Topic 6. Sources and Chain of Infection PDF

After completion of the lesson, the student will be able to:  define infection  describe the agent causing infection  explain the sources of infection: ❑ endogenous ❑ exogenous  describe the link in the chain of infection  discuss the way of breaking the chain of infection As...

After completion of the lesson, the student will be able to:  define infection  describe the agent causing infection  explain the sources of infection: ❑ endogenous ❑ exogenous  describe the link in the chain of infection  discuss the way of breaking the chain of infection Asepsis  It is a state of being free from living pathogenic microorganisms that are capable of causing diseases Cross-contamination  Transmission of infectious micro-organisms from one person or object to another Infection  An invasion of body tissue by microorganisms and their growth there Infectious disease  Refers to the pathologic events that result from the invasion and multiplication of microorganisms in a host Sterilization  Process of destroying all micro-organisms and pathogen Virulence  Degree to which microorganism can cause infection in the host or invade the host  Biological agent – living organisms that invade the host. E.g.; Bacteria, Virus, Fungi, Parasites  Chemical agent - substances that can interact with the body. E.g.; food additives, medications & industrial chemicals  Physical agent – factor in the environment that are capable of causing disease. E.g.; heat, light, noise, radiation & machinery Biological agent  Living organisms that invade the host such as: bacteria, virus, fungi, protozoa and parasite 1. Bacteria  Single cell microorganism capable of causing disease in humans  Most common infection causing microorganism  All are capable of reducing organ function by invading tissue and cause inflammation  Can be transmitted through food, air, water, soil, vectors or sexual activity 1. Bacteria (…cont)  Some of the most deadly diseases and devastating epidemics in human history have been caused by bacteria, including:  Cholera  Diphtheria  Dysentery  Plague  Pneumonia  Tuberculosis  Typhoid  Typhus Infections Causative organism Brain (bacterial Streptococcus pneumoniae, Neisseria, meningitis) meningitides, Haemuphilus influenzae, Streptococcus agalictaiae, Listeria monocytogenes Ear (otitis media ) Streptococcus pneumoniae Pneumonia Commonly acquired - Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus. Atypical - Mycoplasma pneumoniae, Chlamydia pneumoniae, Legionella pneumophila Tuberculosis - Mycobacterium tuberculosis Infections Causative organism Upper respiratory Streptococcus pyogenes, tract infection Haemophilus influenzae Gastritis Helicobacter pylori Food poisoning Campylobacter jejuni, Salmonella, Shigella, Clostridium, Staphylococcus aureus, Escherichia coli Eye infections Staphylococcus aureus, Neisseria gonorrheae, Chlamydia trachoma Sinusitis Streptococcus pneumoniae, Haemophilus influenzae Multidrug-resistant microorganism include:  Methicillin-resistant staphylococcus aureus (MRSA) can cause a variety of problems ranging from skin infections and sepsis to pneumonia to bloodstream infections (septicaemia).  Vancomycin-resistant enterococci (VRE) 2. Virus  Invades host, attaches to a cell, enter and release genetic material (DNA or RNA).  This genetic material helps the virus multiply; takes control of the cell, reproduce more new virus which is then release and infect new cells.  Not all viruses destroy their host cell.  Sometimes lies dormant in a cell; and reactivate years later making the host ill e.g. varicella- zoster virus.  Viruses may target skin cells and cause warts. 2. Virus (…cont)  An individual may become infected by:  inhaling the virus  bitten by infected insects or animal  through sexual contact  Respiratory infections of the upper airways, nose and throat are the most common forms of viral infections.  Some antiviral medications may help, either reduce the virus' ability to reproduce, or boost the patient's immune system. 3. Fungi  Tiny primitive organisms feeding on living plants, animals and decaying organic material.  Reproduce by spores which people either inhale or pick up on their skin.  Infection caused by fungi is known as mycosis.  