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🏠4.1 Microbes and Impact on Health

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Question Bank

1
What is a microbe?
Show answer
A microscopic organism

2
What is bacterial replication?
Show answer
The process by which bacteria reproduce

3
What is bacterial pathogenicity?
Show answer
The ability of bacteria to cause disease

4
What is a microbe?
Show answer
Microscopic organisms that can or can’t be seen by naked eye.

5
Which of the following are examples of different life forms that microbes include?
Show answer
Bacteria, Viruses, Fungi, Parasites

6
What is one type of microbe that can be seen by the naked eye?
Show answer
Fungi

7
What type of cellular structure do prokaryotes have?
Show answer
unicellular

8
How is the DNA of prokaryotes organized?
Show answer
circular with no protein

9
What is the primary method of cell division in prokaryotes?
Show answer
binary fission

10
What is the study of bacteria primarily focused on?
Show answer
Bacteriology

11
Which field of study is concerned with the classification and identification of bacteria?
Show answer
Taxonomy

12
What is the primary goal of bacteriology in medical research?
Show answer
Understanding bacterial infections

13
Which bacterial family is associated with the genus Bacillus?
Show answer
Bacillota

14
What is the bacterial family name for bacteria from the genus Mycoplasma?
Show answer
Mycoplasmataceae

15
Which bacterial family is derived from the genus Clostridium?
Show answer
Clostridiaceae

16
What is the primary reason bacteria outnumber human cells in the human body?
Show answer
They outnumber the total number of cells by about 10 to 1.

17
Which of the following is NOT a type of bacteria found in the oral cavity?
Show answer
Escherichia coli

18
What does the term 'Gram-positive bacteria' refer to?
Show answer
Bacteria that retain the crystal violet stain during Gram staining

19
What is the outermost part of a bacterial cell called?
Show answer
Cell Envelope

20
Which part of the bacterial cell is responsible for attachment and movement?
Show answer
Appendages

21
What is the internal structure of a bacterial cell referred to as?
Show answer
Cell Interior

22
What is the genetic material found in the bacterial cytoplasm?
Show answer
double stranded genetic material (nucleoid)

23
How is the nucleoid in bacteria described?
Show answer
circular, supercoiled DNA

24
What does the bacterial cytoplasm contain?
Show answer
ribosomes, double stranded genetic material (nucleoid) and plasmids

25
What are ribosomes primarily composed of?
Show answer
30S and 50S subunits

26
What type of DNA is found in plasmids?
Show answer
circular non-chromosomal double stranded DNA

27
What can plasmids contain genes for?
Show answer
antibiotic resistance or virulence factors

28
What is the primary component of the cell membrane?
Show answer
phospholipid bilayer

29
What role do carrier lipids play in the cell membrane?
Show answer
active transport of nutrients

30
Which of the following is NOT a function of the cell membrane?
Show answer
Site of action for certain antibiotics

31
What are the primary components of the cell wall in Gram-positive bacteria?
Show answer
Thick peptidoglycan layer, lipoproteins, and polysaccharide polymers

32
Which acids are unique to Gram-positive bacteria and contribute to their structural integrity?
Show answer
Lipoteichoic acids and Teichoic acids

33
What are the roles of lipoteichoic acids and Teichoic acids in Gram-positive bacteria?
Show answer
Contribute to structural integrity and are important in pathogenesis

34
What is the primary component of the inner membrane in Gram-negative bacteria?
Show answer
peptidoglycan

35
What toxic component is released from dying Gram-negative bacteria?
Show answer
Lipid A

36
Which enzyme may be found between the outer and inner membrane in certain Gram-negative bacteria?
Show answer
β-lactamase

37
What is the primary component of the cell wall in Gram-positive bacteria?
Show answer
teichoic acid

38
Which of the following is NOT a component of the envelope in Gram-negative bacteria?
Show answer
lipoteichoic acid

39
What is the name of the layer found in Gram-positive bacteria between the cell wall and the membrane?
Show answer
Peptidoglycan

40
What is the primary function of the capsule in bacteria?
Show answer
Protects the bacteria from phagocytosis

41
What structure is the capsule composed of?
Show answer
Polysaccharide

42
Which of the following is NOT a role of the bacterial capsule?
Show answer
Increases bacterial motility

43
What are flagella primarily composed of?
Show answer
flagellin protein

44
What is the main function of pili or fimbriae?
Show answer
facilitate bacterial adherence to the host cells

45
What are conjugation pili used for?
Show answer
DNA passage from one bacterial cell to the second

46
What is the primary function of endospores?
Show answer
Survival response to protect the bacteria in extreme conditions.

