Basics of Infection, Immunity and Neoplasia Module

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Questions and Answers

What role do virulence factors play in pathogenic bacteria?

They help bacteria reproduce rapidly.

They enable bacteria to digest nutrients more efficiently.

They assist bacteria in invading host, causing disease, and avoiding host defenses. (correct)

They only allow bacteria to attach to surfaces.

Which type of bacterial factor is primarily responsible for the binding of bacteria to host cells?

Exotoxins

Adherence factors (correct)

Siderophores

Capsules

What is the function of siderophores in bacteria?

To produce toxins

To bind iron and compete with the host for this essential nutrient (correct)

To degrade host tissues

To facilitate bacterial reproduction

How do capsules assist pathogenic bacteria?

By protecting bacteria from opsonization and phagocytosis (B) Signup and view all the answers

What are endotoxins associated with, and what effects do they cause?

They are lipopolysaccharide components causing fever and inflammation. (D) Signup and view all the answers

Which group of normal flora is characterized by microorganisms that regularly inhabit an area and can quickly reestablish themselves if disturbed?

Resident flora (B) Signup and view all the answers

Which of the following accurately describes transient flora?

They are typically nonpathogenic organisms that inhabit for a short duration. (D) Signup and view all the answers

What types of toxins are classified as exotoxins?

Proteins and enzymes secreted by pathogenic bacteria (D) Signup and view all the answers

What was one of Louis Pasteur's major contributions to microbiology?

Development of vaccines against anthrax and rabies (C) Signup and view all the answers

What does Koch's Postulate primarily describe?

Specific diseases are caused by specific microorganisms (C) Signup and view all the answers

Which of the following is NOT one of the conditions of Koch's Postulate?

The microorganism must be the only one present in the infected individual (C) Signup and view all the answers

Which of the following statements about exceptions to Koch's Postulate is true?

Healthy individuals can carry pathogens without symptoms (A) Signup and view all the answers

Which organism is mentioned as being difficult to grow in a laboratory setting?

Treponema pallidum (C) Signup and view all the answers

What major achievement is Robert Koch known for in bacteriology?

Introduction of solid media for culturing bacteria (B) Signup and view all the answers

Which disease did Robert Koch discover the causative agent for?

Tuberculosis (C) Signup and view all the answers

What concept states that a specific disease is caused by a specific type of microorganism?

Germ Theory of Diseases (C) Signup and view all the answers

What idea did Hippocrates pioneer regarding the causes of illness?

Illnesses arise from natural causes. (A) Signup and view all the answers

Which of the following factors did Hippocrates believe could lead to ill health?

Changes in air and climate. (B) Signup and view all the answers

What was Antony Van Leeuwenhoek known for?

First to observe bacteria using a microscope. (B) Signup and view all the answers

What does the theory of abiogenesis propose?

Living things arise from non-living matter spontaneously. (A) Signup and view all the answers

Which famous philosopher founded the theory of spontaneous generation?

Aristotle. (B) Signup and view all the answers

In Needham's experiment, what was the main flaw that led him to believe in spontaneous generation?

He did not properly sterilize the flask. (C) Signup and view all the answers

What conclusion did Needham incorrectly draw from his experiment with broth and grain?

Microorganisms can spontaneously generate in flasks. (C) Signup and view all the answers

Which characteristic does NOT pertain to the theory of biogenesis?

Living organisms can be created from non-living substances. (D) Signup and view all the answers

What significant development in microbiology occurred in America during the early 1900s?

Microbiology became widely practiced. (A) Signup and view all the answers

Which American bacteriologist is known for establishing a primary reference in microbiology in 1923?

David Bergey (A) Signup and view all the answers

What is happening during the lag phase of bacterial growth?

Bacteria adapt to new environmental conditions. (C) Signup and view all the answers

Which factor does NOT contribute to the limited duration of the log phase?

Optimal temperature conditions (B) Signup and view all the answers

What aspect of microbiology became a focus in the period since the 1940s?

Identification of disease-causing microbes. (B) Signup and view all the answers

What is one key advantage of using microorganisms in research?

They provide insights into studying complex life processes. (C) Signup and view all the answers

What occurs during the stationary phase of bacterial growth?

