p.1
Activation of B Cells and Antibody Production
What initiates the activation of B cells?
A) Interaction with cytotoxic T cells
B) Encounter with a microbial antigen
C) Exposure to bacterial toxins
D) Contact with natural killer cells
E) Interaction with suppressor T cells
B) Encounter with a microbial antigen
Explanation: B cells become activated when they encounter a microbial antigen, which initiates a series of events mediated by helper T cells and cytokines.
p.1
Cytokines and Clonal Expansion
What role do cytokines play in the activation of B cells?
A) They inhibit B cell maturation
B) They mediate clonal expansion
C) They destroy microbial antigens
D) They suppress antibody production
E) They neutralize viral infections
B) They mediate clonal expansion
Explanation: Cytokines mediate clonal expansion, increasing the number of B cells capable of recognizing the antigen and activating their maturation into plasma cells.
p.1
Primary and Secondary Immune Responses
What is the function of B memory cells?
A) To produce antibodies immediately upon first exposure to an antigen
B) To remain quiescent until a second exposure to the original antigen
C) To destroy host cells infected with microorganisms
D) To neutralize microbial toxins
E) To inhibit bacterial motility
B) To remain quiescent until a second exposure to the original antigen
Explanation: B memory cells remain quiescent in the body until a second or subsequent exposure to the original antigen occurs, at which point they rapidly produce specific antibodies.
p.1
Activation of B Cells and Antibody Production
Which of the following is NOT a way antibodies protect the host?
A) Opsonization
B) Neutralizing microbial toxins
C) Promoting bacterial clumping
D) Inhibiting bacterial motility
E) Destroying host cells infected with microorganisms
E) Destroying host cells infected with microorganisms
Explanation: Antibodies protect the host by helping phagocytes ingest and kill microorganisms, neutralizing microbial toxins, promoting bacterial clumping, inhibiting bacterial motility, and blocking viruses from entering host cells, but they do not destroy host cells infected with microorganisms.
p.1
Role of T Lymphocytes in Cell-Mediated Immunity
What is the primary function of cytotoxic T cells?
A) To produce antibodies
B) To recognize and destroy host cells infected with microorganisms
C) To mediate regulatory responses within the immune system
D) To interact with B cells to facilitate antibody production
E) To neutralize microbial toxins
B) To recognize and destroy host cells infected with microorganisms
Explanation: Cytotoxic T cells recognize and destroy human host cells that have been invaded by microorganisms, which is crucial for eliminating infecting pathogens.
p.1
Primary and Secondary Immune Responses
What is the significance of the primary antibody response?
A) It provides immediate protection against infections
B) It delays antibody production upon first exposure to an infectious agent
C) It results in the rapid production of antibodies upon first exposure
D) It eliminates the need for nonspecific response defenses
E) It prevents the production of B memory cells
B) It delays antibody production upon first exposure to an infectious agent
Explanation: The primary antibody response is delayed when the host is first exposed to an infectious agent, emphasizing the importance of nonspecific response defenses like inflammation to hold the invading organisms in check.
p.1
Activation of B Cells and Antibody Production
Which cells are involved in antibody production without the intervention of helper T cells?
A) Cytotoxic T cells
B) Natural killer cells
C) B cells activated by bacterial capsules and outer membranes
D) Suppressor T cells
E) B memory cells
C) B cells activated by bacterial capsules and outer membranes
Explanation: Some antigens, such as bacterial capsules and outer membranes, can activate B cells to produce antibodies without the intervention of helper T cells, but this does not result in the production of B memory cells.
p.2
Activation of B Cells and Antibody Production
What is the primary target of antibody-mediated immunity?
A) Microorganisms inside human cells
B) Microorganisms outside human cells
C) Host cells containing microorganisms
D) Endogenous proteins
E) Exogenous proteins
B) Microorganisms outside human cells
Explanation: Antibody-mediated immunity targets microorganisms outside human cells, whereas cell-mediated immunity targets microorganisms inside human cells.
p.2
Role of T Lymphocytes in Cell-Mediated Immunity
What is required for T cell activation?
A) Direct interaction with pathogens
B) Interaction with antigen-presenting cells
C) Binding to antibodies
D) Exposure to cytokines
E) Contact with B cells only
B) Interaction with antigen-presenting cells
Explanation: T cells must be activated through interactions with other cells that process microbial antigens and present them on their surface, such as macrophages, dendritic cells, and B cells.
p.2
Role of T Lymphocytes in Cell-Mediated Immunity
What is the role of activated helper T cells?
