The ongoing spread of tuberculosis is worldwide and still seen present day. Efforts are directed at examining the respiratory system functions of physiology patterns before pathogenic Mycobacterium tuberculosis infection occurs. The respiratory system is responsible for oxygen exchange and ensuring the body excretes carbon dioxide while taking in oxygen. Tuberculosis can affect the normal homeostasis pattern and cause signs and symptoms of respiratory illness. Understanding of the host immune response, with an emphasis of the roles of fights against engendering protective immunity, can help differentiate a normal respiratory system from an infected respiratory system. Tuberculosis addresses the ability of the bacteria to survive within the respiratory system and develop resistance to multiple antibiotic measures. Resistance to antibiotics requires more diagnostic testing and testing to confirm the presence of the contagious disease tuberculosis. Increased attention of this disease and the integration of studies have allowed for a greater understanding of tuberculosis and the steps necessary to control this infection. Continued research is being done to elaborate on this issue and to develop prevention mechanisms.
Keywords: Tuberculosis, respiratory system, antibiotic resistance
Tuberculosis is a disease that has occurred in many countries for a very long time. Although it is not as common today, tuberculosis is still present although it may not be visible. Depending on latent or active tuberculosis, both mainly affect the respiratory system, more specifically the lungs. The normal physiology of the respiratory system is affected and can result in the human body compensating and visualizing signs and symptoms that may require future testing to confirm the disease. Research is being conducted to eliminate this disease and preventive measures are being conducted to prevent the spread of tuberculosis. In order to understand how to reach preventive measures and research, the respiratory system healthy anatomy must be understood.
The human respiratory system consists of the organs responsible for taking in oxygen and expelling carbon dioxide. The primary organs include the lungs, which carry out this exchange of gases and is the main organ affected with tuberculosis. The lungs are located below the rib cage and above the diaphragm (Marinho, 2019). Another important organ in the respiratory system is the trachea, which conducts inhaled air into the lungs through the bronchi. The bronchi are divided into tiny branches known as bronchioles before becoming clusters of microscopic air sacs, and alveoli (Marinho, 2019). In the alveoli, oxygen from the air gets absorbed into the blood. Carbon dioxide, the end waste product, travels from the blood to the alveoli, where it can be exhaled (Marinho, 2019). The lungs are covered with a thin tissue layer called known as the pleura. This layer of fluid acts as a lubricant allowing the lungs to slide smoothly as they expand and contract with each breath (Marinho, 2019). The major function of the lungs is to perform gas exchange, which requires blood from pulmonary circulation. This blood supply contains deoxygenated blood and travels to the lungs where erythrocytes, pick up oxygen to be transported to tissues throughout the body( May 2019). The pulmonary artery carries deoxygenated arterial blood to the alveoli. Normal respiratory breathing occurs by the dilation and constriction of the airway through the parasympathetic and sympathetic nervous systems (May 2019). The parasympathetic system causes bronchoconstriction, while the sympathetic nervous system stimulates bronchodilation (May 2019). During this process, red blood cells collect oxygen from the lungs and carry it to the parts of the body where it is needed (May 2019). During the process, the red blood cells collect the carbon dioxide and transport it back to the lungs, where it leaves the body when a person exhales. A healthy functioning respiratory system is vital to survival which requires the conduction of effective homeostasis.
During a normal homeostasis pattern, when a human breathes, air enters through the mouth and nose, travels down the throat, into the trachea and lungs, through the right and left main bronchi, into the smaller bronchi airways and into the alveoli (May, 2019). Each alveolus is covered by capillaries. These capillaries are the site for an exchange of oxygen and carbon dioxide (May, 2019). The heart sends deoxygenated blood to the lungs. As the blood passes through the tiny, thin-walled capillaries it receives oxygen from the alveoli, next, returns carbon dioxide through the thin walls to the alveoli. The oxygen-rich blood from the lungs is sent back to the heart, where it is pumped through the entire body (May 2019). The carbon dioxide is breathed out of the lungs and alveoli through the mouth and nose. The pressure differs allowing for oxygen and carbon dioxide to diffuse in and out of the blood (May, 2019). Gas exchange in the respiratory system helps the body maintain acid balance if the pH of the blood becomes too acidic, the breathing rate increases. This reduces the amount of carbon dioxide in the blood, so the pH increases toward normal. Blood that is too alkaline will slow the breathing rate to increase the amount of carbon dioxide and lower the pH. Normal breathing patterns can be disrupted by certain conditions, such as tuberculosis.
