Review of Medical Microbiology and Immunology †MyAssignmenthelp

Question: Discuss about the Review of Medical Microbiology and Immunology. Answer: Introduction Sterilization is the process that is used to eliminate microorganisms such as bacteria, yeast viruses and fungi on the surfaces and bodies on which they are found(Levinson, 2013). The microorganisms can cause diseases to humans if they are not sufficiently controlled.Vegetative microorganisms are easily controlled by moist heat, however bacterial spores for example endospores are difficult to control by moist heat and are called thermoduric i.e. they can withstand even higher temperatures of steam above 100 degrees centigrade. There are different types of sterilization methods apart from saturated steam sterilization that include: chemical sterilization, done using chemicals; physical sterilization done using gamma rays. Sterilization is a very important process in the clinical set as well as in the day to day life. In the hospitals, sterilization is done to reduce the bio-burden in the environment. The areas may include hospital floors, tables, surfaces as well as the medical equipm ent used in the hospital. In the pharmaceutical industries where manufacture of drugs take place, this process of sterilization is important to keep the equipment and handlers microbial free so as to prevent contamination of the final medicines manufactured (AusHFG,2016). The principal used in sterilization by saturated steam involves using saturated steam at high temperature and pressure in an enclosed container, where there is total air removal from the container and the articles being sterilized maintained at points accessible to the steam over a sufficient period of time to ensure total destruction of the microbes(Levinson, 2013). The sterilization process by saturated steam is monitored by either using thermocouples (a temperature and pressure gauge), chemical indicators or biological indicators like the bacteria Bacillus Stearothermophilus provided as spore strips for monitoring sterilization. Sterilization by saturated steam is a preferred and ideal method for sterilizing art icles because it is efficient, fast and not toxic to the user and the environment.Biocidal activity of saturated steam is due to the high amount of latent heat released from steam that penetrates and destroys the cellular structure of the of the microbes causing death in even the most resistant spores. Dry heat on the other hand produces little energy that destroys the cellular components of the microbes, however it may not destroy resistant spores. The sterilization time generally includes 121 degree centigrade, 101 kPa and 15 minutes for liquids and 134 degree centigrade, 203 kPa and 3 minutes for medical devices and surgical linens. Tyndallisation is an old method of sterilization that involves heating the substance to boiling point or just below the boiling point and holding it there for about 15 minutes, repeated for 3 consecutive days. This experiment is crucial in its application in the field of microbiology since it helps to control microorganisms in places and objects where they are not required, thereby helping in controlling incidences of microbial infections.(Levinson, 2013) Aim. To understand the significance of sterilization. To establish the use of moist heat in the process of sterilization. To determine the fundamental requirements for sterilization by saturated steam. Materials. Sterile forceps. Paraffin oil. Sterile bottles with rubber seals capped with screw. Four paper strips inoculated with Bacillus Stearothermophilus spores. Two 250ml Schott bottles Two Sterikon with bio-indicator vials. Sterile water 10ml. Two sterile Pasteur pipettes. Five adhesive labels circular in nature. Two Thermalog sterilization indicators. Tryptone Soy Broth (TSB). Automatic pipette. Labels were placed on the caps of the 5 screw capped bottles. The bottles were then labelled 1, 2, 3,4 and 5.Strips of paper inoculated with Bacillus stearothermophilus were aseptically placed in bottles 1, 2, 3 and 4. With the aid of the pipette 6 drops of sterile water were added to bottle number 2. The spore strip in bottle number 4 was covered with paraffin oil. The caps of bottles 2, 3 and 4 were fastened tightly and then they were placed in a sterilizer.Bottle 1 was not processed. Two Thermalog strips were placed in the 2 Schott bottles.2ml of water was added to one of the bottles and then loosely caped. The second bottle was tightly caped. The two Schott bottles and a Sterikon plus bio-indicator vials were placed in the sterilizer along other bottles and kept at 121 degree Centigrade for an hour.The second bio-indicator was not sterilized. The Thermalog strips were then examined at the end of the sterilization. 3ml TSB was added to bottles 1, 2, 3 and 5. The spore strip in bottle 4 was aseptically transferred to bottle 5. Bottle 4 was discarded into paraffin discard. The bottles and the two Sterikon plus indicator vials were incubated for 3 days at 56 degree Centigrade. The results were based on the colour changes that occurred on each of the bottles upon incubation at 37 degrees centigrade. For the Thermalog strips their colour change were also examined and recorded as below. Bottle Conditions Growth Reason 1. Turbid+++ Present Due to lack of sterilization. 2. No turbidity Absent Due to sterilization. 3. No turbidity Absent Due to sterilization. 5. No turbidity Absent Due to sterilization. Turbidity key: ++++ Thermalog strips Material Treatment 1 Treatment 2 Thermalog strips Blue No colour change Material Before Incubation After Incubation Sterikon Vial 1 Pink Clear and pink Sterikon Vial 2 Pink Cloudy and yellow From the results above, it can be deduced that saturated steam sterilization is effective against bacteria and other microbes since turbidity was not observed on the bottles 2, 3 and 5 that were subjected to sterilization process then afterward incubated for microbial growth. Turbidity is a sign of microbial growth(Levinson, 2013). Bottle 1 which was not sterilized became turbid upon incubation, an indicator of microbial growth. The Thermalog strips(bio-indicators) were examined in the first and second treatments. On examinationthe strip in the first treatment showed growth indication by turning bluebecause it was not subjected to sterilization process which is needed to destroy the microbes whereas the strip in the second treatment showed no growth indication because it was subjected to sterilization process thus the spores of the bio-indicator were destroyed completely ,thus, no growth upon incubation. The Sterikon vials 1 and 2 were both pink before incubation, however, after incubation the Sterikon vial 1 became clear and pink indicating lack of microbial growth. This is because the Sterikon vial 1 was subjected to the process of sterilization whereas Sterikon vial 2 was not subjected to sterilization which hence microbes were not destroyed and grew upon incubation. The unexposed strips are cultured when examining the biological indicators after sterilization so as to allow for the growth of the bacteria in the unexposed strip, a confirmation that lack of exposure to the sterilization process leads to persistence of the microbes on the strip. Other physical control methods for sterilization include use of gamma rays and physical barriers like in membrane filtration process(Levinson, 2013). Prions are infectious spore forming particles of microbes that are very difficult to control and can cause serious infections for example, anthrax, gangrene, tetanus and food poisoning. They are described as thermoduric i.e. they can tolerate temperatures up to 100 degrees centigrade and cannot be therefore effectively controlled by steam sterilization. They thus need other physical methods of control like the use of gamma rays. References AusHFG. (2016). AusHFG. Retrieved from https://healthfacilityguidelines.com.au/: https://healthfacilityguidelines.com.au/part/part-introduction-and-instructions-use-0 Levinson, W. (2013). Review of Medical Microbiology and Immunology (Lange Medical Books) 13th Edition. San Francisco: Mc Graw Hill Educator.