A) Directly destroy host cells containing microorganisms
B) Produce antibodies
C) Facilitate inflammation by releasing cytokines
D) Recognize endogenous proteins
E) Present antigens to B cells
C) Facilitate inflammation by releasing cytokines
Explanation: Activated helper T cells work with B cells for antibody production and facilitate inflammation by releasing cytokines.
p.8
Epidemiology and Prevention of Infectious Diseases
What is the primary focus of epidemiology?
A) Studying the genetic makeup of pathogens
B) Tracking and characterizing infections and infectious diseases
C) Developing new antibiotics
D) Studying the immune response to infections
E) Analyzing the economic impact of diseases
B) Tracking and characterizing infections and infectious diseases
Explanation: Epidemiology focuses on tracking and characterizing infections and infectious diseases to understand their sources, transmission, and impact on public health.
p.6
Primary and Secondary Immune Responses
What is the term for infections that develop quickly?
A) Chronic infections
B) Latent infections
C) Acute infections
D) Silent infections
E) Persistent infections
C) Acute infections
Explanation: Infectious processes that develop quickly are referred to as acute infections, while those that develop and progress slowly are known as chronic infections.
p.3
Pathogen Characteristics and Virulence Factors
What role do virulence factors play in microorganisms?
A) They help microorganisms avoid host defenses and damage host cells
B) They help microorganisms produce more nutrients
C) They help microorganisms reproduce faster
D) They help microorganisms become non-pathogenic
E) They help microorganisms form spores
A) They help microorganisms avoid host defenses and damage host cells
Explanation: Virulence factors provide microorganisms with the capacity to avoid host defenses and damage host cells, tissues, and organs in various ways.
p.8
Epidemiology and Prevention of Infectious Diseases
What role do microbiologists in clinical laboratories play in epidemiology?
A) They develop new antibiotics
B) They recognize patterns suggesting potential outbreaks or epidemics
C) They study the economic impact of diseases
D) They focus on genetic research
E) They monitor environmental changes
B) They recognize patterns suggesting potential outbreaks or epidemics
Explanation: Microbiologists in clinical laboratories often recognize patterns that suggest potential outbreaks or epidemics, playing a crucial role in early detection and prevention.
p.5
Pathogen Characteristics and Virulence Factors
What are pathogenicity islands (PAIs) primarily composed of?
A) Only virulence-associated genes
B) Only mobility genes
C) Virulence-associated genes and mobility genes
D) Only antimicrobial resistance genes
E) Only plasmids
C) Virulence-associated genes and mobility genes
Explanation: PAIs typically comprise one or more virulence-associated genes and 'mobility' genes (e.g., integrases and transposases) that mediate movement between various genetic elements.
p.6
Epidemiology and Prevention of Infectious Diseases
What are the main factors determining the outcome of an infectious disease?
A) Host's diet and exercise
B) Host's health, pathogen virulence, and ability to clear the pathogen
C) Pathogen's color and shape
D) Host's age and gender
E) Pathogen's size and weight
B) Host's health, pathogen virulence, and ability to clear the pathogen
Explanation: The outcome of an infectious disease depends on the state of the host’s health, the virulence of the pathogen, and whether the host can clear the pathogen before it causes irreparable harm or death.
p.8
Epidemiology and Prevention of Infectious Diseases
Which of the following is NOT a factor that epidemiology focuses on to prevent infectious diseases?
A) Sources of pathogens
B) Mode of transmission
C) Human risk factors
D) Genetic makeup of pathogens
E) Factors contributing to good and bad outcomes
D) Genetic makeup of pathogens
Explanation: Epidemiology focuses on sources of pathogens, mode of transmission, human risk factors, and factors contributing to outcomes, but not specifically on the genetic makeup of pathogens.
p.5
Biofilm Formation and Its Implications
What is a biofilm?
A) A single microorganism floating freely
B) An accumulation of microorganisms embedded in a polysaccharide matrix
C) A type of antibiotic
D) A type of virus
E) A single-celled organism
B) An accumulation of microorganisms embedded in a polysaccharide matrix
Explanation: A biofilm is an accumulation of microorganisms embedded in a polysaccharide matrix, which helps them adhere to surfaces and protect against environmental threats.
p.5
Biofilm Formation and Its Implications
Which of the following is NOT a characteristic of biofilm-forming strains?
