Intro To Microbial Diseases Flashcards
What is Ro (Basic Reproductive Number)?
Ro is the average number of people infected by an infected individual over the disease infectivity period in a totally susceptible population.
Why is Ro important in infectious diseases?
It determines how quickly a disease spreads and affects vaccine coverage requirements. High Ro means a higher vaccination coverage is needed to control the disease.
What are Koch’s postulates?
A set of criteria used to determine whether a particular microorganism is the cause of a disease.
What is the iceberg principle in infectious diseases?
Many infections are asymptomatic or mild, and only a small proportion of cases show severe disease, just like the visible tip of an iceberg.
What is the difference between a primary and a secondary pathogen?
Primary pathogen: Causes disease in a healthy host.
Secondary pathogen: Requires special conditions, such as immunosuppression, to cause disease.
High Ro diseases require higher vaccine coverage for
Herd immunity
Koch’s postulates help determine
causative pathogens but have limitations (e.g., for viruses).
Not all infections lead to disease;
some microorganisms only colonize without causing symptoms.
Nosocomial infections are
hospital-acquired and often resistant to antibiotics.
Public health measures like vaccination and epidemiological tracking are key in
controlling infectious diseases.
All infections result in disease.
False
Treponema pallidum causes syphilis.
True
Measles is caused by a bacterium.
(False – it is caused by a virus.)
Koch’s postulates can always be used to prove causation of infectious diseases.
(False – they do not always apply, especially for viruses.)
The study of how diseases spread and how to control them is called ______________.
(Epidemiology)
Infection that occurs in a hospital setting is known as a ______________ infection.
(Nosocomial)
The pathogen responsible for typhoid fever is ______________.
(Salmonella typhi)
The term for an infection without causing disease is ______________.
(Colonization)
Which of the following is a strict human pathogen?
a) Escherichia coli
b) Staphylococcus aureus
c) Salmonella typhi
d) Pseudomonas aeruginosa
Answer: (c) Salmonella typhi
Which of the following best describes the term ‘pathogen’?
a) Any microorganism
b) A microorganism capable of causing disease
c) A non-infectious agent
d) An antibiotic-resistant bacterium
Answer: (b) A microorganism capable of causing disease
Which disease is an example of an acute infectious disease?
a) Tuberculosis
b) Measles
c) HIV/AIDS
d) Hepatitis B
Answer: (b) Measles
A patient presents with a high fever, cough, and a rash. Lab tests confirm a viral infection. The Ro value for this disease is 12–18. What is the likely diagnosis, and what does the high Ro suggest about control measures?
The likely diagnosis is measles. The high Ro suggests that vaccination coverage must be very high to prevent outbreaks.
A person who traveled abroad returns with symptoms of severe diarrhea. Lab tests confirm the presence of Vibrio cholerae. What public health measures should be taken to prevent an outbreak?
Ensure clean water supply, promote hygiene, provide vaccines in endemic areas, and implement rapid isolation if needed.
A hospital experiences an outbreak of pneumonia among ICU patients. The isolated organism is resistant to multiple antibiotics. What type of infection is this, and what steps should be taken?
This is a nosocomial infection. Infection control measures such as strict hand hygiene, isolation of infected patients, and antibiotic stewardship are essential.
Pathogenesis:
The process by which a disease develops.
Nosocomial Infection:
A hospital-acquired infection.
Epidemiology:
The study of disease distribution and control.
Virulence Factors:
Components that enable a pathogen to cause disease.
Colonization:
Presence of a microorganism without causing disease.