Balance between reproduction and death of cells. (B) Signup and view all the answers

What is the main reason for the decline in the death phase of bacterial growth?

Accumulation of metabolic waste products. (A) Signup and view all the answers

Prokaryotes are characterized by which of the following attributes?

Smaller size compared to eukaryotes. (C) Signup and view all the answers

Which of the following organisms is classified as a eukaryote?

Algae (B) Signup and view all the answers

How can continuous-culture systems help maintain bacterial growth?

By continuously adding fresh medium. (B) Signup and view all the answers

Which of the following enhances resistance to bacterial infections?

Phagocytic cells and an intact immune system. (A) Signup and view all the answers

What characteristic differentiates prokaryotes from eukaryotes, despite prokaryotes being simpler?

Prokaryotes have a more complex cell wall. (D) Signup and view all the answers

Which of the following statements accurately describes eukaryotes in comparison to prokaryotes?

Eukaryotes are 5-20 times larger than bacteria. (D) Signup and view all the answers

What is the relationship between bacterial virulence and host resistance?

Bacterial infectivity results from a disturbance between virulence and resistance. (C) Signup and view all the answers

Which statement about host susceptibility to infection is correct?

Young and old individuals have higher susceptibility to infections. (A) Signup and view all the answers

What type of bacteria can grow in both the presence and absence of oxygen?

Facultative Aerobes (A) Signup and view all the answers

Which of the following bacteria require a neutral pH for optimal growth?

Neutrophilic (B) Signup and view all the answers

What is the generation time for E. coli under optimum conditions?

20 minutes (A) Signup and view all the answers

Which bacteria are described as being able to tolerate the presence of oxygen while not utilizing it for metabolism?

Aerotolerant Anaerobes (D) Signup and view all the answers

Hyperthermophilic bacteria can grow at temperatures exceeding which of the following?

250°C (B) Signup and view all the answers

Which of the following best describes the process by which bacteria divide to form two daughter cells?

Binary Fission (B) Signup and view all the answers

What type of bacteria can only grow in environments devoid of oxygen?

Obligate Anaerobes (B) Signup and view all the answers

In bacterial metabolism, which two categories do most biochemical reactions fall into?

Catabolism and Anabolism (C) Signup and view all the answers

Signup and view all the answers

Study Notes

Module Information

Department: Anesthesia
Module title: Basics of infection, immunity and neoplasia module
Module ECTS: 3 ECTS
Module code: BioMM - 2321

Introduction to Microbiology

Microbiology is the science that studies living organisms too small to be seen with the naked eye.
It investigates the minute, microscopic forms of life and their relationships to humans and other organisms.
Branches of microbiology include medical microbiology, industrial microbiology, food microbiology, soil microbiology, agricultural microbiology, and water microbiology.

Scopes of Microbiology

Microbiology studies include cell structure, metabolism, genetics and growth control.
These subjects create career opportunities in various fields like healthcare, biotechnology, research, environmental science, and agriculture.

Medical Microbiology

This branch focuses on microorganisms related to humans.
It investigates etiologic agents, epidemiology, diagnosis, treatment, and prevention of pathogenic microorganisms.
It also explores the body's defenses against these pathogens.
Some microbes are pathogenic, while others are non-pathogenic or part of the normal flora.

Subdivisions of Microbiology

Bacteriology: the study of bacteria
Mycology: the study of fungi
Phycology: the study of algae
Protozoology: the study of protozoa
Virology: the study of viruses