47
What component is essential for endospore germination?
Show answer
Calcium dipicolinate

48
Which of the following is NOT a spore-forming bacteria genus mentioned?
Show answer
Staphylococcus

49
What is the composition of the outer membrane in gram-negative bacteria?
Show answer
Proteins, phospholipids, and lipopolysaccharide

50
What is found in the peptidoglycan layer of gram-positive bacteria?
Show answer
Peptidoglycan (with teichoic acid)

51
What is the primary component of the cell membrane in gram-negative bacteria?
Show answer
Proteins, phospholipids

52
Which phase of the bacterial growth curve is characterized by a rapid increase in cell number?
Show answer
Exponential phase

53
What happens during the lag phase of bacterial growth?
Show answer
Cells are constant in number

54
In the death phase of the bacterial growth curve, what leads to cell death?
Show answer
Prolonged nutrient depletion and replication arrest

55
What type of bacteria require oxygen for growth using respiratory metabolism?
Show answer
Strict/obligate aerobes

56
Which enzyme protects bacterial cells from reactive oxygen species (ROS) in strict/obligate aerobes?
Show answer
Superoxide dismutase

57
What is the metabolic pathway used by strict/obligate anaerobes for growth in very low oxygen concentrations?
Show answer
Fermentation

58
What type of bacteria are facultative anaerobes?
Show answer
Most pathogenic bacteria

59
How do facultative anaerobes respond to the presence of air?
Show answer
Shift from a fermentative to a respiratory metabolism

60
What is the metabolic capability of aerotolerant anaerobes?
Show answer
Fermentative metabolism with and without oxygen

61
What type of oxygen requirement do microaerophiles have?
Show answer
Require the presence of small amounts of oxygen

62
What process is depicted in the bacterial replication diagram?
Show answer
Binary fission

63
Which of the following is NOT a part of the bacterial cell structure shown?
Show answer
Nucleus

64
What is the final step in the bacterial replication process?
Show answer
Cell Splitting into Two

65
What is the term for the free-floating individual bacterial cells?
Show answer
Planktonic

66
What substance do bacterial cells in the biofilm state become embedded in?
Show answer
Extracellular polymeric substance (EPS) matrix

67
What process is described as occurring when individual species alter their gene expression to cooperate with other cells in the biofilm?
Show answer
Quorum sensing

68
What is the magnification level shown in the scanning electron micrograph?
Show answer
6,000×

69
What is the primary subject of the scanning electron micrograph?
Show answer
biofilm on the surface of a tooth

70
Who is the photographer credited for the image?
Show answer
Steve Gschmeissner

71
What is pathogenicity described as in the context of microbes?
Show answer
a highly skilled trade

72
What are most bacteria primarily engaged in?
Show answer
browsing and recycling the rest of life

73
What does pathogenicity often seem like to Dr. Lewis Thomas?
Show answer
a sort of biological accident

74
What is the term used to describe the capability of a bacterial species to cause disease in a susceptible human host?
Show answer
Pathogenicity

75
Which of the following is an example of an intracellular pathogen?
Show answer
Mycobacterium tuberculosis

76
What term defines the degree of pathogenicity?
Show answer
Virulence

77
What are primary pathogens?
Show answer
Primary pathogens tend to cause disease in healthy hosts regardless of immune system status.

78
What are opportunistic pathogens?
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Opportunistic pathogens are capable of causing disease if the host has a weakened immune system or altered microbiota.

79
What is dysbiosis?
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Dysbiosis refers to microbial imbalance between the different microbial populations inside the body.

