Internal_Medicine_Medical_School_Crash_Course_Unabridged_11_A_T

This chapter discusses infectious diseases and their management. Acute diseases usually resolve on their own, while chronic diseases require more extensive treatment. Sepsis is a life-threatening infection that affects the whole body. It can arise from various sources and has specific symptoms. Treatment involves finding and treating the source, giving fluids and antibiotics, and managing complications. Pneumonia is inflammation of the lungs caused by an infection. It can be bacterial, viral, or fungal. Treatment includes antibiotics and managing symptoms. Chapter 8 Infectious Disease. This chapter involves the discipline of infectious diseases. There are a wide variety of acute and chronic infectious diseases an internist comes in contact with as part of everyday practice. Most acute diseases are relatively self-limited and require no intervention or antimicrobial therapy to control the symptoms until the disease passes. Chronic infectious diseases can be more difficult to treat, with systemic implications and treatments that go beyond just giving antimicrobial therapy. This section will discuss the management of two acute infectious processes that are relatively commonly seen in an internist's practice. Both the management of sepsis and the management of acute pneumonia will be discussed. The management of the septic patient. Sepsis is a life-threatening infectious process that can stem from many different sources. The infection begins at a site in the body but then becomes systemic, leading to a response to the infectious process that causes destruction of the body's own organs and tissues. Most people with sepsis have a specific set of findings, including fever, tachycardia, tachypnea, and altered mental status. The initial symptoms depend on the source of the infection and are organ-specific. When the infectious process becomes systemic, there are changes in oxygenation that affect the cardiorespiratory system and that affect the blood flow and oxygenation of vital end organs. The lack of blood flow is evidenced by low blood pressure readings, elevated serum lactate levels from anaerobic metabolism in the muscle cells, and decreased output of urine. Sepsis leads to septic shock, in which there is persistently low blood pressure, even after attempts are made to provide adequate fluid intake. Sepsis is more than just a generalized infection, it stems from the body's immune response to the infection. Most causes of sepsis are bacterial in origin, but other pathogens can be responsible. Sepsis can arise from lung infections, urinary tract infections, gastrointestinal infections, and brain infections. Those most likely to get septic are young people and old people as well as those with poor immune function secondary to things like traumatic injuries, diabetes, or cancer. While sepsis is a systemic condition, it does not have to mean there is a blood infection. Blood culture should always be obtained before beginning antimicrobial therapy, but the blood culture does not have to be positive to have the diagnosis of sepsis. Besides treating the systemic response, the goal of treatment is to find the original source of the infection and treat it. Imaging studies may be necessary to find the infectious source. The mainstay of sepsis treatment is the giving of large amounts of intravenous fluids and antimicrobial medications. Antibiotics are started promptly that have coverage against the most likely organisms. Patients with sepsis are generally seen in the intensive care unit for maximal treatment. If IV fluids are inadequate to bring the blood pressure into normal range, vasopressors are used to increase systemic vascular resistance. Many patients with sepsis require mechanical ventilation, and some patients require dialysis for poor renal function. Because there is significant disruption of the vasculature, a central venous catheter is often required, along with an arterial catheter, to monitor arterial blood gases and blood pressure parameters. Secondary processes such as pulmonary emboli, pressure ulcers, and gastric ulcers need to be managed expectantly. The rate of death from sepsis is about 30 to 50%. If the patient is in active shock, the rate of death is as high as 80%. Evidence of sepsis varies from case to case. There tends to be symptoms related to the original source of the infection, as well as systemic findings like fever, a reduction in body temperature, tachypnea, tachycardia, mental status changes, and peripheral edema. Glucose metabolism can be impaired so that blood sugars are high. Blood coagulation can be affected with abnormal clotting that leads to end organ dysfunction. Clotting factors and platelets can be used up, resulting in a secondary bleeding disorder. Low blood pressure leads to shock. The most common original sites of infection in shock are the abdomen, the lungs, and the urinary tract. Half of all septic shock patients begin with lung infections. Up to a third of the time, no original cause can be found. Both gram-negative and gram-positive bacterial infections can lead to sepsis. A small percentage of sepsis stems from fungal infections, such as yeast infections. Sepsis needs to be identified as early as possible with blood tests to include a CBC, serum lactate level, electrolytes, kidney function tests, glucose, and blood cultures. If possible, two sets of blood cultures should be obtained before starting the antibiotic. Cultures of suspected origins of the infection should be taken, such as urine cultures, cerebrospinal fluid cultures, wound cultures, and sputum cultures. Fluid resuscitation should be the initial