Introductory Disclaimer: This essay’s information is scientific in nature, so please perform your own due diligence in understanding the terminology and techniques prescribed forthcoming and tailor them to your own needs. I am not responsible for any damage/injury caused in the misuse of this information.
Patients undergoing routine operations were at very high risk of infection in the early 1900s due to the limited concept of aseptic conditions. This lack of understanding of microbes, caused high levels of infection and even death during surgical procedures of their day. Some factors of the spreading of microbes in times past were that surgeons operated in street clothes without washing their hands. They used sewing thread to suture wounds, and stuck the needles in their frock coats then using the same needle on different patients without washing. Cotton/jute from the floors of cotton mills were the surgical dressings of the day.
Pasteur was the father of germ theory and spent most of his life to the calling in disease related to surgery. He held many inventions such as the autoclave in which to sterilize surgical instruments. It utilized steam and high pressure over a period of time to eliminate microbes. In addition, he was the inventor of what you might already know—pasteurizing milk.
English surgeon, Joseph Lister, founded modern antiseptic surgery and based much of his advancements from the study of Luis Pasteur. Lister used a solution of carbolic acid (phenol), to disinfect patients before and during surgical procedures. Evidence proved that the mortality rate of patients improved whilst utilizing his techniques and procedures. However, selling that idea to the masses of surgeons whom held mindset that nothing they can’t see could possibly kill their patient, would take some years and hard checking of “egos” in order to become mainstream in surgical advancements.
The control of microbial growth is necessary in agriculture, medicine, and even food sciences. Microbiology has spawned from these needs in today’s world. This “control” has two main outcomes: (1) killing microorganisms (2) inhibiting the growth of microorganisms.
Cidal agents are ones in which kill microbes. Static agents inhibit the growth of cells, which means they don’t kill microbes but just hinder growth.
In microbiology, sterilization refers to the complete destruction or elimination of all viable organisms. There are no degrees of sterilization. In other words, it is either sterile or not. Some of the current sterilization procedures that I will discuss will involve the use of heat, radiation, chemicals, or the actual physical removal of bacterial cells.
METHODS OF STERILIZATION
Heat: Heat is a sensitive technique that not only the temperature must be selected but time of sterilization—they both are coupled together for desired results. The end goal is to ensure 100% destruction of all microorganisms. The toughest and nasty of these organisms are endospores. It is the measure of sterility when their destruction is guaranteed.
Incineration: Warning: only use objects considered not to be destroyed in the incineration process. Such objects would be considered as needles, inoculating wires, surgical instruments, glassware, and anything all metallic. Microbes are burned to death, so-to-speak, during this process.
Boiling: If you’re hiking in the woods and you fetch water form a stream to drink, please boil it to 100 degrees Celsius for a duration of 30 minutes. This is a good start, as it will kill all microbes except possibly leave some endospores. Remember an endospore can stay dormant for a hundred years and spring up as nasty bacteria. A common endospore is tetanus. A sterilization of over 6 hours in boiling water will surely kill all endospores along with everything else.
Autoclaving: This is by far the most efficient means of sterilization. Autoclaves operate on a time/temperature relationship. Higher temperatures ensure more rapid killing of microbes. As would be expected, larger loads or denser materials to sterilize would require longer times. Autoclaving is used for most any type of sterilization such as biohazards, surgical dressings, glassware, microbiologic media, liquids, et al. However, You might have recalled that story of the spread of the AIDs virus during colonoscopy in Orange County California a few years back (procedure utilizing fiber-optic endoscopes), well these types of medical instruments cannot withstand autoclaving which would surly destroy all living matter. They were cleaned with toxic chemicals and wasn’t good enough. A new technique has emerged to sterilize such instruments with gas treatment.
Dry heat: Hopefully everyone reading this has access to a cooking oven—a dry autoclave. Dry heat is not as effective as moist heat in an autoclave. So to compensate for utilizing dry heat in sterilization of equipment, higher temperatures are needed for longer periods of time. Warning: be sure to use glassware, metal, and objects that won’t melt—now you understand why an autoclave is much better due to its “higher pressure temperature” resulting in less time and lower heat.