80
What is the first stage in the process of pathogenicity?
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Exposure

81
Which surfaces are important ports of entry for microbes?
Show answer
Mucosal surfaces

82
What facilitates bacterial adherence to host cells?
Show answer
Pili or fimbriae or capsule

83
What type of bacteria membrane is rich with adhesin proteins?
Show answer
Gram-negative bacteria membrane

84
What can bacteria form after adherence to host cells?
Show answer
Biofilm

85
What enzyme does the pathogen use to degrade the extracellular matrix?
Show answer
Collagenase

86
What does the pathogen use to convert fibrinogen to fibrin?
Show answer
Coagulase

87
Which protease inactivates IgA at the mucosal surface?
Show answer
Immunoglobulin protease

88
What does successful multiplication of the pathogen lead to?
Show answer
infection

89
What is a local infection confined to?
Show answer
a small area

90
What type of infection spreads throughout the whole body?
Show answer
systemic infection

91
When does disease transmission occur?
Show answer
when the pathogen moves from one host to the second

92
Common ports of transmission for pathogens are?
Show answer
mucus membranes

93
What are examples of structural bacterial products mentioned as virulence factors?
Show answer
antiphagocytic capsules, endotoxins and IgG-binding proteins

94
Which enzyme is collagenase used as a virulence factor for?
Show answer
Clostridium histolyticum

95
What are some extracellular gene products listed as virulence factors?
Show answer
collagenase, IgA-degrading proteases, exotoxins, etc.

96
What is the primary component of endotoxin?
Show answer
Lipid A

97
Which of the following is NOT a function of endotoxin?
Show answer
Inhibit cytokine release

98
What does endotoxin cause in various tissues?
Show answer
Ischemic or hemorrhagic necrosis

99
What type of exotoxin does Staphylococcus aureus secrete?
Show answer
alpha toxin

100
Which bacterium secretes streptolysin that creates pores in the cell membrane?
Show answer
Streptococcus pyogenes

101
What does the pore-forming exotoxin disrupt?
Show answer
host cell membranes

102
What does S. aureus secrete that causes cytokine release?
Show answer
toxic shock syndrome toxin (TSST-1) and enterotoxin superantigen

103
Which toxins does S. pyogenes secrete?
Show answer
erythrogenic toxins A and C

104
What type of cells are recruited by S. pyogenes superantigens?
Show answer
massive number of T cells

105
Which bacterium secretes diphtheria toxin?
Show answer
Corynebacterium diphtheriae

106
What does Shiga toxin produced by Shigella dysenteriae affect?
Show answer
60S ribosomes

107
Which toxin produced by Enterohemorrhagic E. coli affects both 60S ribosomal subunit and inhibits protein synthesis?
Show answer
verotoxin

