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Flashcards in Micro - Clinical Bacteriology Deck (160)
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1
Q

What are the two functions of the peptidoglycan layer in bacteria?

A

Rigid support and protection against osmotic damage

2
Q

What is the chemical composition of the bacterial peptidoglycan layer?

A

A sugar backbone with cross-linked peptide side chains

3
Q

What is the major surface antigen in gram-positive bacteria?

A

Cell wall

4
Q

Which two cytokines does teichoic acid induce?

A

Tumor necrosis factor and interleukin-1

5
Q

What structure in gram-negative bacteria induces tumor necrosis factor and interleukin-1?

A

The lipid A component of lipopolysaccharide

6
Q

What is the major surface antigen in gram-negative bacteria?

A

Outer membrane (polysaccharide component of lipopolysaccharide)

7
Q

Where is endotoxin (lipopolysaccharide) located in gram-negative bacteria?

A

In the outer membrane

8
Q

Which bacterium has a nonpolysaccharide capsule?

A

Bacillus anthracis (which has D-glutamate)

9
Q

_____ are bacterial structures that mediate adherence to the host cell surface and are composed of glycoprotein.

A

Fimbriae (pili)

10
Q

What bacterial structure establishes attachment between two bacteria during conjugation?

A

Sex pili

11
Q

_____ are bacterial structures that provide motility and are composed of protein.

A

Flagella

12
Q

What bacterial structure provides resistance to desiccation, heat, and chemicals?

A

Spores

13
Q

What is the chemical composition of a spore?

A

Keratin-like coat and dipicolinic acid

14
Q

What kind of genetic information is stored in the bacterial plasmid?

A

Genes for antibiotic resistance, enzymes, and toxins

15
Q

What structure aids bacteria in adhering to foreign objects, such as indwelling catheters?

A

Glycocalyx

16
Q

What is the chemical composition of glycocalyx?

A

Polysaccharide

17
Q

What structures are common to both gram-positive and gram-negative bacteria?

A

Flagellum, pilus, capsule, peptidoglycan, and cytoplasmic membrane

18
Q

What structure is unique to gram-positive organisms?

A

Teichoic acid

19
Q

What structures are unique to gram-negative organisms?

A

Outer membrane (endotoxin/lipopolysaccharide)-lactamases in periplasmic space

20
Q

What is between the capsule and peptidoglycan layers in gram-negative organisms?

A

The outer membrane (which contains endotoxin/lipopolysaccharide)

21
Q

What is the difference between the peptidoglycan layer of gram-positive organisms and that of gram-negative organisms?

A

The peptidoglycan layer in gram-positive bacteria is much thicker than that of gram-negative bacteria

22
Q

What is between the inner cytoplasmic and outer membranes in gram-negative organisms?

A

Periplasmic space (the location of many enzymes, including -lactamases)

23
Q

Name the two major gram positive cocci.

A

Staphyloccus and Streptococcus

24
Q

What are the major gram negative cocci?

A

Neisseria

25
Q

Clostridium is a _____ (gram positive/gram negative) _____ (coccus/bacillus) .

A

Gram positive bacillus

26
Q

Corynebacterium is a _____ (gram positive/gram negative) _____ (coccus/bacillus).

A

Gram positive bacillus

27
Q

Listeria is a _____ (gram positive/gram negative) _____ (coccus/bacillus).

A

Gram positive bacillus

28
Q

What unique staining characteristic do Mycobacterium and Nocardia possess?

A

Mycobacterium and Nocardia are acid fast

29
Q

Haemophilus is a _____ (gram positive/gram negative) _____ (coccus/bacillus).

A

Gram negative bacillus

30
Q

Legionella is a _____ (gram positive/gram negative) _____ (cocci/bacillus).

A

Gram negative bacillus

31
Q

Bordatella is a _____ (gram positive/gram negative) _____ (coccus/bacillus).

A

Gram negative bacillus

32
Q

Yersinia is a _____ (gram positive/gram negative) _____ (coccus/bacillus).

A

Gram negative bacillus

33
Q

Francisella is a _____ (gram positive/gram negative) _____ (coccus/bacillus).

A

Gram negative bacillus

34
Q

Brucella is a _____ (gram positive/gram negative) _____ (cocci/bacillus).

A

Gram negative bacillus

35
Q

Pasteurella is a _____ (gram positive/gram negative) _____ (coccus/bacillus).

