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Tulane University School of PH&TM Global Environmental Health Sciences Environmental Microbiology Lecture Outline Role of Microorganisms in the Environment – Algae, Fungi, Viruses and Bacteria Microbial growth – Optimum conditions : pH, Oxygen, Temperature, Nutrients, – Microbial Growth Curve Microorganisms in Water Microorganisms in Food Microorganisms in Waste Microorganisms in Soil, the Nitrogen, Sulfur and Carbon Cycles Management of Microorganisms in Health care facilities *Control of Nosocomial Infections *CDC Manual for Infections *Universal Precautions *Disinfection techniques *Sterilization Environmental Microbiology ALGAE Chlorella FUNGI Basidiomycete BACTERIA Gram Negative Bacilli Algae Algae Algae Environmental Benefits Algae uses photosynthesis to capture sunlight energy and carbon dioxide to produce oxygen and carbohydrates. It grows so quickly and can produce 15-50 times more Biofuel per acre than any other crop such as soy beans and corn Food for humans (sea weed) and fish. Algae-Based BioFuel Algae a new energy source that has been getting a lot of attention lately. Certain types of algae contain natural oils that can be readily distilled into a vegetable oil or a number of petroleum-like products that could serve as drop-in replacements for gasoline, diesel, and jet fuel. National Algae Association Benefits of Algae It can thrive in nutrient poor environment . Algae farms can be located near carbon dioxide producing industries and help clean the air by utilizing carbon dioxide to grow. Algae can grow in fresh and salt water , in sewage and the high quality protein which can be harvested and converted to livestock feed Algae Environmental Impact – – – – – Oxygen depletion Clogging water filters Algal Blooms/Eutrophication Color, taste and odors in Drinking water Red tide caused by Dinoflagellates (Algae), produce toxins FUNGI Basidiomycete Fungi Bacteria Bacteria Salmonella Vibrio cholera Diplococci Spirochetes Microbial Growth Factors: Temperature Oxygen pH Moisture Osmotic Pressure Food Growth Factors(conti.) Temperature Cryophilic < 20 0 C Mesophilic 20 – 45 0 C Thermophilic 46 - 65 0 C Thermoduric > 66 0 C Growth Factors (conti.) Oxygen Oxygen: Aerobic: requires free Oxygen Anaerobic : combined oxygen Facultative : free or combined pH Optimum pH 6.5-8.5 Moisture Osmotic Pressure Food Growth Curve Lag phase Log phase Stationary phase Decline phase GROWTH CURVE Number of organisms 7 6 5 4 3 2 1 0 2.5 5 7.5 Time 10 12.5 15 Microorganisms In Water Water Contamination Water Treatment: Filtration: slow sand filters Rivers and Stream and ponds Microorganisms In Wastewater Biological Treatment of Sewage activated sludge trickling filters biodiscs Biological Treatment of solid waste Biological Treatment of toxic chemicals Microorganisms In Food Food Contamination: diseases disinfection pasteurization sterilization Food Industry: cheese, fermentation Microorganisms in Soil Most are present in the top 3 inches Aerobic, anaerobic and facultative Degrade and in many cases detoxify toxic chemicals. Sulfur, nitrogen and carbon cycles Sediment microbial population . THE NITROGEN CYCLE Animal Metabolism Nitogen Fixation by Azotabacter and Rhizobium Complex Nitrogenous Compounds in Plants Complex Nitrogenous Compounds in Animals Loss of NH3 into the Atmosphere Decomposition by Microorganisms in the Soil Decomposition and Reduction of Nitrogenous Compounds to Ammonia by Organisms in the Soil Ammonia (NH3) in the Soil Oxidation by Microorganisms (Nitrosomonas) in the Soil Plant Metabolism Nitric Acid Salts (NaNO3) Industries, commercial fertilizer, volcanic DENITRIFICATION Oxidation by Microorganims (Nitrobacter) in the Soil LIGHTNING Nitrous Acid Salts (NaNO2) THE SULFUR CYCLE Organic Compounds (cystine, methionine, glutathione,etc) in plants and animals Putrefactive microorganisma (use S as H-acceptor) Sulfate-reducing microorganims : Desulfovibrio, etc. Food of plants and animals H2SO4 Sulfur oxidation by Thiobacillus, Thiorhodaceae, etc Sulfur oxidizing bacteria : Thiorhodaceae, etc. H2 S S Sulfur compounds from non-living source: mines, waters, volcanic gases, etc. THE CARBON CYCLE PHOTOSYNTHESIS Organic compounds in plants (Green plants, Combustion; Metabolism; Decomposition by Microorganims Atmospheric or free CO2 Microbial reduction to Organic compunds in animals Microbial oxidation CH4 Management of Hospital Environment Areas Covered: – – – – – – – Hazardous Materials Waste/solid /gas and liquid Food / water/air Emergency Preparedness Safety Security Medical Equipment Microbiology Of Health Care Institutions Equilibrium :Host, agent and the environment. Any misbalance might increase or decrease the chance of diseases . Control the agent, protect the Host and clean the environment. CDC Manual: In 1970 the CDC published a detailed manual “Isolation Techniques For Use In Hospitals” In 1985 the CDC issued the “Universal Precautions Standard” – Designed to protect employees from exposure to the blood and fluids of AIDS Patients. Universal Precautions Standard (conti.) The standard contains