A) Increased antibiotic resistance
B) Nutrient deprivation
C) Reduced susceptibility to antimicrobial agents
D) Enhanced planktonic growth
E) Differential gene expression
D) Enhanced planktonic growth
Explanation: Biofilm-forming strains exhibit increased antibiotic resistance, nutrient deprivation, reduced susceptibility to antimicrobial agents, and differential gene expression compared to their planktonic counterparts.
p.8
Epidemiology and Prevention of Infectious Diseases
What is a key indicator of an inflammatory process in the patient's laboratory results?
A) Low white blood cell (WBC) count
B) Elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level
C) Normal blood pressure
D) Low hemoglobin levels
E) High platelet count
B) Elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level
Explanation: Elevated ESR and CRP levels are clear indicators of an inflammatory process, which correlates with the patient's elevated white blood cell count.
p.3
Survival Strategies Against Host Defenses
How do some microorganisms avoid being destroyed by phagocytes?
A) By producing a capsule
B) By producing antibodies
C) By increasing their size
D) By hiding in the bloodstream
E) By producing more toxins
A) By producing a capsule
Explanation: Some microorganisms, such as Streptococcus pneumoniae, avoid phagocytosis by producing a large capsule that inhibits the phagocytic process.
p.4
Survival Strategies Against Host Defenses
How do microorganisms avoid complement activation?
A) By producing antibodies
B) By producing a capsule that covers bacterial surface antigens
C) By increasing their metabolic rate
D) By reducing their size
E) By changing their DNA sequence
B) By producing a capsule that covers bacterial surface antigens
Explanation: Microorganisms can avoid complement activation by masking their activating molecules, such as through the production of a capsule that covers bacterial surface antigens.
p.4
Survival Strategies Against Host Defenses
What is a common strategy used by pathogens to survive the immune response?
A) Rapid invasion and multiplication
B) Decreasing their metabolic rate
C) Increasing their size
D) Changing their DNA sequence
E) Producing more antibodies
A) Rapid invasion and multiplication
Explanation: Pathogens can survive the immune response by rapidly invading and multiplying, causing damage to the host before the immune response can be fully activated.
p.5
Biofilm Formation and Its Implications
What is the role of acyl homoserine lactone (AHL) in biofilm formation?
A) It is a nutrient source
B) It is a signaling molecule in gram-negative bacteria
C) It is an antibiotic
D) It is a structural component of the biofilm
E) It is a toxin
B) It is a signaling molecule in gram-negative bacteria
Explanation: Acyl homoserine lactone (AHL) is a signaling molecule used in gram-negative bacteria for communication during biofilm formation.
p.5
Biofilm Formation and Its Implications
Which of the following is NOT a benefit of biofilm formation for microorganisms?
A) Protection from desiccation
B) Barrier against toxic compounds
C) Enhanced nutrient availability
D) Prevention of loss of protective molecules
E) Increased susceptibility to antibiotics
E) Increased susceptibility to antibiotics
Explanation: Biofilm formation provides protection from desiccation, forms a barrier against toxic compounds, and prevents the loss of protective molecules, but it does not increase susceptibility to antibiotics; rather, it decreases it.
p.7
Activation of B Cells and Antibody Production
Which of the following is an example of natural passive immunization?
A) Vaccination against polio
B) Administration of antibiotics
C) Passage of maternal antibodies to the newborn
D) Use of antiseptics
E) Wearing masks to block airborne microorganisms
C) Passage of maternal antibodies to the newborn
Explanation: The passage of maternal antibodies to the newborn is a key example of natural passive immunization, providing temporary protection to the newborn.
p.6
Primary and Secondary Immune Responses
What is the term for infections that are clinically silent before causing severe and acute infection?
A) Chronic infections
B) Acute infections
C) Latent infections
D) Persistent infections
E) Recurrent infections
C) Latent infections
Explanation: Some pathogens can be clinically silent inside the body without any noticeable effect on the host before suddenly causing a severe and acute infection. During this silent phase, the infection is said to be latent.
p.5
Pathogen Characteristics and Virulence Factors
Which of the following organisms is NOT mentioned as having PAIs that play a role in virulence?