108
What toxin produced by Vibrio cholerae leads to increased synthesis of cAMP?
Show answer
Cholera toxin

109
What does the cholera toxin primarily affect within the enterocyte?
Show answer
Protein kinase activity

110
What imbalance caused by cholera toxin leads to watery diarrhea?
Show answer
Electrolyte imbalance

111
What bacteria is responsible for secreting tetanus toxin?
Show answer
Clostridium tetani

112
What does tetanus toxin interfere with?
Show answer
release GABA

113
What is the early symptom of tetanus toxin exposure?
Show answer
muscle rigidity

114
What is the primary cause of botulism?
Show answer
Germination of Clostridium botulinum spores

115
Which condition is characterized by reduced muscle tone due to botulinum toxin?
Show answer
Flaccid paralysis

116
What are the two types of botulinum toxin?
Show answer
A & B

117
What are exotoxins primarily produced by?
Show answer
Gram-positive and Gram-negative

118
Where are endotoxins primarily found?
Show answer
Part of the cell wall. Released after cell death.

119
How are exotoxins typically classified in terms of antigenicity?
Show answer
Highly antigenic

120
What is the primary focus of Laboratory Diagnosis?
Show answer
Diagnosing diseases through laboratory tests

121
Which of the following is NOT a typical step in laboratory diagnosis?
Show answer
Patient consultation

122
What does laboratory diagnosis primarily involve?
Show answer
Analyzing biological samples

123
What is the term for bacteria that grow in chains?
Show answer
Strepto-

124
How do diplococci bacteria typically grow?
Show answer
in doublets

125
What type of bacteria remain in clusters?
Show answer
Staphylococci

126
What is the primary use of Gram Stain for cocci?
Show answer
most cocci are G +ve

127
Which staining technique is used to detect intracellular microbes?
Show answer
Giemsa

128
What prevents Gram staining in certain bacteria?
Show answer
High lipid content of cell wall (mycolic acid)

129
What is the primary stain used in Gram staining?
Show answer
Crystal Violet

130
Which bacteria stain purple in Gram staining?
Show answer
Gram-positive bacteria

131
What is the final counter stain used in Gram staining?
Show answer
Safranin

132
What is the reaction on blood agar for a bacterium exhibiting no hemolysis?
Show answer
No color change (reddish agar with bacterial colonies)

133
What type of hemolysis is characterized by a greenish-brown discoloration on blood agar?
Show answer
Alpha hemolysis

134
What does complete lysis on blood agar appear as?
Show answer
Yellowish discoloration

135
What is the role of the enzyme catalase?
Show answer
Catalase neutralizes the bactericidal effects of hydrogen peroxide by converting it into water and oxygen.

136
Which bacterium accelerates clot formation by secreting staphylocoagulase?
Show answer
Staphylococcus aureus

137
What does the enzyme catalase convert hydrogen peroxide into?
Show answer
Water and oxygen

138
What are examples of enzymes mentioned in 2-G-ve tests?
Show answer
maltase, oxidase, urease

139
What is the K antigen associated with?
Show answer
bacterial capsule

140
Where is the H antigen located?
Show answer
flagellar protein

141
What is the cell wall O antigen part of?
Show answer
outer polysaccharide portion of LPS

142
How many different O antigens were identified in the Salmonella genus?
Show answer
more than 1500

143
What are bacteria primarily known for in the context of human disease?
Show answer
causing infections

144
Which of the following is NOT a type of bacteria involved in human disease?
Show answer
Virus

145
What is the primary role of antibiotics in treating bacterial infections?
Show answer
killing bacteria

146
Which of the following is NOT a bacterium causing sexually transmitted infections?
Show answer
Herpes simplex virus

147
Which virus is NOT listed as a sexually transmitted infection in the provided slide?
Show answer
Influenza

148
Which of the following is NOT a type of parasite mentioned in the context of sexually transmitted infections?
Show answer
Malaria

149
What is the most common bacterial cause of sexually transmitted infections in the US?
Show answer
Chlamydia trachomatis

150
Where do Chlamydia trachomatis bacteria typically reside in the human body?
Show answer
human genital tract and eyes

151
What type of bacteria is Neisseria gonorrhoeae?
Show answer
Gram-negative diplococci

152
What disease does Treponema pallidum cause?
Show answer
syphilis

153
How are Chlamydia trachomatis, Neisseria gonorrhoeae, and Treponema pallidum transmitted?
Show answer
sexual contact and during vaginal delivery

154
What is the term used to describe the detection of bacteria through a staining method?
Show answer
Gram Positive Bacteria

155
Which staining technique is used to differentiate bacteria based on their cell wall composition?
Show answer
Gram Staining

156
What does the term 'Gram Positive' indicate about the bacterial cell wall?
Show answer
Thick peptidoglycan layer

157
What does the Catalase test differentiate?
Show answer
staphylococci from streptococci

158
Which bacterium is associated with the presence of Coagulase?
Show answer
Staphylococcus aureus

159
What is the primary function of the enzyme Catalase?
Show answer
breaks down hydrogen peroxide

160
What is the primary cause of abscesses associated with the species Staphylococcus aureus?
Show answer
β-lactamase conferring antibiotic resistance

161
How does Staphylococcus aureus typically spread?
Show answer
direct contact (hands) or inhalation

162
Which enzyme produced by S. aureus is responsible for penicillin antibiotic resistance?
Show answer
Beta lactamase enzyme

163
What is the primary role of toxic shock syndrome toxin (TSST) in the body?
Show answer
It is a superantigen that causes toxic shock syndrome by stimulating cytokine release from helper T cells, especially interleukin-2.

