Bacteriology (MICR213) Tutorial 2
Due: 10 March 2023
TOTAL: 30 MARKS
A. Answer the following questions and submit the Tutorial before the beginning of the tutorial
session. Late submissions will not be accepted.
B. Students must come to the tutorial session with their own copies for reference
during the session.
Section A
[10 marks]
1. _________
refers to the dose or number of pathogens that kill 50% of an
experimental group of hosts within a specified period.
A.
B.
C.
D.
E.
2.
Infectious dose 50 (ID50)
Pathogenic potential
Lethal dose 50 (LD50)
Infectivity potential
Virulence factor
_____ measures the number of individuals that become ill due to a specific
disease within a susceptible population during a specific time interval.
A.
B.
C.
D.
E.
Prevalence rate
Mortality rate
Morbidity rate
Epidemiology
Endemic
3.
__________is a type of infection associated with virulent organisms.
A.
B.
C.
D.
E.
Bacteraemia
Septicaemia
Nosocomial
Sepsis
All of the above
4. Zoonoses______________________________.
A.
B.
C.
D.
E.
are animal diseases transmitted to humans
are hospital acquired diseases
are passive carriers of pathogens
occurs occasionally and at irregular intervals in a human population
are sudden, unexpected occurrence of a disease, usually in a limited segment of
a population
5. Putrefaction can be best described as a______________________.
A. proteolysis and anaerobic breakdown of proteins, yielding foul-smelling amine
compounds
B. toxic condition caused by growth of a fungus in grains70%
C. carcinogens produced in fungus-infected grains and nut products
D. carcinogens produced in fungus-infected corn
E. None of the above are correct
6. Which of the following is NOT an intrinsic factor that affect the growth of
microorganisms in food?
A.
B.
C.
D.
E.
Water activity (aw)
pH
Oxidation- reduction potential
Nutrient content
Temperature
7. Which of the following is NOT an extrinsic factor that affect the growth of
microorganisms in food?
A.
B.
C.
D.
E.
Temperature
Relative humidity
Gases (CO2, O2) present
Types and numbers of microorganisms present in the food
Biological structure of food
8. Airborne transmission is acquired from_________________.
A.
B.
C.
D.
E.
droplets or dust particles < 1-4 μm diameter
coming together or touching of source/reservoir and host
inanimate materials or objects involved in pathogen transmission
passive carriage of a pathogen on the body of a vector
hospitals and/or clinical care facilities
9. Which of the following is NOT part of the primary step in the waste water treatment
process?
A.
B.
C.
D.
E.
Removal of insoluble particles by physical procedures
Screening the incoming water content
Addition of coagulants
Settling insoluble particles
The use of trickling filters and lagoons
10. Food-Borne intoxications is the_________________________.
A. ingestion of toxins in foods in which microbes have grown
B. ingestion of microbes, followed by growth, tissue invasion, and/or release of
toxins
C. ingestion of raw food
D. ingestion of Common food pathogens such as Campylobacter, Salmonella,
Shigella, Clostridium, Staphylococcus, Escherichia coli.
E. Putrefaction process followed by intoxication
Section B
1.
[20 marks]
Provide a term/phrase that best match the following descriptions
[5]
1.1. A disease occurring occasionally and at irregular intervals in a human population.
1.2. A disease caused in hospitalized patients by pathogens acquired in a hospital or
clinical care facility.
1.3. A disease that maintains a steady, low-level frequency at a moderately regular
interval.
1.4. Total number of individuals infected in a population at any one time.
1.5. proteolysis and anaerobic breakdown of proteins, yielding foul-smelling amine
compounds
2. Differentiate between prebiotics and probiotics.
[2]
3. Name three extrinsic or environmental factors that affect the growth of microorganisms in
food.
[3]
4. Wastewater treatment involves a number of steps that are spatially segregated. Briefly describe
the following stages:
4.1. Primary treatment
[2]
4.2. Secondary treatment
[2]
4.3. Tertiary treatment
[2]
5. Imagine you are the Epidemiologist for the National Department of Health. You have been
asked to prepare a National health report for the year 2016 in which there was a sharp increase in
listeriosis cases.
5.1. In one month, there were 280 new cases of listeriosis per 100 000 individuals.
Calculate the morbidity rate.
[2]
6. Differentiate a common-source epidemic from a propagated epidemic.
[2]