What Can Pneumonia Cause?

What is Pneumonia?

Pneumonia is an acute infection of lung parenchyma including alveolar spaces and interstitial tissue. maybe confined to an entire lobe-Lobar pneumonia
• A segment of a lobe-Segmental or lobular pneumonia
• Alveoli contiguous to bronchi - Bronchopneumonia
• Interstitial tissue - Interstitial pneumonia

These distinctions are generally based on x-ray observations.

This Predisposing factors that can cause pneumonia 

• Preceding respiratory viral infections
• Alcoholism
• Cigarette smoking
• Underlying diseases such as Heart failure, COPD
• Age extremes
• Immunosuppressive therapy and disorders
• Decreased consciousness, coma, seizure, etc
• Surgery and aspiration of secretions

Microbial Pathogen that causes Pneumonia: depend on the setting in which pneumonia is acquired

1. Community-acquired pneumonia
o Streptococcus pneumoniae ( pneumococcal pneumonia ) commonest cause
o Mycoplasma pneumoniae
o Chlamydia pneumoniae
o Haemophilus influenza
o Oral anaerobic bacteria
o Staphylococcus aureus
o Legionella pneumophila
o Mycobacterium tuberculosis

2. Aspiration pneumonia: This occurs when a large amount of oropharyngeal or gastric contents are aspirated into the lower respiratory tract. Aspiration occurs more frequently in patients with:
• Decreased level of consciousness (alcoholism, seizure, strokes or general
anesthesia)
• Neurologic dysfunction of oropharynx and swallowing disorders.
• People with periodontal disease are affected more.
Common Etiologic agents of Aspiration pneumonia: It is often polymicrobial
o Anerobic organisms in the oral cavity
o Enterobateriacae
o S. pneumoniae
o S.aureus
Patients present with cough and foul-smelling sputum. 
The cough may be chronic forming lung abscess and may resemble TB. There will be signs of a cavity on the physical exam and CXR. It is treated with crystalline penicillin and metronidazole IV for several weeks if lung abscess develops.

3. Community-acquired Pneumonia in Immunocompromised hosts:
Immunocompromised hosts such as transplant recipients, HIV infected patients, and
patients on Chemotherapy etc. are prone to develop pneumonia. The etiologic agents are
o Common bacterial causes of CAP : St. Pnumoniae , H.influenzae,
Mycoplasma
o Gram negative organisms : enterobacteriaceae
o Funguses such as Pneumocystis carinii ( jerovecii ), C. neoformans ,
Histoplasmosis , Aspergillus
o Mycobaterium tuberculosis
o Viruses : HSV , CMV
4. Hospital-acquired pneumonia: a patient is said to have hospital-acquired pneumonia if the symptoms begin 48 hours after hospital admission and not incubating at the time of admission. Common organisms that cause hospital-acquired pneumonia are:-
o Gram-negative bacilli including Pseudomonas aeroginosa, K.pneumoniae
o Staphylococcus aureus ( may be drug-resistant )
o Oral anaerobes.

What are the common symptoms:
• Sudden onset with a single shaking chill. This is followed by high-grade fever (up to 40.50c )
• Cough productive of purulent, blood-streaked or rusty sputum
• Pleuritic chest pain on the involved side worsened during inspiration and coughing
• Dyspnea ( shortness of Breath )
• Headache, myalgia, arthralgia and fatigue

What complications can pneumonia cause:
We can divide the complications of pneumonia into two by their location. Pneumonia can cause various complication through our body. To list some:

• Local: Parapneumonic effusion or pus in the pleural space (empyema).
• Distant complications: include septic arthritis and meningitis. Pneumonia can progress to sepsis, sometimes with septic shock.

Diagnosis

Diagnosis of pneumonia is usually made clinically in developing countries but chest X-ray is the best way to diagnose pneumonia.
Chest X-Ray findings usually show patchy opacities meaning white dot-like structures on the lung film, Which is shown in the picture below.

How pneumonia is treated

First, we start out with symptomatic therapy which means treating the symptoms of pneumonia-like, fever, headache, shortness of breath and, sometimes mental confusion.

Then we go to specific therapy depending on the severity of pneumonia.

Antibiotics. These medicines are used to treat bacterial pneumonia. It may take time to identify the type of bacteria causing your pneumonia and to choose the best antibiotic to treat it. If your symptoms don't improve, your doctor may recommend a different antibiotic.

Cough medicine. This medicine may be used to calm your cough so that you can rest. Because coughing helps loosen and move fluid from your lungs, it's a good idea not to eliminate your cough completely. In addition, you should know that very few studies have looked at whether over-the-counter cough medicines lessen coughing caused by pneumonia. If you want to try a cough suppressant, use the lowest dose that helps you rest.

Fever reducers/pain relievers. You may take these as needed for fever and discomfort. These include drugs such as aspirin, ibuprofen (Advil, Motrin IB, others) and acetaminophen (Tylenol, others).