A

Gram negative bacillus

36
Q

Bartonella is a _____ (gram positive/gram negative) _____ (cocci/bacillus).

A

Gram negative bacillus

37
Q

Gardnerella is a _____ (gram positive/gram negative) _____ (coccus/bacillus).

A

Gram negative bacillus (gram staining can be variable)

38
Q

What are the two types of gram positive branching, filamentous bacteria?

A

Actinomyces and Nocardia

39
Q

Name three types of spirochetes.

A

Leptospira, Borrelia, Treponema

40
Q

What type of bacteria contains sterols but lacks cell walls?

A

Mycoplasma

41
Q

What type of bacteria contain mycolic acid in their cell walls and have high lipid content?

A

Mycobacteria

42
Q

Name six organisms that do not stain well by Gram stain.

A

Treponema, Rickettsia, Mycobacteria, Mycoplasma, Legionella pneumophila, and Chlamydia Remember: These rascals may microscopically lack color

43
Q

Name two methods used for visualizing treponemes.

A

Dark field microscopy and fluorescent antibody staining

44
Q

Name three predominantly intracellular parasites that do not Gram stain well.

A

Rickettsia, Legionella, and Chlamydia

45
Q

Mycobacteria can be visualized by acid-fast stain as a result of what characteristic?

A

High lipid content in the cell wall

46
Q

What is the reason that Mycoplasma do not Gram stain?

A

It does not have a cell wall

47
Q

Which primarily intracellular organism does not Gram stain well but can be seen with silver stain?

A

Legionella pneumophilia

48
Q

Borrelia, Plasmodium, Trypanosoma, and Chlamydia species can be visualized using what type of stain?

A

Giemsa stain

49
Q

Periodic acid-Schiff (PAS) staining is used to stain what types of metabolic substances?

A

Glycogen and mucopolysaccharides (PASs the sugar)

50
Q

True or False: Periodic acid-Schiff staining is used to diagnose Whipples disease.

A

TRUE

51
Q

Ziehl-Neelsen stain is used to stain what organisms?

A

Acid-fast bacteria

52
Q

India ink and mucicarmine can be used to visualize what pathogen?

A

Cryptococcus neoformans

53
Q

Silver stain is used to stain what organisms?

A

Pneumocystis and Legionella

54
Q

Haemophilus influenzae requires what medium to grow?

A

Chocolate agar with factors V (NAD) and X (hematin)

55
Q

Neisseria gonorrhoeae requires what medium to grow?

A

Thayer-Martin (VPN) media

56
Q

Bordetella pertussis requires what medium to grow?

A

Bordet-Gengou (potato) agar

57
Q

Which media are used to culture Corynebacterium diphtheriae?

A

Tellurite plate, Loefflers medium

58
Q

Mycobacterium tuberculosis requires what medium to grow?

A

L&wenstein-Jensen agar

59
Q

Lactose-fermenting enterics on MacConkeys agar grow colonies that are what color?

A

Pink

60
Q

Legionella requires what medium to grow?

A

Charcoal yeast extract agar buffered with cysteine

61
Q

Fungi require what medium to grow?

A

Sabourauds agar

62
Q

In what medium can Mycoplasma pneumoniae grow?

A

Eatons agar

63
Q

Escherichia coli can grow on what medium other than MacConkeys agar?

A

Eosin-methylene blue agar

64
Q

What is the appearance of Escherichia coli when it is grown on eosin-methylene blue agar?

A

Colonies with blue-black color and metallic sheen

65
Q

Which bacteria are obligate aerobes?

A

They are all obligate aerobes (remember: Nocardia, Pseudomonas aeruginosa, Mycobacterium tuberculosis, and Bacillus = Nagging Pests Must Breathe)

66
Q

Why does Mycobacterium tuberculosis have a predilection for the apices of the lung?

A

The apices of the lung have the highest partial pressure of oxygen

67
Q

Which aerobe is commonly associated with burn wound infections, nosocomial pneumonia, and pneumonias in patients with cystic fibrosis?

A

Pseudomonas aeruginosa (remember: Pseudomonas AERuginosa is an AERobe)

68
Q

What do Clostridium, Bacteroides, and Actinomyces have in common?

A

They are obligate anaerobes (remember, they Cannot Breathe Air)

69
Q

The lack of which enzymes makes obligate anaerobes susceptible to oxidative damage?

