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There are various pathogens omnipresent around us. But we often ignore the presence of the pathogen around us which in case of lack of care, get a chance to induct the disease inside our body. Most people are unconscious about their health due to hectic life schedules or due to a lack of awareness about their eating behavior and the type of food. They do not know which food contains which nutrients and in how much amount they need to intake to have a balanced diet. This optimization of diet is somewhere missing in today’s scenario. A majority of the people do not know the fact that food itself is medicine and medicine itself is food depending on the amount it is taken. Secondly, people underestimate their bodily requirements with age. With age, there is always a decline in the bodily requirements of hunger and thirst with respect to both the internal world and external world. The most important factor that increases the risk of any kind of disease is the lack of immunity which is more prevalent in people of the older age group. If we look and inquire about health from different people, the definition of health is different for everyone due to different occupations and different perceptions of health which they have due to experience factors. Although WHO has given a standard definition of health, the definition of health has more angles to look into before defining it. According to me as a healthcare person, Health is just a combating mechanism at right time with strict observation of the body in response to internal stimuli or external stimuli demonstrating a sense of disturbance.
Role of Immunity:-
We have billions of cells in our body that perform different functions either individually or in a cluster to execute a particular function. We have blood cells that are mobile in nature floating in blood plasma. If we segregate the blood cells, we have RBC, WBC, and blood platelets. When it comes to RBC, its primary function is to import essential nutrients and oxygen to all the cells and to export all toxic substances outside the cell so as to keep the body cells healthy. When it comes to platelets, its main function is related to blood clotting in case of injury occurrence either inside or outside the body. But when it comes to WBC, the entire immune mechanism revolves around it and which is a major cell that fights against a foreign antigen. If we further classify WBC, we have neutrophils, basophils, eosinophils, lymphocytes,s, and monocyte. As every cell contains many receptors which serve as a different function for maintaining the viability of the cell. This classification is also done on the basis of proteins called a receptor, present on the cell membrane of different kinds of WBC and which has an affinity to bind with ligands that best fit the receptor. External receptors serve as a sensor in monitoring the sign of danger, infection, or abnormal cell death. Some receptors also float inside the cell in the cytoplasm particularly to monitor the environment inside the cell. The default ultimate outcome or setting of every defense mechanism is full protection against pathogens. (1)
Example: Suppose a virus-infected person comes in contact with another healthy person, assuming that infection proceeds with direct contact. The healthy person now acquires it. The virus will attach to the receptor present on the cell membrane of the host cell which in this case is a healthy person. Slowly, the capsomere of the viral capsid undergoes conformational changes in order to enter inside the cell. There are two pathways available for the virus to enter into the cell which include endocytic and non-endocytic pathways. In the endocytic pathway, a clathrin protein present on the cell membrane of the host forms a vesicle or pit around the virus and then endocytosis of the virus happens. In the non-endocytic pathway, the virus can directly enter the cell by the fusion of its envelope with cell membrane of the host at neutral pH and delivering its nucleic acid inside the cell of the host. This entry protein as well as the nucleic acid of the virus triggers the immune response inside the cell. The nucleic acid binds with the receptor of the cytoplasm to penetrate inside the nucleus of the cell for replication of nucleic acid and viral envelope protein so as to assemble into multiple daughter viruses until the host cell gets bursts. Once this binding happens, cell surface starts releasing cytokines to stimulate cell signaling among nearby healthy cells to indicate infection is there. This signaling gathers immune cells particularly neutrophils and macrophages at the site of infection which then secrete highly destructive substances containing enzymes and reactive chemicals. These substances then destroy and kill the pathogen and make the dead pathogen and dead damaged cells to be engulfed by phagocytosis. If the infection is not handled properly by neutrophils and macrophages then lymphocytes come into the picture which works on adaptation and memory of infection. Lymphocytes try to generate a specific response through the release of different