Community-Acquired Pneumonia - Causes, Symptoms, and Treatment

Introduction

Pneumonia that affects people who have no exposure to hospitals or healthcare is called community-acquired pneumonia. The common causes of this infectious disease are Streptococcus pneumoniae and Haemophilus influenzae. It is less likely caused by viral pathogens like influenza and rhinovirus. The causative pathogens like bacteria, viruses, or fungi for community-acquired pneumonia vary depending on the age of the patient. The mortality rate of community-acquired pneumonia is relatively high in older patients. The specific cause of the condition is unknown because most of the affected patients do not undergo proper screening. Community-acquired pneumonia is the second most common disease among lung disorders.

What Are the Causes of Community-Acquired Pneumonia?

The various causes of community-acquired pneumonia are as follows:

• Age - Children above five years of age and middle-aged individuals are prone to community-acquired pneumonia.

• Second-Hand Exposure - The infection in community-acquired pneumonia spreads from the infected person to other people in the family, hostels, and camps. It occurs due to long-term exposure in a confined environment.

• Birds - Community-acquired pneumonia due to a pathogen called Chlamydia spreads through birds like parrots and macaws.

• Skin Infection - Community-acquired pneumonia spreads through skin infections caused by Staphylococcus aureus. It can eventually lead to necrotizing pneumonia. It is commonly seen in young adults.

• Neutropenia - Individuals with decreased neutrophils in the blood are likely to get affected by community-acquired pneumonia.

• Immunocompromised Individuals - Individuals with low immunity levels due to the use of steroids, HIV (human immunodeficiency virus) infection, and lung transplants are prone to community-acquired pneumonia.

• Lung Disorders - Pre-existing lung diseases like cystic fibrosis and bronchiectasis cause community-acquired pneumonia.

• Anthrax - The cutaneous contact with infected animals causes anthrax and community-acquired pneumonia.

• Plague - It occurs when the individual contacts the fluid infected by rodents. This affects the lungs and causes community-acquired pneumonia.

• Tularemia - Contaminated food and inhalation of infectious agents cause tularemia leading to community-acquired pneumonia.

What Are the Symptoms of Community-Acquired Pneumonia?

The symptoms associated with community-acquired pneumonia are similar to the symptoms of pneumonia. They are as follows:

• Fever - The pathogens in community-acquired pneumonia elicit a high body temperature due to infection.

• Cough - Infants with community-acquired pneumonia get a dry cough, while adults with the disease get sputum with a cough.

• Chest Pain - The pathogens produce pus and spread infection in the space present in the chest. It causes chest pain.

• Dyspnea - There is breathlessness in patients with community-acquired pneumonia due to exertion. It is not present during resting or sleeping hours.

• Abdominal Pain - There is a pain in the upper abdominal region due to the infection in the lower lobe of the lungs.

• Tachypnea - Since community-acquired pneumonia affects a major portion of the lungs, there is abnormally rapid breathing.

• Tachycardia - Due to shortness of breath, patients with community-acquired pneumonia have a rapid heartbeat.

• Restlessness - Infants with community-acquired pneumonia throw tantrums and become restless more often.

• Diarrhea - Diarrhea is commonly present in young children affected by community-acquired pneumonia.

• Nausea and Vomiting - Pathogenic infections result in symptoms like nausea and vomiting due to the involvement of the digestive tract.

• Cyanosis - The infants appear bluish due to severe infection.

• Breath Sound - The bacterial infection in community-acquired pneumonia affects the respiratory mechanism and causes high-pitched sounds while breathing.

• Confusion - The patient stays confused due to low blood pressure and dehydration.

What Are the Diagnostic Procedures Used to Diagnose Community-Acquired Pneumonia?

The initial diagnosis for community-acquired pneumonia is a clinical examination of the patient by a pulmonologist. The following diagnostic tests are recommended to diagnose community-acquired pneumonia:

• Chest X-Rays - The chest X-rays cannot diagnose the type of infection, but they are helpful in observing the lung changes due to community-acquired pneumonia. Multiple lobes are infected due to Streptococcus pneumoniae. The infected lining of the lungs appears more opaque.

• Blood Cultures - The blood culture is done in patients with severe community-acquired pneumonia. It helps in investigating the type of bacterial infection. This condition is known as bacteremia. The changes in eosinophilic cell count indicate infection. If the routine blood test does not help in identifying the cause, then the pneumococcal antigen test is done. The presence of pneumococcal antigen in the blood indicates that the immune system is fighting against the pathogens.

• Sputum Test - The pathogen of community-acquired pneumonia is identified by the sputum test. This test will be inaccurate if there is saliva contamination. So a bronchoscope is used to collect the sputum.

• Urine Test - This test has higher sensitivity and specificity. The urine sample is collected from the patients suspected of community-acquired pneumonia. It is tested in the laboratory for the presence of pneumococcal antigen.

What Are the Various Treatment Methods for Community-Acquired Pneumonia?

There is no specific treatment for community-acquired pneumonia as it involves many pathogens. Treatment is given to those patients to help relieve symptoms, which include:

• Antibiotics - Children less than five years of age are treated with Amoxicillin or Azithromycin. Children above five years and adults are treated with Clavulanate. Children who are previously vaccinated for pneumonia are treated with Ampicillin. Non-vaccinated children are treated with Ceftriaxone. The co-infections in community-acquired pneumonia are treated by multi-drug therapy.

• Antiviral Medications - Oseltamivir is given orally, twice daily, for five days for children with viral fever and community-acquired pneumonia. Acyclovir is given to adults with community-acquired pneumonia. The children are continuously monitored, and the dosage is reduced according to the existing symptoms.

• Supportive Therapy - Since dehydration is the major cause of community-acquired pneumonia; the patient should be managed with high fluid intake. Supplemental oxygen therapy is given to patients who are deprived of airflow. Prophylactic drugs are given to prevent pulmonary embolism.

Conclusion

The mild form of community-acquired pneumonia does not require any hospitalization. They are mostly treated on an outpatient basis. Patients with community-acquired pneumonia should avoid smoking. The pulmonologist should identify the triggering pathogen and treat the same as soon as possible to avoid complications. If there is no improvement in the symptoms, then the patient is referred to an infectious disease specialist. Before the disease progresses to sepsis syndrome, symptoms should be managed with medication because mortality depends on the pathogenesis of the organisms. In a few patients who do not respond to the first line of drugs and show resistance, the pulmonologist will prescribe a different drug of choice in such conditions.