Historical Background of Microbiology

Throughout history, humans have faced diseases, initially attributed to divine punishment.
Early Greeks proposed abiogenesis (living from non-living matter), and the notion that life could come from stones.
Aristotle believed that life could spontaneously arise from dissimilar organisms or from soil.
Hippocrates suggested that diseases had natural causes, observing links between illness and factors like air, wind, water, climate, food, and environmental conditions.
Antony van Leeuwenhoek, the "father of microbiology," discovered the first microscope and observed "animalcules" in water samples, including bacteria.
He accurately described the different shapes of bacteria.
Two major theories were formulated: Theory of Abiogenesis and Theory of Biogenesis.
Abiogenesis stated that living things arise from non-living matter.
Biogenesis stated that living things arise from pre-existing living things.
Francesco Redi disproved spontaneous generation of maggots from decaying meat.
Lazzaro Spallanzani repeated Needham's experiments, but with improved sterilization techniques, to disprove spontaneous generation for microorganisms.
Louis Pasteur further disproved spontaneous generation by demonstrating that microorganisms exist in the air and can contaminate sterile mediums.
Louis Pasteur's swan-neck flask experiment provided significant evidence against the ideas of spontaneous generation by proving that access to outside particles is required for the growth in a given medium.
The germ theory of disease, proposed by Pasteur and Robert Koch, posited that specific diseases are caused by specific microorganisms.
Robert Koch developed Koch's postulates: an experimental procedure to establish a cause-and-effect relationship between a microbe and a disease.
Koch's postulates include specific steps, such as isolating the microorganism and reproducing the disease in an experimental animal.
Several exceptions to Koch's postulates exist since some pathogens are difficult to cultivate in a laboratory setting.
Major achievements of Robert Koch included introducing solid medium culture, identifying the causative agents of diseases, and furthering development of bacteria studies.
Scientific progress in microbiology continued into the 20th century.
The establishment and flourishing of microbiology occurred in America in the early 1900s.

Types of Microorganisms

Microorganisms are categorized as prokaryotes (simpler cells) or eukaryotes (more complex).
Eukaryotes include algae (excluding blue-green algae), protozoa, fungi, and slime molds.
Prokaryotes include bacteria, blue-green algae (cyanobacteria), and archaebacteria.
Prokaryotes are generally simpler than eukaryotes, except for their complex cell wall.

Bacterial Classification and Nomenclature

Bacteriology is the study of bacteria.
There's no official bacterial classification system. Methods used for classifications of bacterial taxonomy include phenotyping (microscopic, macroscopic morphology, biochemical activities), analytical, and genotypic (nucleic acid hybridization, plasmid analysis, and ribotyping).
Bacteria are categorized in Bergey's Manual of Determinative Bacteriology (1974), using criteria including morphology (shape), staining (Gram stain), motility, growth characteristics, nutritional requirements, biochemical activities, and pathogenicity.

Morphology

Bacteria show varied sizes and shapes (cocci, bacilli, spirals).
Different bacteria also present with arrangements/forms (streptococci, staphylococci, diplobacilli).

Bacterial Nomenclature (Binomial System)

The binomial system, developed in the 18th century, gives each organism two names: genus and species.
Genus name is capitalized; species name is lower case.
Example, Escherichia coli or E. coli.

Basic Features of Bacterial Cells

Bacteria are typical prokaryotic cells, contain DNA and RNA, often grown in artificial media, replicate via binary fission, and possess a rigid cell wall.

Structure of Bacteria

Bacteria have characteristic size, shape, consistency, texture, and color. -Their structure is generally divided into the cell envelope, intracellular components, and external cell structures.

Cell Envelope

A key structural component composed of a capsule, cell wall, and a plasma (cytoplasmic) membrane.
Cell Wall: provides shape and structural strength and made up of peptidoglycan.
Cell wall structure is either Gram-positive (thick peptidoglycan layer) or Gram-negative (thin peptidoglycan layer with an outer membrane).

Chemical Composition of Cell Wall

The main component of the bacterial cell wall is peptidoglycan (PG), a polymer of disaccharides cross-linked by peptides.
Peptidoglycan is made up of N-acetyl muramic acid and N-acetyl glucosamine.

Types of Cell Walls

Gram-positive bacteria have a thick peptidoglycan layer.
Gram-negative bacteria have a thin peptidoglycan layer with an outer membrane.

Capsule

A gelatinous layer often present external to the cell wall.
The composition varies amongst prokaryotes.
It protects the cell from phagocytosis and aids in tissue attachment.

Cytoplasmic (Plasma) Membrane

A barrier between the interior and exterior of the cell.
It exhibits selective permeability for the transport of materials.
It plays important roles in enzyme synthesis, excretion, and bacterial transport systems (e.g., oxidative phosphorylation).

