Microbiology & Parasitology: Nursing Context

Introduction to Microbiology and Parasitology

• Focus is on microorganisms and their relationship to health and illness within a Bachelor of Science in Nursing context during the 2nd exam week.
• Course draws material from lectures and laboratory work.
• Color-coded medical waste containers aid in proper disposal: Yellow for infectious waste, Black containers for dry, non-infectious waste, and Green are designated for wet, non-infectious waste products.

Microbiology

• The study of tiny organisms requires magnification to be seen.
• The term roots come from Greek: mikros (small), bio (life), and logos/logia (study of).
• Disease-causing bacteria are called germs, derived from Latin germen (to grow or sprout quickly).
• Those germs that can cause illness are called "pathologic".

Parasitology

• Focuses on parasitic protozoa, parasitic worms (helminths), and arthropods, which can directly cause disease or act as vectors.

Microorganisms in General

• They are tiny living things, also called microbes or germs.
• Pathogens are microorganisms that can lead to illness in humans.
• Microbial diversity includes bacteria, archaea, viruses, fungi, prions, protists, protozoa, and algae.
• They are vital for ecosystems and human health due to their diversity and adaptability.

Importance of Microbes in Human Health

• Microbes influence digestion, immunity, and mental health.
• The microbiome is a source of new targets for medical studies and treatments.

Microbes in Industry

• They are essential for fermentation and bioremediation.
• They revolutionize biotechnology through enzyme and bioactive compound development and use.

Divisions of Microbiology

• Microbiology can be divided into pure and applied sciences.
• Taxonomy-based pure microbiology includes:
  • Bacteriology that focuses on the study of bacterial organisms.
  • Immunology that focuses on the study of the immune system and response to pathogens.
  • Mycology that focuses on the study of fungal organisms, such as yeasts and molds.
  • Parasitology that focuses on the study of parasite organisms. Note not all are microorganisms, however if they are bacterial, their study is in the realm of bacteriology.
  • Phycology that focuses on algal organisms.
  • Virology that focuses on virus organisms.

History of Microbiology

• Groundbreaking revelations in science include Leeuwenhoek's observations and Koch's postulates.

Evolution of Microbiology

• The archeological record indicates fossils of microorganisms exist as far back as 3.5 billion years ago.
• Historical records, such as the Plague in Egypt (1122), describe millennia of infectious diseases.
• Before formal microbiology, Jainism suggested the existence of microbiological life.
• The first century book On Agriculture by Marcus Terentius Varro hinted at disease spread through unseen organisms.

Key Figures in Microbiology

• Robert Hooke (1665): Discovered cells using microscopy and documented findings in Micrographia.
• Anton van Leeuwenhoek (1670): Known as the father of microbiology, bacteriology, and protozoology due to his single-lens microscope observations of "animalcules."
• Edward Jenner (1796): He developed the smallpox vaccine.
• Louis Pasteur (1800s): Studied the Germ Theory of Disease, invented pasteurization, and developed rabies and anthrax vaccines.
  • Pasteurization heats liquids like milk between 60-100°C.
  • Coined the terms "aerobes" and "anaerobes."
  • Showed alcoholic fermentation converts organic molecules into acids, gases, or alcohol without oxygen.
• Robert Koch (1876): The first to link specific bacteria to specific diseases, used microscopy to identify bacteria in cultures and developed pure culture techniques.
• Richard J. Petri: Koch's assistant, who invented the Petri dish for microbial culture growth and manipulation, and used gelatin.
• Fanny Hesse: She developed the use of agar as a solidifying agent for microbiological studies.
• Ignaz Philip Semmelweis (1840): Saved mothers by advocating antiseptic procedures like handwashing with chlorinated lime solutions to combat puerperal fever.
• Joseph Lister introduced antiseptic surgery including handwashing, instrument sterilization, and carbolic acid dressings.
• Paul Ehrlich (around 1910): He developed Salvarsan, a "magic bullet" cure for syphilis.
• Alexander Fleming (1928): Discovered penicillin from Penicillum Notatum mold, which targets bacteria and not viruses.
• Selman Abraham Waksman: He is known as the father of antibiotics.
• Hans Christian Gram: Credited with developing Gram stain to differentiate bacteria due to Gram stain reaction and cell wall composition.
• Theodor Escherich (1919): Discovered Bacterium Escherichia Coli.
• John Tyndall: Determined endospores cause heat resistance in hay infusions and showed that dust carried germs and used a fractional/intermittent sterilization process to sterilize over 3 days with heat.
• Albert Neisser identified Neisseria gonorrhoeae which causes Gonorrhea.
• John Snow mapped cholera cases in London, pinpointing contaminated water as the source.
• Luc Montagnier (1983): He discovered the Human Immunodeficiency Virus (HIV).