Irradiation: For you medical personnel whom have access, the goal with irradiation is to destroy nucleic acids. Remember from your high school biology class, that nucleic acid is one of the ingredients to deoxyribonucleic acid, so essentially you are destroying the DNA in the bacterial cell so that it cannot reproduce. There are many types of radiation techniques, which are utilized today: ultraviolet, x-rays, gamma and electron beams.
European countries are the first to latch onto the notion that irradiating of fruits and vegetables increase their shelf life up to 500%. How this works for the Prepper is that pasteurizing fruit juices through a high intensity ultraviolet light source and having a stream of juice pass under will preserve the juice much longer without refrigeration.
There are commercial level UV systems used today for waste management systems and water treatment plants. The UV lights that one would use for personal use will aid in the control of bacteria, viruses and protozoa.
The FDA has approved irradiation for a number of food products such as meats, fruits/vegetables, nuts, et al. Irradiation does not make food radioactive, however it does kill a significant number of insects, bacteria/parasites. In the recent past, bacteria that are controlled by irradiation include E. coli and Salmonella. This process is also endorsed by the United Nation’s World Health Organization and the American Medical Association.
Ultraviolet lamps are used to sterilize workspaces and tools. Personal UV lights are calibrated at germicidal wavelengths having two peaks oscillating at 185 nm and 265 nm. The lights cause thymine molecules, another component of DNA, to demise thus inhibiting DNA replication. This might not kill the organism outright, but will effectively neutralize its ability to reproduce. Caution: When utilizing UV illumination be sure to light all fissures, cracks and shaded areas, with ample time and light.
Gamma radiation is used primarily in the health care industry. Cobalt-60 is the main ingredient and is used to emit Gamma rays. When the rays are properly delivered during sterilization it will break down chemical bonds. Remember form your organic chemistry class regarding atomic constituents (essentially any atoms attached to the main carbons) that by interacting with their electrons, it will break down. Gamma rays have insufficient energy to impart radioactivity, so they don’t leave a residue.
Electron beam (e-beam) radiation, this is a process whereby it also alters chemical molecular bonds. It has a low penetration and high-dose rates through a steady stream of electrons by converting electricity. Sterilization of instruments can range from syringes to cardiothoracic devices to other types of plastic, which might otherwise melt or become significantly damaged if placed into an autoclave.
Filtration is just what it implies, the physical removal of all microbes. This process is excellent for sterilization of solutions. Think about the hiker’s filtering system such as in the field for water purification. A typical pore diameter is about 0.3 micron pleated glass fiber with a carbon core for these filtering systems. They are used to remove the smallest known bacterial cells and can be purchased over the counter at a sporting goods store. The Hiker and the Prepper can be reasonably assured to “eliminate” Giardia, Cryptosporidium and most other forms of bacteria.
Ethylene oxide and formaldehyde, coupled with glutaraldehyde are all used for sterilization techniques in a hospital setting. Some chemical sterilization techniques are hydrogen peroxide, and can be purchased for household use.
Ethylene oxide is an easy process as it behaves as a gas at room temperature. Petri dishes, pipettes, syringes, medical devices are sterilized through this process. It must be carried out in a specialized gas chamber as it interferes with DNA hence stopping the reproduction of microbes. This is a safe process in that it doesn’t affect the integrity of the instrument.
Ozone sterilizer—This is another process primarily used in a hospital setting with a Low Temperature Gas Plasma (LTGP) coupled with a small amount of liquid hydrogen peroxide (H2O2). The plasma forms when energized with a specific radio frequency. In recent times there have been discussion of removing free radicals in your body—essentially a free radical is an unpaired electron in a molecular structure. This is the same process which will destroy the organism.
