Microbiology Flashcards
What is microbiology?
The study of all living organisms too small to be seen with the naked eye
What are living organisms that are too small to be seen with the naked eye?
microbes
What are some examples of microbes?
Bacteria, fungi, protozoa, viruses, archaea, prions, algae (helminths?)
T/F Microbes are vitally important to virtually all processes on Earth with a key role in causing & controlling disease.
T - also have key roles in nutrient cycling, biodegradation, climate change, food spoilage & biotechnology
_______ - disease in which a transmissible agent invades through physical barriers (skin, GI, respiratory mucosa) and overcomes the innate & adaptive immune defenses to cause injury/disease.
infectious disease
What is an infectious disease?
disease in which a transmissible (infectious) agent invades through the physical barriers (skin, GI, respiratory mucosa) and overcomes the innate & adaptive immune defenses to cause injury/disease
T/F Viroids and prions can cause infection.
T - Bacteria, viruses, viroids, & prions can all cause infection.
Eukaryotic cells are _____ than prokaryotic cells regarding their size
larger (eukaryotic cells ~10,000 - 100,000 nm; prokaryotic cells ~200 - 10,000 nm)
Viruses, viroids, & prions are ______ than prokaryotic cells regarding their size
smaller (viruses ~50-200 nm; viroids ~5-150 nm; prions ~2-10 nm)
What are the differences between prokaryotes and eukaryotes?
Prokaryotes - simple, mostly UNICELLULAR organisms that LACK membrane bound organelles, nuclei, & mitochondria; 2 domains: Archaea & BACTERIA
Eukaryotes - mostly multicellular organisms whose cells CONTAIN a nucleus surrounded by a membrane & DNA bound together by proteins (histones) into chromosomes (I.e., fungi & helminths)
T/F Viruses are noncellular
T - they are noncellular but are an obligate INTRACELLULAR pathogen
Viruses contain ______ - packets of nucleic acid encased in a protein capsid/coat
infectious particles
Spore-producing eukaryotic organisms that include yeasts and molds
Fungi
Mitochondria are absent in which of the following?
A. viruses
B. bacteria
C. fungi
D. parasites
E. Both A & B
F. Both A & C
E. Both A & B (viruses & bacteria)
Which of the following contains EITHER DNA or RNA in its protein capsid & lipoprotein envelope?
A. viruses
B. bacteria
C. fungi
D. parasites
A. viruses
- the rest of the options contain BOTH DNA & RNA
Protozoa & helminths are…
A. viruses
B. bacteria
C. fungi
D. parasites
D. parasites
Which of the following’s outer surface is a rigid wall containing peptidoglycan?
A. viruses
B. bacteria
C. fungi
D. parasites
B. bacteria
Which of the following’s outer surface is a rigid wall containing chitin?
A. viruses
B. bacteria
C. fungi
D. chitin
C. fungi
What can be classified as either gram positive or gram negative?
Bacteria
How is the human body a hospitable site for microorganisms to grow and flourish?
- Sufficient nutrients*
- Appropriate temperature* & humidity*
Microorganisms make up normal microbiome, also known as _____, of body
flora
What is the major reservoir of the human body where microorganisms thrive?
GI tract (but also female genital tract, oral cavity, nasopharynx, etc.)
How is beneficial homeostasis between humans & microorganisms maintained?
via:
1. physical integrity of the gut
2. mechanisms that sequester these microorganisms on the mucosal surface (MALT)
What are the 3 major ways microbiome is thought to contribute to health and disease?
- Provides instruction to the developing immune system
- Can confer susceptibility or resistance to pathogen colonization
- harbors a diverse reservoir of antibiotic resistance genes
- colonization resistance = ability of members of the normal flora to limit the growth of pathogens - Contributes to nutrition & human health
- gut bacteria aid digestion by breaking down otherwise indigestible plant fibers
- synthesize variety of micronutrients including several of the B vitamins, vitamin K
- Impact on the absorption of key minerals (I.e., iron)
_____ microbiotas likely impacts a patient’s susceptibility to infectious diseases & responses to vaccines
Individuals’ microbiotas
__________ - any change in composition of resident commensal communities (associated with many chronic diseases (obesity, IBDs, T2D, CVD, colon CA, depression))
microbiome dysbioses
Microorganisms of the human body can be organized into what 2 groups?