approach to hypotension, with central venous catheters and central venous oxygen measurements taken in refractory shock. Serum lactate levels should be followed to assess for perfusion of muscles. Infections that may require surgical interventions should be looked for aggressively so that surgery can be undertaken to control the infectious source. Sepsis is likely the problem if the temperature is either too high or too low, the heart rate is elevated, the respiratory rate is elevated, and the white blood cell count is either too high or too low. Sepsis proceeds in stages from early sepsis to severe sepsis and finally to septic shock. Patients with severe sepsis have at least one end organ that is failing because of low perfusion. Septic shock is identified when blood pressure remains low after giving IV fluids. Just about any end organ can fail in sepsis. The lungs can develop acute respiratory distress syndrome and can oxygenate poorly. The brain can be involved in symptoms suggestive of encephalopathy. The liver can fail to make clotting factors. The kidney can put out low urine volumes. The heart can pump inefficiently. Patients can require vasopressors to bring the blood pressure up, and can have metabolic acidosis secondary to lactate excesses. Damage to the lungs can result in poor gas exchange in the alveoli, which causes systemic hypoxia. Other typical findings in sepsis include a decreased Glasgow Coma score, decreased cognitive abilities, low platelet count, elevated bleeding parameters, renal dysfunction, and liver dysfunction. Most patients with these findings are indeed septic. However, sepsis can be misidentified in alcohol withdrawal situations, severe pancreatitis, burn hypotension, pulmonary embolism, anaphylaxis, thyroid storm, neutrogenic shock, and adrenal insufficiency. Sepsis is more than a severe infection. There are microbial factors that play into becoming septic, as well as immune factors that act to adversely affect the organs of the body. The beginning of sepsis involves elevations in inflammation and the overuse of inflammatory reserves. This leads to a failure of the immune system and an inability to fight infection. Patients with multiple trauma and severe burns can have sepsis in the absence of a blood infection. Patients with chemical pneumonitis or pancreatitis can develop signs and symptoms of sepsis without having a true bacterial source. Blood vessels become dilated by molecules like nitric oxide, and there can be a lack of molecules that constrict blood vessels, so blood pressure declines. There are many things that need to be managed in suspected shock patients. All patients need systemic antibiotics after cultures are taken. All patients need intravenous resuscitation with parenteral fluids. Lactic acid should be followed to measure muscle perfusion. Patients need high-flow oxygen, monitoring of urine output, and hemodynamic monitoring. Most septic patients need mechanical ventilation at some point, and some need blood product transfusion. Enteral feeding should be established to keep up with metabolic demands. Enteral feeding should be established to keep up with metabolic demands, and vasopressors need to be given if colloid replacement doesn't increase the blood pressure. High blood sugars need insulin management. Prevention of gastric ulcers needs to take place and there should be steps in place to prevent deep vein thromboses. Usually, two broad-spectrum antibiotics should be started as soon as sepsis is suspected. The finding of a positive blood culture is not necessary to establish sepsis, nor is it necessary to start IV antibiotic therapy. The choice of antibiotic depends on the suspected source. Intravenous fluids are given to maintain an adequate blood pressure and urine output. Often this takes large volumes of crystalloids. If there is acute respiratory distress syndrome as a complication of sepsis, smaller amounts of intravenous fluid should be given to maximize gas exchange. Besides crystalloids, albumin can be given to bring up the intravascular fluid volume. If the hemoglobin is decreasing, packed red blood cells should be given to keep the hemoglobin stable. The most common vasopressor used to bring the blood pressure up is norepinephrine. Epinephrine can be used if this fails. If the heart function is inadequate, a dose of endobutamine is given to bring the blood pressure up. Patients with septic shock and acute respiratory distress syndrome may benefit from intravenous corticosteroid use. Antibiotics should be continued for 7 to 10 days even after the patient has stabilized. The Management of the Patient with Pneumonia Pneumonia is basically an inflammation of the lung parenchyma secondary to some type of infectious process. The infection can be bacterial, viral or fungal in origin. Rarely, pneumonia can be non-infectious and can be caused by a toxin affecting the lungs. Pneumonia can be mild or fatal, depending on the patient's ability to fight the infection. Pneumonia is more common in the elderly, who handle infections more poorly. Young children can also be affected by pneumonia, as can people with chronic health conditions. There are basically two types of pneumonias. There is community-acquired pneumonia that develops outside of a hospital setting. It happens most often in wintertime when respiratory infections are more common. Hospital-acquired pneumonia happens when the patient is in a hospital setting for another health reason. It tends to be more severe because the patient is already sick and may be on ventilator support. Pneumonia can be classified according to the way the lung is affected. In bronchopneumonia, for example, the infection is more