Questions and Answers
What is the primary cause of foodborne transmission?
Which of the following diseases is an example of biological transmission?
What is the primary mode of transmission for diseases such as cholera and typhoid?
Which of the following insects is most commonly associated with mechanical transmission?
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What is the term for transmission from mother to child?
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Which of the following is an example of a disease that can be contracted through contaminated food, water, air, hands, and person-to-person contact?
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What is the term for person-to-person transmission that is not between mother and offspring?
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Which of the following diseases is an example of vector transmission?
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What is defined as a culture medium whose exact chemical composition is known?
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Which medium type would be best to promote the growth of bacteria that can utilize a specific nutrient component?
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What does the term 'Multiplicity of Infection' (MOI) refer to?
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What effect might be observed in virus-infected cells, indicative of cytopathic effects (CPE)?
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Which of the following media types specifically supports the growth of selected microorganisms while inhibiting others?
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Which component is NOT characteristic of enrichment media?
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What is the primary characteristic of differential media?
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Which statement about permissive cells is TRUE?
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What is the primary advantage of using hybridisation techniques with nucleic acid probes?
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Which of the following best describes the purpose of molecular tests in medical diagnostics?
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What element is crucial for the polymerase chain reaction (PCR) process?
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What does the term 'titre' refer to in the context of serological tests?
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What is a significant characteristic of indirect methods such as serological tests?
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What type of information is gained from molecular tests regarding antibiotic resistance?
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In which situation would molecular tests be particularly advantageous?
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Which of the following statements about detection methods is true?
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Which of the following is an advantage of using microscopy for microbial detection?
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What is a major disadvantage of using serological tests?
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What prerequisite is necessary for using nucleic acid detection methods?
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Which statement about the culture method for detecting microorganisms is incorrect?
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Which of the following antiviral agents targets the attachment and entry stage of viral infection?
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Which method is least suitable for agents that cause clinical disease before antibody production?
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What is the primary mechanism by which antimicrobial drugs, such as those targeting nucleic acid synthesis, exert their effects?
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What is true about the selective toxicity of antimicrobial agents?
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Which of the following is a common mechanism by which antiviral agents target viral protein synthesis?
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What is a common issue associated with serological tests?
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Which of the following is NOT a mechanism by which antimicrobial resistance develops?
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Which of the following accurately describes a disadvantage of using microscopy?
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Antimicrobial resistance is a growing concern because it can lead to:
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Which of the following is a primary strategy for combating antimicrobial resistance?
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Study Notes
Foodborne Transmission
- Typically occurs due to bad sanitation practices leading to contamination of food with pathogens
- Examples include Anthrax, Tuberculosis, Salmonella, Cholera, Typhoid, and Legionella
Vector Transmission
- Transmission of disease via animals that carry disease from one host to another
- Insects are the most important animal vectors
- Mechanical Transmission: Passive transport of pathogens on vector's body, often through flies
- Biological Transmission: Pathogen spends part of its life cycle in the vector and transmission to the host is through a bite
- Examples of Biological Transmission include Malaria, Zika virus, Dengue fever, Schistosomiasis, and Rabies
Horizontal vs Vertical Transmission
- Transmission from mother to child is called vertical transmission
- Can occur in utero across placenta, at the time of delivery, or during breast feeding
- Person-to-person transmission that is not between mother and offspring is called horizontal transmission
Microbiology Laboratory Techniques
- Depends on culture of microorganism on solid nutrient media (agar plates) to produce colonies
- A colony is composed of thousands of bacteria growing on the surface that originate from a single cell
- Types of medium: • Defined medium: exact chemical composition is known • Enrichment medium: contains some component that permits the growth of specific types or species of bacteria • Selective medium: designed to support the growth of only specific microorganisms • Differential medium: distinguishes closely related microorganisms growing on the same media based on differences in colony appearance
Direct Methods: Culture of Viruses
- Propagation requires cell cultures as viruses only replicate in living cells
- Cells that support viral replication are called permissive
- Multiplicity of infection (MOI) refers to the number of virions that are added per cell during infection
- A virus-infected cell can show dramatic changes in appearance or cytopathic effects (CPE)
Direct Methods: Detection of Nucleic Acids
- Molecular tests can detect the presence of bacterial and viral DNA or RNA in a patient specimen
- Can be used to detect organisms that are slow or difficult to grow in the laboratory, antibiotic resistance genes, or virulence factors
- Very sensitive and specific
- Two main types: • Hybridisation techniques with nucleic acid probes • Polymerase chain reaction (PCR)
Indirect Methods: Serological Tests
- Determine the presence of antibodies in serum or microbial antigens in tissue or body fluids
- Titre refers to antibody concentration in the sample and is associated with the number of times one can dilute a sample and still detect the antibody
Direct vs Indirect Methods
- Culture: confirms presence of organism, organism is multiplied and can be used for additional testing
- Microscopy: quick and easy preliminary results, not very specific
- Detection of nucleic acids: results available within hours, very sensitive and specific
- Serological tests: not limited to blood serum, well established, inexpensive, and easy to perform
Strategies to Treat Infection
- Selective toxicity: antimicrobial agents need to inhibit the growth of the microbe while doing minimal damage to the patient
- Antimicrobial agents target: • Nucleic acid synthesis • Protein synthesis
- Antiviral agents target: • Attachment and entry • Nucleic acid synthesis • Assembly and budding
Antimicrobial Drug Resistance
- Ability of a microorganism to survive and multiply in the presence of an antimicrobial agent that would normally inhibit or kill this particular kind of organism
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Description
Explore the concept of foodborne transmission and how poor sanitation practices lead to the contamination of food with various pathogens. Learn about diseases such as anthrax, salmonella, and the role of animals and insects in vector transmission.