- resident microbiota - relatively fixed types of microorganisms regularly found in a given area at a given age; if disturbed => promptly reestablishes itself
- transient microbiota - nonpathogenic or potentially pathogenic microorganisms derived from ENVIRONMENT that inhabit body sites for hours/days/weeks
- Does NOT typically produce disease & does NOT establish itself permanently
- Generally little significance as long as normal resident flora remains intact
Under what circumstance may transient microbiota colonize, proliferate & cause disease?
when resident microbiota is disturbed
T/F - Most infections are caused by organisms not part of normal microbiota/flora and are strictly pathogens.
F - most infections are caused by organisms that are part of normal microbiota (Ex. S. aureus, S. pneumoniae, Pseudomonas aeruginosa)
What are true pathogens?
“all the time bad guys” - bypass normal defenses; in adequate numbers (minimum infective dose) = infection
T/F A minimum number of true pathogens/microorganisms is needed to cause infection.
T - called the “minimum infective dose”; varies by pathogen
What are opportunistic pathogens?
“sometimes bad guys”; frequent members of body’s normal flora
rarely, if ever, cause disease in immunocompetent people; can cause serious infection in patients with reduced host defenses (immunocompromised)
Ex. physical trauma to GI tract during surgery; oral/systemic (candidiasis in HIV/AIDS)
Infectious diseases disproportionately affect ______, ____ & persons in ____ countries.
children < 1 year; adults > 70 years; low-/middle-income
What are Koch’s 4 Postulates which would consider something to be a bacterial infection?
- Bacteria must be present in EVERY case of the disease
- Bacteria must be isolated from the host with the disease and grown in pure culture
- Specific disease must be reproduced when a pure culture of the bacteria is inoculated into a healthy susceptible host
- Bacteria must be recoverable from the experimentally infected host
What were the top 5 leading causes of death globally between 2000 and 2019?
- Ischaemic heart disease
- Stroke
- COPD
- Lower respiratory infections
- Neonatal conditions
What were the top 3 leading causes of death in low-income countreis between 2000 & 2019?
- Neonatal conditions
- Lower respiratory infections
- Ischaemic heart disease
COVID-19 (SARS-CoV-2) is an example of _______ as it is a new strain of coronavirus
reemergence - a new strain of “old” infections
How does reemergence of infectious diseases occur?
- New strains of old infections (cholera, malaria, yellow fever, dengue fever, diphtheria)
- Antibiotic resistance (malaria, TB, Strep pneumoniae, Staph aureus, etc.)
- Decreased vax’s (measles, polio, pertussis)
- Bioterrorism (smallpox, anthrax, & plague)
What causes emerging infectious diseases?
- vast & rapid urbanization
- poverty, social inequality, war & famine
- Global travel
- Global warming
- Poor antibiotic stewardship
- Human encroachment into wilderness areas
“Emerging epidemics of noncommunicable diseases & injuries becoming more prevalent in both industrialized and developing countries alike, in addition to ongoing major communicable diseases” describes ________
Dual burden of disease
22 cases of legionellosis occurred within 3 weeks among residents of a particular neighborhood (usually 0 or 1 per year) is an example of a:
A. outbreak
B. endemic
C. Pandemic
D. Epidemic
A. outbreak - rise in disease cases over what is normally expected in a small & specific location generally over a short period of time (I.e., salmonella infections)
Number of new infections in a particular population that GREATLY exceeds number usually observed
epidemic (Ex. ebola (2014-2016)
> 20 million people worldwide died from influenza in 1918-1919 is an example of:
A. outbreak
B. epidemic
C. pandemic
D. endemic
C. Pandemic - epidemic that spreads over a large area as a continent or worldwide (I.e., COVID)
~60 cases of gonorrhea are usually reported in this region per week, slightly less than the national average is an example of:
A. outbreak
B. epidemic
C. pandemic
D. endemic
D. endemic - diseases with relatively high, but constant, rates of infection in a particular population
_____ - any disease that spreads from animals to people
zoonotic disease
What is a “spillover event”?
reservoir population with a high pathogen prevalence comes into contact with a novel host population of DIFFERENT species
Which of the following describes a reservoir?
A. Organism that harbors parasite or another organism where there is a symbiotic relationship between 2 organisms
B. Animal, plant, or environment in which disease can subsist for extended periods of time
C. Living creature (usually insects) that passes a disease to another living creature
B. Animal, plant, or environment in which disease can subsist for extended periods of time
I.e., contaminated soil/water, breast milk, other animals (zoonotic ticks), another human
I.e., fruit bats (Ebola)
Which of the following is a living creature that passes a disease to another living creature?
A. reservoir
B. host
C. vector
C. vector