 Hello, welcome to Pneumonia Part 1. In this section, we'll discuss how to classify pneumonia. We'll also discuss the signs and symptoms of pneumonia. Pneumonia is defined as the inflammation of the lung parenchyma. In pneumonia, the avial air spaces are filled with exudate and inflammatory cells. It can be caused by infection in most of the cases. It can also be caused by other reasons such as chemical exposure. In this segment, we'll be most interested in infectious causes of pneumonia. We want to know about pneumonia because it kills. Out of all the patients, we'll have pneumococcal pneumonia with bacteremia. The mortality rate is 1 in 5. The older the patient, the higher the mortality rate. In terms of classification, the two broad classification has to do with the patient and the setting from which they acquire their pneumonia. We'll talk about each of them. First, we want to know something about our patient, whether they're healthy or whether they have any comorbidities. The comorbidities are separated into conditions that make them more prone to infection. That can include a list of different conditions, such as diabetes, HIV infection, medications include anti-rejection medications, steroids, and so on. Other comorbidities we care about also include existing lung problems, such as COPD and asthma. Lastly, we want to know if the patient is at a higher risk for aspiration. Those patients include those with neurological conditions, such as seizures and strokes. Knowing who the patient is is important, since the organisms infecting the patient will be different based on what the patient is like. The second part of the equation has to do with the setting. The setting means where did the patient acquire this pneumonia. Broadly, it is divided into community acquired, that means patients live independently in their own home, and they're not subjected to other people who are sick. The hospital acquired, which means the patient picks up the infection from a hospital setting. And lastly, healthcare acquired. These are patients who are living in long-term healthcare facilities, such as nursing homes. Knowing both the patient and the setting will help us decipher which organisms are involved to cause their pneumonia. The categories of the organisms include bacteria. They can be gram-positive, gram-negative, or anaerobes, virus, and rarely fungal. We will focus our discussion on mostly bacterial and viral pneumonia. Let's talk about our most basic patient, a healthy patient who comes from home, who lives independently, so a community acquired pneumonia. It can be by bacteria or virus. Bacteria infection is divided into typical or atypical bacteria. Typicals are the one that give the most typical signs and symptoms, which we'll discuss further. The bacteria include strep pneumoniae, moraxilla catarallis, and hemofluous influenza, or H-flu for short. Of the three typical, strep pneumonia is the most common cause of community acquired pneumonia that is typical. In terms of atypical organisms, they can include mycoplasma and chlamydia. These organisms do not give the typical signs and symptoms of pneumonia. For viral infection, multiple viruses can cause pneumonia, including the influenza virus and RSV. Virus infections often come in epidemics. Patients who have been infected by a viral pneumonia can also have bacterial pneumonia as well. What about patients with community acquired pneumonia who have a comorbidity? They are also subjected to all the organisms we talked about before. However, their comorbidities might mean that they are either more susceptible to infection in general, or they're more susceptible to certain organisms. For patients who are immunosuppressed, it depends on why they're immunosuppressed. Patients with HIV are more likely to get PCP pneumonia and TB. Those without a displean are more susceptible to encapsulated organisms such as strep. Those who are immunosuppressed because of medications such as chemotherapy drugs, steroids, are more likely and more susceptible to general infection. In patients with underlying lung diseases, they are more likely to get infection generally. They are also more likely to undergo multiple courses of antibiotics frequently. Therefore, we're much more worried about drug-resistant organisms in them. Lastly, for the patient who have increased aspiration risks, since the aspirate is from the GI tract, we're worried about anaerobes such as klepsiella and fusobacterium. Next, we'll talk about hospital and healthcare acquired pneumonia. It is defined by a pneumonia that occurs more than 48 hours after hospital admission. It is also known as nosocomial pneumonia. The most common cause for nosocomial pneumonia is bacteria. These bacteria include pseudomonas, klepsiella, E. coli, staph aureus, and in particular methyl-cylind-resistant staph aureus. It can also be from streptococco pneumoniae and H. flu, which are the two bacteria we have already seen with community acquired pneumonia. Depending on whether there is a viral infection outbreak, sometimes we do see viral causes such as influenza as the cause for nosocomial pneumonia. How do patients with pneumonia present? We'll divide this into typical and atypical presentation. In patients with typical pneumonia, they will present with fever, cough, tachypnea, and sputum production. On exam, they are usually tachycardic and may be in respiratory distress. They might be confused. On your respiratory exam, you may hear eventitious sounds such as crackles, rails, ronkais, or wheezes. There might be decreased breath sounds and dullness to percussion. If there is a pleurofusion, you may also hear pleurofriction rub. Patients can also present with atypical symptoms, particularly if they're at the extremes of age, the very old or the very young. They can present with mental status changes, dyspnea, or shock. They may not give you the history of fever, cough, or sputum production. In summary, we'll discuss a bit of an approach to patients with pneumonia. To figure out what organisms might be causing the pneumonia, we want to start with the patient. Is he healthy? Or are there co-orbidities? If so, what are they? Next, we decide on the setting that the patient could have contracted the pneumonia. Is it their own home, a hospital setting, or healthcare facility setting? From these factors, we will be able to best decide what organism is causing the pneumonia. We also talked about the typical symptoms and atypical symptoms that patients with pneumonia might present with. In the next section, we will discuss how to diagnose and treat the patients with pneumonia. Thank you for watching.