164
Which of the following is NOT a function of Staphylococcus aureus enterotoxin?
Show answer
It does not cause blood poisoning (sepsis).

165
What does Protein A in Staphylococcus aureus bind to?
Show answer
The heavy chain of IgG, leading to decreased phagocytosis.

166
What is the term for a bacterial skin infection commonly caused by Staphylococcus or Streptococcus?
Show answer
Impetigo

167
Which of the following is a serious infection that can rapidly affect the heart?
Show answer
Acute endocarditis

168
What is a potential complication of Staphylococcus infections in medical implants?
Show answer
Biofilm

169
What is the most common cause of skin abscesses in the United States?
Show answer
Methicillin-resistant Staphylococcus aureus (MRSA)

170
Which antibiotic do MRSA strains respond to?
Show answer
Vancomycin

171
What is the role of Staphylococcus epidermidis in medical devices?
Show answer
Contaminating and making biofilms on permanent medical devices like prosthetic joints

172
How are Streptococci classified based on hemolytic properties?
Show answer
into alpha and beta

173
What further classification is used for beta-hemolytic streptococci?
Show answer
Lancefield grouping into 21 classes

174
Which Lancefield groups are medically important?
Show answer
group A and B

175
What type of bacteria is Streptococcus pyogenes?
Show answer
Gram-positive cocci

176
Which of the following is NOT a virulence factor of Streptococcus pyogenes?
Show answer
Antibiotic

177
Where does Streptococcus pyogenes primarily reside?
Show answer
human throat and skin

178
What type of diseases are characterized by the production of toxins that cause severe symptoms like necrotizing fasciitis?
Show answer
Toxigenic diseases

179
Which of the following is NOT a symptom of Streptococcal toxic shock syndrome (STSS)?
Show answer
Headache

180
What is the primary cause of Streptococcal toxic shock syndrome (STSS)?
Show answer
S. pyogenes

181
What type of bacteria are Streptococcus agalactiae?
Show answer
Gram-positive cocci

182
Where do Streptococcus agalactiae primarily reside?
Show answer
human vagina

183
What type of hemolysis is associated with Streptococcus pneumoniae?
Show answer
alpha hemolytic

184
Which disease can Streptococcus pneumoniae cause in adults?
Show answer
pneumonia

185
What type of bacteria are Streptococcus pneumoniae?
Show answer
encapsulated

186
What is the characteristic color of Viridian Streptococci colonies on blood agar?
Show answer
greenish

187
Which of the following is NOT a habitat of Viridian Streptococci?
Show answer
skin

188
Which of the following diseases is NOT caused by Viridian Streptococci?
Show answer
measles

189
What is the pathogen described in the slide?
Show answer
low virulence organism with no known toxins

190
What component of the pathogen's glycocalyx enhances adhesion?
Show answer
polysaccharide

191
Which antibiotic prophylaxis is recommended for patients with prosthetic heart valves before invasive dental procedures?
Show answer
Penicillin group

192
Which species of Streptococcus is associated with the highest risk of infective endocarditis?
Show answer
S. mutans

193
What does the size of the circles in the graph represent?
Show answer
Number of IE cases

194
Which of the following species has a moderate risk of infective endocarditis?
Show answer
S. mitis/oralis

195
What is the habitat of Enterococcus faecalis?
Show answer
Normal gut microbiota; Also, isolated from endodontic infections.

196
What characteristic defines Enterococcus faecalis?
Show answer
G +ve facultative anaerobic bacteria, non-spore forming.

197
What infections can Enterococcus faecalis cause?
Show answer
Subacute infective endocarditis in hospitalized patients, urinary tract infections.

198
What type of bacteria causes anaerobic infection: Clostridium difficile?
Show answer
Obligate anaerobic Gram-positive spore-forming bacilli.

199
How does Clostridium difficile typically enter the human body?
Show answer
Following ingestion of spores.

200
Which route is commonly associated with the transmission of Clostridium difficile?
Show answer
Fecal-oral route.

201
What can lead to the over-proliferation of Clostridium difficile?
Show answer
Disruption of normal flora upon use of broad-spectrum antibiotics or chemotherapy.

