LC

Microbiology

Microbiology 101

  • Microbiology - scientific study of microorganisms and their effects on other living organisms

    • Micro - small

    • Bio - life

    • ology - the study of

  • Divisions of Microbiology

    • Bacteriology - study of bacteria

    • Rickettsiology - the study of rickettsia

    • Virology - study of viral diseases

    • Protozoology - science and study of protozoa

    • Mycology - the study of fungi

  • History

    • 1400s-1500s: Girolamo Fracastoro disproved miasma theory

    • 1600s: Antoni van Leeuwenhoek began working on the microscope to view his “animalcules”

      • Francesco Redi proves that fly eggs on rotting meat came from flies and not spontaneous generation

    • 1800s: Louis Pasteur developed biogenesis theory stating that life only comes from other life

    • 1860s: Joseph Lister proved that microorganisms are the cause of infection and heating instruments and using phenol during surgery would prevent this

    • 1870s: Robert Koch demonstrated a relationship between Bacillus anthracis and anthrax in cattle and developed Koch’s postulates

    • 1900s: Paul Ehrlich began working on drug remedies for bacterial disorders

Classifying Organisms

  • Prokaryotes

    • Small and simple organisms

    • No nucleus

    • No membrane-bound organelles

    • unicellular or multicellular

    • genetic information contained in a nucleoid

  • Eukaryotes

    • More complex and organized organisms or cells

    • Unicellular or multicellular

    • Genetic information contained in a nucleus

    • Membrane-bound organelles

    • Genetic information exists in chromosomes and DNA is complex

  • Nomenclature

    • Binomial Nomenclature - used in science to assign a genus and species to each organism using taxonomy

    • Taxonomy - groups organisms into cohorts based on similarities

  • Taxa

    • Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

  • When referring to Organims

    • All organisms have a first and last name

    • First name is the genus

    • Last name is the species'

    • Genus is capitalized and italicized

    • Species is just italicized

    • with bacteria, the names often give us much more information

  • Domains of Life

    • Archaea

      • Prokaryontes

      • Single celled

      • No peptidoglycan in cell wall

      • Most are anaerobic

      • Inhabit extreme environments

      • Do not usually cause human disease

    • Bactieria

      • Prokaryotes

      • Peptidoglycan in the cell wall

      • Single-celled

      • can exist on their own or as parasites

      • Present everywhere

      • often cause disease

    • Eukaryotes

      • Animals, plants, protists

      • Complex and organized cells within a nucleus or nuclei

      • Complex structure

  • Broad Classification

    • Bacteria - Prokaryotes found everywhere; they reproduce via Asexual reproduction

    • Viruses - tiny simple parasitic structures that are not cellular and not technically living; they require a host cell to replicate

    • Protazoa - unicellular eukaryotes that look like tiny animals; reproduction method varies

    • Fungi - a group of eukaryotes that are unable to photosynthesize, reproduce via spores

Anatomy and Morphology

Bacterial Anatomy & Morphology

  • Bacteria – a prokaryotic single-celled microorganism of the Kingdom Monera (monera being single cell), existing as free-living organisms or as parasites, multiplying by binary fission.

  • Morphology – the study of living organisms and the relationship they have with their structure

  • Anatomy – a branch of morphology that studies the structure of living organisms

Size of Bacteria

  • A bacterial cell can be anywhere from 1 to 10 microns long and up to 1 micron wide. A micron is a measurement for biological cells. Bacteria are not visible to the naked eye.

  • Bacterial colonies, however, can be seen with the naked eye. A bacterial colony is a visible group of bacteria, presumably arising from a single microorganism.

  • Bacteria are generally much larger than viruses. Bacteria in the mycoplasma genus are the smallest.

  • Colonies - a visible group of bacteria, presumably arising from a single microorganism

  • Bacteria that can change their shape, size, etc. are referred to as pleomorphic.

