Hyperbaric Oxygen Therapy & Clostridium perfringens

Hyperbaric Oxygen Therapy

• A breathing therapy that treats wounds infected with Clostridium perfringens by increasing oxygen in the bloodstream.
• Kills bacteria vulnerable to oxidative death, inhibiting their growth and toxin production.
• Inhibits alpha toxin release, which is produced by C. perfringens, and enhances the effects of antibiotics.

Clostridium perfringens

• Susceptible to increased oxygen concentrations.
• Thrives in anaerobic conditions, and is classified as an anaerobe.

Clostridium perfringens Infection

• The "alpha toxin" produced by C. perfringens enters muscle tissue through a wound.
• The toxin destroys tissue and produces gas, leading to gas gangrene, which can cause sepsis and death.

Bacterial Population Doubling

• Population size doubles every 30 minutes with plenty of food available.
• To predict the number of cells (Nt) that will arise during a long growth period: Nt = (N₁) 2^n.
• N₁ represents the starting number of cells.
• n = generation number.

E. coli Population Calculation

• E. coli divides every 20 minutes under normal conditions.
• The population after 12 generations, assuming all cells survive, is 4,096.

Bacterial Generation Time

• If a bacterium has a generation time of 2 hours, and the population begins with 10 cells, the population after 10 hours will be 320 cells.

Antibiotic Treatment and Biofilms

• Antibiotic treatment is not sufficient to treat infections on foreign materials because the infected material in the body frequently forms biofilms.
• Biofilms must be physically removed, often by replacing the artificial material, because a single biofilm is usually a partnership among multiple microbial inhabitants.

Treatment of Infected Foreign Material

• Patients with infected foreign material must undergo surgery to clean the wound, remove biofilm formation, and potentially replace the foreign object.
• Antibiotics are needed post-surgery to clean up remaining bacteria in the wound and bloodstream.

Population Growth and Resources

• Individual organisms need resources like food and water, and as a population grows, competition for resources increases.
• Increased competition results in increased mortality and/or decreased reproduction, and the rate of population growth slows down.

Carrying Capacity

• Eventually, a population reaches a maximum size, which is the carrying capacity, determined by available resources, resulting in logistic population growth.

Bacterial Growth on Tofu

• Bacteria grew on a piece of tofu, increasing from a few hundred to ten million in the first 20 hours and the population growth slowed and then stopped.
• Once the bacteria had exhausted all the resources in the tofu, the bacteria could no longer keep growing.

Logistic vs. Exponential Growth

• In logistic population growth, as population size increases, struggle for limited resources increases, leading to increased mortality and/or decreased reproduction, thus population growth slows and stops.
• Exponential growth occurs when resources are abundant and there is little to no competition.

Bacterial Growth Curve Stages

• Lag phase: Initial stage with no signs of growth.
• Exponential (log) phase: Period of maximum growth while cells have adequate nutrients and a favorable environment.
• Stationary phase: Period where the birth and death rates of cells are equal, and the division rate is slowing due to depleted nutrients, oxygen, and waste accumulation.
• Death stage: Cells die at an exponential rate due to waste accumulation and inability to multiply, and the speed of death is determined by the species' resistance and the toxicity of the conditions.

Pathogens: Colonization and Infection

• Pathogens colonize and infect humans from different reservoirs and circumstances because of adaptations that allow them to survive in both high and low temperatures.

Gut Microbiota in Mice Studies

• Scientists identified that mice had more cold-protective bacteria in their guts with low temperatures giving them better metabolic health and less susceptibility to obesity.
• Mice with extremely reduced gut microbiotas had more intense hypothermia, but a fecal transplant from mice living at cold temperatures allowed mice in room temperatures to experience the cold protective benefits of the different microbiome.

An Essential Nutrient

• An essential nutrient is any substance that must be provided to an organism.
• They are categorized between Macro and Micronutrients because they have slightly different functions.
• Macronutrients: Chemical substances required in large quantities, and play principal roles in cell structure and metabolism. (carbon, hydrogen, oxygen).
• Micronutrients: Chemical substances needed in small amounts, and are involved in enzyme function and maintenance of protein structure. (manganese, zinc, nickel).

Inorganic vs. Organic Compounds:

• Inorganic: An atom or simple molecule that contains a combination of atoms other than carbon and hydrogen.

Chemical Analysis of Microbial Cytoplasm

• 6 inorganic elements make up 96% of the dry weight of the cell which include: Sodium (NA) Calcium (CA) Magnesium (Mg) Chlorine (CI) Iron (Fe) Trace Metals.
• 4 organic compounds make up 97% of the dry weight of the cell: Carbohydrates, Lipids, protein, and nucleic acids.
• Water makes nearly 70% of all components.

