Lec.-6.-Contamination-and-Decontamination.pptx

Contamination and Decontamination SMD Learning Objectives Define contamination and decontamination Discuss ways on how to decontaminate  Definition of Terms Contamination - the process of making something dirty or poisonous, or the state of containing unwanted or dangerous su...

Contamination and Decontamination SMD Learning Objectives Define contamination and decontamination Discuss ways on how to decontaminate  Definition of Terms Contamination - the process of making something dirty or poisonous, or the state of containing unwanted or dangerous substances Microbial contamination = is the unintentional introduction of microbial agents such as bacteria, viruses, chemicals or parasites. Humans are often exposed to these contaminants after they somehow enter the food chain and are inadvertently consumed.  Decontamination is a term used to describe a process or treatment that renders a medical device, instrument, or environmental surface safe to handle. Sterilization, disinfection, and antisepsis are all forms of decontamination. All infectious materials and all contaminated equipment or apparatus should be decontaminated before being washed, stored, or discarded.  Levels of Decontamination The effectiveness of decontamination ranges from high-level sterilization to simple cleaning with soap and water. Levels of decontamination include: Disinfection uses a liquid chemical to eliminate virtually all pathogenic microorganisms, with the exception of bacterial spores, on work surfaces and equipment. Effectiveness is influenced by the kinds and numbers of organisms, the amount of organic matter, the object to be disinfected, and chemical exposure time, temperature, and concentration. Antisepsis is the application of a liquid antimicrobial chemical to skin or living tissue to inhibit or destroy microorganisms. It includes swabbing an injection site on a person or animal and hand washing with germicidal solutions. Manufacturer recommendations for appropriate use of germicides should always be followed.  Cleaning uses water, detergent, and some mechanical action such as scrubbing with a gloved hand or brush. Cleaning is often a required step before sterilization or disinfection of inanimate objects because it removes all material such as soil or organic material and reduces the number of microorganisms on an object.  Sterilization uses a physical or chemical procedure to destroy all microbial life, including highly resistant bacterial endospores  Physical Method of Sterilization (In Vitro) Agent Mode of Action Remarks Radiation Short invisible UV Germicidal; direct exposure Can kill vegetative cells Burning or Open Instruments (needle) Flame/ Controlled Heating at 65 deg C Causes coagulation Heat Dry Heat Oven Uses tempt of 160-170 deg C Instruments like petri dish, test 1-2 hrs tubes etc.  Physical Method of Sterilization (In Vitro) Agent Mode of Action Remarks Boiling Tempt of 100 deg C or higher Kills vegetative state, Filtration Passage of liquid or gas through HEPA, membrane filters a screenlike material with pores Autoclave, Steam Steam confined under pressure in Kills bacteria including its under Pressure small chamber, 121 deg C 15-20 spores mins,  Chemical Method of Sterilization (In Vitro) CHEMICAL MECHANISM OF PREFERRED USED REMARKS AGENT ACTION PHENOLS & Disruption of Rarely used,; for Has irritating qualities and PHENOLICS plasma standard disagreeable odor 1. Phenol membrane; comparison only denaturation of enzyme 2. Phenolics Disruption of Environmental Derivative of phenol; reactive plasma surfaces, even in the presence of organic membrane; instruments, skin material denaturation of surfaces, & (Meytol, Dettol) enzyme mucous membranes 3. Disruption of Disinfectant hand EG: triclosan- broad spectrum; Bisphenols plasma soaps and skin most effective against gram membrane lotions positive  Chemical Method of Sterilization (In Vitro) Disruption of plasma Skin disinfection, BIGUANIDE Bactericidal to Gram S membrane especially for surgical positive & gram (Chlorhexe scrubs Negative ; nontoxic xidine) (Betasept) HALOGENS Iodine- inhibits protein Iodine- effective May act alone or as function; strong antiseptic* components of organic oxidizing agent Chlorine- disinfect and inorganic Chlorine- forms strong water, daily equipment, compounds oxidizing agent; alters eating utensils, cellular components household items, & glasswares ALCOHOLS Protein denaturation & Thermometers, and Bactericidal & lipid