Microbiology Week 3 PDF

Control of Microbial Growth Chapter 2, 3, 8, Appendix B Week: 3 Course: Microbiology and Infection Control Learning Outcomes Discuss the importance of controlling microorganisms. asepsis and cross-contamination and discuss the pathways of Define cross-contamina...

Control of Microbial Growth Chapter 2, 3, 8, Appendix B Week: 3 Course: Microbiology and Infection Control Learning Outcomes Discuss the importance of controlling microorganisms. asepsis and cross-contamination and discuss the pathways of Define cross-contamination. sterilization, disinfection, bactericidal agents, bacteriostatic Define agents, pasteurization, and lyophilization. Compare the various methods of sterilization. Compare the various methods of disinfection. Discuss the factors that influence microbial growth. 2  Learning Outcomes the differences between thermophillic, psychrophillic and Discuss mesophillic bacteria. between obligate aerobes, obligate anaerobes and facultative Differentiate bacteria. Discuss the difference between alkalinophillic and acidophillic bacteria. Discuss the difference between halophillic and haloduric bacteria. List the factors that influence effectiveness of antimicrobials. List 3 common antimicrobials used in dentistry. 3 Learning Outcomes the effectiveness of sulfonamide and penicillin drugs on Discuss bacteria. Discuss the reasons for caution with the use of antibiotics. List 3 common antibiotics recommended for use in dentistry the components and importance of an infection control Explain quality assurance program. the standards of the CDC, and summarize their Define and discuss recommendations for infection control in dentistry. 4  Infectious disease: occurs when a microorganism in the body multiplies and causes damage to the tissue Pathogens: the microorganisms that cause infectious diseases Opportunistic pathogens: the causative agents of infectious diseases caused by microorganisms normally present or on in the body, that will not cause harm unless favourably conditions exists for them to express their disease-producing potential Endogenous diseases: are causes by microorganisms in or on the body Exogenous diseases: are caused by microorganisms not normally present on or in the body; will contaminate the body from the outside Toxigenic diseases:exogenous microorganisms causing disease without entering& multiplying in the body( e.g after eating food in which mo’s have multiplied and produced toxins- botulism, Staphylococcus food poisoning Why Control Microorganisms? Control of microorganisms is important to the dental hygienist to prevent the transmission of diseases in the dental setting. It is important to protect ourselves and our clients for possible exposure to sickness and disease. 6 Source of the Microorganism Major source of disease agents= MOUTH How do we control the spread of pathogens in the office?  Standard precautions 7  Definitions: Asepsis A method that prevents contamination by unwanted microorganisms. The absence of infection or infectious materials or agents. E.g. the cleaning and disinfection of the dental chairs. Cross-Contamination A process that allows the transfer of microorganisms between persons and/or environmental surfaces or to a sterile object. E.g. touching a clients chart with dirty gloves. Universal Precautions to consider all clients as being infected with bloodborne pathogens and therefore applying infection control procedures to the care of all clients. 8 Definitions Standard Precautions Are a set of infection control practices used to prevent the transmission of diseases through the contact with: 1. blood 2. all body fluids, secretions, and excretions (except sweat) regardless of whether they contain blood 3. nonintact skin 4. mucous membranes. 9 Definitions Body substance isolation: designed to reduce the risk of transmission of pathogens from moist body surfaces Asymptomatic carriers: persons who have disease agents on or in their bodies but have no recognizable symptoms Rationale for Infection Control Principles: 1. Take action to stay healthy(education, immunization, safe medical devices, hand hygiene, culture of safety, management of hazardous materials) 2. Avoid contact with infectious materials(PPE, HVE, sharp containers, gloves, hands free soap dispensers, etc) 3. Limit the spread of contaminants( use of barriers, waste management, PPR, use of rubber dam, HVE, single use items) 4. Make objects safe for use(sterilization of instruments, follow manufacturer instructions for use) Goal of Infection Control To reduce the dose of microorganisms that may be shared between individuals or between individuals and contaminated surfaces. The more the dose is reduced, the better the chances for preventing disease spread. Disease prevention is based on reducing the dose and increasing the resistance of the body Health or disease= virulence x dose/body resistance Pathways for Cross-Contamination To Occur 1. Client to Dental Team 2. Dental Team to Client 3. Client to Client 4. Dental Office to Community 5. From Community to Client 13 Modes