Unit 4 Summer 24 Finals PDF

Microbiology and Physiology Unit 4 - Control of Microbial Growth Learning Objectives: At the end of the lecture discussion, the students will be able to: 1. Define terminologies used in the control of microbial growth. 2. List down the factors that affect microbial growth. 3. Identify...

Microbiology and Physiology Unit 4 - Control of Microbial Growth Learning Objectives: At the end of the lecture discussion, the students will be able to: 1. Define terminologies used in the control of microbial growth. 2. List down the factors that affect microbial growth. 3. Identify the different antimicrobial methods. 4. State the importance of microbial growth control. Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN  Importance of Microbial Growth Control 1. To prevent and control infectious diseases in humans, animals, and in plants; 2. To preserve food; 3. To prevent contaminating microbes from interfering with certain industrial processes; 4. To prevent contaminating microbes of pure culture research; Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN Factors in Preventing and Controlling Spread of Infectious Diseases 1. Destroying or inhibiting disease-causing microbes; 2. Blocking the sources, routes, and vectors of transmission of disease agents; 3. Protecting an infected person from the consequences of disease by building up the body's defenses and administering appropriate chemotherapeutic drugs. Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN In the past, people developed many primitive procedures to control the microorganisms and "cures" that were often more harmful than helpful to human beings. Now, we all know how to avoid, inhibit and destroy pathogenic microorganisms to prevent diseases. This is important to those working in health fields to learn the importance of controlling microbes in: ü patient's rooms ü operating rooms ü treatment rooms ü emergency rooms Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN Nurses should be aware of: proper aseptic techniques in doing: -wound dressing -giving injections -respiratory treatments -assisting physicians in delicate procedures proper handling of contaminated: -linen (blanket) -wound dressings -bedside equipment -laboratory specimens Purpose: To avoid infecting nurses themselves, the patients and others who have direct contact with the patient care management. Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN Important Terms to remember: Sterilization -the complete destruction of all living organisms, including cells, viable spores, and viruses. Disinfection -the destruction or removal of infectious or harmful microorganisms from non- living objects by physical or chemical methods. Microbicidal agents -is one that kills microbes. bactericidal -kills bacteria fungicide -kills fungi virucide -destroys viruses germicide -any agents/substance that destroy microorganisms Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN Microbistatic agents -is a drug or chemical that inhibits growth and reproduction of microorganisms. Bacteriostatic agent – is one that specifically inhibits the metabolism and reproduction of bacteria. Microbistatic agents and processes include: -desiccation (drying) -freezing temperatures -concentrated sugar and salt solutions -antimicrobial agents (antibiotics) Asepsis -the absence of pathogens on living tissues. Aseptic technique -is designed to eliminate and exclude all infectious microbes by sterilization of equipment, disinfection of the environment, and cleansing of body tissues with antiseptics. Sterile Technique -preventing all microorganisms from gaining entrance to laboratory or surgical area. Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN Factors Influencing Microbial Growth There are many environmental factors that enhance or inhibit growth of microorganisms. A. Temperature For every microorganism there is this: -optimum temperature to grow best; -minimum temperature that would stop to grow; -maximum temperature that would destroy them; Categories of microorganisms based on Temperature Tolerance: 1. Mesophiles = 20 to 40 ºC 2. Psychrophiles = 0 to 20 ºC 3. Thermophiles = 55 to 75 ºC 4. Psychroduric =very cold frozen temperature 5. Thermoduric =survive boiling; like spores Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN B. Moisture Some organisms can survive the complete drying process (desiccation). Another method is by dehydration of frozen organisms (lyophilization). used in industry to preserve foods, antibiotics, antisera and other microorganisms. C. Osmotic pressure Is the pressure exerted on the cell membrane by solutions inside and outside of the cell. a. hypertonic -make the cell shrinks b. isotonic -in and out of cell (normal cell) c. hypotonic -make the cell swells (crenation) Plasmolysis -cytoplasm shrink away from cell wall. Hemolysis -swell andMicrobiology burstingandofParasitology cell. Joel P. Defensor RN,USRN,MAN Example: Preservation of food by killing microorganisms: -Sugar solutions for jellies, dates -Salt solutions for pickles, salted food There are microbes that can survive in salty environment: haloduric -can survive in salty environment halophilic -prefer salty environments Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN D. Barometric Pressure barophiles -microoganisms survive in a very high atmospheric pressure Autoclaves and pressure cookers kills microbes by a combination of high pressure and high temperature. E. Gases The types of gases available in the environment. some bacteria will die if there is oxygen. Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN Antimicrobial Methods A. Physical Antimicrobial Methods Heat sterilization -most frequently used, Two factors: time and temperature a. Thermal death point -lowest temperature to kill microbes b. Thermal death time -length of time to kill microbes Important: -must remove first pus, feces, vomitus, mucus and blood that would serve as protective coating before sterilizing equipment with heat. 1. dry heat (160 to 165 ºC) for 2 hours -flaming (use of direct fire) ü Like flaming the surface of metal forceps is an effective way of killing microorganisms. Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN 2. moist heat (90 to 100 ºC) for 10-30 minutes -heat applied in he presence of moisture as in Boiling water and steamer. - this is faster and more effective than dry heat. - articles made of metals, and glass such as needles and simple instruments maybe disinfected by boiling for 30 minutes. - the endospores of bacteria such as those that causes anthrax, tetanus, gas gangrene and botulism are heat resistant and often survive by boiling. Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN 3. pressurized steam (121.5 ºC) for 20 minutes -autoclave -large metal pressure cooker: high temperature and moisture -effective in destroying spores. Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN 4. Cold -freezing inhibit and stop microbes reproduction. - most microorganisms are not killed by cold temperatures and freezing, but their metabolic activities are slowed, greatly inhibiting their growth, it does not completely inhibit growth. 5. Drying -drying food can prevent microbial growth because of the absence of moisture. in the hospital setting, dried specimens and dust may contain viable microorganisms. Joel P. Defensor RN,USRN,MAN Microbiology and Parasitology 6. Radiation -killing microbes by the use of UV rays. (example X- ray) -exposed to direct sunlight can kill microorganisms. -this will directly damage DNA. -UV lamp or germicidl lamp are helpful to continuously kill bacteria in places light newborn nurseries, operating roms, cafeteria, and classrooms. -People should be carefull not to expose their eyes and skin cause this can cause severe burn or even cancer. Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN 7. Ultrasonic waves -use for cleaning and sterilizing delicate equipment. -use of short sound waves to dislodge organic debris on instruments and glassware. - ultrasonic cleaners consists of tanks filled with liquid solvents (usually water). 8. Filtration -use to separate or filter cells larger viruses, bacteria and other microbes. -filters with tiny pores (micropore filters) are used in the laboratories to filter bacteria and viruses out of liquids. Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN Chemical Antimicrobial Methods Chemical disinfection is the use of chemical agents to inhibit, prevent and control the growth of microorganisms. Nurses should understand an important limitation of chemical disinfection. Many disinfectants might not be effective in the actual or clinical environment. Most disinfection methods do not destroy spores that are present in any instruments. Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN Characteristics of good chemical antimicrobial agent: 1. It must kill pathogens within reasonable period and in specified concentration. 2. It must be nontoxic to human tissues and nondestructive to materials. 3. It must be soluble in water and easy to apply. 4. It should be inexpensive and easy to prepare. 5. It must be is stable in the dissolved or solid form, so that it can be stored for a reasonable period of time. 6. It should be stable pH and temperature changes within reasonable limits. Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN How Antimicrobial Agents Work A. Injury of Cell Membranes 1. soap and detergents -surfactants -surface active agents that helps remove bacteria in the surface. -Safeguards and Dial contain disinfectants to kill bacteria. -concentration of weak acids like acetic and benzoic acids may also be used for soap. Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN B. Inactivation of Enzymes 1. Alcohols (ethyl and isopropyl) 70% -good skin antiseptics -use to sterilize thermometers -can't destroy spores 2. Phenolics (phenol, carbonic acid, xylenols) -example: Lysol, very effective in the presence of organic materials and can be active on surfaces for extended period. -too irritating and toxic to skin 3. Salt of heavy metals (mercury chloride) -example: Merthiolate and Silver nitrate (Argyrol) -Silver nitrate is used in the eyes of newborns to kill Neisseria gonorrhoeae. 4.Chemical oxidizing -example: Hydrogen peroxide Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN 5. Chlorine -example: Clorox -kills HIV by soaking instruments for 10 minutes. 6. Iodine -example: Betadine solution -effective skin antiseptics and disinfectants. C. Damage to Genetic Materials -example:Formaldehyde ( Formaline) -antimicrobial as well as sporicidal. -cannot be used in living tissues, very irritating. -usually used to preserve specimens and also dead human and animal bodies. Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN CHEMOTHERAPY (In vivo) Chemotherapeutic agents - are substances (drugs) used to treat disease, including infectious diseases. Antimicrobial agents - are chemotherapeutic agents used to treat infectious diseases. Antibiotics - are substances produced by microorganism that is effective in killing or inhibiting the growth of other microorganisms. Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN Types of antimicrobial agent Antibacterial -Drugs used to treat bacterial disease. Antifungal agents -Drugs used to treat fungal disease. Antiprotozoal -Drugs used to treat protozoal disease. Antiviral -Drugs used to treat viral disease. Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN Major Discoveries of Chemotherapy It started in the late 1800s when Paul Ehrlich began his search for chemcals that would destroy bacteria. He tested and discarded more than 600 chemicals. He finally discovered an arsenic compound that is effective treatment for syphilis. In 1928, Alexander Fleming discovered a substance produced by a mold, Penicillium notatum, inhibited the growth of staphylococci. Penicillium notatum was also considered to be nontoxic to animals and humans. Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN  During World War II, Sir Howard Walter Florey and Ernst Boris were two biochemists that purified penicillin and demonstrated its effectiveness in the treatment of various bacterial infections. By 1942, the U.S. drug industry was able to produce sufficient penicillin for human use. Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN  Characteristics of Antimicrobial Agents The ideal antimicrobial agent should: 1. kill or inhibit the growth of pathogens 2. cause no damage to the host 3. cause no allergic reaction in the host 4. be stable when stored in solid or liquid form 5. remain in specific tissues in the body long enough to be effective 6. kill the pathogens before they mutate and become resistant to it. Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN  Mechanisms of action of Antimicrobial agents 1. Inhibition of cell wall synthesis 2. Damage to cell membrane 3. Inhibition of nucleic acid synthesis (either DNA or RNA synthesis) 4. Inhibition of protein synthesis 5. Inhibition of enzyme activity Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN Types of antibiotics A. Narrow-spectrum antibiotics -are drugs that destroy gram positive bacteria. ü vancomycin -are drugs that destroy gram negative bacteria. ü colistin and nalidixic acid. B. Broad-spectrum antibiotics -are drugs that are destructive to both gram negative and positive bacteria. ü Ampicillin ü Chloramphenicol ü tetracycline Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN Side Effects of Antimicrobial Agents 1. Microorganisms may mutate and become resistant to the drugs. 2. The patient may become allergic to the drugs. 3. One few antibiotics may be toxic to humans. Example: chloramphenicol (Chloromycetin) that may cause aplastic anemia; streptomycin which can damage the auditory nerve and cause deafness. 4. Prolonged use of drugs may destroy the normal flora of the mouth, intestine, or vagina. Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN End of Unit 4 Microbiology and Parasitology Joel P. Defensor RN,USRN,MAN