c1-INFECTION CONTROL.docx

INFECTION CONTROL ================= Cycle of infection ------------------ Transmitting a pathogen requires connecting the six links in the chain or cycle of infection. - Infectious agent - Reservoir - Portal of exit - Mode of transmission - Portal of entry - Susceptible host The...

INFECTION CONTROL ================= Cycle of infection ------------------ Transmitting a pathogen requires connecting the six links in the chain or cycle of infection. - Infectious agent - Reservoir - Portal of exit - Mode of transmission - Portal of entry - Susceptible host The cycle begins with a pathogen or infectious agent that is capable of causing disease (virus, bacterium, fungus, protozoan delivery). An environment that supports the survival of these pathogens is a reservoir. In a clinical setting, the reservoir is often the patient, but it can also be an object such as a piece of medical equipment. The human body makes an ideal reservoir for microbial growth because of the presence of nutrients, moisture, and an ideal temperature and pH. The portal of exit is the passageway the pathogen uses to exit the reservoir. Portals of exit can occur through the respiratory, gastrointestinal, or urinary tract; mucous membranes; or nonintact skin. Effective infection control means breaking this chain, thus preventing the continuation of the cycle. Means of transmission --------------------- Once the pathogen exits the reservoir, a mode of transmission is necessary for the cycle to continue. Direct transmission takes place when there is contact with the infected person or body fluid carrying the pathogen. Indirect transmission occurs when there is an intermediate step between the portal of exit and the portal of entry. Fomites (such as medical equipment and supplies) and vectors (such as insects) play a role in indirect transmission. Other objects that can harbor infectious agents and are often overlooked are telephones, doorknobs, computer keyboards, faucets, pens, books, eyeglasses, and laboratory coats. Once the pathogen has a means of transmission, it will need a new portal of entry to continue the infectious cycle. Pathogens often enter a host via an open wound, mouth, nose, eye, intestines, urinary tract, or reproductive system. The final step in the cycle is the presence of a susceptible host. Several variables make the human body-especially that of an immunocompromised patient-the ideal susceptible host. If one of the links in the infection cycle is broken, the transmission stops. All health care professionals must help break this cycle. The main way to break the chain of infection is through effective hand hygiene. Each pathogen has a specific route or routes by which transmission can occur. Clinical facilities issue specific isolation practices according to the pathogen (once laboratory testing has identified it). - **Standard precautions** apply to every patient. This includes using personal protective equipment (such as gloves) when handling body fluids, nonintact skin, or mucous membranes; practicing meticulous hand hygiene before and after contact with each patient; and safely disposing of used equipment, needles, and other sharps. - **Airborne precautions** are required for patients who have infections that spread via droplets that are smaller than 5 microns in diameter (varicella, tuberculosis, measles). This means wearing respiratory protection (mask, N95 respirator) when interacting with these patients. - **Droplet precautions** are required for patients who have infections that spread via droplets that are larger than 5 microns in diameter, including rubella, meningitis, and some respiratory infections. This means wearing a mask when interacting with these patients. - **Contact precautions** are required for patients who have infections that spread via direct contact or contact with the environment (herpes simplex, wound infections, some bacterial infections, scabies). This means wearing gloves and gowns when interacting with these patients. Stages of infection ------------------- When a person has an injury or exposure to a pathogen, the body reacts by activating the inflammatory response. This is a series of protective mechanisms that defend the body against the invasion. When there is inflammation, classic symptoms appear: erythema, edema, pain, and heat. When the pathogens invade, they damage cells at the site of invasion. The first thing the body does in response is send specific mediators of inflammation to the site: histamine, kinins, and prostaglandins. These substances cause specific actions that bring white blood cells (WBCs) to the infected site. In a predictable manner, blood vessels at the site dilate, and that causes the erythema and heat. The walls of those blood vessels become more permeable so that the WBCs can get to the site and form a type of capsule around it to protect the surrounding areas from the invasion. Plasma from the