Bacterial Shapes

  • Coccus (pl. Cocci) – the type of bacteria that is spherical

  • Bacillus (pl. Bacilli) – rod-shaped bacteria

Spiral bacteria:
• Spirillum (pl. Spirilla) – spiral-shaped bacteria having a rigid cell wall
• Spirochete (pl. Spirochetes) – spiral-shaped bacteria having a flexible cell wall
• Vibrio (pl. Vibrios) – spiral bacteria which are curved or bent rods that resemble commas

Bacterial Arrangements

  • Cocci

    • Diplococcus (pl. Diplococci) – two round bacteria

    • Streptococcus (pl. Streptococci) – spherical-shaped bacteria occurring in chains

    • Staphylococcus (pl. Staphylococci) – gram-positive, nonmotile, opportunistic bacteria which tend to aggregate in irregular, grape-like clusters

  • Bacilli

    • Diplobacillus (pl. Diplobacilli) – two rod-shaped bacteria

    • Streptobacillus (pl. Streptobacilli) – rod-shaped bacteria occurring in chains

Bacterial Structure

  • All bacteria have a nucleoid, ribosomes, cytoplasm, and a plasma membrane. All bacteria except mycoplasmas have a cell wall. Bacteria may also have other structures contributing to their virulence or effectiveness.

Cell components

  • Capsule – a gelatinous coating that surrounds some bacterial cells that helps to protect against phagocytosis

    • Present in a large number of bacteria

    • Slimy coating outside the cell wall

    • Made of polysaccharides and amino acids

    • Provides protection against phagocytosis, antibiotics, desiccation, etc.

  • Cell wall – a rigid layer outside the cell membrane of plants, fungi, and bacteria

    • Inside of the capsule

    • Rigidity gives bacteria shape and provides protection

    • Made of polysaccharides, proteins, and lipids

    • Peptidoglycan is another cell wall component for almost all bacteria

  • Cell/Plasma membrane – a thin, selectively permeable membrane that is internal to the cell wall and contains the cytoplasm

    • Thin, elastic layer that allows for some contents to remain in the cell and some to move freely into or out of the cell

    • Phospholipid bilayer allows for permeability

    • Mesosome is a circular, coiled structure that disappears as the cell is stretched

      • Think of the mesosome as a folded or pinched-off part of the membrane

      • Thought to contain respiratory enzymes and assist in DNA replication

  • Cytoplasm – aqueous or semifluid matrix inside of the plasma membrane

    • Comprised of carbohydrates, proteins, enzymes, lipids, vitamins, salts, and nucleic acid

    • Granular appearance because of organelles called ribosomes

    • Responsible for holding all of the organelles in the cell, providing protection, and containing molecules that are necessary for cellular function and processes

  • Organelles – structures within a cell (in the cytoplasm) that have a specific function and a specialized structure

    • Ribosome – organelle functioning in protein synthesis

      • Able to link amino acids together in a sequence specified by mRNA

      • Amino acids are the building blocks of proteins

  • Nucleoid – bacteria chromosome comprised of a closed loop of double-stranded and supercoiled DNA

    • “Naked” or “primitive” nucleus

    • Contains the genetic material of bacterial cells

  • Endospore – a thick-walled body produced by a bacterium to enable it to survive unfavorable environmental conditions

    • Highly resistant coating that allows cells to go dormant

    • When conditions are more favorable, cells can emerge or germinate

    • Sporulating bacteria are inactive, dormant cells that are forming or have formed an endospore

    • Vegetative bacteria are actively reproducing and metabolizing

    • Nothing, outside of complete sterilization, will kill endospores

  • Flagella – fine, thread-like appendages that assist with movement

    • Extend through the cell wall and slime layer

    • Help bacteria to “swim” in their environment

  • Pili – hair-like growths on bacterial cell surfaces

    • Function in attachment

    • Can sometimes function in DNA transmission from one cell to another

    • Present in almost all gram-negative bacteria

Gram Staining

  • Gram staining is a differential stain which means it only reacts with certain structures. This procedure allows us to further categorize bacteria.

  • Gram-positive bacteria stain violet because they have a thick peptidoglycan cell wall.

  • Gram-negative cells stain red because they have a thin peptidoglycan wall.

    • often have a high level of antibiotic resistance and can release endotoxins.