Systemic mycoses due to primary or opportunistic pathogens;  a primary pathogen causes disease because of its presence in a healthy human,  an opportunistic pathogen causes disease in a host with a weakened immune system. 3. Fungi  Patient at risk to develop fungal infection include:  On long-term strong antibiotics  HIV/AIDS  Receiving chemotherapy  Uncontrolled diabetes  Example of diseases cause by fungi are ringworm (tinea), candidiasis. 4. Protozoa  Single celled organisms.  Reproduce by binary fission.  Live in a wide variety of moist habitats including fresh water, marine environments and the soil.  Can be free-living or parasitic in nature.  Infections range from asymptomatic to life threatening, depending on the species and strain of the parasite and the resistance of the host. 4. Protozoa (…cont)  Transmission can occurs;  through a faecal-oral route (for e.g., contaminated food or water or person-to- person contact) - Entamoeba histolytica causes amoebiasis.  to other humans by an arthropod vector (for e.g., through the bite of a mosquito or sand fly)- Plasmodium (some of which cause malaria) 5. Helminth  Can be free-living or parasitic in nature.  They are large, multicellular organisms  E.g. Flukes (Trematodes)  Tapeworms (Cestodes)  Roundworms (Nematodes)  Transmitted from hand to mouth  Cause infection in the gastrointestinal tract Can be divided into two main group:  Endogenous  Exogenous From individual’s own body → own normal flora  Resident: ❑ Always present in the body ❑ Benefits (if they remain in the site with which they associated)  Prevent the overgrowth of harmful microorganisms by competing for attachment & nutrients.  Some synthesize vitamins that are absorbed as nutrients by the host (e.g. Vit K & B12).  Some produce substances that inhibit pathogenic species.  Benefits (if they remain in the site with which they associated)  Stimulate the development of certain tissues, e.g. colon and lymphatic tissues in gastrointestinal tract.  Stimulate production of cross-reactive antibodies.  If they turn up at a site with which they are not normally associated. E.g.; staphylococcus aureus is normal in upper respiratory tract but if goes to the lower tract will cause pneumonia  Transient flora ❑ Survive on skin less than 24 hours ❑ Easily removed with soap and water ❑ Acquired during contacts with contaminated areas mouth, nose, perineal area, genitals, anal area  Examples of normal Flora in human Area of body Commensal organism Mouth & Bacteria: Staphylococci, Streptococcus teeth mutans, Yeast: Candida Throat Bacteria: Streptococci pneumoniae, Neisseria species, Haemophilus influenzae Skin Bacteria: Staphylococci, Streptococcus, Cornynebacterium Bowel Bacteria: Escherichia coli, Enterobacteriacea, Enterococci, Clostridium species Vagina Bacteria: lactobacilli, Staphylococci (adult) Yeast: Candida  An individual’s immunity against own normal flora becomes compromised when there is:  Contamination during surgery  Malnutrition  Impairment of blood supply  Debilitating diseases such as AIDS, diabetes or any other accompanying infection  Caused by organism not normally present in the body but which have gained entrance from the environment  Source include: 1. Human ❑ From sexually transmitted organism: - treponema pallidum causes syphilis - N.gonorrhea causes gonorrheal infection ❑ Exposure to blood and other body fluids – by needle stick injuries, mucous membrane, and skin exposure - hepatitis B and C - human immunodeficiency virus (HIV) Gonorrheal infection to the baby … Source include 2. Animal/vector  Zika virus - spread to people through the bite of infected mosquitoes.  Rabies – spread through bite of infected dog or wild animal and broken skin causes acute encephalitis (inflammation of the brain)  Anthrax – spread through handling infected animals or other materials containing anthrax spores, eating infected meat or breathing in spores.  