blood also enters the site, which causes edema. Edema exerts pressure on the nerves in the area, which causes pain. The blood brings clotting factors to stop any bleeding and other proteins to help repair the damaged area by replacing the injured cells. Next, the action of chemotaxis brings even more WBCs to the site to engage in phagocytosis, which is somewhat like eating and digesting and thus destroying the pathogens and the cells they damaged. The containment of these materials plus WBCs creates the substance that often appears with an infection, called pus. Several scenarios are possible following the inflammatory response. The infection can heal locally, and the inflammatory response has done its job. If the invasion is too strong for containment at the local level, the infection can spread to the lymph nodes, causing an increase in WBCs and lymphadenopathy. The worst scenario is that the infection spreads to the bloodstream, causing an infection of one or more systems, leading to septicemia. This can be fatal without the proper medical treatment. For a bacterial infection, that means antibiotics will be included in the treatment plan. Infections can be one of four distinct types: acute, chronic, latent, or opportunistic. - With an acute infection, symptoms appear suddenly, beginning gradually with initial cell damage and worsening quickly. With a well-functioning immune system, and sometimes medical treatment, the body recovers within a few weeks. The common cold is an example of an acute infection. - A chronic infection lingers, sometimes forever. Although symptoms might not last for long periods of time, the person can transmit it to others. Hepatitis B, a type of infection of the liver, is an example of a chronic infection. - With latent infections, the person has periods of remission and relapse. An example of a latent infection is herpes simplex, which manifest as a recurrent cold sore on the lip. - With opportunistic infections, the person has a weak immune system. Micro-organisms that might not easily cause disease in a person who has a fully functional immune system can result in serious infections. Oral candidiasis is an example of an opportunistic disease that is relatively common with patients who have AIDS. Medical and surgical asepsis ---------------------------- Medical asepsis consists of removing micro-organisms after they leave the body. The goal of medical asepsis is to reduce the number of micro-organisms, prohibit growth, and prevent transmission. Hand hygiene is an essential medical aseptic technique. This type of asepsis does not eliminate pathogens, but it greatly reduces their numbers and ability to multiply and cause infections. Phlebotomists use medical aseptic technique daily. Washing or sanitizing hands prior to and after each patient encounter prevents the spread of infection to protect both the patient and phlebotomist. Warm water and friction are the most important components of handwashing. Wash hands for a minimum of 20 seconds, rinse with fingers pointed downward, and turn the faucet off with a paper towel for an effective medical aseptic handwashing. Alcohol-based rubs are acceptable for rapid sanitation if there is no obvious soil on the skin and handwashing sinks are not readily available. Also make sure the work space is clean and use gloves when there is any possibility of contact with body fluids. Clean and disinfect supplies to prevent the spread of micro-organisms. Surgical asepsis is mandatory for invasive procedures and when there is a penetration of the patient\'s skin or mucous membranes. The goal is to eliminate micro-organisms and prevent them from entering the body. Surgical asepsis involves sterile gloves, supplies, and equipment; gowns; and drapes. Antiseptic skin preparation is mandatory with surgical aseptic technique prior to puncturing a patient\'s skin. Phlebotomists do not typically use surgical asepsis but need to know when to use medical vs. surgical aseptic techniques. There are also several actions phlebotomists can take to reduce the chances of pathogen transmission. Breaking the cycle of infection can take place with the simple act of covering the nose and mouth during a sneeze or avoiding patient encounters when the phlebotomist has a cold or other illness. Cough etiquette --------------- The Centers for Disease Control and Prevention recommends respiratory and cough etiquette for reducing the spread of diseases that spread via airborne and droplet transmission. The basics are as follows: - Cover the mouth and nose with a tissue when coughing or sneezing. - Use facial tissues to contain respiratory secretions. Use the nearest waste receptacle to dispose of tissues after use. - Perform hand hygiene after contact with respiratory secretions and contaminated objects or materials. - Offer masks to anyone who is coughing or sneezing. - Keep anyone who is coughing or sneezing 0.9 m (3 feet) away from others.