Bacterial Physiology

  • Binary fission - form of asexual reproduction in a prokaryotic cell resulting in two individual cells with genetic consistency

    • Occurs under favorable conditions only

    • Bacterial colony - a visible group of bacteria, presumably arising from a single microorganism

General Information

  • Limits

    • Minimum - the minimum at which growth can occur

    • Maximum - the maximum at which growth will occur

    • Optimum - the ideal conditions for growth

  • pH

    • pH - power or potential of hydrogen

    • Measures how acidic, basic, or alkaline is

    • 7 is Neutral

    • lower than 7 is acidic

    • above 7 is alkaline

  • Concentrations

    • Solute - what is being dissolved

    • Solvent - what is dissolving

    • Concentrated - lots of solutes

    • Dilute - lots of solvents

  • Facultative

    • takes place under some conditions; occurring in response to a change

      • Responsive, reactive, depends on outside factors

  • Obligate/Strict

    • Required, not flexible

Conditions affecting bacterial growth

  • Osmotic pressure - the force applied to a solution to inhibit the inward movement of water across a semipermeable membrane

    • When the solution outside of a cell is dilute, it is HYPOTONIC

    • When the solution outside of a cell is highly concentrated, it is HYPERTONIC

    • When a solution outside of a cell is the same concentration as what is in the cell, it is isotonic. Nothing happens.

  • Oxygen Requirements

    • Strict Aerobe - a microbe that can live only in the presence of free oxygen

    • Facultative Aerobe - a microorganism that prefers an environment devoid of oxygen but has adapted so that it can live and grow in the presence of oxygen

    • Strict Anerobe - a microbe that can live only in the absence of free oxygen

    • Facultative Anaerobe - a microorganism that prefers an environment with the presence of oxygen but has adapted so that it can live and grow in its absence

    • Microaerophilic - organism that grows best in an oxygen-reduced environment

  • Food Requiremnets

    • Autotrophic bacteria - self nourishing bacteria

    • Heterotrophic - organisms that must obtain nourishment from complex organ matter

    • Strict saprophyte - an organism that can only survive on dead or decaying organic matter

    • Facultative Saprophyte - prefers living matter but can adapt to use dead organic matter under certain conditions

    • Strict parasite - organism that is completely dependent on its living host for survival

    • facultative parasite - prefers dead organic matter as a source of nutrition but can adapt to use living organic matter under certain circumstances

  • Temperature requirements

    • Thermophile - high temperatures 40C - 70C

    • Mesophile - moderate temperatures - 25C - 40C

    • Psychrophile - Cold Tempretures - 0C - 25C

Infection

  • Infection – a condition in which the body or a part of it is invaded by a pathogenic agent that can multiply and produces injurious effects; a disease caused by microorganisms, especially those that release toxins or invade body tissues

  • Infection usually begins with contamination:

    • Contamination – the act of introducing pathogens or infectious material into or on an inanimate object

Etiology

  • Etiology – the study of the cause of disease

  • Exogenous infection – a form of infection caused by a pathogen or agent nor normally present in the body

  • Endogenous infection – a form of infection caused by a pathogen or agent normally
    present in the body

  • Acute – an infection with rapid onset and short duration

  • Chronic – an infection with slow onset and long duration

  • Acquired – a disease, condition, or abnormality that is not hereditary or innate

  • Non-communicable – a disease that cannot be transmitted from one individual to another

  • Communicable – a disease that may be transmitted from one individual to another

  • Primary infection – an infection that develops in an otherwise healthy individual

  • Secondary infection – an infection made possible by a primary infection that lowers host resistance

  • Mixed infection – infection caused by two or more organisms

Pathology

  • Pathology – the science that deals with the study of disease

  • Signs – objective indications of the presence of disease

  • Symptoms – subjective indications of the presence of disease

  • Syndrome – set of signs and symptoms associated with a particular disease

  • Complication – un unfavorable condition arising during the course of disease

  • Diagnosis – the term denoting the identification of a disease or syndrome; to recognize the nature of a disease

Pathogenesis

  • Pathogenesis – the origin and development of a disease

  • Local infection – an infection confined to one area of the body

  • Systemic (General) infection – an infection in which the infecting organisms circulate
    throughout the body

  • Focal infection – an infection originally confined to one area but may spread to other parts of the body

  • Terminal infection – an infection resulting in death

  • Febrile – pertaining to or characterized by fever

  • Recurrent – reappearance of symptoms after a period of remission

  • Exacerbation – increase in severity of a disease

  • Remission – a cessation of the symptoms of disease

Epidemiology

  • Epidemiology – the study of the distribution an determinants of diseases and wellness in populations and the use of this data to enhance public health

