Module 6 - Microbiology

Question 1

Defines the logarithmic phase of bacterial replication.

Answer 1

Logarithmic phase of bacterial replication is an exponential increase in bacterial cells.

During the logarithmic phase, bacterial cells reproduce rapidly, resulting in an exponential growth in their numbers.

Question 2

During host-microbe relationships, commensalism is defined as

Answer 2

one organism benefits, the other is not harmed.

Question 3

After viral attachment to the host cell surface, what is the next fundamental stage of the viral lifecycle?

Answer 3

Uncoating to release the viral genome.

Question 4

Do Viruses contain a cell wall and ribosomes

Answer 4

Viruses do not have cell walls or ribosomes. They are much simpler in structure compared to cells and do not possess the organelles found in living cells.

Question 5

Both community and hospital-acquired urinary tract infections are most frequently caused by which microbial pathogen?

Answer 5

Escherichia coli.

Question 6

In nosocomial settings, which route of infection is NOT generally associated with hospital transmission?

Answer 6

Vector-borne transmission.

Nosocomial infections typically occur through respiratory droplet transmission, direct/indirect contact transmission, airborne transmission, and other routes within the healthcare facility environment, but vector-borne transmission is less common in such settings.

Question 7

What is pasteurization

Answer 7

Pasteurization is a method of heat treatment that aims to reduce the number of viable pathogens and spoilage microorganisms in food and beverages but does not achieve complete sterilization. The other options listed (moist heat and pressure, UV radiation, gamma irradiation, dry heat) are examples of sterilization methods that aim to kill all forms of microbial life.

Question 8

Systemic mycoses are defined as fungal infections that

Answer 8

grow and spread into internal organs.

Systemic mycoses are fungal infections that affect internal organs and can spread throughout the body.

Question 9

Why are viruses not considered living organisms?

Answer 9

Viruses are not considered living organisms because they lack essential characteristics of life. They do not have cellular structures, cannot carry out metabolic processes independently, do not grow or respond to stimuli, cannot reproduce without a host cell, lack homeostasis, and have limited evolution driven by host selective pressures.

Question 10

What are the key components of a virus?

Answer 10

Viruses consist of genetic material (either DNA or RNA) and a protein coat called a capsid. Some viruses also have an outer lipid envelope.

Question 11

Describe the basic aspects of the viral lifecycle.

Answer 11

The viral lifecycle involves 1. attachment to host cells, 2. entry
3. replication
4. assembly, and release of new virus particles.

It can be lytic (resulting in host cell destruction) or lysogenic (integrating into the host genome).

Question 12

What are the pathogenic consequences of viral infection?

Answer 12

Viral infections can lead to a wide range of diseases, including the common cold, influenza, HIV/AIDS, and COVID-19. The severity varies depending on the virus and the host’s immune response.

Question 13

Provide examples of viral diseases.

Answer 13

Examples of viral diseases include influenza, HIV/AIDS, COVID-19, hepatitis, and the common cold.

Question 14

Describe the basic structure of a fungus.

Answer 14

Fungi have a eukaryotic cellular structure with a cell wall made of chitin. They can exist as single-celled yeast or multicellular molds and mushrooms.

Question 15

Describe the different types of fungal infections and give medically relevant examples of each type.

Answer 15

Fungal infections can be
1. superficial (e.g., athlete’s foot),
3. subcutaneous (mandura foot)
3. systemic (e.g., histoplasmosis).

Question 16

Describe the three different types of parasites and give medically relevant examples of each type.

Answer 16

Parasites include

1. protozoa (e.g., Plasmodium causing malaria),
2. helminths (e.g., pinworms),
3. arthropods (e.g., ticks causing Lyme disease).

Question 17

Define Koch’s postulates

Answer 17

Founder of germ theory. Koch’s postulates are a set of criteria used to establish a causal relationship between a microorganism and a specific disease.

1. The suspected pathogen must be present in all cases of the disease and absent from healthy animals.
2. Suspected pathogen must be grown in pure culture.
3. Cells from a pure culture of the suspected pathogen must cause disease in a healthy animal.
4. The suspected pathogen must be resisolated and shown to be the same as the original.

Question 18

What is an infectious disease?

Answer 18

An infectious disease is a condition caused by the invasion and multiplication of microorganisms (e.g., bacteria, viruses, parasites) within a host organism. Infection in one person can be transmitted to others.

Question 19

Describe the features that differentiate Gram-positive and Gram-negative bacteria.

Answer 19

Gram-positive bacteria have a thick peptidoglycan cell wall and retain the violet stain in Gram staining, while Gram-negative bacteria have a thinner peptidoglycan layer and do not retain the violet stain.

Question 20

Why is it important to know about bacterial characteristics, particularly in the healthcare setting?

Answer 20

Understanding bacterial characteristics is essential for diagnosing and treating infections, selecting appropriate antibiotics, and implementing infection control measures in healthcare settings.

Question 21

How do bacteria reproduce, and what are their growth phases? How can bacterial growth be measured?

Answer 21

Bacteria reproduce through binary fission and have growth phases: lag, log (exponential), stationary, and death. Bacterial growth can be measured by counting colony-forming units (CFUs) or using optical density measurements.