Microbial Definitions

• Heterotrophs: Organism that relies upon organic compounds for carbon and energy.
• Autotrophs: Microorganism that requires only inorganic nutrients with carbon dioxide as its sole carbon source.
• Photoautotrophs: Organism that utilizes light for energy and carbon dioxide for its carbon needs.
• Chemoheterotrophs: Organism that derives both carbon and energy from organic compounds.
• Chemotrophs: Gets energy from chemical compounds.
• Saprobes: Serve as decomposers of plant litter, animal matter, and dead microbes.
• Parasites: Live in or on a host, causing harm.
• Obligate parasites: Unable to grow outside a living host.
• Pathogens: Organism that causes disease in another organism.
• Ectoparasites: Parasites that live on the body.
• Endoparasites: Parasites that live in the organs and tissues.
• Essential Nutrients include: Carbon, hydrogen, oxygen, nitrogen, phosphate, sulfur (CHONPS).

Microbes use for nutrients

• Potassium is essential for protein synthesis and membrane function.
• Sodium is important for certain types of cell transport.
• Calcium is stabilizer of the cell wall and of the endospores of some bacteria.
• Magnesium is a component of chlorophyll and a stabilizer of membranes and ribosomes.
• Iron is an important component of the cytochrome proteins of cell respirtation.
• Zinc is an essential regulatory element for eukaryotic genetics. Is a major component of “zinc fingers” – binding factors that help enzymes adhere to specific DNA sites.
• Neisseria gonnorrohoeae and Neisseria meningitidis grow more rapidly in presence of carbon dioxide.

Cardinal Temperature

• Is the range of temperatures for microbial growth.
• Includes the minimum temperature, the maximum temperature, and the optimum temperature.

Psychrophiles

• Capable of growing at 0 degrees C.
• Optimum temperature is below 15 degrees C.
• Cannot grow above 20 degrees C.

Mesophiles

• Have adapted to live in the bodies of humans and animals.
• Optimum temperature of pathogenic bacteria is about 37° C, ranging from 20-40° C.

Thermophiles

• Have an optimum growth temperature of 45 to 80° C.
• Cannot grow below temperature of about 45° C.

Atmospheric Gases

• The atmospheric gases that influence microbial growth are O2 and CO2.
• Classified by oxygen use:
• Aerobes use gaseous oxygen in their metabolism and possesses the enzymes needed to process toxic oxygen products.
• Facultative anaerobes do not require oxygen for metabolism.
• Anaerobes lack the metabolic enzyme systems for using oxygen in respiration
• Aerotolerant anaerobes do not utilize oxygen but can survive and grow to a limited extent in its presence.
• Microaerophiles are harmed by normal atmospheric concentrations of oxygen but require a small amount of it in metabolism.

Capnophiles

• Microbes that grow best at higher CO2 tension that is normally present in the atmosphere.
• Neisseria is a Capnophille, a genus which causes gonorrhea and meningitis.

pH

• pH is the acidity or alkalinity (basicity) of a solution.
• The extremes of pH will kill cells by damaging enzymes and other cellular substances.
• Proteus metabolizes urea and neutralizes the acidity of the urine to colonize and infect the urinary system.

Osmotic Pressure

• Microorganisms obtain almost all their nutrients in solution from the surrounding water and their composition is Isotonic to water.
• If a microbe is placed in a higher solute concentration medium or hypertonic, water passes out through the cell membrane into the surrounding solution causing loss of water which is Plasmolysis.
• When we use salt to preserve foods like pickles, the high concentration of salt causes water to leave the bacteria and other microbes in the food, which makes the bacteria shrink and die and stops food spoilage,

Radiation

• Phototrophs can use visible light rays as an energy source.

Biofilms: The Epitome of Synergy

• Quorum sensing is the chemical interaction of bacteria with bacteria of the same species or of different species in its surroundings to monitor the size of the population in the biofilm.

Binary Fission

• Generation: the number of fission cycles to form 2 daughter cells from a parent cell. 2n, n is the generation number.
• Generation time: the time required for a complete cycle to form two daughter cells from a parent cell via binary fission.
• CFU's colony forming unit, a unit used to estimate the number of viable (cells that can multiply in binary fission in controlled conditions) bacteria or fungal cells in a sample

Medical Moment: Osmosis and IV fluid

• In case of Isotonic solution used as IV, the tonicity of the solution is same as the body's plasma: the net movement of water is very little between body tissues and blood vessels
• In case of hypertonic solution used as IV, the tonicity of the solution is higher than the body's plasma: the net movement of water is moving from extravascular spaces into the bloodstream to increase the intravascular volume, thus attempting to dilute the higher concentration of electrolytes in the IV fluid.
• 4.In case of hypotonic solution used as IV, the tonicity of the solution is _lower than the body's plasma

Medical Moment: MRSA: PCR Over Culture

• MRSA carrier state is typically diagnosed use PCR by nasal swab.
• It detects bacterial DNA in the sample + is a rapid teset
• Contact isolation, gown and gloves, private rooms, daily cleaning, separate frequently using medical equipment.