A) Helicobacter pylori
B) Pseudomonas aeruginosa
C) Escherichia coli
D) Mycobacterium tuberculosis
E) Staphylococcus aureus
D) Mycobacterium tuberculosis
Explanation: The text lists several organisms with PAIs playing a role in virulence, but Mycobacterium tuberculosis is not mentioned among them.
p.2
Pathogen Characteristics and Virulence Factors
What are virulence factors?
A) Characteristics that enable microorganisms to survive outside the host
B) Characteristics that enable microorganisms to cause disease
C) Factors that prevent microorganisms from causing disease
D) Host defense mechanisms
E) Components of the immune system
B) Characteristics that enable microorganisms to cause disease
Explanation: Virulence factors are characteristics that enable microorganisms to cause disease by protecting the organism against host attack or mediating damaging effects on host cells.
p.7
Epidemiology and Prevention of Infectious Diseases
Which of the following is NOT a strategy for preventing the transmission of infectious diseases?
A) Wearing gloves
B) Using sterile medical techniques
C) Food preservation
D) Wearing masks
E) Avoiding direct contact with infected persons
C) Food preservation
Explanation: Food preservation is a strategy for controlling microbial reservoirs, not directly for preventing the transmission of infectious diseases.
p.6
Epidemiology and Prevention of Infectious Diseases
Which of the following is NOT a factor that contributes to controlling or clearing an infection?
A) Severity of the infection
B) Accuracy in diagnosing the pathogen
C) Patient's diet
D) Appropriate treatment for the infection
E) Host and microbial interactions
C) Patient's diet
Explanation: Factors that contribute to controlling or clearing an infection include the severity of the infection, accuracy in diagnosing the pathogen, and whether the patient receives appropriate treatment for the infection.
p.3
Survival Strategies Against Host Defenses
How do some pathogens survive within phagocytes?
A) By inhibiting phagosome-lysosome fusion
B) By producing more antibodies
C) By increasing their size
D) By hiding in the bloodstream
E) By producing more toxins
A) By inhibiting phagosome-lysosome fusion
Explanation: Some pathogens avoid phagocyte-mediated killing by inhibiting phagosome-lysosome fusion, allowing them to survive within phagocytes.
p.4
Types of Bacterial Toxins: Endotoxins and Exotoxins
What is the main difference between endotoxins and exotoxins?
A) Endotoxins are produced by gram-positive bacteria
B) Exotoxins are released only when the bacterial cell is destroyed
C) Endotoxins are a component of the cellular structure of gram-negative bacteria
D) Exotoxins are inactive within the host
E) Endotoxins are specific to host cells
C) Endotoxins are a component of the cellular structure of gram-negative bacteria
Explanation: Endotoxins are a component of the cellular structure of gram-negative bacteria and are released when the bacterial cell is destroyed.
p.8
Epidemiology and Prevention of Infectious Diseases
Why is diagnostic microbiology important in epidemiology?
A) It helps in developing vaccines
B) It identifies the etiologic or causative agents of infections
C) It studies the genetic variations of humans
D) It monitors environmental changes
E) It focuses on the economic impact of diseases
B) It identifies the etiologic or causative agents of infections
Explanation: Diagnostic microbiology is crucial in epidemiology because it helps identify the etiologic or causative agents of infections, which is essential for tracking and preventing diseases.
p.6
Epidemiology and Prevention of Infectious Diseases
What are signs of infection?
A) Headache and fatigue
B) Nausea and vomiting
C) Fever and rash
D) General aches and pains
E) Sore throat and cough
C) Fever and rash
Explanation: Signs are measurable indications or physical observations, such as an increase in body temperature (fever) or the development of a rash or swelling.
p.7
Epidemiology and Prevention of Infectious Diseases
What is one of the most effective methods for minimizing the risk of disease development when exposure to infectious agents occurs?
A) Sanitation
B) Vaccination
C) Isolation
D) Food preservation
E) Water treatment
B) Vaccination
Explanation: Vaccination, also referred to as immunization, is one of the most effective methods for minimizing the risk of disease development by taking advantage of the specificity and memory of the immune system.
p.2
Role of T Lymphocytes in Cell-Mediated Immunity
What is the primary function of MHC I molecules?
A) Present extracellular molecules
B) Present endogenous proteins
C) Activate B cells
D) Release cytokines
E) Facilitate inflammation
B) Present endogenous proteins
Explanation: MHC I molecules are located on every nucleated cell in the body and are predominantly responsible for the recognition of endogenous proteins expressed from within the cell.
p.4
Types of Bacterial Toxins: Endotoxins and Exotoxins
What is a notable example of intoxication caused by preformed bacterial toxins?