dissolution swabbing skin before fungicidal; not effective injection on endospore or non enveloped viruses; commonly used are ethanol & isopropanol HEAVY Denaturation of Silver nitrate** Heavy metals- silver & Chemical Method of Sterilization (In Vitro) SURFACE- Mechanical removal Skin Many antibacterial soaps contain ACTIVE of microbes through degerming & antimicrobials AGENT scrubbing removal of 1. Soaps & debris acid- anionic detergent 2. Acid- May involve in Sanitizers in Wide spectrum of activity, anionic enzyme dairy & food- nontoxic, noncorrosive, fast- detergents inactivation or processing acting disruption industries 3. Cationic Enzyme inhibition, Antiseptic for Bactericidal, bacteriostatic, detergents protein skin, fungicidal, virucidal, against (quarternary denaturation, & instruments, enveloped viruses (eg:Zephiran & ammonium disruption of utensils, & Cepacol) compounds) plasma membranes rubber goods Chemical Organic Method Metabolic of Sterilization Ascorbic (In acid & benzoic Widely used to control molds, Acids inhibition , acid- effective at low foods & cosmetics Vitro) mostly affecting pH; parabens much molds; action used in cosmetics, not related to shampoos & calcium their acidity propionate in bread Aldehydes Protein Glutaraldehyde Very effective antimicrobials denaturation (Cidex)- less irritating than formaldehyde: both are used in disinfection of medical equipment Gaseous Protein Excellent sterilizing Ethylene oxide (most sterilants denaturation agent common) Peroxygens Oxidation Contaminated surfaces, Ozone- supplement for (Oxidizing deep wounds, effective chlorination; hydrogen agent) against oxygen peroxide- poor antiseptic but sensitive anaerobes good disinfectant; Control of Bacterial Growth in Vivo 14 Action of Antimicrobial Drugs  Actions of Anti Microbial Agents Damage to plasma membrane Q: What is the function of plasma membrane? Effects: cellular contents leak into the surrounding medium, damage to proteins & nucleic acid Eg: Polymxin B  Actions of Anti Microbial Agents Inhibition of cell wall synthesis Q: What is the function of cell wall? Cell wall protects bacteria from injury. Inhibit cell wall synthesis is one of the most common modes of action for antibiotics. Eg: penicillin, cephalosporins, Actions of Anti Microbial Agents Inhibition of protein A protein synthesis inhibitor is a synthesis substance that stops or slows the growth or proliferation of cells by disrupting the processes that lead directly to the generation of new proteins. Eg. Chloramphenicol, Erythromycin Actions of Anti Microbial Agents Inhibition of synthesis of metabolites compounds that resemble a certain metabolite and interferes with the normal metabolism involving that metabolite. Eg. Sulfanilamides, Trimethoprim Actions of Microbial Control Agents Inhibition of Nucleic Acid synthesisA nucleic acid inhibitor is a type of antibacterial that acts by inhibiting the production of nucleic acids. There are two major classes: DNA inhibitors and RNA inhibitors. Eg. Quinolones, rifampicin  Antimicrobial Drugs Drugs Action Penicillin inhibiting the transpeptidase that catalyzes the final step in cell wall biosynthesis, the cross-linking of peptidoglycan Effective on Gram+ bacteria Exs. Ampicillin, amoxicillin 21  Antimicrobial Drugs Drugs Action Bacitracin inhibits the formation of linear peptidoglycan chains, which are the main component of bacterial cell membranes. Effective on Gram+ but not much in Gram – Exs. Polisporin, Neosporin 22  Antimicrobial Drugs Drugs Action Chloramphenicol Bacteriostatic but maybe bactericidal in higher concentration. - stops bacterial growth by binding to the bacterial ribosome (blocking peptidyl transferase) and inhibiting protein synthesis. Exs. Chloromycetin, Levomycetin 23  Antimicrobial Drugs Drugs Action Tetracycline Inhibits protein synthesis, cell can no longer grow and replicate Exs Doxycyline Erythromycin Bactericidal and Bacteriostatic Exs. Erycin, Erythrocin 24  Antimicrobial Drugs Drugs Action Polymyxin B disrupts the outer cell membrane of Gram negative bacteria, binds and neutralizes lipopolysaccharide, and inhibits respiration of Gram-negative bacterial cells Exs. Neomycin 25 Characteristics of an ideal Antimicrobial Drug 1.Kill or inhibit the growth of pathogen 2.Cause no damage to the host 3.Cause no allergic reaction in the host. 4. Be stable when stored in sold or liquid form 5. Remain in specific tissues in the body long enough to be effective 6. Kill the pathogen before they mutate and become resistant