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High risk microbes Prof Esam Objectives • Microbes transmission, routes, survival outside bodies • Examples for microbes in different body systems Microbes are Mostly Normal, Nonpathogenic Flora • Microbes like bacteria, virus, parasites and fungi may naturally colonize skin and mucous membranes...

High risk microbes Prof Esam Objectives • Microbes transmission, routes, survival outside bodies • Examples for microbes in different body systems Microbes are Mostly Normal, Nonpathogenic Flora • Microbes like bacteria, virus, parasites and fungi may naturally colonize skin and mucous membranes without any sign of illness, for a longer or shorter period, in all humans, animals, fish, parasites, plants and all other living beings. • Some types may be more invasive in human tissue than others. • Many microbes are free-living in the environment —in water, soil and air and on equipment—as a part of the normal microbial flora on the Earth. • Most of them are not dangerous and live in peaceful symbiosis with other living beings and may also be transferred between living species, from man to animal or man to plants and environment—and vice versa. • New and old human pathogenic microbes are increasing all over the world. Some agents, like drug-resistant bacteria and highly pathogenic viruses, are more dangerous than others, and some microbes may cause chronic devastating diseases. • The existence of humans and animals is dependent on a rich and active bacterial flora in the gut, participating in the decomposition of food substances to energy and growth. • Large amounts of bacteria in the gut (1–2 kg) and on the skin is a normal condition. • Humans are releasing microbes into the environment and air wherever they move and —at the same time—are picking up new microbes from the environment. Pathogenic Microbes: New and Old • Pathogenic microbes cause illness in most humans if introduced into sterile tissue. • “Opportunistic” microbes may cause problems in people with reduced immune defense and/or if large amounts are introduced in sterile tissue. • Nonpathogenic microbes nearly never cause illness in humans. Human pathogenic microbes often survive for a long time outside the body—in the environment. • Therefore, they are special threats to patients, personnel and visitors in healthcare institutions where there often is an accumulation of infectious diseases. • New and old human pathogenic microbes are increasing all over the world. • Some agents, like drug-resistant bacteria (methicillin-resistant Staphylococcus aureus, MRSA, multidrug-resistant tubercle bacilli and others) and highly pathogenic viruses (Ebola, SARS and others), are more dangerous than others. • Other viral agents may cause chronic devastating diseases like HIV and hepatitis B and C. Microbes may have preselected locations and tissues in the host Like influenza virus, pneumococci and tuberculosis mostly in lungs, hepatitis viruses in the liver and blood, Clostridium difficile and norovirus in the gut, coagulase negative staphylococci on the skin, etc. Transmission Routes: Spread of Infection • Transmission routes depend on the robustness of the microbe in the environment, virulence, infectious dose, anatomical site in the body, etc. • Pathogenic microbes are spread by contact, air, water, food, beverages, contaminated equipment and environment and are more seldom vector-borne, by insects or animals. • Drug-resistant microbes and/or resistance genes are common on the global food market for humans, animals and fish. • In addition, increased mobility, climatic changes, overcrowding, war and disasters, poor hygiene and poor infection control are increasing the transmission rate. • Prudent use of antimicrobial drugs, proper hygiene and good infection control for humans, animals and fish are essential for stopping spread of infections. Classification of infective microorganisms by risk group (WHO) • Risk Group 1 (no or low individual and community risk): A microorganism that is unlikely to cause human or animal disease. • Risk Group 2 (moderate individual risk, low community risk): A pathogen that can cause human or animal disease but is unlikely to be a serious hazard to laboratory workers, the community, livestock or the environment. Laboratory exposures may cause serious infection, but effective treatment and preventive measures are available and the risk of spread of infection is limited. • Risk Group 3 (high individual risk, low community risk): A pathogen that usually causes serious human or animal disease but does not ordinarily spread from one infected individual to another. Effective treatment and preventive measures are available. What is the high risk group of microorganisms? • Risk Group 4: (high individual and community risk): A pathogen that usually causes serious human or animal disease and that can be readily transmitted from one individual to another, directly or indirectly. • Effective treatment and preventive measures are not usually available. Countries (regions) should draw up a national (regional) classification of microorganisms, by risk group, taking into account: • Pathogenicity of the organism. • Mode of transmission and host range of the organism. • These may be influenced by existing levels of immunity in the local population, density and movement of the host population, presence of appropriate vectors, and standards of environmental hygiene. • Local availability of effective preventive measures: These may include: prophylaxis by immunization or administration of antisera (passive immunization); sanitary measures, e.g. food and water hygiene; control of animal reservoirs or arthropod vectors. • Local availability of effective treatment: This includes passive immunization, post-exposure vaccination and use of antimicrobial, antivirals and chemotherapeutic agents, and should take into consideration the possibility of the emergence of drug-resistant strains. • The most dangerous microbes cause a very high mortality, are identified as high-risk agents or “biohazard-level 4” agents and are treated at the highest level of infection protection with strict isolation measures. • Dangerous microbes occur as a problem mostly in countries with low hygiene standards/high population density and in tropical-subtropical areas. • Infection control must always be based on hygienic measures and strict infection protection. Biosafety and Biosafety Levels • What is Biosafety? Biosafety is the application of safety precautions that reduce a laboratorian’s risk of exposure to a potentially infectious microbe and limit contamination of the work environment and, ultimately, the community. • What are Biosafety Levels (BSLs)? There are four biosafety levels. Each level has specific controls for containment of microbes and biological agents. The primary risks that determine levels of containment are infectivity, severity of disease, transmissibility, and the nature of the work conducted. Origin of the microbe, or the agent in question, and the route of exposure are also important. Each biosafety level has its own specific containment controls that are required for the following: • Laboratory practices • Safety equipment • Facility construction • The biosafety levels range from BSL1 to BSL-4. Each biosafety level builds on the controls of the level before it. • Every microbiology laboratory, regardless of biosafety level, follows standard microbiological practices. THANK YOU