Bacterial Structure; Gram staining Flashcards
1
Q
Ziehl-Neelsen, Kinyoun, Auramine-Rhodamine, Pappenheim, Baumgarten, Wadefite, Gabett
A
Acid Fast
2
Q
Neisser’s, Albert’s, Ljubinsky, LAMB (Loeffler’s Alkaline Methylene Blue), Burke’s
A
Metachromatic granules
3
Q
Dyar, Victoria Blue, Calcofluor white (for Fungal chitin)
A
Cell wall
4
Q
Levaditi Silver Impregnation, Fontana tribondeau
A
Spirochetes
5
Q
Dorner’s, Wirtz-Conklin, Schaeffer-Fulton (primary stain is malachite green, mordant is green, decolorizer is tap water, 2nd stain - safranin; Green spore, Pink bacteria)
A
Endospore
6
Q
Gray’s, Leifson, Caesares Gil, Fisher-Conn
A
Flagella
7
Q
Anthony’s, Nigrosin, India Ink = negative stain
A
Capsule/Negative stains
8
Q
Acridine orange, Feulgen
A
Nucleic acid/DNA
9
Q
Gimenez, Macchiavello
A
Rickettsia
10
Q
Dienes stain
A
Mycoplasma
11
Q
McFadyean
A
Bacillus anthracis
12
Q
Toluidine blue
A
Helicobacter pylori
13
Q
Wayson’s
A
Bipolar bodies (Y. pestis)
14
Q
Structure that includes the cell wall, plasma membrane, and other components defining the bacterial surface.
A
Cell Envelope
15
Q
Bacterial classification basis
A
Cell wall is the primary basis of bacterial classification.
16
Q
Peptidoglycan layer
A
Composed of N-acetyl-D-glucosamine (NAG) & N-acetyl-D-muramic acid (NAM).
17
Q
Absence of outer membrane and periplasmic space; thick peptidoglycan; teichoic acid present; 2 basal rings for flagella; resistant to physical destruction.
A
Gram-positive
18
Q
Presence of outer membrane and periplasmic space; thin peptidoglycan; lipopolysaccharide present; 4 basal rings for flagella; sensitive to physical destruction.
A
Gram-negative
19
Q
Most important differential staining test in microbiology; stains the microorganism’s cell wall.
A
GRAM STAIN
20
Q
Most critical step in Gram stain
A
Decolorization.
21
Q
Primary stain used in Gram staining.
A
Crystal violet
22
Q
Mordant used in Gram staining.
A
Gram iodine
23
Q
Alcohol-acetone mixture used in Gram staining.
A
Decolorizer
24
Q
Counterstain used in Gram staining.
A
Safrinin
25
Color after 2nd stain (Gram-positive)
Purple.
26
Color after 2nd stain (Gram-negative)
Pink.
27
Overdecolorization, old culture, acidic iodine, B-lactam drugs treatment
Gram-positive bacteria may appear Gram-negative.
28
Underdecolorization, too thick smear
Gram-negative bacteria may appear Gram-positive.
29
Direct smear
From specimen.
30
Indirect smear
From culture media.
31
Smear preparation steps
Smear → Air-dry → Fixation (10 mins. at 60°C or 1 min. in 95% methanol).
32
Direct smear reporting
Gram reaction, morphology, arrangement, and other elements seen.
33
QC Gram-positive
Staphylococcus aureus (purple to deep blue).
34
QC Gram-negative
Escherichia coli (pink to deep magenta).
35
Resists Decolorization
Acinetobacter, Kingella, Psychrobacter, Methylobacterium (may appear Gram-positive).
36
Gram Neutral/Ghost form
Bacillus anthracis (ghost capsule), Mycobacteria (poorly stained).
37
Poorly stained with Gram stain
Campylobacter, Brucella, Tropheryma whipplei.
38
Poorly stained with Safranin
Legionella, Gram-negative anaerobes, Francisella.