Question 22

How does the healthcare environment contribute to the incidence of infectious disease?

Answer 22

Promotes atypical/resistant organisms compared to community-acquired
1. older and more vulnerable hosts
2. multiple routes of infection
3. use of antimicrobials

Question 23

What does MRSA stand for, and what are its key virulence factors and pathophysiology?

Answer 23

MRSA stands for Methicillin-Resistant Staphylococcus aureus. Key virulence factors include cell wall components, toxins, and the ability to form biofilms. MRSA can cause skin infections, pneumonia, and bloodstream infections.

Question 24

Describe other significant bacterial healthcare-associated infections (HCAIs).

Answer 24

Other significant HCAIs include Clostridium difficile (C. diff) infections, surgical site infections, and urinary tract infections (UTIs).

Question 25

Explain the basic antibiotic modes of action.
4 steps

Answer 25

Antibiotics work through various mechanisms, including inhibition of cell wall synthesis, protein synthesis, nucleic acid synthesis, and disruption of cell membranes.

Question 26

Describe bacterial antibiotic resistance mechanisms and how they can be transferred (gene transfer).

Answer 26

Antibiotic resistance can result from mutations or horizontal gene transfer, where resistance genes are shared among bacteria through mechanisms like conjugation, transformation, and transduction.

Question 27

What human practices can lead to antibiotic resistance, and what can be done to prevent it?

Answer 27

Practices like overuse and misuse of antibiotics can lead to resistance. Preventive measures include proper antibiotic stewardship, patient education, and the development of new antibiotics.

Question 28

Outline the requirements for successful infection control.

Answer 28

Infection control requires proper hand hygiene, use of personal protective equipment (PPE), sterilization and disinfection, isolation precautions, and adherence to protocols.

Question 29

Describe the difference between sterilization and disinfection, and give an example method to achieve each of these.

Answer 29

Sterilization eliminates all microorganisms, including spores, while disinfection reduces the number of microorganisms. Autoclaving achieves sterilization, while using disinfectants like bleach achieves disinfection.

Question 30

Describe the additional infectious disease risks associated with the healthcare environment.

Answer 30

Healthcare-associated infections (HCAIs), drug-resistant infections, and the potential for disease outbreaks are additional infectious disease risks in healthcare settings.

Question 31

Outline the infection control methods in place in healthcare settings.

Answer 31

Infection control methods include hand hygiene, isolation precautions, vaccination, use of PPE, sterilization and disinfection, and surveillance and reporting of infections.

Question 32

Why are in-patients more vulnerable to infections?

Answer 32

In-patients are often more vulnerable to infections due to underlying medical conditions, weakened immune systems, exposure to healthcare-associated pathogens, and invasive medical procedures.

Question 33

During host-microbe relationships, mutalism is defined as

Answer 33

Both organsims benefiting and depending on each other

Question 34

During host-microbe relationships, parasitism is defined as

Answer 34

One organism benefitting and the other is adversely affected

Question 35

During host-microbe relationships, opportunism is defined as

Answer 35

A change in living relationship resulting in parasitism (staph infection)

Question 36

Define subclinical infections

Answer 36

No symptoms are apparent but immune response is induced.

Question 37

Define localised infections

Answer 37

Confined to one area of the body

Question 38

Define systemic infections

Answer 38

infection spreads to other organ systems

Question 39

Define pathogen

Answer 39

A microrganism capable of causing disease

Question 40

Define pathogenesis

Answer 40

process by which disease arises (not unique to infectious disease)

Question 41

Define Pathogenicity

Answer 41

Measure of the ability of a pathogen to cause disease

Question 42

Steps/Progress of infection

Answer 42

1. Attachment + entry into body (infection)
2. Local or general spread in the body (spread)
3. Multiplication
4. Evasion of host defences
5. Shedding (transmit to someone else)
6. Cause damage in host (Symptoms)

Question 43

Stages of an infectious disease

Answer 43

1. Incubation
2. Prodromal phase (vague symptoms)
3. Invasive phase (Mot severe signs and symptoms)
4. Acme (Peak of infection)
5. Decline Phase (immune cell engulf the microorganism to clear from body)
6. Convalesce period (recovery)

Question 44

Define Bacteria

Answer 44

Prokaryote - No nucleus, no membrane bound organelles. Good & Bad bacteria.

Question 45

Name the process of bacterial reproduction that splits a cell into two parts and describe growth phases of bacterial replication

Answer 45

Binary Fission is the process by which prokaryotic cells split into new cells.

Growth Phase;
1. DNA replicates within a cell
2. DNA molecules separates as the cytoplasmic membrane grows longer
3. The cell begin to invaginate or fold back on itself
4. A wall called a “cross wall” forms between the two cells
5. The two resulting cells called “daughter cells” are complete and separate from one another.

Question 46

What are the three major groups of Fungi

Answer 46

1. Macroscopic filamentous fungi with large fruiting bodies (mushrooms)
2. Multicellular filamentous moulds
3. Single-cell yeasts

Question 47

A staff member of a pathology laboratory was given a bacterial sample to identify. Under the
microscope, the Gram stained sample looked like pairs of purple circles. How would you
describe the morphology of the bacterial cells?

Answer 47

Gram-positive diplococcus.