Microbiology Staining Techniques Quiz

Microbiology: Basic and Clinical Principles

• This is a microbiology textbook, second edition.
• It is presented by Janet Dowding, Ph.D., St. Petersburg College.
• The copyright is 2023 Pearson Education, Inc.

Introduction to Microbiology

• The book presents an introduction to microbiology.
• A case study on a mystery pathogen is included.

A Brief History of Microbiology

• This section covers the history of microbiology.
• Key figures such as Semmelweis, Lister, and Nightingale are studied.
• Students should be able to define microorganism, differentiate between pathogens and opportunistic pathogens, compare and summarize biogenesis and spontaneous generation, identify the goals of aseptic techniques, and summarize the work of Robert Koch.

What is Microbiology?

• Microbiology is the study of microorganisms, or microbes, often invisible to the naked eye.
• Microbes include cellular organisms (bacteria, archaea, fungi, protists, and helminths), and nonliving entities (viruses and prions).
• A table lists living and nonliving agents studied in microbiology, their cell types, and notes.
• At least half of Earth's life is microbial.
• Microbes inhabit nearly every region on Earth (from deep-sea trenches to glaciers).
• Prokaryotic cells evolved about 3.5 billion years ago.
• Eukaryotic cells include multicellular organisms and some unicellular microorganisms.
• Humans depend on microbes for food production, medication, and breaking down environmental hazards.

Microbes and Disease

• Pathogens are microbes that cause diseases.
• Only a small percentage of microbes are pathogenic (around 1.400 out of 1,000,000).
• Opportunistic pathogens cause disease only in weakened hosts.

Great Advances Occurred in and Around the Golden Age of Microbiology

• The Golden Age of microbiology was from 1850-1920.
• Key developments included advancements in microscopes, isolation and growth of microbes, and observational studies.

Figure 1.1 Early History of Microbiology

• This figure shows a timeline of important events in the early history of microbiology, featuring key figures and their discoveries.

Spontaneous Generation Versus Biogenesis

• Early debates centered on whether life could arise from nonliving matter (spontaneous generation) or pre-existing life (biogenesis).
• Francesco Redi's experiments tested spontaneous generation, showing maggots did not spontaneously arise from decaying meat.
• Louis Pasteur further disproved spontaneous generation with his experiments involving S-necked flasks.

Germ Theory of Disease

• The germ theory of disease states that microbes cause infectious diseases.
• Robert Koch developed a technique to identify the specific cause of infectious diseases.
• Koch's work involved anthrax caused by Bacillus anthracis.
• Koch's postulates are outlined.

Koch's Postulates of Disease

• Key steps for identifying the cause of a disease.
• These include presence in every diseased case, isolation and pure culture, replication in healthy host, and re-isolation from diseased host.
• Modern limitations are described, indicating that not all bacteria can be cultured.

Hand Hygiene and Aseptic Techniques

• Importance of hand-washing emphasized from the 1800s to 1900s.
• Semmelweis promoted hand-washing to reduce childbed fever.
• Lister's work involved aseptic surgery with carbolic acid.
• Nightingale established aseptic practices in nursing.

The Scientific Method

• The scientific method is the guiding principle in microbiology.
• Before modern times, diseases were believed to be caused by evil spirits or imbalances in the body.
• The method starts with a question, develops a hypothesis, researchers perform observations and analysis, conclusions are drawn and based on the data, and a conclusion is made, and this supports or refutes the hypothesis.

Observations Versus Conclusions

• Observations are collected using senses or instruments.
• Conclusions interpret and analyse those observations to provide accurate interpretations.

Law Versus Theory

• Scientific laws describe specific occurrences, often with mathematical formulas; while theories explain the "how" and "why" of phenomena.

Classifying Microbes and Their Interactions

• Microbiology uses taxonomic hierarchies (domain, kingdom, phylum, class, order, family, genus, and species) to classify microbes and their interactions, including symbiosis (parasitism, commensalism, mutualism).
• The binomial nomenclature system is used, which means two-names, for naming organisms.
• Normal microbiota (flora) is described, including bacteria, archaea, and eukaryotic microbes.