39
Not stained
Intracellular (Chlamydia, Rickettsia, Ehrlichia, Coxiella), No cell wall (Mycoplasma/Ureaplasma), Spirochetes (Dark-field microscopy).
40
Quantitating Organisms: None
No organism seen.
41
Quantitating Organisms: Rare
1+ <10 on complete smear.
42
Quantitating Organisms: Few
2+ 3–5 per OIF.
43
Quantitating Organisms: Moderate
3+ 6–10 per OIF.
44
Quantitating Organisms: Many
4+ >20 per OIF.
45
Quantitating Host cells: None
No host cells seen.
46
Quantitating Host cells: Rare
1+ <2 per LPF.
47
Quantitating Host cells: Few
2+ 2–10 per LPF.
48
Quantitating Host cells: Moderate
3+ 10–25 per LPF.
49
Quantitating Host cells: Many
4+ >25 per LPF.
50
Ghost forms
Cryptosporidium.
51
Ghost spherule
Coccidioides.
52
Q Score for Grading Clinical Sample
Used to evaluate sample quality based on neutrophil count and squamous epithelial cells.
53
Q Score 0
Average neutrophils: 0; no squamous epithelial cells.
54
Q Score +1
Average neutrophils: 1-9 (few); squamous epithelial cells: -1.
55
Q Score +2
Average neutrophils: 10-24 (moderate); squamous epithelial cells: -2.
56
Q Score +3
Average neutrophils: ≥25 (many/numerous); squamous epithelial cells: -3.
57
Interpretation of Q Score
Higher score indicates better quality of sample; a score of zero means the sample is superficial and not cultured.
58
Resists Decolorization
Acinetobacter, Kingella, Psychrobacter, Methylobacterium (may appear Gram-positive)
59
Appears as Gram Neutral/Ghost
Mycobacteria (Poorly stained)
60
Poorly stained with Gram stain
Campylobacter, Brucella, Tropheryma whipplei
61
Poorly stained with Safranin
Legionella, Gram-negative anaerobes, Francisella
62
NOT STAINED
Intracellular (Chlamydia, Rickettsia, Ehrlichia, Coxiella), No cell wall (Mycoplasma/Ureaplasma), Spirochetes (Dark-field microscopy)
63
Demonstrates presence of Mycolic Acid or Hydroxymethoxy Acid in bacterial cell wall; confirms suspected TB cases if patient is symptomatic or CXR is suggestive
Acid Fast Stain
64
SPUTUM Quality Screening Bartlett's classification
<10 epithelial cells, >25 pus cells under LPO
65
DSSM (Direct Sputum Smear Microscopy)
2x3 cm smear; 300 OIF examined
66
Present in the cell wall of Mycobacteria
Mycolic Acid
67
Ziehl-Neelsen Method (Hot Method)
1st Stain: Carbol Fuchsin; Mordant: Heat; Decolorizer: 3% Acid Alcohol; Counterstain: Methylene Blue; Acid-fast: Red/Pink; Non-acid fast: Blue
68
Kinyoun Method (Cold Method)
1st Stain: Carbol Fuchsin; Mordant: Phenol/Targetol; Decolorizer: 3% Acid Alcohol; Counterstain: Methylene Blue or Malachite Green; Acid-fast: Red/Pink; Non-acid fast: Green
69
Best Routine AFS Method
Ziehl-Neelsen
70
Best Tissue AFS Method
Kinyoun
71
Most Sensitive AFS Method
Auramine-Rhodamine (read 30 LPF)
72
Auramine-Rhodamine Method
1st Stain: Auramine Rhodamine; Decolorizer: 0.5% Acid Alcohol; Acid-fast: Yellow Fluorescence; Non-acid fast: No Fluorescence
73
Auramine-Rhodamine Quenching Agent
0.5% KMNO4/Potassium Permanganate
74
3% Acid Alcohol Composition
3% HCl and 95% Ethanol
75
AFB Smear Sensitivity
20-80%
76
Sensitivity of Acid-fast Stain
5,000 – 10,000 AFB/mL
77
Newly Required Number of Sputum Samples for TB Detection
2 samples (1 random, 1 early morning sputum)
78
Spot-Spot / Frontloading Method
2 samples, one-hour apart: 1 spot-AM & 1 spot-early morning
79
Confirmed Case of Tuberculosis
1/2 or 2/2 positive AFB samples