Significance of Microbiology to Nursing

• Microbes populate the environment and human body as "normal flora".
• They play a role in biotechnology for food, beverage, and pharmaceuticals.
• They are a source of antimicrobial medications.
• They perform roles as saprophytes or decomposers.
• Understanding microorganisms and their functions can improve therapeutic interventions.

Fundamental Properties of Microbial Life

• Basic and applied branches include studying bacteria (bacteriology), microbial metabolism, the function of the immune system (immunology), and related processes. Environmental and disease-related microbiology fall under applied.

Classification of Microorganisms

• Bacteria: Single-celled, small prokaryotic organisms with peptidoglycan-rich cell walls, and no nucleus.
• Binary fission reproduction which occurs asexually.
• Classification by Oxygen Requirements:
• Aerobic Bacteria: Grow in the presence of available oxygen.
• Anaerobic Bacteria: Do not need oxygen to grow.
• Facultative Anaerobes: Can survive in an environment with or without available oxygen.
• Viruses: Acellular, obligate intracellular parasites that cannot replicate without a host. Made of DNA or RNA, encased in a protein coat (capsid), which may or may not be enveloped. Examples include HIV; or the viruses which cause Varicella, Rubella, Rubeola, Mumps; or cause influenza, Ebola, Polio, Hepatitis, MERS, SARS, COVID 19.
• Fungi: Eukaryotic organisms with chitinous cell walls, true nuclei and organelles that reproduce sexually or asexually. Can be unicellular or multicellular.
• Yeast are unicellular.
• Molds are multicellular.
• Protozoa: Unicellular eukaryotic parasites that reproduce asexually or sexually. Motility is achieved via pseudopods, flagella or cilia.
• Amoeboid protozoa/Amoebas (e.g., Entamoeba histolytica, which causes amebiasis, a type of dysentery).
• Ciliates (e.g., Balantidium coli, which causes balantidiasis that leads to diarrhea).
• Flagellates (e.g., Trypanosoma brucei are responsible for African sleeping sickness.
• Sporozoa are called apicomplexans, are uninucleate, covered by a pellicle, and lack cilia or flagella.
• Examples Plasmodium and Cryptosporidium.
• Multicellular Animal Parasites: Large, multicellular eukaryotic organisms, containing flatworms (trematodes/flukes, cestodes/tapeworms), thorny-headed worms or roundworms.
• Algae: Eukaryotic, plant-like organisms with cellulosic cell walls that create organic substances and oxygen through photosyntehsis. Can be unicellular or multicellular. Many contain pigments.
• Archaea: Unicellular prokaryotes without peptidoglycan in their cell walls. Initially classified as bacteria. There have been pathogenic species identified. May be extremophiles in extreme environments like hot/cold or salty regions.
• Bacteriophages: Special viruses that infect bacteria.

Microscopes

• Microscope as a tool to examine microscopic specimens is a key element for diagnosis.
• The study of microbes with microscopes is the science of microscopy.

Types of Microscopes

• The simple microscope features one lens, like a magnifying glass.
• The compound microscope has lenses at both the eyepiece and the objective.
• Light Microscopy: Field illumination lets scientists see stained specimens. Limited to objects larger than 0.2 um.
• Fluorescent Microscopy: Immunofluorescence shines against a dark background, detecting antigens and antibodies.
• Confocal Microscopy: With computer support, fluorescent dyes are scanned by lasers to create 3D images and study cell physiology.

Microscopic Techniques

• Electron microscopes use electron beams amplified by magnets to achieve magnifications up to 2 million times allowing extremely detailed analyses of viruses and cellular components.
• Scanning electron microscope provides 3-D structures via electrons.
• Scanning probe microscopes rely on physical probes and computer mapping to visualize details at the atomic level.