of Disease Transmission 1. Direct Contact: Contact with microorganisms at the source as in the clients mouth. Touching soft tissue or teeth. Can penetrate the body through small breaks or cuts in the skin, fingernails of ungloved hands Ex: Herpes infections of the fingers, STD’s, Skin diseases 14  Modes of Disease Transmission 2. Indirect Contact: Contact with items contaminated with a clients microorganisms such as: surfaces, hands, contaminated sharps, contaminated instruments, equipment. carry a variety of pathogens through blood, saliva, other secretions from previous client Hep B and C viruses Ex: Needlesticks Skin infection and common cold are spread by this mode 15 Modes of Disease Transmission 3. Droplet Infection: Contact with sprays, splashes, aerosols or splatter containing microorganisms. E.g use of cavitron Transmitted through close contact Enter through unprotected skin, eyes, nose, mouth. Masks, eyeglasses, face shields Influenza, mumps, rubella, herpes virus 16 Modes of Disease Transmission 4. Airborne Infection: smaller particles, can remain airborne for hours, can be inhaled Tuberculosis, chickenpox, measles Surgical masks are not designed to protect N-95 respirator 17 Chain of Infection. There are six elements in the chain of infection. All six need to be present for infection to spread. Absence of any one of these elements will break the chain Routes of Entry Into the Body 1. Inhalation: breathing aerosol particles from a prophy angle 2. Ingestion: swallowing droplets of saliva/blood spattered into mouth 3. Mucous Membranes: droplets of saliva/blood spattered into eyes, nose, or mouth 4. Breaks in the skin: directly touching microorganisms or being spattered with saliva/blood onto skin with cuts/abrasions/punctures with contaminated sharps 19  Sterilization: Disinfection: process intended to destroy/kill process that destroys mo’s, NOT all mo’s in a material or on an spores & viruses OR object decreases/minimizes amount of highest level that can be pathogenic organisms on objects achieved. or in materials so that they pose Destroys spores which are the no threat of disease. most difficult to destroy. 20 More Definitions Bactericidal - agent that kills bacteria. Bacteriostatic - stops the growth of bacteria but does not necessarily kill the bacteria. Pasteurization - heat process employed to reduce # of bacteria and destroy pathogens. ( Ex: prevent spoilage in mild and other dairy products) Lyophilization: a process of preserving microbes from a substance by removing the water, rapidly freezing the sample,, then drying it by using a vacuum pump, at very low temperature (Ex: Freeze drying) For long term preservation of blood, serum, bacterial cultures, to preserve vaccines) SPORES One of the resistant forms of life against heat, drying, and chemicals Bacteria that develop a defense mechanism against death Biologic monitors: spores of Geobacillus stearothermophilus, and Bacillus atrophaeus used to monitor use and function of heat and gas sterilizers 22 Sterilization The sterilization process must be able to achieve the destruction of high levels bacterial endospores (sporicidal). The three common types of sterilization used in dentistry are: 1. Heat Sterilization 2. Gas Sterilization 3. Liquid Chemical Sterilization 23 Heat Sterilization Steam, dry heat, and unsaturated chemical vapour Heat sterilizers 121C-190.6C and monitored using bacterial spores (biological monitoring) Effective 24 Gas Sterilization Ethylene oxide gas sterilizers- not commonly used Long exposure time High cost of gas sterilizers Special handling of ethylene oxide gas sterilant 25 Liquid Chemical Sterilization Room temp Used on items that can be damaged by heat sterilization Glutaraldehyde, special hydrogen peroxide, Glutaraldehyde-phenate No spore tests, difficult to monitor Estimate chemical concentration of active sterilant 26 Disinfection is a process that is intended to reduce and kill disease producing microorganisms but not bacterial endospores. It involves using liquid chemicals at room temperature to kill microorganisms on surfaces. Some types of disinfectants are not sporicidal, but can kill other microorganisms 27 Disinfectants 1. Alcohols 2. Quaternary ammonium compounds 3. Glutaraldehyde 4. Iodophors 5. Chlorine Compounds 6. Phenols 28 Factors Influencing Microbial Growth Changing environmental conditions and competition for nutrients can control and prevent expansion of microbial populations. Some factors that influence the growth of microorganisms are: 1. Temperature 5. Osmotic Pressure 2. Atmospheric 6. Hydrostatic Pressure Pressure 7. Radiation 3. pH 4. Salinity 29 Temperature All microorganism grow over a broad range of temperatures. The optimal growth for a microorganism depends on a narrow range in temperature. Microorganisms can be classified by the temperature at which they thrive. 30 Temperature o Optimal growth is at body temperature (37oC). Eg. human body. o Can grow @ temperatures ranging from 22-45oC o Bacteria in human body, including those causing infectious diseases such as: caries, periodontal disease, tuberculosis, bacterial pneumonia, tetanus. 