Tuberculosis is a disease caused by the bacteria Mycobacterium tuberculosis that spreads from person to person through microscopic droplets released into the air (Schezle, 2019). This can occur by a person with the untreated, active form of tuberculosis coughs, speaks, sneezes, spits, laughs or sings (Schezle, 2019). This is a potentially serious infectious disease that mainly affects the lungs first. Tuberculosis is commonly presented as a disease of the lungs; however, the infection can spread via blood from the lungs to all organs in the body. Besides the lungs, tuberculosis can be in the pleura, bones, urinary tract, sexual organs, intestines and skin (Rathawati, 2019). Latent tuberculosis is tuberculosis infection, but the bacteria in the body remain in an inactive dormant state and cause no symptoms(Schezle, 2019). It can turn into active tuberculosis; this condition has visible sickness and can spread to others. It can occur in the first few weeks after infection with Mycobacterium tuberculosis bacteria, or it might occur years later once the immune system becomes weak (Schezle, 2019). A nodule forms in the lung, usually in the outer portion of the upper lobes. The body’s defenses stop the infection from expanding and the bacteria is trapped inside the nodule and is inactive until the immune system becomes weak (Schezle, 2019). As tuberculosis progresses, it can cause damage to the surrounding lung tissue and progress into the blood vessels, future spreading to any part of the body (Rathawati, 2019). A person with active tuberculosis may show signs and symptoms of this disease.
Signs and Symptoms
Abnormalities in the body may be seen as a result of the body trying to compensate and remain the normal homeostasis level. This can lead to abnormal actions by the body as it compensates for the improper work of the lungs. Coughing lasts three or more weeks, due to the ability of the lungs trying to regulate oxygen and carbon dioxide levels (Marinho, 2019). Coughing is important for expelling mucus and clearing the airways. Coughing up blood and mucus from deep inside the lungs, this mucus usually traps bacteria, and viruses, before progressing further into the body, during tuberculosis the mucus is infected and needs a way out (Marinho, 2019). Chest pain, pain with breathing or coughing, unintentional weight loss, fatigue, fever as the body fights infection, night sweats, chills, and loss of appetite can all be signs and symptoms present with tuberculosis due to the body out of normal homeostasis pattern, trying to compensate (Schezle, 2019). The pain is felt due to bacteria damaging the lungs, making them unable to bring enough oxygen to the blood (Schezle, 2019). When the body doesn’t get enough oxygen, it cannot function properly. As the infection progresses, people feel tired and generally unwell, and weight loss may be due to loss of appetite (Schezle, 2019). These signs and symptoms represent the respiratory system is not working to maintain homeostasis.
Failure of homeostasis
Within the respiratory system, there are numerous interaction points for airborne Mycobacterium tuberculosis droplets to attach too and disrupt the normal homeostasis function. Lungs are directly exposed to the air and enable gas exchange. The lungs are constantly invaded by microbes from both outside and inside as a prototypic host-adapted airborne pathogen, Mycobacterium tuberculosis traverses the lung and has several spots that it must overcome to cause infection (Marinho, 2019). Once inhaled, the infectious droplets settle throughout the airways. The initial defense is the bacilli trapped in the upper parts of the airways by mucus produced catching these foreign substances, and the cilia on the surface remove these foreign pathogens (Marinho, 2019). Bacteria in droplets bypass the system and reach the alveoli are quickly surrounded and engulfed by alveolar macrophages. These macrophages, the next line of host defense, are part of the innate immune system and provide an opportunity for the body to destroy the invading mycobacteria and prevent infection (May 2019). Macrophages are cells that fight many pathogens without previous exposure to the pathogen (May 2019). The subsequent phagocytosis by macrophages initiates a cascade of events that results in either successful control of the infection, followed by latent tuberculosis, or progression to active disease. The outcome is essentially determined by the quality of the host defenses and the balance that occurs between host defenses and the invading mycobacteria.