diffuse and is found in the air sacs. Lobar pneumonia involves an infection of one lobe of the lung, affecting all of the air spaces in the lobe. Lipoid pneumonia involves a build-up of fats in the alveoli of the lungs, caused by oil aspiration or blockage of the airways. Pneumonias can also be identified by the organism causing the infection. Bacterial pneumonia is caused by bacteria, viral pneumonia is caused by viruses, and fungal pneumonia is caused by fungi. Pneumonia can be further classified into the specific organism causing the infection. Pneumonia can be classified as to the cause of the infection. For example, aspiration pneumonia can be caused by inhaling a drink, spit, or vomit into the lungs from an impairment in the swallowing reflex. Atypical pneumonia is caused by certain types of bacteria. Ventilator-associated pneumonia stems from getting a lung infection while being on a ventilator. In general, pneumonia is not particularly contagious. It takes the combination of an infectious agent and a weakened immune system to bring about the lung infection. In theory, any type of pneumonia could be considered contagious, but the host must be susceptible to getting the infection. Certain types of pneumonia are more contagious than others, including mycoplasma pneumonia and tuberculosis. A person with pneumonia always has the potential to pass the infection on to another person, but the time frame varies from organism to organism. The range of contagion can be between a day or so to several weeks. While the sick person is still sneezing or coughing from their illness, they can spread droplets of infection to another person. In bacterial pneumonia, the person is considered to be less contagious after they've been on adequate antibacterial coverage for at least two days. However, this can vary with the type of infection. With tuberculosis for example, it can take a couple of weeks on therapy before the contagion risk is diminished. Viral pneumonia is usually caused by the influenza virus, which affects both the upper and lower respiratory tract. Children can have pneumonia from respiratory syncytial virus. Viral pneumonia is usually caused by the influenza virus, which affects both the upper and lower respiratory tract. Children can have pneumonia from respiratory syncytial virus. Viral pneumonia is usually caused by the influenza virus, which affects both the upper and lower respiratory tract. Children can have pneumonia from respiratory syncytial virus. Viral pneumonia is usually caused by the influenza virus, which affects both the upper and lower respiratory tract. In immunosuppressed people, fungal organisms can cause pneumonia. These include cryptococcus pneumonia, histoplasma pneumonia, and coccyx pneumonia. In immunosuppressed people, fungal organisms can cause pneumonia. These include cryptococcus pneumonia, histoplasma pneumonia, and coccyx pneumonia. In immunosuppressed people, fungal organisms can cause pneumonia. These include cryptococcus pneumonia, histoplasma pneumonia, and coccyx pneumonia. In immunosuppressed people, fungal organisms can cause pneumonia. These include cryptococcus pneumonia, histoplasma pneumonia, and coccyx pneumonia. In immunosuppressed people, fungal organisms can cause pneumonia. These include cryptococcus pneumonia, histoplasma pneumonia, and coccyx pneumonia. In immunosuppressed people, fungal organisms can cause pneumonia. These include cryptococcus pneumonia, histoplasma pneumonia, and coccyx pneumonia. In immunosuppressed people, fungal organisms can cause pneumonia. These include cryptococcus pneumonia, histoplasma pneumonia, and coccyx pneumonia. Symptoms of pneumonia include having a weak immune system from cancer or immunosuppressed diseases, being under the age of 2, being older than 65 years of age, and having a chronic disease such as cystic fibrosis, COPD, diabetes, heart disease, asthma, or sickle cell anemia. Symptoms of pneumonia include having a weak immune system from cancer or immunosuppressed diseases, being under the age of 2, being older than 65 years of age, and having a chronic disease such as cystic fibrosis, COPD, diabetes, heart disease, asthma, or sickle cell anemia. Swallowing problems can also contribute to aspiration which is another cause of pneumonia. Patients with malnutrition or a history of cigarette smoking have an increased risk of developing pneumonia. Typical signs and symptoms of pneumonia depend upon the individual's current state of health at the time the pneumonia develops. Most patients with severe pneumonia get a cough, chest pain, shortness of breath, fever, chills, tiredness, and the coughing up of mucus. Non-respiratory symptoms associated with pneumonia include nausea, vomiting, and diarrhea. Infants with pneumonia have atypical findings including restlessness or lethargy. Older adults with pneumonia tend to have fewer typical symptoms of pneumonia and instead have a change in mental status because of the infection. The diagnosis of pneumonia involves taking a careful history and physical examination. The lung evaluation often results in findings of pneumonia including decreased lung sounds, crackling in the lungs, and audible wheezing. A chest x-ray can be done to see if there is consolidation in part of the lung. Rarely, a CT scan needs to be performed to find the pneumonia. Pulse oximetry can detect hypoxia from gas exchange impairment. Cultures of the blood or sputum can reveal the causative organism. Internists can do a bronchoscopy to find sputum in the bronchial tree to test for pneumonia. Most pneumonias can be treated with antibiotics directed at the offending bacterium or fungus. The choice of medication depends