancomycin
Enterococci
138
The single cell–wall active agent available for use against gram-positive organisms resistant to betalactams
Vancomycin
139
Typically lancet-shaped and occurs singly, in pairs, or in
| short chains
S. pneumoniae
140
May elongate to form coccobacilli, although cocci are the primary morphology.
Leuconostoc
141
Organisms discussed in this chapter will grow on standard laboratory media such as 5% sheep blood and chocolate agars except ________.
Abiotrophia and Granulicatella
142
Abiotrophia and Granulicatella will not grow on MacConkey agar but will grow on _______. (Give 2)
CNA (Columbia agar with colistin and nalidixic acid) and PEA (phenylethyl alcohol agar).
143
Supplied on blood and chocolate agars for Abiotrophia and Granulicatella to grow on these media
Pyridoxal (Vitamin B6)
144
Media used to detect genital carriage of group B streptococci during pregnancy
Todd-Hewitt broth with antimicrobials
145
Use of Todd-Hewitt broth with antimicrobials
Suppresses the growth of vaginal flora and allow growth of S. agalactiae following subculture to blood agar
146
Visualization of beta-hemolysis is enhanced by ___________.
Anaerobic conditions (Stab inoculating loop)
147
Most organisms (Streptococcus) will grow on agar media within __________ of inoculation.
48 hours
148
_________ streptococci may have a distinctive buttery odor.
Beta hemolytic
149
Grayish white, transparent to translucent, matte or glossy; large zone of beta hemolysis
Group A beta hemolytic streptococci
150
Larger than group A streptococci; translucent to opaque; flat, glossy; narrow zone of beta hemolysis; some strains
nonhemolytic
Group B beta hemolytic streptococci
151
Grayish white, glistening; wide zone of beta hemolysis
Group C beta hemolytic streptococci
152
Grayish white, small, matte; narrow to wide zone of beta hemolysis
Group F beta hemolytic streptococci
153
Grayish white, matte; wide zone of beta hemolysis
Group G beta hemolytic streptococci
154
Small, gray, glistening; colonies tend to dip down in the center and resemble a doughnut (umbilicated) as they age; if organism has a polysaccharide capsule, colony may be mucoid; alpha-hemolytic
S. pneumoniae
155
Minute to small, gray, domed, smooth or matte; alpha-hemolytic or nonhemolytic
Viridans
156
Small, cream or white, smooth, entire; alpha-, beta-, or non-hemolytic
Enterococcus spp.
157
Can be used to identify Group A Streptococci
PYR test
158
Can be used to identify Group B Streptococci
CAMP or Hippurate test
159
Only species of beta-hemolytic streptococci that will give a positive PYR reaction.
S. pyogenes
160
Able to hydrolyze hippurate and is positive in the CAMP test.
S. agalactiae
161
Detects production of a diffusible, extracellular protein that enhances the hemolysis of sheep erythrocytes by Staphylococcus aureus
CAMP test
162
Positive CAMP test
Appearance of an arrowhead shape at the juncture of the S. agalactiae and S. aureus streaks
163
Confirmatory and is based on the ability of bile salts to lyse S. pneumoniae
Bile Solubility Test
164
Presumptive test for S. pneumoniae
Optochin Test
165
Produce a zone of inhibition (optochin)
S. pneumoniae
166
Grow up to the disk (optochin-resistant)
Viridans