Non Sterilizing Methods— if sterility is not the desired end-point, for some other reason such as preventing spoilage of food, here are some methods:
Low temperature: Are obtained through the process of refrigeration and freezing. Perishable foods are stored at low temperatures, due to slowing down the growth of microbes and hence halting spoilage. Low temperatures don’t outright destroy bacteria, but just slow their growth—one microbe in particular is called Psychrotrophs, which can withstand cold temperatures and the culprits in food spoilage. In rare instances few microbes will grow in a super cooled environment lower than 20 degrees centigrade but the majority of foods can be preserved in a household freezer.
Drying: The removal of H2O forces most microorganisms into a non-growth state. This is yet another method to preserving foods. As Preppers, you might have been acclimated to freeze-dried foods? How about utilizing oxygen absorbers in your canned goods once freeze dried? Well all methods of drying involve one or many of the following: evaporation, freeze-drying, and the addition of salt or sugar for food preservation.
Control of microbes:
Antiseptics, as well as drugs are used in the treatment of diseases, many of which can become infectious if not treated immediately. These types of controls are used to eradicate microbes in both plant and animal kingdoms.
Antiseptics: Some of these might be common and stocked in your home: alcohols, mercurial, silver nitrate, iodine solution, and detergents. These harmless enough to be applied to your skin and within the mucous membranes. Caution: please do not take these internally.
Disinfectants: Hypochlorites, chlorine compounds, lye, copper sulfate, quaternary ammonium, formaldehyde and phenolic will all kill microorganisms but not always their spores. These compounds are not safe for application to living tissues; usually they are used as hardened cleaning products.
Preservatives: In short, these will inhibit the growth of microorganisms. Since these are most often used in the preservation of foods, use nontoxic preservatives so they can be eaten.
Salt/Sodium [nitrate, chloride, diacetate] – retards bacterial growth and is the most common in food preservation for bread making, pickled foods, meats/fish, and antimicrobial agent in cheese, and yogurt. Warning: these are not good for blood pressure.
Nitrates – Usually found in types of cheeses. Note if they are utilized by looking for a pink color in cured meats. This can also be used in canning as it prevents botulism. Warning: Children can cop a reaction to its utilization and is potentially carcinogenic.
Sulfur Dioxide and Sulfites –prevents browning in fruit juices, soft drinks, dried fruits and vegetables. How sulfites work is by preventing yeast growth. They are also used in wine [grapes] to retard bacterial growth, dried fruits and molasses. Warning: utilization of sulfur as a preservative will destroy vitamin use in your body and can cause asthma and/or hyperactivity.
Benzoic Acid and Sodium Benzoate – This was the fun one for me as like to eat seafood. It is used in the preservation of sauces (oyster, fish, shrimp, et al.). In addition, pickled products, ketchup, confections, baked goods, salads, non-alcoholic beverages, fruit juices, margarine, cheeses, and jams.
Propionic Acid and Propionates – These are preservatives utilized in bread—even various types of chocolate products, and some dairy.
Sorbic Acid and Sorbates – prevent mold formation in cheese and flour confectioneries.
Sugar—Preserves, jams, syrups, jellies, et al. from microbial spoilage.
Wood smoke— prevalent in making jerky. Used for meats and fish to prevent microbial spoilage.
A little about me: I am currently an older college student, in my 40s, taking microbiology for a nursing career change from receptionist.
An Aside: I am a little perturbed at the teaching at the university level in the contempt and even hatred towards men. For young college girls to form study groups, bar men as being their lab partner—so boys have to work alone, those bulletin board advertisements for women only groups and STEM is only for women, the university curriculums geared towards ladies only, the rape awareness posters adornning every stall in the restrooms, the campus police/security and cameras in droves, and girls “discussing” evil towards their brothers in the restrooms and common areas is quite frankly SCARRY!
A few ancillary comments: over the years I’ve noticed the media has cleverly and strategically placed “Mom” in titles of articles to devalue women into believing that being under the spiritual authority of one man [which God said in his word is a woman’s primary place], her husband, that the term “wife” is now chastised as indebted servitude, even slavery or taking away human rights of a woman. Women/ladies we need to fight for family rights! The human right of ALL women across the globe to be placed back under the authority of her husband—dubbed a family! Else we are about to loose this great country God gave us without ever firing a bullet upon us.