Avian influenza (bird flu)- through direct or close contact with infected poultry Rabies … Source include 2. Animal/vector  Salmonella bacteria – from animal product such as raw meat, unpasteurized milk, and raw eggs can cause food poisoning. … Source include 3. Water  Can be a major source of infection especially when in contact with sewage  Waterborne disease – transmitted by consumption of infected water  Common microorganism – protozoa and bacteria which can cause diarrhea … Source include 4. Food  May contaminated during processing, handling with contaminated hands or tools  Good environment for bacterial or any other pathogen to multiply and produce toxin  Bacteria cause food poisoning – salmonella, E. coli, campylobacter, listeria  Shigella can cause dysentry (severe diarrhea) 5. Environment include soil and air  Soil can be contaminated with human faeces that contain several pathogenic organism which have sporing capabilities enabling them to survive harsh environments such as:  Clostridium tetani – causes tetanus  Clostridium botulinum – causing food poisoning 5. Environment include soil and air  Air can be contaminated with organism shed from the skin or respiratory tract such as:  Meningococci  Measles  Haemophilus influenza  Mumps  Corynebacterium diphtheria which causes diphtheria What are the agent causing infections & give example?  Biological (bacteria, virus, fungi, parasites), The microorganism that only can grow and replicate in living cell is called Virus  The organisms that comes from own body is known as Endogenous  The organism that gain entrance from environment is known as Exogenous What is the agent causing infections that spread by contaminated food with human & animal feces?  Protozoa What is the agent causing infection that causes ringworm?  Fungi  1 2 6 3 5 4 What is the chain of infection?  It is a model used to understand the infection process  The information is needed to interrupt or prevent an epidemic  The spread of infectious disease follows a well- known sequence of events of six links  Each cycle of links represents step in transmission of infection  All the six elements need to be present and linked to each other in order for an infection to be able to spread  It is the microorganisms that can cause infection or disease  Infectious agent are: ❑ Bacteria 1 ❑ Viruses ❑ Fungi ❑ Parasites ❖ Protozoa ❖ Helminths  The place where organisms can lives and reproduce such as: 2 ❑ People ❑ Animals ❑ Inanimate objects ❑ environment  The route by which the infectious agent leaves one host and travel to another  Common route: 1. Skin & mucosa – when there is open 3 wound. A wound can be an entry point and portal of exit. ….Common route 2. Gastrointestinal tract –feces may transport the typhoid from infected person  Common route for bacteria or viruses to escape an infected host  Common infection – hepatitis A, salmonella species  Through: ❑ Mouth – saliva, vomitus ❑ Anus – Faeces, ostomies 3. Genitourinary tract – through urethral meatus, urinary diversion ….Common route 4. Respiratory tract  Released by nose or mouth through sneezing, coughing, breathing or talking  Common infectious disease- measles, mumps, pulmonary tuberculosis & influenza...Common route 5. Blood  Through: ❑ Open wound ❑ Needle puncture site ❑ Any disruption of intact skin or mucous membrane surface  Common infectious disease - Hepatitis B,C, HIV...Common route 6. Reproductive tract  Through: ❑ Vagina – vaginal discharge ❑ Urinary meatus – semen, urine  Common infectious disease – gonorrhea, syphilis, Herpes simplex, Hepatitis B  The way the microorganism is transported to a new host. Mode of transmission include;  Contact transmission – direct and indirect  Airborne transmission  Vehicle transmission  Vector transmission 4  1. Contact transmission includes: a. Direct b. indirect a. Direct contact transmission  Agents is transmitted by physical contact between two individuals – person to person contact, e.g.  Touching  Kissing,  Sexual intercourse  Droplets sprays a. Direct contact transmission e.g. … cont.  Touching an infected individual. Contaminated hands are one of the most common source of direct transmission  Kissing,  Sexual intercourse  Droplets sprays from sneezes, cough, spitting, singing  Mother to child during pregnancy, breast feeding or birth b. Indirect contact transmission  Involves inanimate objects called fomites that become contaminated by pathogens from an infected individual or reservoir;  Indirect source include:  Door knobs, handrails  Tables, beds, chairs  Washroom surfaces  Cups, dishes, cutlery, trays  Medical instruments  Pens, pencils, phones, office supplies 2. Airborne transmission  Generated through droplets in sneezing, coughing or talking  Droplets can also be generated during certain medical procedures, such as bronchoscopy  These droplets travel through