For systems with intact cell-mediated immunity, the next defensive step is the formation of granulomas around the Mycobacterium tuberculosis organisms. These nodular-type lesions form from an accumulation of activated T lymphocytes and macrophages, which creates a micro-environment that limits replication and the spread of the mycobacteria(May 2019). Mycobacterium tuberculosis organisms change to enhance survival (Marinho, 2019). This condition restricts further growth and establishes the dormant stage. An adequate immune system generally undergoes fibrosis and calcification, successfully controlling the infection so that the bacilli are contained and remain dormant (May 2019). Less effective immune systems progress to active tuberculosis. In patients infected with Mycobacterium tuberculosis, droplets can be coughed up from the bronchus and spread the infection.
There are two main types of tests that are used to detect tuberculosis bacteria in the body, the tuberculosis skin test (TST) and tuberculosis blood tests. A positive tuberculosis skin test or tuberculosis blood test only tells that a person has been infected with bacteria (Schezle, 2019 ). It does not tell whether the person has latent or has progressed to active. Additional tests such as a chest x-ray and a sample of sputum, are needed to confirm the tuberculosis disease (Rathawati, 2019). Healthcare workers need to ask about the patient’s history of exposure, infection, or disease. It is also an important factor to consider demographic factors, country of origin, age, ethnic or racial group, and occupation, which may increase the patient’s risk for exposure to tuberculosis or to drug-resistant (Wilson, 2018). Those with diabetes, cancer, on steroids, HIV/AIDS, and older adults are at risk for developing tuberculosis and conditions need to be closely monitored (Wilson, 2018). A physical exam can provide valuable information about the patient’s overall condition and other factors that may affect how TB is treated. The Mantoux tuberculin skin test (TST) or the TB blood test can be used to test for Mycobacterium tuberculosis infection (Schezle, 2019). This is done is by injecting a small amount of fluid of tuberculin into the skin of the lower part of the forearm (Schezle, 2019). The test is read within 48 to 72 hours after, observing for a reaction on the arm that may appear as a firm red bump or nodule in the area of the test (Schezle, 2019). The tuberculosis blood test measures the patient’s immune system reaction to Mycobacterium tuberculosis. Future testing such as a posterior-anterior chest radiograph is used to detect chest abnormalities and may be ordered after the initial test to confirm and look for lesions that may appear anywhere in the lungs (Rathawati, 2019). Any abnormalities may suggest tuberculosis. A chest radiograph may be used to rule out the possibility of tuberculosis in a person who has had a positive reaction to a TST or TB blood test and no symptoms of disease (Rathawati, 2019). The presence of acid-fast-bacilli (AFB) on a sputum smear or other specimen often indicates tuberculosis. Acid-fast microscopy is easy and quick, but it does not confirm a diagnosis of TB because Mycobacterium tuberculosis is not acid-fast (Schezle, 2019). Therefore, a culture is needed on all initial samples to confirm the diagnosis. A positive culture for Mycobacterium tuberculosis confirms the diagnosis of tuberculosis (Schezle, 2019). For all patients, the initial Mycobacterium tuberculosis isolate should be tested for drug resistance. It is an important factor to identify drug resistance to ensure effective treatment.