cytokines by reading the environment through its receptor present on the external surface of it. The activation of the receptor then causes gene switching which led to some genes encoded through DNA to on mode and some genes to off mode. This on and off regulation of genes is important to synthesize specific cytokines to specific infections by creating a backup memory for the particular infection. But in the case of the virus, it is difficult to predict its surface protein or entry protein because each daughter virus synthesized inside the cell is different in terms of its outer surface protein which creates difficulty in killing the virus. The chemicals which were used to kill the virus previously inside the body by neutrophils and macrophage at first sight now does not work and this time resistance factor triggers in a virus which makes it more powerful. Further, as the rate of replication of the virus inside the cell increases along with viral circulation throughout the body it triggers a severe antigen-antibody reaction which causes fever which proceeds along with the increase in death of killer cells (neutrophils and macrophages). If at that time, immunity is compromised then the person may die due to other superficial infections if he or she acquires. (1) (2)
Types of immunity:-
The immune system of our body has two components: innate and adaptive components. The innate or native immunity of our body responds to the foreign antigen either by developing inflammation or phagocytosis. The innate component of our immunity is semi-specific. The adaptive component of immunity is highly specific which means inflammatory response developed as a result of antigen-specific lymphocytes fighting with antigen contribute to the development of immunological memory. The adaptive or acquired immunity involves both humoral and cell-mediated immunity components. Acquired immunity can be acquired by either natural way or artificial ways. Natural ways can be further classified into active and passive immunity. Inactive natural acquired immunity when a person is exposed to a pathogen, B lymphocyte cells of our body start forming antibodies inside the body and store it for future response to avoid second-time infection. In passive natural acquired immunity, the antibodies like IgG are transferred to the fetus through the placenta via the FcRn receptor on placental cells and some antibodies like IgA passes during breastfeeding to the newborn infants for fighting against bacterial infection until he or she starts developing his or her antibody. Inactive acquired artificial immunity, the use of vaccines that are attenuated antigen given intramuscularly or intravenously to generate antibodies in response to it. In passive acquired artificial immunity, the use of human or animal blood plasma containing different immunoglobulin protein is administered in the form of monoclonal antibody to fight against infection. Sometimes in the case of passive acquired artificial immunity, there is the transfer of activated T cells or sensitized T cells (after getting sensitized in presence of antigen) from one person to another is done where this T cell is responsible for producing antibodies by activating B cells of the recipient as an immunity booster. But it is difficult to find the T cells of the donor as well as recipient to be the same. In many cases, graft versus host disease occurs in the recipient if T cells are incompatible with the recipient. (3)
Challenges in dealing with infection:
In our environment, there are various kinds of disease-causing microbes like bacteria, viruses, fungi, and protozoa. And the drugs are also specific for killing a particular microbe like antibacterial for bacterial killing. Similarly, an antifungal for fungal killing, an antiviral for viral killing, and antiprotozoal for protozoal killing. But all these drugs kill a particular organism by a common mechanism that is constant inside the body. And if we use the same drug or medication again and again for killing a particular microbe, microbes undergo internal modification in its structure or functionality in such a way that if we use the same drug further to deal with it delivers no impact on it. With the advent of the drug resistance factors, it becomes difficult to find again a new drug for the same organism because drug discovery and clinical testing of the novel drugs take a long time and huge money before coming into the market. Some people use antibiotics more often without knowing the actual organism causing it and abuse the antibiotics in dealing with infection for more than 7 days. With the continuous use inside the body, microbial adaptability increases to that particular drug. Sometimes, microbial resistance also happens in which microbes are resistant to the entire class of that drug as well as the novel drugs discovered whose structure resembles to some extent with previous drugs used. In the case of the virus, where genetic mutation happens inside the virus every time due to the use of antiviral drugs is the most challenging and never-ending war to be fought by pharmaceutical manufacturing companies every time.