the air and are inhaled through the respiratory system or absorbed through mucous membrane- eye, nose, or mouth  E.g. :Tuberculosis, Chickenpox, Measles 3. Vehicle-borne transmission  It is any substance act as transporter/medium to introduce an infectious agent into a susceptible host. Such medium include:  Water  Food  Air – pathogens are carried on droplets nuclei in dust for a distance greater than 1 meter 4. Vector-borne transmission  Vectors are living organisms that can transmit infectious diseases between humans or from animals to humans  Transmission occur by injecting salivary fluid during biting or depositing feces or other materials on the skin through bite wound or traumatized skin area  Examples of vector are flies, mites, fleas, tick  The most common vector for disease is the mosquito which can transmit malaria and dengue  Are the doorways or pathways into the host  Usually, microorganisms enter the body of the host by the same route they used to 5 leave the source.  Respiratory tract – by  Gastrointestinal tract- inhaling contaminated by ingesting particles or droplet contaminated food or water  Genitourinary-  Broken skin – bites, through contamination cuts, punctures, with infected vaginal abrasions and burns secretion or semen  Transplants – blood, organs  Transplacental – mother to unborn child  A susceptible host is any person who is at risk for infection  A compromised host is a person at increased risk and more likely 6 than others to get infection  Impairment of the body’s natural defenses and a number of other factors can affect susceptibility to infection Level of susceptibility depends upon:  Age ❑ The very young and the very old are usually more susceptible to diseases than older children and young adults ❑ Congenital infection during gestation ❑ Neonatal infection occur in 1st 28 days of life due to maybe mother’s vaginal flora, or direct/indirect transmission from hospital staff.  Gender ❑ Due to anatomical differences – urinary infection common in female than male  Stress ❑ Prolonged physical or emotional stress alters body’s hormonal balance and reducing resistance to disease ❑ Stress compromised people often suffer outbreaks of oral or genital herpes lesion  Occupation ❑ Workers who exposed to pathogenic sources such as needles, chemical agents, animals Drugs /chemical – impairs body defenses and ability to fight infection ❑ Smoking – predispose to respiratory infection ❑ Alcohol – in excess increase susceptibility ❑ Corticosteroid drugs – suppress inflammatory and immune responses ❑ Antibiotic drugs – destroy normal body flora ❑ Immunosuppressant drugs – suppress immune system  Nutritional imbalance – people who have poor nutritional habit are susceptible  Lifestyle – practices such as having multiple sex partner, lack of exercise slows circulation and lymph flow and decrease phagocytes  Immunization – certain people are not fully immunized  Chronic illness  Nonintact skin – wounds provide a portal or entry for microorganism  Breaking at least one link stop the spread of infectious disease  Focus on breaking the chain by applying proper infection control practices 1. The infectious agent  identify individuals who are infected or colonized & treat appropriately  Rapid accurate identification of the organism and treatment  Clean and disinfect used equipment and surfaces  Thorough hand hygiene 2. Reservoir  Proper hand washing - the single most effective and important way to prevent spread of microorganisms  Used of standard precaution - Personal protective equipment (PPE) such as gown, mask, eye shield, gloves  Good employee health- vaccination for employees  Appropriate isolation technique 2…Reservoir  Potential host and carriers must maintain good personal hygiene  Use of disinfectants for elimination of pathogen except spores, from inanimate objects  Sterilization to eliminate all microorganism including spores. Methods include: moist heat, steam, radiation, chemicals and ethylene oxide gas Moist heat sterilization Steam sterilization Chemical sterilization Ethylene gas oxide 3. Portal of exit  Thorough hand washing  Use of standard precaution – PPE such as gown, mask, eye shield, gloves  Control of secretion and excretion  Proper disposal of contaminated waste  Educate clients/others regarding measures to prevent transmission  Cover broken