202
What is the primary cause of pseudomembranous colitis?
Show answer
enterotoxin toxin A and the Cytotoxin, toxin B

203
Which antibiotic is typically used for severe cases of pseudomembranous colitis?
Show answer
vancomycin

204
What are the potential complications if pseudomembranous colitis is left untreated?
Show answer
colon rupture and sepsis

205
What is the term used to describe bacteria that do not stain with Gram stain?
Show answer
Gram Negative Bacteria

206
Which of the following is NOT a characteristic of Gram Negative Bacteria?
Show answer
Thick peptidoglycan layer

207
What type of staining method is used to identify Gram Negative Bacteria?
Show answer
Gram Stain

208
What is the primary habitat of Helicobacter pylori?
Show answer
human stomach

209
Which of the following is NOT a characteristic of Helicobacter pylori?
Show answer
gram-positive

210
What does Helicobacter pylori synthesize that can damage gastric mucosa?
Show answer
urease

211
What is the primary habitat of Pseudomonas aeruginosa?
Show answer
Water resources and environment

212
Which toxin produced by Pseudomonas aeruginosa can cause fever and shock?
Show answer
exotoxin A

213
Which of the following is NOT a characteristic of Pseudomonas aeruginosa?
Show answer
anaerobic growth

214
Which of the following is a Lactase fermenter within the Enterobacteriaceae family?
Show answer
Escherichia

215
Which bacterium is classified as a Non Lactase fermenter?
Show answer
Salmonella

216
Which group includes bacteria such as Escherichia and Salmonella?
Show answer
Enterobacteriaceae

217
What is the characteristic Gram stain reaction of Escherichia coli?
Show answer
Facultative Gram-negative bacilli

218
How is Escherichia coli typically acquired?
Show answer
during vaginal birth or by the fecal–oral route

219
Which of the following is NOT an antigen used for classification of Escherichia coli subtypes?
Show answer
L antigen

220
What type of diarrhea is caused by the Shiga-like Toxin Producing E. coli (STEC) O157:H7 strains?
Show answer
bloody diarrhea

221
Which E. coli strain is associated with traveler’s diarrhea?
Show answer
Enterotoxigenic E. coli (ETEC)

222
How does Enteroinvasive E. coli (EIEC) cause diarrhea?
Show answer
mechanically damaging the intestinal epithelium

223
What is Enteropathogenic E. coli (EPEC) primarily responsible for?
Show answer
Causes watery diarrhea in children <2 years old.

224
What is Uropathogenic E. coli (UPEC) mainly responsible for?
Show answer
Mainly responsible for the development of urinary tract infections in females.

225
What does STEC stand for?
Show answer
Shiga toxin-producing Escherichia coli

226
Which symptom is associated with ETEC?
Show answer
Watery diarrhea

227
What is a key symptom of EIEC?
Show answer
Chills

228
What type of bacilli is Salmonella enteritidis?
Show answer
Gram-negative facultative bacilli (non-capsulated)

229
How is Salmonella enteritidis transmitted?
Show answer
fecal–oral route

230
Which toxin does Salmonella enteritidis produce?
Show answer
endotoxin

231
What is the primary disease associated with Salmonella typhi?
Show answer
Typhoid fever

232
Where does the Salmonella typhi bacterium primarily reside?
Show answer
gall bladder

233
What type of bacilli is Salmonella typhi?
Show answer
Gram-negative facultative bacilli

234
What are the primary factors considered in the classification of bacteria?
Show answer
shape, stain, oxygen requirement

235
Which of the following is NOT a stage of pathogenesis?
Show answer
Latent stage

236
What does G+ve refer to in clinical bacteriology?
Show answer
Gram-positive bacteria

237
Which of the following is NOT a title of a book shown in the image?
Show answer
Dental Microbiology and Pathology

238
Who is the author of the book 'Medical Microbiology'?
Show answer
Kenneth J. Ryan

239
Which book is edited by Richard J. Lamont?
Show answer
Oral Microbiology and Immunology