31 Temperature heat-loving bacteria. range of 45-70oC. (Ideal temp.for growth is 56oC) Eg. Compost, “geyser” hot water 3. cold-loving bacteria. Temperature ranges from 1-22oC, (Ideal temp. for growth is 7oC) Eg. Refrigerator, ocean bacteria, principal cause of spoilage of refrigerated food 32  Atmospheric Pressure (oxygen metabolism) Many microorganisms require molecular oxygen to carry on metabolic activities. Microorganisms can also be classified according to the requirement for oxygen: 1. Obligate Aerobes- grow only in presence of oxygen (20% concentration). 2. Obligate Anaerobes- grow only in absence of oxygen 33  Atmospheric Pressure cont’d 3. Facultative Anaerobes- grow in the presence or absence of oxygen - in absence of oxygen they undergo anaerobic respiration or fermentation & produce less ATP=less growth 4. Microaerophiles- can tolerate only low conc. of oxygen (4%) 99% of the bacteria in the mouth are obligate anaerobes or facultative anaerobes 34  pH Almost all microorganisms grow best at a neutral pH (7.0). Acidophiles pH 1.0-5.5 Neutrophiles pH 5.5-8.0 Alkalophiles pH 8.5-11.5 Acidotolerant & alkalotolerant microbes can persist for a short period under these conditions - no reproduction. Large changes in (H+) can: disrupt cytoplasmic membrane potential for ATP generation (energy). inhibit enzymes & transport proteins 35  pH ACIDOGENIC = Bacteria that produce acids during growth ACIDURIC= bacteria that survive and grow in an acidic environment (pH1000m deep): 600-1,000atm Pressure (pressure exerted by a fluid) Barotolerant-survive in varying pressure environment; adaptable A barophile, also sometimes called a piezophile, is an organism which thrives at high pressures, such as deep sea bacteria or archaea. 41 Radiation - Ultraviolet Light Damages DNA Mutations will result indirectly in cell death -inability to replicate chromosome -inability to correctly transcribe mRNA No, it’s not a tanning bed! 42 Antimicrobials 43 History of Antimicrobials Paul Ehrlich (1854-1915) was the first person to use chemotherapeutic drug or antimicrobials to treat a bacteria infection. He used sulfonamides to treat the disease syphilis. Alexander Fleming (1881-1955) discovered a“Penicillium”mold producing a substance he called“Penicillin”that killed staphylococci bacteria. 44 What Is An Antimicrobial? term used to designate all the categories of drugs used to treat infections. help the body’s defense mechanism overcome pathogens without harming the client. is meant to destroy or control a microbial infection to numbers that can be eliminated by the immune system How Do Antimicrobials Work? Interfere with growth and replication of microbes. Inhibit the metabolic machinery of the host cell to replicate. Cause damage to the host cells. 46 Antimicrobials Commonly Used In Dentistry 1. Chlorhexidine-0.12%- E.g. Peridex 2. Phenols - e.g. Listerine 3. Quaternary Ammonium Compounds-E.g Cepacol, Crest Pro Health Rinse 4. Stannous Fluoride 5. Sanguinarine- Viadent 6. Antibiotics 47  Antimicrobials (with the exceptions of antibiotics) are used in dentistry and may be added to mouth washes, gels or toothpastes. Antimicrobials are antibacterial act on the cell membrane of the bacteria, making it more permeable and easier to lyse. alter the bacteria cell surface and prevent it from adhering to the tooth surface. 48 Factors that influence effectiveness of antimicrobial agents: Duration or Level of mo’ exposures of Microbial Temperature of resistance to the mo’s to Population size treatment antimicrobial antimicrobial agent agent Physical Number and Organic /Chemical location of mo’s /Inorganic Matter Factors 49 Antibiotics Discovery of antibiotics occurred in the 1950’s Antibiotics are one type of antimicrobial and act on a bacterial cell (prokaryotic cell). Antibiotics do not impact or harm eukaryotic cells or viruses. 50  Chemicals that interfere with some metabolic activity of the bacterium but do not affect the metabolic activity of human body cells Ex: Penicillin prevent the formation of cell wall in certain bacteria prevent Antibiotics their growth and kills the bacteria Human body cells do not have cell walls= Penicillin does not affect the growth of human body cells 51 Sulfonamide Antimicrobial agents Bacteriostatic and inhibit growth and multiplication of bacteria, but do not kill them. 52  Penicillin and its derivatives Antibiotics Recommended Tetracycline In Dentistry Erythromycin 53 Overuse of Antibiotics There is an increasing amount of misuse and overuse of these drugs today. Because of this, some bacterial species are becoming resistant and untreatable with antibiotics. A prolonged use of antimicrobials, especially an antibiotic can lead to: 1. Toxicity 2. Increase in incidence of allergic reactions 3. Resistance to the antimicrobial References Chris Miller & Charles John Palenik. Infection Control & Management of Hazardous Materials for the Dental Team. 7th Edition, 2023, Elsevier/ Mosby, ISBN-13:978-0-323-08257-0 CDHO Standards of Practice 55