on which organism is involved, the chance of resistance, and the patient's underlying health problems. Community-acquired pneumonia can often be managed at home with oral medications. Empiric treatment can be used until a culture result returns. A few cases of community-acquired pneumonia require hospitalization, particularly if the individual has an underlying medical condition. Antibiotics are not used in cases of viral pneumonia. In most cases, no medication is used. However, some immunosuppressed patients require antiviral medications to decrease complications of the disease. Oseltamivir and Zanamivir are antiviral agents used to treat pneumonias secondary to influenza. The typical complications of pneumonia include sepsis in which the pneumonia bacterium infects the bloodstream. Other cases of pneumonia result in pleural effusions, fluid buildups between the lungs and the chest wall. The pleural effusion can be sterile or infected with bacterial organisms. Abscesses can develop in the lung itself. Most patients with pneumonia experience improvement in symptoms within 5 days after starting the antibiotic. Mild symptoms like fatigue and cough may last a longer period of time, even after the infection has cleared. The death rate from pneumonia can be as high as 30% in severe cases. About 5-10% of hospitalized pneumonia cases are fatal. Those with a weakened immune system and those who are elderly have a higher risk of death from pneumonia. Key Takeaways. Patients with sepsis may or may not have a positive blood culture for bacteria. Sepsis patients are treated for both the infection and their inflammatory response to the infection. The most serious complication from sepsis is end organ damage from poor perfusion of the peripheral tissues. Pneumonia can be community acquired or acquired in a hospital setting. Most cases of pneumonia are bacterial, although fungal and viral pneumonia can happen. Pneumonia is generally not fatal. However, up to 10% of hospitalized patients with pneumonia die from the disease. Quiz. Number 1. Which type of infection is most likely to result in a secondary sepsis? A. Acute pneumonia. B. Acute sinusitis. C. Osteomyelitis. D. Skin infection. Answer. A. Respiratory infections, gastrointestinal infections and urinary tract infections are at the highest risk of secondary sepsis. Number 2. The patient with sepsis is often hypotensive. This is best treated with what kind of therapy? A. The administration of blood products. B. Intravenous colloidal solutions. C. Intravenous albumin. D. Vasopressive agents. Answer. B. Most patients with sepsis can be successfully managed with intravenous colloidal solutions when they have sepsis and hypertension. Number 3. Which organ system tends to fail first in cases of sepsis? A. The kidneys. B. The liver. C. The heart. D. The lungs. Answer. D. The lungs and the gas exchange in the alveoli tend to fail first in cases of sepsis, which cause the heart to fail and blood pressure to become low. Number 4. What statement is true about sepsis? A. Cases of sepsis are due to an uncontrolled bacterial infection. B. Septic patients suffer from hypotension. C. The body temperature is elevated in sepsis. D. Sepsis is more common in immunocompromised hosts. Answer. D. Sepsis is more common in immunocompromised hosts. The body temperature may be high or low, the blood pressure may be normal or low, and there are non-bacterial causes of sepsis. Number 5. Which vasopressor is most commonly used in the treatment of sepsis? A. Norepinephrine. B. Epinephrine. C. Dobutamine. D. Dopamine. Answer. A. The most commonly used vasopressor in the treatment of sepsis is norepinephrine, with epinephrine being a second-line treatment. Number 6. Which type of drug must be used in all cases of sepsis? A. Vasopressor therapy. B. Corticosteroids. C. Antibiotics. D. Proton pump inhibitors. Answer. C. Antibiotics must be used in all cases of sepsis, even when the source of infection is unclear and the blood cultures are negative. Number 7. Which patient is likely to develop pneumocystis pneumonia? A. An elderly patient living in the community. B. An infant living in the community. C. A ventilator-dependent patient. D. A patient with AIDS. Answer. D. Pneumocystis pneumonia is most likely to occur in a patient with AIDS. It is rarely found outside of this setting. Number 8. Which type of virus is most commonly responsible for pneumonia? A. Adenoviruses. B. Influenzaviruses. C. Coronaviruses. D. Human immunodeficiency viruses. Answer. B. Influenzaviruses are the most common virus associated with acute pneumonia. Number 9. The patient has community-acquired pneumonia by X-ray evaluation showing lober consolidation. How is this patient treated? A. Sputum cultures are obtained and the patient is treated after the culture returns. B. Antiviral agents are given as the source is likely viral in nature. C. Empiric antibiotic therapy is started. D. Antifungal agents are started until cultures return. Answer. C. Patients with community-acquired pneumonia can be treated with empiric antibiotic therapy. The findings on X-ray are most consistent with a bacterial infection. Number 10. Why are stroke patients at a higher risk of pneumonia? A. They have weakened immune systems so infection is more likely. B. They are not very active putting them at a higher risk for infection. C. They are often hospitalized making them a higher risk of hospital-acquired pneumonia. D. They often have swallowing problems making aspiration more likely. Answer. D. Stroke patients are at a higher risk of pneumonia because they often have swallowing problems putting them at an increased risk of aspiration and secondary pneumonia.