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Questions and Answers
What is the main characteristic of mutualism in symbiotic relationships?
What is the main characteristic of mutualism in symbiotic relationships?
In commensalism, what is the outcome for the host?
In commensalism, what is the outcome for the host?
Which of the following describes parasitism?
Which of the following describes parasitism?
What is the distinguishing feature of prokaryotic organisms?
What is the distinguishing feature of prokaryotic organisms?
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How do most bacteria reproduce?
How do most bacteria reproduce?
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What structure surrounds most bacteria and determines their shape?
What structure surrounds most bacteria and determines their shape?
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What is the term for two organisms living together without affecting each other?
What is the term for two organisms living together without affecting each other?
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Which group of organisms includes pathogenic bacteria?
Which group of organisms includes pathogenic bacteria?
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What is a primary characteristic of atypical bacteria?
What is a primary characteristic of atypical bacteria?
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How do pathogenic protozoa primarily transmit infections?
How do pathogenic protozoa primarily transmit infections?
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Which of the following best describes fungi?
Which of the following best describes fungi?
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What distinguishes helminths from other microorganisms?
What distinguishes helminths from other microorganisms?
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Which statement accurately characterizes viruses?
Which statement accurately characterizes viruses?
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What type of reproduction can fungi undergo?
What type of reproduction can fungi undergo?
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What is one of the main focuses of medical microbiology?
What is one of the main focuses of medical microbiology?
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Which group of organisms do tapeworms belong to?
Which group of organisms do tapeworms belong to?
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Which of the following groups includes microorganisms?
Which of the following groups includes microorganisms?
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What is a common characteristic of all fungi?
What is a common characteristic of all fungi?
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What was the Miasma Theory believed to explain?
What was the Miasma Theory believed to explain?
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Which ancient civilization used antiseptics such as salt?
Which ancient civilization used antiseptics such as salt?
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What did Hippocrates classify diseases into?
What did Hippocrates classify diseases into?
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What characterizes a microorganism as a pathogen?
What characterizes a microorganism as a pathogen?
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What is the primary factor in determining virulence?
What is the primary factor in determining virulence?
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Which of the following is a characteristic of Eukaryotic cells?
Which of the following is a characteristic of Eukaryotic cells?
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What is one of the results of the study of medical microbiology?
What is one of the results of the study of medical microbiology?
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According to molecular Koch's postulates, what should happen when the suspected pathogenic gene is inactivated?
According to molecular Koch's postulates, what should happen when the suspected pathogenic gene is inactivated?
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Which of the following statements best defines infection?
Which of the following statements best defines infection?
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Which term refers to microorganisms that are beneficial?
Which term refers to microorganisms that are beneficial?
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What is a consequence of microbial colonization?
What is a consequence of microbial colonization?
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How can an infection differ from a disease?
How can an infection differ from a disease?
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Which point is NOT one of the molecular Koch's postulates?
Which point is NOT one of the molecular Koch's postulates?
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What does the host-parasite relationship imply?
What does the host-parasite relationship imply?
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What theory proposed that diseases were caused by contamination in the air?
What theory proposed that diseases were caused by contamination in the air?
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Which scientist is considered the father of modern microbiology?
Which scientist is considered the father of modern microbiology?
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What is the significance of Koch's postulates in microbiology?
What is the significance of Koch's postulates in microbiology?
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What observation did Anton van Leeuwenhoek make in the 17th century?
What observation did Anton van Leeuwenhoek make in the 17th century?
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What practice did Joseph Lister implement to reduce infections during surgery?
What practice did Joseph Lister implement to reduce infections during surgery?
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What outcome is associated with the inoculation of isolates in Koch's postulates?
What outcome is associated with the inoculation of isolates in Koch's postulates?
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What technique is attributed to the work of Louis Pasteur?
What technique is attributed to the work of Louis Pasteur?
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What was one of the primary observations of Girolamo Fracastoro regarding disease transmission?
What was one of the primary observations of Girolamo Fracastoro regarding disease transmission?
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Study Notes
Introduction to Medical Microbiology
- Microbiology is the study of microbes (microorganisms)
- Microbes are minute living things usually too small to see with the naked eye
- Examples of microbes include bacteria, fungi, protozoa, algae, and viruses
- Some microbes are pathogenic (cause disease)
- Many microbes are beneficial
Learning Objectives
- Understand basic concepts of microbiology history
- Distinguish between different microorganism groups
- Identify prokaryotic and eukaryotic cells
- Learn the general characteristics of bacteria, parasites, viruses, and fungi
What is Microbiology?
- Microbes are living things too small to be seen without magnification
- Microbes can be pathogenic, and cause disease
- Other microbes are beneficial
Medical Microbiology
- Medical microbiology is the study of microbes that cause disease in humans, and their reactions to infections.