Other Intracellular Components

Mesosomes: invaginations of the cytoplasmic membrane. They are involved in DNA segregation during cell division, protein secretion, and active transport.
Ribosomes: sites of protein synthesis. Prokaryotic ribosomes are smaller (70S) than eukaryotic ribosomes (80S).
Cytoplasmic Inclusions: reserve materials including glycogen, polyhydroxybutyrate, or sulfur granules.
Nuclear Material (Nucleoid): concentrated DNA, often a single circular chromosome, without an enclosing membrane. Plasmids are extra-chromosomal genetic material.

External Cellular Elements (Appendages)

Flagellum: a locomotory appendage composed of flagellin. It exhibits different arrangements: monotrichous, lophotrichous, amphitrichous, and peritrichous.
Pili: short, hair-like appendages that attach bacteria to surfaces or in the process of genetic material transfer (sex pili).

Bacterial Spores

Specialized resistant structures formed by some bacteria (e.g., Bacillus, Clostridium).
They are highly dehydrated and resistant to various harsh conditions (heat, drying, freezing, and chemicals).

Bacterial Metabolism and Growth

Metabolism: comprises all the cellular processes required for survival and replication.
Two major categories of metabolic reactions are catabolism (energy production) and anabolism (building of cellular components).
Bacteria require water, energy, carbon, nitrogen, and various inorganic salts for optimal growth.
Environmental factors like oxygen, pH, temperature, and light affect bacterial growth rates.
Diverse nutritional categories for bacteria exist (autotrophs & heterotrophs).
Autotrophs gain their required carbon from inorganic sources like carbon dioxide, while heterotrophs obtain carbon from organic sources.
Temperature requirements for bacterial growth vary; they are often categorized into psychrophiles, mesophiles, thermophiles, and hyperthermophiles.

Bacterial Growth Curve

Bacterial growth has four major phases: lag phase, log phase, stationary phase, and death phase.
The lag phase, characterized by no increase in cell number, is a time of bacterial adaptation.
The log phase shows exponential increase in cell number.
The stationary phase represents a balance between cell division and death rate.
The death phase occurs due to nutrient exhaustion and toxic product build-up.
These four phases compose the bacterial growth curve.

Continuous Culture

Techniques for maintaining bacterial populations in a continuous exponential growth state, which involves constant addition of fresh medium while the total volume remains constant through an overflow tube.

Host-Parasite Relationship

Bacterial infectivity emerges from an imbalance between bacterial virulence factors (factors that help bacteria invade the host, cause disease, evade host defenses) and the host's resistance mechanisms.
- Host factors that protect from infection: numerous chemical and physical defenses (antibacterial secretions on mucosal surfaces, rapid replacement of skin/mucosal epithelial cells and a virtually devoid iron environment)
Host susceptibility to infection: resistance to bacterial infections can be enhanced by phagocytic cells and an intact immune system.

Bacterial Infectivity

Bacterial infectivity arises from a disturbance in the balance between bacterial virulence factors and host resistance responses.

Normal Flora

Normal microbial flora comprises the microorganisms inhabiting the skin and mucous membranes of healthy individuals. These are divided into resident flora and transient flora.
Resident flora are relatively constant and significant to host health.
Transient flora are non-pathogenic or potentially pathogenic organisms that don't establish residency and are often temporary.
Some of the roles of the normal flora are preventing or competing with pathogenic microbes, or contributing to the health by synthesizing vitamin K & B vitamins.

Bacterial Staining

Staining is used to add color to microorganisms for visual identification and differentiation using a microscope.
Key staining methods include Gram stain, Ziehl-Neelsen (acid-fast) stain, and others.
Gram staining differentiates bacteria based on their cell wall structure (Gram-positive & Gram-negative), while acid-fast staining differentiates specific groups of bacteria that are resistant to the decolorization step.

Culture Media

These contain the required nutrients for growth of a given microbial organism.
Different culture media types include basic, enriched, selective, and differential, each designed for a specific purpose or use based on requirements.

Biochemical Tests

Biochemical tests aid in precise categorization and identification of different bacteria based on the products or byproducts of chemical reactions of different bacteria.

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Description

Explore the foundational concepts in microbiology, including the study of microbial life and its implications for humans. This quiz covers various branches of microbiology and their relevance to healthcare and environmental science. Gain insights into medical microbiology's role in diagnosing and treating diseases.