80
CDC AFB Grading - No AFB Seen
0 AFB/300 fields
81
CDC AFB Grading - Indeterminate
1-2 AFB/300 fields
82
CDC AFB Grading - 1+
1-9 AFB/100 fields
83
CDC AFB Grading - 2+
1-9 AFB/10 fields
84
CDC AFB Grading - 3+
1-9 AFB/field
85
CDC AFB Grading - 4+
>9 AFB/field
86
DOH AFB Grading - 0
No AFB/300 fields
87
DOH AFB Grading - +n
n AFB/100 fields
88
DOH AFB Grading - 1+
10-99 AFB/100 fields
89
DOH AFB Grading - 2+
1-10 AFB/field (at least 50 fields)
90
DOH AFB Grading - 3+
>10 AFB/field (at least 20 fields)
91
Fluorescence Issues - Photobleaching
Permanent loss of fluorescence due to chemical damage of fluorochrome
92
Fluorescence Issues - Quenching
Result of transfer of light energy to nearby molecules such as free radicals, salts of heavy metals, or halogens
93
Staining Methods - Pappenheim’s Staining (Urine)
M. smegmatis (Blue) vs M. tuberculosis (Red)
94
Staining Methods - Baumgarten’s Staining (Tissue)
M. leprae (Red) vs M. tuberculosis (Blue)
95
Staining Methods - Fite-Faraco Stain
Used for M. leprae
96
Modified Acid-Fast Stain
Used for partial acid-fast microorganisms like Nocardia, Coccidians (CIC); uses weak decolorizer such as 1% H2SO4 Alcohol
97
Found only in Gram-negative bacteria; Initial barrier to the environment; Composed of Lipopolysaccharide giving negative charge
Outer Membrane
98
Permeability barrier; Involved in cell wall synthesis; Site of energy/ATP synthesis (counterpart of mitochondria)
Inner Membrane
99
Found only in Gram-negative; Gel-like substance that captures nutrients and detoxifies solutes like antibiotics
Periplasm/Periplasmic Space
100
dsDNA
Bacterial DNA
101
Extrachromosomal DNA that carries antibiotic resistance genes
Plasmid
102
70s in bacteria; 80s in fungi; Responsible for protein synthesis
Ribosome
103
Can be removed by boiling (100°C); consists of polysaccharide/carbohydrates (except for B. anthracis) which has Poly-D-glutamic acid/protein; contributes to bacterial colonization and anti-phagocytic properties
Capsule
104
Encapsulated bacteria include N. meningitidis, S. pneumoniae, K. pneumoniae, H. influenzae, Cryptococcus neoformans; lab diagnosis via Neufeld Quellung reaction and K or Vi Ag typing
Encapsulated Bacteria
105
Food reserve granules that lessen osmotic pressure
Metachromatic Granules
106
Babes-Ernst bodies are associated with this bacterium
C. diphtheria
107
Bipolar bodies are associated with this bacterium
Y. pestis
108
Bacteria that produce many granules, related to this disease
M. tuberculosis
109
Bacteria associated with sulfur granules
Nocardia
110
Structure for attachment (common pili); also involved in gene transfer (sex pili, F factor)
Pili or Fimbriae
111
Bacteria with pili for attachment include N. gonorrhoeae and B. pertussis
Pili or Fimbriae (Attachment)
112
Process involving the uptake of naked or free DNA
Transformation
113
Gene transfer method involving transposons, plasmids, and a sex pilus
Conjugation
114
Gene transfer method involving a bacteriophage (virus)
Transduction
115
Structure composed of Calcium dipicolinate, providing resistance to heat, chemicals, nutrient deprivation, and drying
Endospore
116
Endospore location for Bacillus anthracis
Center
117
Endospore location for Clostridium tetani
Terminal
118
Endospore location for Clostridium botulinum
Subterminal
119
Structure responsible for locomotion in bacteria
Flagella
120