A

Catalase and/or superoxide dismutase

70
Q

What are characteristics of anaerobe infections in tissue?

A

They are generally foul smelling and difficult to culture and produce carbon dioxide and hydrogen gas

71
Q

Why are aminoglycosides ineffective against anaerobes?

A

AminOglycosides require Oxygen to enter a bacterial cell

72
Q

Which organisms are obligate intracellular organisms that cannot make their own ATP?

A

Rickettsia and Chlamydia (remember: Stay inside (cells) when it is Really Cold)

73
Q

Which bacteria are facultative, intracellular organisms?

A

Salmonella, Neisseria, Brucella, Mycobacterium, Listeria, Francisella, Legionella, and Yersinia (remember: Some Nasty Bugs May Live FacultativeLy)

74
Q

Name five encapsulated bacteria.

A

Klebsiella pneumoniae, Salmonella, Streptococcus pneumoniae, Haemophilus influenzae and Neisseria meningitidis (remember: Kapsules Shield SHiN)

75
Q

A polysaccharide capsule adds virulence by what mechanism?

A

Preventing phagocytosis

76
Q

Which test is used to see if an organism is encapsulated?

A

The Quellung reaction, in which the capsule swells (remember: Quelling = capsular swellung)

77
Q

What part of the bacteria is used as antigen in vaccines against Streptococcus pneumoniae, Haemophilus influenzae type B, and Neisseria meningitidis?

A

The capsule

78
Q

In the synthesis of vaccines against encapsulated bacteria, conjugation of polysaccharides with protein has what effect on the bodys immune response?

A

Increases immunogenicity and T-cell-dependent response

79
Q

Which four bacteria are urease-positive?

A

Helicobacter pylori, Proteus, Klebsiella, and Ureaplasma (remember: Particular Kinds Have Urease

80
Q

Staphylococcus aureus produces a _____ (yellow, red, or blue-green) pigment.

A

Yellow

81
Q

Pseudomonas aeruginosa produces a _____ (yellow, red, or blue-green) pigment.

A

Blue-green

82
Q

Serratia marcescens produces a _____ (yellow, red, or blue-green) pigment.

A

Red

83
Q

_____ produces yellow "sulfur" granules.

A

Actinomyces israelii (remember: Israel has yellow sand)

84
Q

Protein A in Staphylococcus aureus binds to the _____ region of immunoglobulin and disrupts two immune functions, _____and _____.

A

Fc; Opsonization and phagocytosis

85
Q

Immunoglobulin A protease is secreted by which bacteria?

A

Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria

86
Q

What protein from Group A Streptococcus prevents phagocytosis by the bodys immune cells?

A

M protein

87
Q

Exotoxins are found in which of the following: gram-negative bacteria, gram-positive bacteria, or both?

A

Both gram-negative and gram-positive bacteria

88
Q

In what structures and in what type of bacteria are endotoxins found?

A

Endotoxins are found in the outer membrane of most gram-negative bacteria and in Listeria

89
Q

Exotoxins _____ (are, are not) secreted; Endotoxins _____ (are, are not) secreted.

A

Exotoxins are secreted; endotoxins are not secreted

90
Q

What is the difference in the chemical composition of endotoxin vs exotoxin?

A

Exotoxins are polypeptides whereas endotoxins are lipopolysaccharides

91
Q

Where are the genes for exotoxin located?

A

In the plasmid or the bacteriophage

92
Q

Where are the genes for endotoxin located?

A

In the bacterial chromosome

93
Q

What are the major clinical effects of endotoxin and how are they induced?

A

Fever and shock due to induction of tumor necrosis factor and interleukin-1

94
Q

Which bacterial toxin (endotoxin or exotoxin) can be used as a vaccine?

A

Exotoxin toxoid is used as a vaccine against exotoxin-producing organisms

95
Q

_____ (endotoxin, exotoxin) is heat stable; _____ (endotoxin, exotoxin) is not.

A

Endotoxins (stable at 100°C for 1 hour), exotoxins (destroyed rapidly at 60°C, except staphylococcal enterotoxin)

96
Q

Which organism produces an exotoxin that is heat stable?

A

Staphylococcus aureus

97
Q

Bacteria that cause tetanus, botulism, and diphtheria involve which kind of toxin?

A

Exotoxins

98
Q

Gram-negative rods that cause meningococcemia and sepsis involve which kind of toxin?