skin 4. Route of transmission  Thorough hand washing  Use of standard precaution – PPE such as gown, mask, eye shield, gloves  Sterilization and disinfectant of instruments  Airflow control (positive and negative pressure)  Hygienic food handling  Effective pest control  Proper disposal of contaminated waste  Appropriate isolation technique Waste disposal …4. Route of transmission  Transmission based precaution- ❑ Limit close contact (>3 feet) with coughing clients ❑ Cover mouth/nose when cough/sneeze with tissue ❑ Offer mask to coughing clients ❑ Isolation of infected person ❑ Not working when contagious 5. Mode of entry  Medical asepsis - including hand washing  Aseptic technique (is a set of specific practices and procedures performed under carefully controlled conditions with the goal of minimizing contamination by pathogens)  Thorough cleansing of skin before an invasive procedure  Cover broken skin  Use of standard precaution 6. Susceptible host  Assessing for degree of risk for infection  Recognizing high risk client  Treating underlying cause  Proper hand washing  Protective isolation if indicated  Promoting good body defenses by providing good nutrition, good hygiene adequate rest and sleep and reduce stress  Correct aseptic technique What is the chain of infection?  Model used to understand the infection process List the six links in the chain of infection  Infectious agent  Reservoir  Portal of exit  Mode of transmission  Portal of entry  Susceptible host What is the common infection that used gastrointestinal tract as a portal of exit?  Hepatitis A, salmonella species In what way can the respiratory tract spread infection?  Sneezing, coughing, breathing or talking The way by which microorganism is transported to a host is known as  Mode of transmission What is the most common source of direct transmission?  Contaminated hands The place where organisms can lives and reproduce is known as  Reservoir What are the examples of reservoir?  Infected wound  Human or animal waste  Animals and insect  Contaminated food and water  Person with infection What is the portal exit?  The route where the infectious agent leaves one host and travel to another How to protect yourself from direct projection of droplet?  Stand within 3 feet of each other, Who is the susceptible host?  Any person who is at risk for infection What is the most effective and important method to prevent spread of microorganisms?  Handwashing Total elimination of all microorganism including spores can be achieved by  Sterilization  An elderly patient, hospitalized with a gastrointestinal disorder, was on bed rest and required assistance for activities of daily living.  The patient had frequent uncontrolled diarrhea stools and the nurse provided excellent care to maintain cleanliness and comfort.  After cleaning the patient and changing the bed linen, the nurse immediately went to a second patient to empty his urine bag.(The second patient had a Foley catheter).  The nurse’s hands were not washed before assisting the second patient.  You are required to relate the scenario with the chain of infection  How to break the chain  Infectious Agent Escherichia coli  Reservoir Large intestine: E. coli, bacteria in the large intestine of humans  Portal of exit E. coli exited the body in feces  Mode of transmission The nurse removed the contaminated linen from the bed. The E. coli organism contaminated the hands of the nurse who then provided care to another patient  Portal of Entry The second patient receiving care had a Foley catheter. The nurse manipulated the tubing attached to the catheter. The E. coli organism on the nurse’s hands contaminated the catheter tubing and ascended to the patient’s meatus and then into the urinary bladder  Susceptible host The second patient with a Foley catheter  Identification The nurse realize that her hand was contaminated – after provide care for the first patient.  Medical asepsis Remove gloves or/and apron. Wash and dry the hands.  Standard precaution Discard the contaminated linen according to hospital protocol 1. Define chain of infection 2. List six process that are involved chain of infection in sequential order 3. List three (3) methods of how pathogen is transmitted 4. Define susceptible host 5. List 8 factors that may contribute to a person’s susceptibility to an infection