- It involves etiology, pathogenesis, lab diagnosis, treatment, and infection control (immunization)
History of Microbiology
- Ancient Egyptians used salt as an antiseptic
- Hippocrates (460-377 BC) focused on observation, and the body's vital fluids, classifying diseases as acute, chronic, epidemic, and endemic
- Early medical practices included washing wounds, applying drugs, and the concept of "bad air" (miasma) causing disease
- Scientists developed experimental methods and research principles for effective medical practices
First Steps
- Early practices included cleaning wounds with hot water and applying treatments
- The miasma theory proposed that diseases were caused by toxic substances from the soil, swamp air, or other sources
- These methods lacked scientific understanding of the true nature and origins of diseases
Middle Ages
- Hippocrates and Galen's views were widely accepted
- Identifying cancer and using substances (like vinegar) as antiseptics was common in antiquity and medieval times,
- Girolamo Fracastoro (1546) proposed that diseases could be transmitted through germs through direct contact, contamination, and living beings.
Spontaneous Generation (Abiogenesis)
- Early belief that living creatures could arise from nonliving matter (e.g., maggots from decaying meat), also applied to disease development
- William Harvey and Francesco Redi's experiments disproved spontaneous generation with regard to some diseases (e.g., the experiment with the meat).
The Germ Theory of Disease
- 1860s, Joseph Lister used chemical disinfectants to decrease surgical wound infections
- Pasteur’s (1822-1895) work showcased microbes in air, causing food spoilage and disease in animals
Anton van Leeuwenhoek (1674)
- First person to observe living microorganisms using a microscope
- Found "wee animalcules" in various samples including rainwater, teeth scrapings, and infusions
- His observations were crucial in advancing scientific and societal understanding of microbes and their prevalence in our everyday experience
Louis Pasteur (1822-1895)
- Disproved spontaneous generation through controlled experiments using a swan-neck flask.
- He investigated the role of microorganisms in fermentation
- Developed techniques like pasteurization and sterilization
- Significant contributor to establishing modern microbiology
Robert Koch (1843-1910)
- Formulated postulates for establishing a link between a specific microbe and a disease
- Developed staining techniques and cultured microbes (e.g., Mycobacterium and Vibrio cholera)
Koch's Postulates
- Set of criteria to demonstrate that a specific microbe causes a specific disease
- Outlines steps to confirm causalities between a disease and the associated microbes
Molecular Koch's Postulates
- Modern approach that uses molecular techniques to identify genes associated with pathogens
- Aims to demonstrate how the loss or inactivation of a gene results in a loss of pathogenic properties
Microorganisms
- Microorganisms are found in all ecosystems and environments
- Microbes play a crucial role in many ecological processes
- They can be harmful or beneficial to humans depending on their interaction with living beings
- Pathogenic microbes that do harm to humans may result in several types of diseases. This can lead to tissue damage, and impairment of body function
Cell Size
- Visual representation of different sizes of organisms and cells. Different means of magnification are useful depending on the size of the subject under analysis
Typical Bacteria
- Most bacteria present in a rigid shape, rods, spheres (cocci), and corckscrews
- The bacterial cell wall determines the shape and gram-positive/negative classification
- Bacteria multiply by binary fission
Atypical Bacteria
- Bacteria such as Mycoplasma, Chlamydia, and Rickettsia lack certain features or components that differentiate them from typical bacteria
Fungi
- Eukaryotic organisms that are non-photosynthetic
- Some are saprophytic, filamentous (molds), or unicellular (yeasts)
- Reproduction can be in different forms (asexual or sexual)
- Pathogenic fungi can cause several types of diseases, differing in severity
Protozoa
- Single-celled eukaryotic organisms that can be free-living or pathogenic
- Infect various parts of the body, such as the blood, urogenital tract, or intestines
- Transmission typically involves ingestion of an infective stage of the parasite or by insect bites
Helminths
- Multicellular eukaryotic worms acting as parasites
- Divided into groups like tapeworms, flukes, and roundworms
- Infect diverse tissues and have complex life cycles
Viruses
- Obligate intracellular parasites that lack cellular structure
- Consists of genetic material (DNA or RNA) surrounded by a protein coat or an envelope
- Rely on host cells to replicate
- Cause a wide range of diseases
Key Definitions
- Infection: presence of microorganisms to cause disease
- Infectious diseases: diseases that occur because of infections.
- Pathogenicity: ability of a microorganism to cause disease
- Virulence: severity of the diseases caused by microorganisms
How Infectious Diseases Start
- Colonization: microbes establish and grow on skin or mucous membranes
- Direct entry into the bloodstream or internal organs
Microbial Colonization
- Microorganisms may not cause disease, but may lead to infections
- Some microbes are harmless, other may cause disease
Host-Parasite Relationship
- The interaction between a host and parasite can involve different roles (parasites may contribute to or take place without causing disease)
- Symbiosis (“living together”), including mutualism, commensalism, and parasitism
Types of Symbiotic Associations
- Mutualism: both host and parasite benefit
- Commensalism: one benefits, the other neither benefits nor is harmed
- Parasitism: one benefits, the other is harmed
Important Definitions (Cont.)
- Infection: The state where a microbe establishes itself in a host (including on body surfaces).
- Pathogenicity: The capacity of a microbe to cause disease.
- Virulence: The degree of pathogenicity or the severity of disease caused.
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