Specialized Microscopy

• In dark-field microscopy light is reflected off specimens to create bright images against a dark background. Transparent objects that absorb little/no light can be observed as outlines using this. This uses reflected light instead of transmitted.
• Phase-contrast microscopy uses optical techniques for enhanced contrast, enabling detailed examination of transparent specimens like tissues slices, live organisms, and subcellular particles, binary fission or motility.
• Differential interference contrast microscopy provides higher resolution with 3D imaging via the use of two light beams.

Gram Staining, Culture Media

• Developed by Hans Christian Gram, staining enhances the microscopic image's contrast through dyes.
• Gram staining differentiates bacteria based on cell wall composition, staining positive bacteria with peptidoglycan, in blue or violet, while gram-negative stain red. Cocci bacteria tends to be gram positive, and bacilli tend to be gram negative.
• Simple stains color cells for basic visualization with dyes like safranin, methylene blue, or crystal violet.
• Differential stains helps to differentiate bacteria from one another.

Acid-fast Staining

• Stain identifies bacteria with high cell wall lipid content, like mycolic acid thus Gram stains cannot help identify.
• Ziehl-Neelsen and Kinyoun techniques use carbol-fuchsin to stain acid-fast bacteria red or pink.
• The method will then utilize acid alcohol as a decolorizer to remove stain from non-acid-fast bacteria and methylene blue, and malachite green as counterstains.
• Ziehl-Neelsen needs heat, where Kinyoun is cold.

Special Stains

• Special stains improve visualization, such as:
  • Lamb stains for bacteria, fungi and parasitic blood smears.
  • Hiss stains for capsules.
  • Fischer-conn for flagella.
  • Doner and Schaeffer-Fulton for endospores.
  • India ink shows Cryptococcus neoformans capsules.

Preparing Culture Media

• Media are aqueous solutions with added nutrients for microorganism growth.
• This media is classified by physical state (liquid, semi-solid, solid), chemical makeup (synthetic or non-synthetic), and function.
• Liquid media, like broth, are suited for large culture volumes.
• Semi-solid media, like agar, are ideal for microaerophiles and motility studies.
• Solid media is typically used for isolation and determining colony traits.

Media by Chemical Type

• Synthetic media has pure, defined compounds. Examples such as dextrose agar
• Non-synthetic media include complex extracts, benefiting fastidious organisms.

Media by Function

• General-Purpose Media: Supports a wide range of microbes, both pathogenic and non-pathogenic.
• Enrichment Media enhances specified organisms.
• Selective Media includes inhibitory substances targeting unwanted microorganisms.
• Differential Media makes it possible to see distinguishing features of various microbes.
• Transport Media prevents specimen drying during transfer.
• Anaerobic Media sustains oxygen-sensitive strains.

Bacterial Morphology

• In summary most bacilli are rod like, and cocci spherelike.

• Cocci have various forms, for example:

  • Diplococci (pairs). Example: Neisseria gonorrhoeae (gonorrhea).
  • Streptococci (chains). Example: Streptococci pyogenes causing Strep throat.
  • Staphylococci (irregular clusters). Example: Staphylococcus aureus causing food poisoning.
  • Bacilli - rod shaped such as Bacillus (Latin for staff or wand)
  • Arrangement, for example Streptobacilli Examples include Streptobacillus moniliformis causing of Rat Bite Fever.
  • Spirilla have helix-like structure and gently curved shape
  • Comma-shaped Vibrio cholerae are vibrios
  • Spirochetes include Spirochaeta, Treponema, Borrelia, in a helical shape with flexible bodies use structures called axial filaments
  • Pleomorphic (variable) example, Corynebacterium diphtheria are also gram-positive, catalase-positive and typically nonmotile

Microbes and Human Society

• Human use of microbes stretches from historical applications such as bread and alcohol fermentation and sanitation to modern uses such as genetic engineering.
• It is important to be careful to prevent a number of infections and diseases. Aseptic technique is essential to prevent contamination and transmission.
• The infectious disease process includes etiological agent, reservoir, exit route, transmission, and entry to a susceptible host.
• • End of summary

Introduction to Microbiology and Parasitology for nursing students. Covers microorganisms, their relation to health and illness, and waste disposal practices. Focuses on bacteria, protozoa, helminths and arthropods.