Those with active tuberculosis need treatment as soon as possible. This might involve medication, preventing the spread by covering the mouth with a tissue when a cough or sneeze occurs and disposing of the tissue into a plastic bag, then throwing it away. With the proper treatment, tuberculosis is almost always curable. Doctors prescribe antibiotics to kill the bacteria, and treatment options for latent and active tuberculosis all include different antibiotics that a doctor will prescribe depending on contraindications and risk factors (Wilson, 2018 ). Treatment of tuberculosis via antibiotics takes longer than most bacterial infections, however, the use of antibiotics destroys the bacteria and prevents for Tuberculosis from spreading through the body and continuing the normal respiratory system. Bacille Calmette-Guérin (BCG) is a vaccine for tuberculosis (Wilson, 2018). This vaccine is not commonly used in the United States, but it is often given to infants and children in countries where Tuberculosis is common (Wilson, 2018 ). BCG does not always prevent tuberculosis, people who were previously vaccinated with BCG may receive a TB skin test to test for infection (Wilson, 2018). A positive reaction to a tuberculosis skin test may be due to the BCG vaccine itself or due to infection with bacteria (Wilson, 2018). Other prevention measures include proper cough etiquette, infection control for those in healthcare settings and education for those at risk. More prevention methods and treatments are currently being placed in healthcare facilities.
The Tuberculosis Epidemiologic Studies Consortium II (TBESC-II) is a partnership of the Division of Tuberculosis Elimination (DTBE) control programs. These programs focus on strategies and tools to increase the diagnosis and treatment of latent tuberculosis infection (LTBI) in high-risk populations (Wilson, 2018). Current research of these programs includes tuberculosis elimination in the United States is and the knowledge of M. tuberculosis infection and finding preventive services for persons with Latent Tuberculosis (Wilson, 2018). These programs include Population-based calculation of tuberculosis prevalence overall and high-risk areas of changes over time and identifying where patients are lost to care in the process from diagnosis to treatment completion (Wilson, 2018). The main goal of the tuberculosis Prevention Cascade is to develop local estimates of tuberculosis prevalence in high-risk populations, and the proportions of those who are identified to complete treatment (Wilson, 2018). Identification of these gaps is the first step to intervening to close the gaps. To assist, TBESC-II is developing a case management system for tuberculosis programs. The Management System contains modules for patient registration, testing, treatment, follow-up, and contact investigations (Wilson, 2018). Other research being done on tuberculosis includes finding new antibiotics to quickly stop the infection. UConn chemist Alfredo Angeles-Boza and colleagues from the Indian Institute of Science, are in the process of current research to try a new drug to kill Mycobacterium tuberculosis in a faster, more effective way (Schezle, 2019). People infected with tuberculosis on antibiotics must take multiple over many months due to the bacteria being susceptible to the drugs when they break out of the macrophage in which they were born and search out a new one to invade (Schezle, 2019). These chemists take antibiotics produced by fish, and experiment with peptides binding to copper atoms. They enable the copper to shift its electrical charge, with the ability to become aggressive, ripping electrons away from some molecules and adding them to oxygen-containing molecules (Schezle, 2019). The oxygen-containing molecules become free radicals, that attack anything they encounter, including Mycobacteria (Schezle, 2019). The antibiotic peptide developed kills Mycobacteria living in macrophages in the lab, but they haven't been able to cure tuberculosis in mice yet. These peptide drugs have various problems the chemist is currently working through. The research is continuing to progress to get this drug to fight tuberculosis and relieve those suffering through months of changing antibiotics.
Both latent and active tuberculosis affects the respiratory system, although latent may remain dormant in the lobes until the immune system is weak and active tuberculosis shows. Forms of tuberculosis can be treated with antibiotics, multiple may have to be used due to the body developing drug resistance to those antibiotics over long periods of time. Signs and symptoms may be present in active, while latent tuberculosis patients may have no symptoms. A skin test can be done, and results provided within a three-day time frame. Future testing may be required, such as culture and x-ray. Due to current research being conducted, a new treatment may arise and those suffering from tuberculosis may get treatment in a proper care setting. Tuberculosis affects the respiratory system, which is a vital system of the body needed to maintain normal homeostasis properties and keep the human healthy