  • Endemic – disease that occurs continuously in a particular region/population
    Epidemic – disease or condition that is currently in higher than normal numbers in a given population

  • Pandemic – an epidemic that has become very widespread or is worldwide

  • Sporadic – a disease which occurs occasionally in a random or isolated manner

  • Bacteria in the blood

    • Bacteremia – the presence of live bacteria in the blood

    • Septicemia – growth and spreading of bacterial cells in the blood stream

    • Toxemia – the presence of toxins in the blood

Virulence

  • Virulence – relative power of an organism to produce disease

  • Pathogenicity – the state of producing or being able to produce pathological changes and disease

Virulence Factors

  • Toxin – a poisonous substance of plant, animal, bacterial, or fungal origin

    • Endotoxin – a bacterial toxin that is liberated only when the cell producing it
      disintegrates

    • Exotoxin – a bacterial toxin produced within a living cell and secreted into its
      surrounding medium

  • Capsule – a gelatinous coating that surrounds some bacterial cells that helps to protect against phagocytosis

  • Endospore – a thick-walled body produced by a bacterium to enable it to survive
    unfavorable environmental conditions

Bacterial classifications

  • Normal flora – the microbial population that lives within or upon the host in a healthy
    condition

  • True pathogen – an organism that due to its own virulence is able to produce disease

  • Opportunist – an organism that exists as part of the normal flora but may become
    pathogenic under certain conditions

  • Attenuation – reduction of the virulence of a microorganism

  • Drug fast - Bacterial resistance to the action of drugs

Levels of control
Sanitation – to reduce microbe populations to a safe level as determined by public health
standards
Sterilization – a process of completely removing or destroying all life forms and their
products including endospores
Disinfection – a chemical or physical agent that kills vegetative forms of microorganisms
on inanimate objects
Antisepsis – the prevention or inhibiting of the growth of causative microorganisms on
living tissue

Methods of Control – Physical
Mechanical / scrubbing – manual process by which microorganisms are removed from a
surface
Temperature:
• Dry heat
o Incineration – a form of sterilization that reduces waste
o Cremation – incineration for human remains
o Hot air – exposure to hot air
• Moist heat
o Boiling – able to kill most vegetative bacteria, viruses, and fungi
o Steam under pressure (autoclave) – sterilization method
• Cold
o Refrigeration – slows decomposition/ microbial activity
o Freezing – slows decomposition/ microbial activity
UV light – radiation method that can control microbial activity

Methods of control – Chemical
Disinfectant – a chemical or physical agent that kills vegetative forms of microorganisms
• Germicide – a substance that destroys microorganisms
• Bactericide – an agent that destroys bacteria but not necessarily their spores
• Fungicide – a substance that kills fungi
• Virucide – an agent destructive to viruses

Influences on disinfection
• Nature and type of disinfectant
• Concentration of disinfectant
• Type of material being disinfected
• Number and type of microbes present
• Length of exposure to disinfectant
• Temperature, light, and pH of environment/ disinfectant

Disinfectants for Mortuary Procedures
Halogens – a group of elements that create a salt when reacting with a metal
• Oxidize microbial cells
• Generally very caustic and aggressive
Types:
• Hypochlorites – chlorine-containing compounds
o Require a high exposure time to kill endospores
• Iodophores – a compound containing iodine
Alcohol – an organic compound containing one or more hydroxyl (–OH) groups
• Denature proteins and dissolve lipids
• Often added to other disinfectants
• Do not kill endospores

Aldehydes – organic compounds containing one or more (–CHO) groups that are able to
cross-link and denature proteins
• Formaldehyde (HCHO) – colorless, strong smelling gas that when used in solution
is a powerful preservative and disinfectant; a known carcinogen
• Formalin – formaldehyde gas dissolved in water at 37% by weight and 40% by
volume
• Glutaraldehyde (C5H8O2) – dialdehyde with a mild odor able to act as a strong
disinfectant and sterilant
Phenolic compounds – compounds containing phenol or carbolic acid
• Denature proteins
• Include cresols (Lysol) and hexachlorophene
Quaternary ammonium compounds – surface disinfectants that are generally used for
disinfection of skin, oral and nasal cavities, as well as instruments