Foodborne and Vector Transmission

Questions and Answers

What is the primary cause of foodborne transmission?

Poor sanitation practices (correct)

Inadequate cooking practices

Contaminated water supply

Insect vectors

Which of the following diseases is an example of biological transmission?

Typhoid

Trachoma

Malaria (correct)

Dysentery

What is the primary mode of transmission for diseases such as cholera and typhoid?

Foodborne transmission (correct)

Vector transmission

Vertical transmission

Horizontal transmission

Which of the following insects is most commonly associated with mechanical transmission?

Fly Signup and view all the answers

What is the term for transmission from mother to child?

Vertical transmission Signup and view all the answers

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?

Dysentery Signup and view all the answers

What is the term for person-to-person transmission that is not between mother and offspring?

Horizontal transmission Signup and view all the answers

Which of the following diseases is an example of vector transmission?

Malaria Signup and view all the answers

What is defined as a culture medium whose exact chemical composition is known?

Defined medium Signup and view all the answers

Which medium type would be best to promote the growth of bacteria that can utilize a specific nutrient component?

Enrichment medium Signup and view all the answers

What does the term 'Multiplicity of Infection' (MOI) refer to?

The ratio of viruses to host cells during infection Signup and view all the answers

What effect might be observed in virus-infected cells, indicative of cytopathic effects (CPE)?

Cell rounding and fusion Signup and view all the answers

Which of the following media types specifically supports the growth of selected microorganisms while inhibiting others?

Selective medium Signup and view all the answers

Which component is NOT characteristic of enrichment media?

Allows growth of a broad range of organisms Signup and view all the answers

What is the primary characteristic of differential media?

It allows visualization of differences between closely related organisms. Signup and view all the answers

Which statement about permissive cells is TRUE?

They provide an environment for viral replication. Signup and view all the answers

What is the primary advantage of using hybridisation techniques with nucleic acid probes?

Fully complementary strands bind strongly. Signup and view all the answers

Which of the following best describes the purpose of molecular tests in medical diagnostics?

To detect the presence of bacterial or viral DNA or RNA. Signup and view all the answers

What element is crucial for the polymerase chain reaction (PCR) process?

Original DNA template. Signup and view all the answers

What does the term 'titre' refer to in the context of serological tests?

The concentration of antibodies in the serum. Signup and view all the answers

What is a significant characteristic of indirect methods such as serological tests?

They measure antibody concentration in serum or fluids. Signup and view all the answers

What type of information is gained from molecular tests regarding antibiotic resistance?

They can identify specific antibiotic resistance genes. Signup and view all the answers

In which situation would molecular tests be particularly advantageous?

When high sensitivity and specificity are demanded. Signup and view all the answers

Which of the following statements about detection methods is true?

Direct methods detect nucleic acids in clinical specimens. Signup and view all the answers

Which of the following is an advantage of using microscopy for microbial detection?

Offers quick and easy preliminary results Signup and view all the answers

What is a major disadvantage of using serological tests?

Specific antibodies may not always be available Signup and view all the answers

What prerequisite is necessary for using nucleic acid detection methods?

Previous knowledge of the DNA sequence Signup and view all the answers

Which statement about the culture method for detecting microorganisms is incorrect?

Results can be obtained quickly Signup and view all the answers

Which of the following antiviral agents targets the attachment and entry stage of viral infection?

Inhibitors of fusion of viral envelope or attachment to receptor Signup and view all the answers

Which method is least suitable for agents that cause clinical disease before antibody production?

Serological tests Signup and view all the answers

What is the primary mechanism by which antimicrobial drugs, such as those targeting nucleic acid synthesis, exert their effects?

Blockage of bacterial enzymes or metabolic pathways essential for DNA and mRNA synthesis Signup and view all the answers

What is true about the selective toxicity of antimicrobial agents?

They need to specifically inhibit microbial growth with minimal patient harm Signup and view all the answers

Which of the following is a common mechanism by which antiviral agents target viral protein synthesis?

Exploitation of differences between eukaryotic and prokaryotic ribosomal proteins, RNAs, and associated enzymes Signup and view all the answers

What is a common issue associated with serological tests?

Prone to false positive results due to antigenic cross-reactivity Signup and view all the answers

Which of the following is NOT a mechanism by which antimicrobial resistance develops?

Changes in the host's immune system Signup and view all the answers

Which of the following accurately describes a disadvantage of using microscopy?

It lacks specificity for distinguishing various organisms Signup and view all the answers

Antimicrobial resistance is a growing concern because it can lead to:

Increased spread of infectious diseases Signup and view all the answers

Which of the following is a primary strategy for combating antimicrobial resistance?

Development of new antimicrobial drugs Signup and view all the answers

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.