Doctor's Notes on Bacterial Pneumonia
Bacterial pneumonia is inflammation of the lung tissue caused by a bacterial infection. A number of different kinds of bacteria can cause pneumonia. Streptococcus pneumoniae is the most common cause of bacterial pneumonia. Other bacteria that can cause pneumonia include Mycoplasma pneumoniae, Legionella pneumophila, and Chlamydia pneumoniae. Pneumonia may affect one or both lungs and can involve any part of the lung or the entire lung.
Pneumonia often begins with symptoms of an upper respiratory infection, like sore throat and nasal congestion or runny nose. Associated symptoms may include fever, chills, cough, chest pain, and shortness of breath. The cough usually produces thick sputum. Other possible symptoms of pneumonia are muscle aches, headache, weakness, and fatigue.
Bacterial Pneumonia Symptoms
Doctors often refer to typical and atypical pneumonias, based on the signs and symptoms of the condition. This can help to predict the type of bacteria causing the pneumonia, the duration of the illness, and the optimal treatment method.
Typical pneumonia comes on very quickly.
- Typical pneumonia usually results in a high fever and shaking chills.
- Typical pneumonia usually leads to the production of yellow or brown sputum when coughing.
- There may be chest pain, which is usually worse with breathing or coughing. The chest also may be sore when it is touched or pressed.
- Typical pneumonia can cause shortness of breath, especially if the person has any chronic lung conditions such as asthma or emphysema.
- Because chest pain also can be a sign of other serious medical conditions, do not try to diagnose self-diagnose.
- Older people can have confusion or a change in their mental abilities as a sign of pneumonia or other infection.
Atypical pneumonia has a gradual onset.
- It is often referred to as "walking pneumonia."
- Sometimes it follows another illness in the days to weeks before the pneumonia.
- The fever is usually lower, and shaking chills are less likely.
- There may be headache, body aches, and joint pain.
- Coughing may be dry or produce only a little sputum. The person may not have any chest pain.
- Abdominal pain may be present.
- There may be other symptoms, such as feeling tired or weak.
- Often the abnormalities on the chest X-ray appear worse than what the patient appears to have clinically, hence the term "walking pneumonia."
Bacterial Pneumonia Causes
- Most pneumonia is caused by bacteria or a virus. Pneumonia from any cause can occur at any age, but people in certain age groups are at higher risk for certain types of pneumonia.
- The most common cause of bacterial pneumonia is a type of bacteria known as Streptococcus pneumoniae. Haemophilus influenzae, Chlamydia pneumoniae, Mycoplasma pneumoniae, and Legionella pneumophila are some other major bacteria that cause pneumonia. Pneumonias of these type are quite common and are often referred to community-acquired pneumonia (CAP). If someone spends significant time around or in hospitals or other health-care facilities, they can be exposed to other types of bacteria that are much more dangerous. Pneumonia from these types of bacteria are referred to as health-care-associated pneumonia (HAP). Doctors use this information in deciding the most appropriate antibiotic treatment.
- People who inhale toxic materials can injure the lungs and cause chemical pneumonia. This is more accurately referred to as chemical pneumonitis, since the process is mainly due to inflammation not from an infectious source.
- Fungi can also cause pneumonia. In certain areas of the United States, specific fungi are well known. Coccidioidomycosis, usually seen in the Southwest, is a type of fungal infection that causes a pneumonia called "San Joaquin fever" or "Valley fever." Histoplasmosis (seen primarily in the Midwest) and blastomycosis (seen primarily in the Southeast) are other fungal diseases that cause pneumonias.
- The most common way you catch pneumonia is to aspirate bacteria from the upper airway, usually the oral cavity. Other ways to catch pneumonia can be by breathing in infected air droplets from someone who has pneumonia. In some cases, the bacteria can be generated by an improperly cleaned air conditioner or Jacuzzi. Yet another source of infection in the lungs is spread of an infection from somewhere else in the body, such as the kidney. Bacteria can enter the bloodstream from any source and be deposited in the lungs, resulting in pneumonia.
- The risk of catching pneumonia is determined by the specific bacteria, virus, or fungus, the number of organisms the person inhales, and the body's ability to fight infections.
- A person cannot "catch pneumonia" by not dressing properly for cold weather or by being caught in the rain.
Bacteria are microscopic, single-cell organisms that live almost everywhere. Bacteria live in every climate and location on earth. Some are airborne while others live in water or soil. Bacteria live on and inside plants, animals, and people. The word "bacteria" has a negative connotation, but bacteria actually perform many vital functions for organisms and in the environment. For example, plants need bacteria in the soil in order to grow.
The vast majority of bacteria are harmless to people and some strains are even beneficial. In the human gastrointestinal tract, good bacteria aid in digestion and produce vitamins. They also help with immunity, making the body less hospitable to bad bacteria and other harmful pathogens. When considering all the strains of bacteria that exist, relatively few are capable of making people sick.
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.