A

Endotoxins

99
Q

Superantigens directly bind to which two receptors?

A

Major histocompatibility complex II and T-lymphocyte receptor

100
Q

The binding of superantigens to MHC II and T-cell receptor results in the widespread release of what factors?

A

Interferon and IL-2

101
Q

Name two characteristic organisms with superantigen exotoxins.

A

Staphylococcus aureus and Streptococcus pyogenes

102
Q

Which two Staphylococcus aureus toxins cause disease in humans?

A

Toxic shock syndrome toxin 1 and enterotoxin

103
Q

What are the symptoms of toxic shock syndrome?

A

Fever, rash, and shock

104
Q

Which toxin produced by Staphylococcus aureus causes food poisoning?

A

Enterotoxin

105
Q

Staphylococcus aureus exfoliatin can cause what illness?

A

Staphylococcus scalded skin syndrome

106
Q

The superantigen released by Streptococcus pyogenes causes what syndrome?

A

Toxic shock-like syndrome (caused by erythrogenic toxin)

107
Q

What are the functions of the two components of the A-B toxins found in certain bacteria, such as Corynebacterium diphtheriae?

A

B (binding) allows endocytosis and A (active) ADP-ribosylates host cell proteins

108
Q

Name four organisms that have adenosine diphosphate ribosylating A-B toxin.

A

Corynebacterium diphtheriae, Vibrio cholerae, Escherichia coli, and Bordetella pertussis

109
Q

Which two organisms adenosine diphosphate ribosylating A-B toxins stimulate adenylate cyclase?

A

Vibrio cholerae and Escherichia coli

110
Q

Diphtheria toxin causes pharyngitis and a pseudomembrane in the throat by the adenosine diphosphate ribosylation of what factor?

A

Elongation factor 2

111
Q

What organism causes pharyngitis with pseudomembrane formation?

A

Corynebacterium diphtheriae

112
Q

What is the effect of increased adenylyl cyclase activity caused by cholera toxin?

A

Increased chloride pumping into gut and decreased sodium absorption, pulling excess water into the gut

113
Q

The toxin released by what bacterium produces what is commonly referred to as rice-water diarrhea?

A

Vibrio cholerae

114
Q

_____ (adenylate, guanylate) cyclase is stimulated by the heat-labile toxin of Escherichia coli, whereas _____ (adenylate, guanylate) cyclase is stimulated by the heat-stabile toxin of Escherichia coli.

A

Adenylate, guanylate (remember: labile like the air, stable like the ground)

115
Q

Which organism causes whooping cough?

A

Bordetella pertussis

116
Q

How does Bordetella pertussis toxin cause lymphocytosis?

A

By the inhibition of the chemokine receptor

117
Q

Pertussis toxin causes the _____ (stimulation/inhibition) of Gi, which results in an _____ (increase/decrease) in cAMP

A

Inhibition; increase

118
Q

Which organism causes gas gangrene and what toxin is responsible?

A

Clostridium perfringens causes gas gangrene by release of its toxin (lecithinase)

119
Q

What is the characteristic finding of Clostridium perfringens plated on blood agar?

A

Double zone of hemolysis

120
Q

Clostridium tetani tetanus causes lockjaw by decreasing the level of what neurotransmitters?

A

Glycine and GABA (both are inhibitory neurotransmitters)

121
Q

What is the mechanism of botulinum toxin-induced paralysis?

A

Inhibition of the release of acetylcholine

122
Q

What foods are associated with botulism?

A

Canned food and honey

123
Q

Name two organisms that produce Shiga toxin.

A

Shigella and Escherichia coli O157:H7

124
Q

What does Shiga toxin do in the host cell?

A

Shiga toxin cleaves host cell rRNA inactivating the 60S ribosomal subunit

125
Q

Exaggerated release of cytokines caused by Shiga toxin can lead to what syndrome?

A

Hemolytic-uremic syndrome

126
Q

Which antibody is used to help diagnose rheumatic fever?

A

Antistreptolysin O antibody

127
Q

Vibrio cholerae toxin causes watery diarrhea by permanently activating which protein?

A

Gs

128
Q

Pertussis toxin causes whooping cough by permanently disabling which protein?

A

Gi (Turns the off off)

129
Q

Both cholera and pertussis toxins act by adenosine diphosphate ribosylation that permanently _____ (activates/inactivates) adenyl cyclase, thereby _____ (increasing/decreasing) cAMP.