A) Tuberculosis
B) Botulism
C) Malaria
D) Influenza
E) Hepatitis
B) Botulism
Explanation: Botulism is a notable example of intoxication caused by the ingestion of preformed bacterial toxins present in food at the time of ingestion.
p.3
Pathogen Characteristics and Virulence Factors
What are opportunistic pathogens?
A) Organisms that always cause disease
B) Organisms that cause infection when host defenses are disrupted
C) Organisms that are part of the normal microbiome and never cause disease
D) Organisms that can only infect animals
E) Organisms that are always non-pathogenic
B) Organisms that cause infection when host defenses are disrupted
Explanation: Opportunistic pathogens are organisms that cause infection when one or more of the host’s defense mechanisms are disrupted or malfunction.
p.3
Microbial Attachment and Invasion Mechanisms
What is the first step of infection and disease development?
A) Microbial invasion
B) Microbial attachment
C) Toxin production
D) Immune response
E) Phagocytosis
B) Microbial attachment
Explanation: The first step of infection and disease development, referred to as pathogenesis, is microbial attachment to a surface.
p.7
Activation of B Cells and Antibody Production
What is the primary difference between active and passive immunization?
A) Active immunization uses antibodies from another host
B) Passive immunization uses modified antigens
C) Active immunization provides temporary protection
D) Passive immunization involves the host's own immune response
E) Active immunization involves the introduction of modified antigens
E) Active immunization involves the introduction of modified antigens
Explanation: Active immunization involves introducing modified antigens from pathogenic microorganisms into the body to cause an immune response, whereas passive immunization involves transferring antibodies produced in one host to another host.
p.2
Pathogen Characteristics and Virulence Factors
What does the term 'pathogenicity' refer to?
A) The degree of damage caused by a microorganism
B) The ability of a microorganism to cause disease
C) The measure of the immune response
D) The presence of microorganisms on body surfaces
E) The severity of symptoms caused by an infection
B) The ability of a microorganism to cause disease
Explanation: Pathogenicity specifically refers to the organism's ability to cause disease, whereas virulence refers to the measure or degree of pathogenicity of an organism.
p.5
Epidemiology and Prevention of Infectious Diseases
Approximately what percentage of hospital-acquired infections are associated with biofilm formation?
A) 25%
B) 40%
C) 50%
D) 65%
E) 80%
D) 65%
Explanation: It has been reported that approximately 65% of hospital-acquired infections are associated with biofilm formation.
p.2
Pathogen Characteristics and Virulence Factors
What is the difference between colonization and infection?
A) Colonization always causes disease
B) Infection does not involve microbial growth
C) Colonization involves microorganisms without apparent detriment
D) Infection does not cause damage to the host
E) Colonization results in notable changes in human physiology
C) Colonization involves microorganisms without apparent detriment
Explanation: Colonization involves the presence of microorganisms on body surfaces without apparent detriment, whereas infection involves the growth and multiplication of microorganisms that result in damage to the host.
p.4
Types of Bacterial Toxins: Endotoxins and Exotoxins
What is the primary characteristic of microbial toxins?
A) They are always beneficial to the host
B) They are biochemically active substances released by microorganisms
C) They are produced only by viruses
D) They are inactive within the host
E) They are always produced by the host cells
B) They are biochemically active substances released by microorganisms
Explanation: Microbial toxins are biochemically active substances released by microorganisms that have specific effects on host cells.
p.7
Primary and Secondary Immune Responses
Which stage of infection is characterized by the peak of characteristic signs and symptoms?
A) Incubation stage
B) Prodromal stage
C) Clinical stage
D) Stage of decline
E) Convalescent stage
C) Clinical stage
Explanation: The clinical stage is characterized by the peak of characteristic signs and symptoms of infection or disease.
p.4
Pathogen Characteristics and Virulence Factors
What is the role of pathogenicity islands (PAIs) in bacterial virulence?
A) They decrease bacterial virulence
B) They encode virulence factors
C) They are inactive genetic elements
D) They are found only in viruses
E) They prevent bacterial replication
B) They encode virulence factors
Explanation: Pathogenicity islands (PAIs) are genomic regions in pathogens that encode virulence factors, contributing to the change and spread of these factors among bacterial populations.