Morphology and Physiology in Bacterial Classification

• Taxonomy studies the classification of organisms based on shared traits.
• Early bacterial classification was based on physical and physiological properties.
• Carl Linnaeus laid the groundwork for taxonomy.

Taxonomic Hierarchy

• Eight levels for classifying organisms (domain, kingdom, phylum, class, order, family, genus, and species).
• Three domains (Bacteria, Archaea, and Eukarya).
• Older 5-kingdom classification and newer 6-kingdom classifications are discussed.

Growing, Staining, and Viewing Microbes

• Key techniques including methods for microbial isolation (streaking).
• Microbial growing media (broths, plates, slants, and deeps).
• Aseptic technique and biological safety cabinet to minimize contamination.

Specimens Are Often Stained Before Viewing with a Microscope

• Staining or dyeing increases contrast and allows visualization.
• Types of stains (simple, structural, and differential).
• Examples of simple stains (methylene blue, crystal violet, safranin, malachite green).
• Examples of acidic dyes used for negative staining (Nigrosin, India Ink).
• Mordants are also needed for certain staining procedures.

Simple Stains

• Simple staining uses a single dye to reveal cell shape, size, and arrangement.

Structural Stains (Capsule, Flagella, Endospore)

• These stains reveal structural features within microbes.

Differential Stains (Gram and Acid-Fast)

• Gram stains distinguish bacteria based on their cell wall composition (Gram-positive vs. Gram-negative).
• Acid-fast stains distinguish bacteria with waxy cell walls (acid-fast) from those without.

Microscopy

• Important for observing microbes.
• Different types of microscopy techniques including light microscopy, electron microscopy (TEM and SEM), and fluorescence microscopy.
• Components of a light microscope (ocular lens, objective lens, condenser, iris diaphragm, coarse and fine focus knobs, stage, slides, and lamp).

Resolution

• Resolution is the ability to distinguish two separate points as distinct.
• Refractive index is the degree to which a substance bends light.
• Immersion oil helps to improve resolution at higher magnification.

Electron Microscopy

• Using electrons to visualize microbes at a higher resolution.
• Transmission electron microscopy (TEM) and scanning electron microscopy (SEM).

Using Fluorescence in Microscopy

• Fluorescence occurs when a substance absorbs energy from UV light and emits a different colour of light.
• Fluorochromes are dyes that fluoresce under UV light, used for identifying specific targets.
• Immunofluorescence, a particular method using antibodies or other molecules attached to fluorochromes.

Establishing Normal Microbiota

• Babies are colonized with microbes at birth and throughout the early weeks of adulthood.
• Variables that influence this process, including delivery method and feeding type.
• Data showing the potential colonization of microbes in fetuses and infants prior to birth.

Disruptions in Normal Microbiota

• Antibiotic treatments can disrupt the normal microbiota, creating a risk for infections by allowing opportunistic pathogens to proliferate.
• Examples including UTIs and diarrhoea resulting from antibiotic treatments.

Transient Microbiota

• Transient microbes are temporary inhabitants and are not permanent residents.
• These are frequently picked up from various sources (environment, contact).
• These microbes can be eliminated through proper hygiene.

Host-Microbe Interactions

• Hosts and microbes have coevolved through symbiotic relationships (mutualistic, commensalistic, and parasitic).
• Diseases, such as malaria, as examples of how microbes and hosts interact.
• Sickle cell anemia as a consequence of host-microbe coevolution.

Biofilms

• Sticky microbial communities embedded in a matrix.
• Biofilms form from freely floating bacteria and are resistant to antibiotics and the immune system.
• Biofilm formation and its implications in healthcare.
• Importance of biofilms in various settings including environmental and industrial applications.

Environmental and Industrial Uses for Microbes

• Using microbes for bioremediation to clean up toxic waste.
• Example usage in degrading oil spills into CO2.

Other important topics/additional notes:

• Various clinical cases (e.g cholera case study) are further described.
• The book has many tables and figures to illustrate topics and concepts.

Test your knowledge on microbiological staining techniques with this quiz. Explore questions related to types of stains, dye functions, and the Gram staining process. Ideal for students studying microbiology and laboratory techniques.