Community-acquired pneumonia: Clinical sciences

Chapters:

Watch video only

Introduction0:00–1:09

Pneumonia is a lung infection that results in inflammation of one or both lungs. Usually, it's caused by bacteria like streptococcus pneumoniae and viruses such as influenza, but rarely pneumonia can be caused by fungi as well.
Now, based on the setting in which pneumonia develops, we can subdivide it into two main types. Community acquired pneumonia or C AP for short and hospital acquired pneumonia or H AP.
When a person develops pneumonia outside of a hospital or within 48 hours after the admission to the hospital, it's considered C AP.
On the other hand, H AP develops after 48 hours of the admission to the hospital. Finally, there's a special subtype of H AP called ventilator acquired pneumonia or V A PVA P refers to pneumonia that occurs in individuals on mechanical ventilation 48 hours after the endotracheal intubation.
The first thing to do when approaching a patient with suspected C is to obtain a focused history and physical examination.

History and Physical, Labs, Pulse oximetry, and Chest X-ray1:09–2:53

Send labs such as ABG CBC and BMP, monitor pulse oximetry and get a chest X ray. Let's start with the history.
Patients with C AP might report coughing, difficulty breathing and chest pain during inspiration. Keep in mind that these symptoms develop either outside of the hospital or within 48 hours of admission.
They may also have a history of risk factors like COPD, diabetes, smoking or alcohol use. Here are some high yield facts to keep in mind, a productive cough can occur with bacterial infections.
However, if the sputum is blood tinged, consider specific organisms like streptococcus, pneumoniae, klebsiella, pneumoniae or legionella, pneumophila.
Now, the physical examination often reveals an elevated temperature, tachypnea and tachycardia pay close attention to lung auscultation which might reveal rail over the affected area.
Additionally, if there's lowbar consolidation, the physical examination might demonstrate bronchial breath sounds egophony and increased tactile fremitus in the affected lobe.
In contrast, patients with a pleural effusion might present with decreased breath, sounds, decreased tactile fremitus and dullness on chest percussion in the affected area.
Finally, pulse oximetry might reveal a drop in oxygen saturation. While chest X ray can show new lung infiltrates once you've diagnosed C AP based on the history and physical labs and imaging study.

Determination of disease severity2:53–3:19

The next step is to determine its severity. This is where the pneumonia severity index or psi comes in psi categorizes patients into five classes based on clinical elements like age and temperature.
Laboratory elements such as bun and glucose and radiographic elements like pleural effusion. Now, let's talk about low risk C AP classes.

Low-risk CAP3:19–4:05

1 to 3 are considered low risk C AP and can be managed at home. The type of treatment is based on whether or not the person has any chronic medical conditions.
So, if your patient has no chronic conditions, start them on oral amoxicillin or doxycycline for five days. However, if they do have a chronic condition such as CO PD or diabetes mellitus, then make sure to start them on an oral respiratory fluoroquinolone like levofloxacin or moxifloxacin or a combination of an oral beta lactam and macrolide for five days.
Ok. Let's switch gears and talk about high risk.

High-risk CAP4:05–7:47

C AP. Classes four and five are considered high risk C AP and require admission to the hospital.
First use the Infectious Diseases Society of America slash American Thoracic Society C AP criteria, better known as I SAA TSC AP criteria to determine if they should be managed on the hospital floor or on the ICU I SAA TSC AP criteria include major criteria such as septic shock or respiratory failure and minor criteria like elevated respiratory rate confusion.
Uremia, high W BC count low platelets, hypothermia, multilobar infiltrates and hypotension. Now, if your patient has no major or less than three minor criteria, admit them to the hospital floor and start them on supplemental oxygen to maintain oxygen saturation above 92%.
Additionally, you should look for a causative pathogen. So don't forget to obtain a blood culture and a sputum sample for culture and gram stain.
You can also test the urine and sputum for pneumococcal antigens. Finally assess their symptoms daily to check how they are responding to treatment.
If your patient has one major or three or more minor criteria, admit them to the ICU and start the same treatment as you do for hospital floor.
Patients. Additionally, if the patients present with respiratory failure, put them on ventilatory support and periodically assess parameters to optimize oxygenation.
However, if the patient presents with sepsis, you should also maintain their systolic BP above 90 millimeters of mercury using IV fluids and vasopressors.
All right. Now, let's move on to antibiotic treatment.
All hospitalized patients admitted to the hospital floor should be started on empiric antibiotic treatment with an IV respiratory fluoroquinolone or a combination of an IV beta lactam and a macrolide patients admitted to the ICU.
On the other hand, should be started on a combination of IV beta lactam and a macrolide or IV beta lactam and respiratory fluoroquinolone.
A high yield fact to remember is that you should also consider multidrug resistant or MDR pathogens when giving empiric antibiotics.
If they were previously diagnosed with a MRSA infection, add vancomycin if they were previously diagnosed with a pseudomonas infection, use an anti pseudomonal antibiotic like piperacillin tazobactam or cefepime.
After you have the culture gram stain or antigen test results, you should switch to tailored antibiotics. Now, if the patient improves after 48 to 72 hours, you should continue tailored antibiotics for at least five more days and evaluate their symptoms for good antibiotic response.
However, if there is no improvement, you need to figure out why. Remember when assessing for complications, the most common reasons include complications like lung abscess or pleural effusion or they also developed hospital acquired pneumonia from a MDR pathogen for complications.
Imaging tests like a CT scan of the chest or point of care. Ultrasonography or pocus can help identify the cause.
If the imaging reveals complications, they might need additional management like bronchoscopy or chest tube placement for drainage for MDR pathogens.

Review7:47–9:27

If they have risk factors like recent hospitalization, recent antibiotic use or prior MDR infections, you should obtain a sputum culture.
Finally, tailor antibiotics to treat the specific pathogen. All right, it's a quick recap community acquired pneumonia or C AP is a lung infection that develops outside of the hospital or less than 48 hours after admission, based on the severity C AP can be categorized as a low or high risk patients with low risk C AP are treated at home with the appropriate oral antibiotics.
On the other hand, patients with high risk C AP should be admitted to the hospital floor or ICU. Hospitalized patients are started on supplemental oxygen.
If hypoxic and samples of sputum, blood and urine are usually taken to identify the causative pathogen. Additionally, ICU patients might need ventilatory support if they are in respiratory failure or BP management with IV fluids and vasopressors if they are in septic shock treatment for all hospitalized patients includes empiric IV antibiotics.
People with prior MDR pathogen infections will need additional empiric antibiotics against those pathogens. Empiric antibiotics can be switched to tailored ones.
When you receive culture results, patients that improve should complete their treatment. But if the patient doesn't improve, you should assess for complications or a new hospital acquired pneumonia and treat them for that.