Six Components: – – – – – – administrative controls work control practices personal protective equipment housekeeping employee health issues Engineering control I- Administrative Controls It places the responsibility on the institution (hospital) to establish An Infection Control Program which should include policies and procedures ,surveillance and staff education. These describe patient care practices, cleaning, disinfection, and sterilization . II- Work Control Practices Handling patients , Handling specimens, hand washing practices is the single most important practice to prevent the spread of infections in a hospital. Laboratory employees. III- Personal Protective Equipment (PPE) These are extra covering put on the employee /patient when handling patients .They include gowns, cloves, masks, eye protection, and face shields. In 1983 CDC manual, Category-Specific Isolation Precautions was developed to assist employees in selecting appropriate protective equipment to use . III-Personal Protective Equipment (conti.) In 1995 the CDC published new document “Guideline for Isolation Precautions in Hospitals” It has two parts: the old Universal Precautions: gloves, masks, gowns, eye protection and the new part (Transmission-Based Precautions) covers Airborne, droplet and Contact. IV- Housekeeping Routine and terminal cleaning of surfaces as well as linen and laundry. Selection of detergents and disinfectants for cleaning surfaces such as beds, bedrails, over-bed tables, chairs, floors, walls in patient rooms Laundry facilities in hospitals are monitored by the local health agencies. The water and dryer temperatures are important to clean and sterilize soiled linen. V- The Employee Health Program To prevent disease transmission from patient to employee and from employee to patient. Most programs include screening and post exposure evaluation. Vaccination against Rubella, Influenza, Mumps etc . vary according to hospitals. VI- Engineering Controls: Consist of cleaning patient care equipment sterilization or disinfection Handling and disposal of infectious waste, air conditioning / ventilation, positive or negative air flow. Sterilization In considering methods for sterilization procedures, it is important to differentiate between sterilization and disinfection. * Sterilization kills all viable microorganisms. * Disinfection only reduces the number of viable microorganisms. Disinfection It is a process that kills most pathogens , rarely kills spores. Three major methods are used: – – – 1- Ultra violet irradiation 2. pasteurization 3. liquid chemicals. 1- Ultraviolet Irradiation Both viruses and bacteria are susceptible. UV light does not penetrate large dust particles, mucus and large droplets . It might cause skin and eye burns. 2- Pasteurization It is hot water disinfection at temperatures about 75 C0. – – – Washer-Rinser-dryer It is simple ,nontoxic, and no chemical residue . It does not kill spores 3- Liquid Chemical Disinfection Disinfection will destroy pathogens except the spores which they are more resistant . Major categories the commonly used disinfectants are – – – – Halogens Phenols Quaternary ammonia (QUUATS) Aldehydes These are NOT sterilants Sterilization The preferred methods of sterilization are high pressure steam/temperature (in autoclaves) for items that can with stand high temperature, and ethylene oxide gas for items that cannot withstand high temperature. However, cold chemical sterilants may be used effectively for many items. Sterilization Two Major Methods: – – – – – 1) Thermal : steam and dry 2) Chemical : Ethylene Oxide(C2 H4 O) ETO mixed with CFC 12/88 , used for heat sensitive articles Chloroflourocarbons ETO: is flammable, toxic air contaminant , probable carcinogen and CFC is an Ozone depleter Other Sterilization Methods Ozone / oxidizes metals, plastics Radiation/ Gamma Plasma: Hydrogen peroxide Microwave Radiation ( Promising ) All react with microorganism cell membrane and destroy cell proteins and DNA Cidex: Active ingredient: 2% Glutaraldehyde. The manufacturer's instructions indicate that a minimum of 10 hours is required for sterilization. Cidex comes in two formulations, Cidex and Cidex-7 (long-life). The shelf life of activated Cidex is 15 days and of activated Cidex-7 is 28 days. Clidox: Active ingredient: Chlorine dioxide. 1:5 mixture must be mixed daily. 1:18 mixture is good for 14 days. 1:5 is a good sterilant; 1:18 is a disinfectant. Alcide: Active ingredient: Sodium hypohlorite 1.37%. The manufacturer's instructions indicate that a minimum of 6 hours is required for sterilization. The shelf life of the activated solution is 14 days. Other acceptable sterilants are the following chemicals classified as sterilants by the Centers for Disease Control (CDC). These are the chemical ingredients of some of the commercial sterilants: – Glutaraldehyde (2%) for a minimum of 10 hours. – Formaldehyde (8%) / Alcohol (70%); minimum of 18 hours. – Stabilized hydrogen peroxide (6%) for a minimum of 6 hours. Dispersants Corexit EC 9527A 2-butoxyethanol Organic Sulfonic acid Propylene Glycol Specific Gravity 30% 10% 1% 0,98-1.02