A

Activates; increasing

130
Q

What is the mechanism of action of Bacillus anthracis edema factor?

A

Edema factor is a bacterial form of adenylate cyclase, which increases levels of cAMP

131
Q

How does anthrax edema factor differ from pertussis, cholera, and Escherichia coli toxin induction of cAMP production?

A

Anthrax edema factor is itself an adenylate cyclase, whereas pertussis, cholera, and Escherichia coli toxins permanently activate endogenous adenylate cyclase

132
Q

What is the chemical composition of endotoxin and where is it found?

A

It is a lipopolysaccharide found in the cell walls of gram-negative bacteria

133
Q

What type of bacteria has endotoxins, gram-positive or gram-negative?

A

Gram-negative bacteria (remember: eNdotoxin is an integral part of the cell wall of gram-Negative bacteria)

134
Q

What is the most active part of an endotoxin?

A

Lipid A

135
Q

Which cell type is activated by endotoxins?

A

Macrophages

136
Q

How is complement activated by endotoxins?

A

Via the alternative pathway

137
Q

Endotoxins activate the coagulation cascade via what factor?

A

Hageman factor

138
Q

The activation of macrophages by endotoxin results in the release of which substances?

A

Interleukin-1, tumor necrosis factor, and nitric oxide

139
Q

The release of which cytokines by endotoxin-activated macrophages results in fever?

A

Interleukin-1 and tumor necrosis factor

140
Q

The release of nitric oxide by endotoxin-activated macrophages results in what condition?

A

Hypotension (shock)

141
Q

Which component of the alternative complement pathway causes hypotension and edema?

A

C3a

142
Q

The activation of the coagulation cascade by endotoxins results in what condition?

A

Disseminated intravascular coagulation

143
Q

What are the four phases of the bacterial growth curve?

A

Lag phase, log phase, stationary phase, and death phase

144
Q

During which phase of the bacterial growth curve is there metabolic activity without division?

A

Lag phase

145
Q

During which phase of the bacterial growth curve is there rapid cell division?

A

Log phase

146
Q

What is the cause of slowed growth during the stationary phase of the bacterial growth curve?

A

Nutrient depletion

147
Q

During which phase of the bacterial growth curve does spore formation occur in some bacteria?

A

Stationary phase

148
Q

What causes cell death during the death phase of the bacterial growth curve?

A

Prolonged nutrient depletion and a buildup of waste products

149
Q

The process of direct DNA transfer from one bacterium to another is called what?

A

Conjugation

150
Q

What type of bacterial genetic transfer involves the phage-mediated transfer of DNA between prokaryotes?

A

Transduction

151
Q

What kind of DNA is transferred during transformation: chromosomal, plasmid, or both?

A

Both

152
Q

What type of bacterial genetic transfer involves the direct uptake of purified DNA by both prokaryotes and eukaryotes?

A

Transformation

153
Q

Are chromosomal and plasmid genes transferred in F+ F- conjugation or in Hfr F- conjugation?

A

Hfr F- conjugation; ONLY plasmid genes are transferred in F+ F- conjugation

154
Q

What kind of DNA is transferred during transposition: chromosomal, plasmid, or both?

A

Both

155
Q

When DNA is transferred from one chromosome (or plasmid) to another within the same cell it is called _____.

A

Transposition

156
Q

When an F+ plasmid is incorporated into the chromosomal DNA of a bacterial cell, that cell is then termed an _____ cell.

A

Hfr

157
Q

What type of transduction is described here: a lytic phage infects a bacterium, cleaves the bacterial DNA, and repackages bacterial DNA in viral capsids to infect other bacteria.

A

Generalized transduction

158
Q

What type of transduction is described here: a lysogenic phage infects a bacterium, inserts DNA into the chromosomal DNA of the bacterium, and repackages flanking chromosomal DNA into its capsid upon excision to infect other bacteria.

A

Specialized transduction

159
Q

In which of the following can chromosomal DNA not be incorporated into transferred DNA: generalized transduction, specialized transduction, F+ F- conjugation, Hfr F- conjugation and transposition.

A

F+ F- conjugation

160
Q

Name 5 bacterial toxins coded for in a lysogenic phage.

A

ShigA-like toxin, Botulism toxin, Cholera toxin, Diptheria toxin, Erythrogenic toxin of Streptococcus pyogenes (remember: ABCDE)