Flagella arrangement where no flagella are present
A-trichous
121
Flagella arrangement with a single flagellum at one end of the cell
Mono-trichous
122
Flagella arrangement with a single flagellum at both ends of the cell
Amphi-trichous
123
Flagella arrangement with a group of flagella located at one end of the cell
Lophotrichous
124
Flagella arrangement with multiple flagella around the surface of the cell
Peritrichous
125
Flagella composed of an axial filament, used for spirochetes to move in a corkscrew motion
Endoflagella
126
Fluid containing thousands of enzymes and the site of protein synthesis in the cell
Cytosol
127
Region of the cell containing the bacterial chromosome, which is circular and complexed with RNA
Nucleoid
128
Genomic regions where virulence factors are encoded
Pathogenicity islands (PAIs)
129
Bacteria involved in biofilm production
S. aureus, Streptococcus, Listeria, Pseudomonas, Candida
130
Composition of biofilm
Monomicrobic or polymicrobic group of bacteria housed in a complex biochemical matrix
131
Function of biofilm in relation to implants and prosthetic devices
Adheres to implants and prosthetic devices; contributes to antibiotic resistance
132
State of cells in a biofilm that are starved, nutrient-deprived, and slow-growing, displaying reduced susceptibility to antimicrobial agents
Persister cells
133
Signaling mechanism in Gram-negative bacteria
Acyl homoserine lactone (AHL)
134
Signaling mechanism in Gram-positive bacteria
Oligopeptides
135
Bacteria known to produce biofilm
S. aureus, CONS, Streptococcus, Listeria monocytogenes, P. aeruginosa, Acinetobacter, Aeromonas, Aggregatibacter spp., Salmonella spp., Enterobacter, Enterococcus, Escherichia coli, Klebsiella, Proteus, Serratia, Citrobacter koseri, and Candida albicans
136
Definition of toxins in relation to host cells
Biochemically active substances that have particular effects on host cells
137
Exotoxins production
Produced by Gram-positive and Gram-negative bacteria
138
Chemical nature of exotoxins
Protein
139
Mode of release for exotoxins
Secreted
140
Heat stability of exotoxins
Destroyed at 100°C
141
Detoxification method for exotoxins
Formaldehyde detoxified
142
Immunogenicity of exotoxins
Immunologic, convertible to toxoid vaccine
143
Specificity of exotoxins
Specific; localized infection
144
Effects of exotoxins on host cells
Kills host cells, interferes in cell signals and protein synthesis
145
Endotoxins production
Produced by Gram-negative bacteria
146
Chemical nature of endotoxins
Protein-lipid-polysaccharide (example: LPS)
147
Release of endotoxins
Reacted upon lysis, intact
148
Detoxification of endotoxins
Not detoxified
149
Immunogenicity of endotoxins
Non-immunologic, not neutralized by antitoxin
150
Specificity of endotoxins
Broad; systemic infection
151
Effects of endotoxins on the body
Either disrupt or form clots (DIC), fever, activation of complement/immune system, hypotension, shock, death
152
Toxin testing includes
Immunodiffusion, PCR, Tissue culture, EIA, RIA, Limulus amebocyte lysate
153
Blood cell that is separated from plasma and lysing them makes a “lysate”, when mixed with endotoxin, it will form clots/precipitates and cause turbidity
Horseshoe crab (Limulus polyphemus) - amebocyte
154
For detection of toxins of Clostridium difficile, E. coli O157, and Rotavirus
Latex agglutination