Antigen, Antibody, and antigen-antibody reaction:
Antigens are a molecule on the surface of which epitope or antigenic determinant is present with which it gets recognized by B cells and T cells for the release of specific antibodies. The released antibody (immunoglobulin:-IgA (dimer: 2 Y-shaped unit attached to each other) , IgG (monomer), IgM (Pentamer) , IgE (monomer), IgD (monomer)) which is a Y shaped protein with two Y-tip regions having antigen-binding site binds with an epitope of antigen to form an antigen-antibody complex. This complex is then transported inside the cellular system to be destroyed or deactivated by cells. The process of interaction between antigen and antibody is called agglutination reaction. It is not always necessary that an antibody has only one antigen-binding site. There may be more than one because the definition of antibody states that antibody is made up of four polypeptide chains. Each polypeptide chain has 110 amino acids and all four chains are connected to each other by a disulfide bond. Out of four chains, two chains are light chains and two chains are heavy chains. In every chain, there is a series of domains present. In the case of each light chain, there is one variable domain and one constant domain. In the case of a heavy chain, there is one variable domain and three to four constant domains. One variable domain of light chain and one variable domain of heavy chain forms the fragment antigen-binding (Fab) site at the Y tip. The gap between constant domains of two parallel heavy chains serves as a hinge and provides flexibility to bind with effector cells. Here the effector cells are natural killer cells and macrophages. Natural killer cells and macrophages have fragment crystallization receptor (FcR) on their surface by which it interacts with the fragment crystallization (Fc) region of the antibody. (4) (5) (6)
Legal aspects of infection prevention and control:
IPC as per legal angle is a practical approach rather than theoretical, which is solely based on the evidence so as to protect healthcare workers and patients from avoidable infections. To achieve quality health care delivery to each of the patients and to ensure the safety of each patient in a healthcare facility requires constant action at all levels of the health care system from policymakers, facility managers, healthcare workers, and that person who access healthcare services. An effective IPC focuses on every aspect of the healthcare system be it hand hygiene, antimicrobial resistance, surgical site infections, injection safety, hospital operation during emergency and outside emergencies. IPC program came into existence to provide quality healthcare and safety because, in every healthcare facility, there are many patients who used to visit daily for some of the other reasons. It is the duty of the hospital workers to prevent infection from being transmitted to healthy patients in every healthcare encounter. No country, no single healthcare facility, or even the highly advanced and sophisticated healthcare system can claim to be free from healthcare-associated infections. That’s why WHO 100 core healthcare indicator list contains IPC programs. (7)
General methods to prevent infection and to control infection:
Hand hygiene is the basic method and inexpensive to prevent infection in which hands are washed using water or alcohol to kill germs present on hands. When water is used, 7 steps are there and when alcohol is used, 5 steps are there as per WHO standard. In America, the American Nurse Association and American Association of Nurse Anesthesiology set some checkpoints to check nurse hand hygiene practice which includes: before checking patient, before putting on PPE and after putting off PPE, before doing procedures, after contamination from a foreign substance, bodily fluids, contact with patient skin and surroundings, and after using the restroom. Nurses and doctors have to wash their hands using a hand sanitizer dispenser containing alcohol, sodium hypochlorite or hydrogen peroxide disinfectant solution so as to ensure proper sanitation inside the healthcare facility. And after washing, drying of hands has to be done using paper towels instead of using warm air hand dryers or modern jet air dryers to prevent the spread of infection in nearby areas of healthcare facilities. (8) (9)
Cleaning, disinfection, and sterilization:
Cleaning is the method of removal of microorganisms from the surface of medical equipment and medical instruments using water or chemicals via rinsing or wiping. Cleaning eliminates microbes substantially. After cleaning the equipment we need to be aware that it should not be touched without clean hands. (9)
Disinfection is achieved by using disinfectant solutions that kill the microbes on the surface of equipment but cannot kill the bacterial endospores. For disinfection, ultraviolet light is also used to kill the bacteria particularly clostridium difficile in the room of infected person after discharge.
Sterilization is the most efficient method because it removes most of the microbes including bacterial endospores. Sterilization is done in four ways which include: using the autoclaving technique, using dry heat, using chemical sterilants such as glutaraldehyde and formaldehyde solutions, and using ionizing radiation. (9)
In autoclaving, high-pressure steam is used to sterilize the equipment and the equipment is ensured to receive steam on its surface for achieving sterilization. Autoclaving is done at a temperature of 121 degrees Celsius and 2 atm pressure for 15-20 minutes usually. But the condition is variable in autoclaving depending on the device which needs sterilization. In the case of rubber items, usual conditions are used. But in the case of wrapped items, 134 degrees Celsius and 310 kPa for 7 minutes are used. Time is counted once the temperature is reached. In steam-based sterilization, four factors need to be monitored carefully to have effective sterilization which includes: adequate contact, high temperature, correct time, and sufficient moisture. (9)
In Dry heat sterilization method, the oven is used to sterilize metal or glass at a temperature of 160-170 degrees Celsius for one to two hours. The substance which cannot melt at that temperature can be sterilized by this method.
Chemical sterilization involves the use of formaldehyde or glutaraldehyde solution. Different chemicals Hydrogen peroxide or peroxyacetic acid is also used sometimes. 8% formaldehyde solution is prepared in which medical items are kept for soaking for 24 hours or more to achieve sterilization. In some cases 2-4% concentrations of chemicals are used for soaking the item to achieve sterilization. The concentration of chemicals depends on the chemical potency to kill microbes. As formaldehyde is a potential carcinogen and can cause skin, eyes, and respiratory tract irritation, it is used very carefully. (9)
Ionizing radiation is used in cases where all other methods do not apply and are less used because of risks associated with this method. (9)
Personal protective equipment:
PPE is basically a special type of clothing that serves as a physical barrier between the potential infectious agent and the healthcare worker who actually wore this clothing. PPE components include gloves, CPR mask, respirator (N95, FFP2, and FFP3), particulate respirator, gowns, bonnets, shoe covers, face shields goggles, surgical masks, shoe covers, and respirators. How these components are used and which components to use at what time is decided by regulations or infection control protocol of the health care facility. In fact, protocols are made on the basis of the mechanism of transmission of the pathogen. There is also a protocol for wearing this clothing like which things to put on first and last, which things to take off first and last to prevent transmission of infection. (9)
Metal-based floor surface has the potential to kill microbes. In metal particularly, copper-based alloys like brass, bronze, cupronickel, and other alloys if installed in a healthcare facility can kill the microbe attached to the metallic surfaces in less than 2 hours. (9)
Different vaccines for different diseases are already available in the public domain for protection against the disease. Examples are the DPT vaccine for diphtheria, whooping cough, and tetanus. Hepatitis B vaccine for hepatitis B virus. Polio vaccine, Mumps vaccine, Measles vaccine, influenza vaccine, and all others. The vaccine is composed of just a small part of pathogen or weak pathogen administered to generate specific antibodies in response to pathogen detection in the form of memory cells. (9)
Surveillance for infection:
The Centre for Disease Control and Prevention (CDC) is always monitoring the infection through data assessment in case of outbreak of any disease which is already existing or new disease. Data entry and monitoring are done through software that feeds data and determines the infection rate using statistical methods. They check what causes the disease, how the pathogen is transmitted in the population, what can be done to have protection against it, what are the risk factors associated with disease, which population group the disease is targeting, etc. (9)
The basic method of any disease prevention is isolation and quarantine. In isolation, a diseased person is isolated till the person recovers from it. In quarantine, healthy people who are suspected to have close contact with an infected person are quarantined until the incubation period for that particular disease is over. (9)
In many countries, certified Infection Control Practitioner is there who are expert in the field of infection control and is trusted. They help in controlling the spread of infection. (9)
Generally, infection prevention and control is not only the responsibility of all healthcare workers but also the general public so as to keep themselves neat and clean from the body part aspect as well as from the aspect of the surrounding. If every person can take a true pledge that he or she will keep his or her body as well as surrounding clean and will always remain aware of his/her hygiene along with close monitoring of his/her body’s internal environment then there is a chance that our society will be disease-free. A basic philosophical saying is that a healthy mind dwells in a healthy body. In today’s scenario, even the billionaire, the one who has unlimited money and wants more money, runs after achieving good sustainable health in the end. The priority of health is sinking at the bottom nowadays due to overpopulation and an increase in competition. A recommendation from my side is that make health your topmost priority in every condition. After all, health is wealth.
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Author: Shubham Kumar, ACS Institute
Editor: Kanishka Vaish, Senior Editor, LexLife India.