Bacterial pneumonia is a common but often overlooked illness, sneaking up on unsuspecting individuals and leaving them feeling weak and fatigued. But this infection is not something to take lightly, as it can lead to serious health complications. Read on to discover the causes, symptoms, and treatments of bacterial pneumonia.
Types of bacterial pneumonia
Pneumonia is a respiratory illness that can vary in both symptoms and severity. Most symptoms are upper respiratory, like cough, sneezing, and shallow breathing. Other symptoms are more systemic, such as fever, weakness, chills, and loss of appetite.
Pneumonia can be viral or bacterial, with bacterial pneumonia usually being more severe.
Generally, bacterial pneumonia can be split into one of two groups: typical pneumonia or atypical pneumonia. The two groups are differentiated by their symptoms as experienced by patients, by the signs doctors see when they examine patients, and by the organisms that cause them.
Both typical and atypical pneumonia are most often community-acquired. That means people just get these infections from whomever they come in contact with in their various communities. They are spread from respiratory droplets like cough, sneezing, and even talking and breathing on one another.
However, both types of pneumonia have their differences, which are summarised in the table below and explained in detail in the following paragraphs.
| Type of pneumonia | Onset | Severity | Specific symptoms | X-ray |
| Typical pneumonia | Acute | More severe | - Coughs with large amounts of yellowish-green mucus.
- Other respiratory symptoms such as chest pain, difficulty breathing, etc.
- Tiredness, fatigue
| Lobar consolidation |
| Atypical pneumonia | Insidious | Less severe | - Dry cough
- Flu-like symptoms: muscle aches, headaches, etc.
| Diffuse interstitial infiltrates |
Typical and atypical pneumonia onset
Typical pneumonia has a very acute onset. Hard and fast, you might say. Very soon after a person gets sick with typical pneumonia, they start to feel very ill.
Atypical pneumonia, on the other hand, has a more insidious onset. It starts more slowly and doesn't make you feel as sick. It also tends to last longer than typical pneumonia does.
Typical and atypical pneumonia symptoms
We know typical pneumonia is more severe, but even beyond that, it has certain symptoms that you will not see in atypical pneumonia. Typical pneumonia presents with coughs that produce large amounts of yellowish-green mucus. People who are suffering from typical pneumonia also feel more under the weather, and probably cannot go to school or work. They will likely also have lots of other respiratory symptoms such as chest pain, difficulty breathing, and so on.
People with atypical pneumonia tend to have a dry cough, without much mucus. The cough is sometimes described as hacking. Atypical pneumonia also tends to have less respiratory and lung symptoms, and more flu-like symptoms like muscle aches or headaches. In fact, people with atypical pneumonia often think they have the flu instead of pneumonia.
Typical and atypical pneumonia X-rays
When a doctor orders an X-ray of the lungs of someone with pneumonia, the appearance of the scan will be very different if it is typical or atypical pneumonia.
Typical pneumonia will show what is called "lobar consolidation". This means that an entire section (sections of the lungs are called lobes) of the lung will be thickened and consolidated due to the bacterial infection. The pneumonia is localized mostly within this lobe.
Atypical pneumonia, on the other hand, will show what is called medically "diffuse interstitial infiltrates", which means lots of increased white markings all over the lungs in a diffuse pattern.
Atypical pneumonia is not localized to any particular lobe, it is spread out all over the lung. Atypical pneumonia is also characterized as looking "worse than it actually is" on an X-ray.
A young person who feels mostly fine, with a bit of dry cough and some tiredness, may go to the doctor and get a chest x-ray done to check for pneumonia, and see these dramatic interstitial infiltrates on their x-ray and become worried. But not to worry! This is just how atypical pneumonia appears and it is not usually a drastic disease.
Figure 1. This illustration compares x-rays indicating typical and atypical pneumonia.
General bacterial pneumonia symptoms
Typical and atypical pneumonia have slightly different symptoms, as we have seen, however, there are overarching symptoms that both types of pneumonia share. The signs and symptoms of bacterial pneumonia by organ system are:
Sinuses and upper airways
What is in a cough? Mucous,
blood, or nothing at all?
Some bacteria cause productive coughs. Productive means there's a lot of mucus, typically green or yellow mucous, seen after a coughing fit. Other bacteria cause dry coughs, which have a dry sound (as opposed to the wet sound of productive coughs) and do not contain mucus.
Sometimes, bacterial pneumonia causes blood to be present in the cough, called hemoptysis. This can be due to the bacteria itself or due to mechanical damage or inflammation of the lungs from coughing too hard and/or too frequently.
Lungs and lower airways
- Chest pain
- Fast breathing (called tachypnea)
- Increased lung sounds on auscultation
Auscultation - typically auscultation involves putting a stethoscope on the chest of a patient and listening for lung sounds. You can auscultate other parts of the body as well, such as the heart and the intestines.
Auscultation is defined as listening to the sounds of certain body organs to help define and decipher a medical diagnosis.
Figure 2. Auscultation.
Systemic
A systemic symptom is one that affects multiple or even all parts of the body, not just one organ system.
- Fever
- Chills
- Nausea
- Loss of Appetite
- Sweating at night
Unique Symptoms
Some symptoms and circumstances are unique to specific bacteria that cause pneumonia. These symptoms are termed "pathognomonic" for that particular bacteria, meaning that when you see that symptom it is a big hint that a particular bacteria is causing the infection.
- Rust-coloured sputum: Sputum means mucus. This observation is pathognomonic for Streptpcoccus pneumonia pneumonia
- Nosocomial infection: a nosocomial infection is one that arises during or after a hospital visit. Pseudomonas pneumonia occurs commonly in people who have been intubated.
- Post viral: Sometimes, bacterial pneumonia follows a viral infection like the flu. Typically, when this happens the culprit organism is Staph. aureus
- Diarrhoea and vomiting: Legionnaires disease, a fancy name for a type of pneumonia caused by Legionella pneumophila, has both respiratory symptoms and also a lot of diarrhoea and vomiting. If it looks like someone has pneumonia and food poisoning at the same time, this is pathognomonic for Legionella.
- Atypical: Pneumonia is typically a very fulminant infection, meaning it occurs quickly, severely, and with a sensation of being acutely ill. This is not the case with all kinds of bacterial pneumonia though. Some bacterial pneumonia; called atypical pneumonia or sometimes called "walking pneumonia", have much more mild presentations, with lesser symptoms, and a dry cough versus the productive cough seen in typical pneumonia. Atypical pneumonia is often caused by Mycoplasma.
Is bacterial pneumonia contagious?
Bacterial pneumonia, like many diseases caused by microorganisms, is contagious and it can be spread through the air by respiratory droplets when an infected person coughs or sneezes. It can also be spread through close contact with an infected person such as sharing eating utensils or touching contaminated surfaces.
Causes of bacterial pneumonia
Bacteria that cause pneumonia
We have already mentioned some symptoms that are pathognomonic for specific bacteria. Now let us examine all the common and some of the uncommon bacterial pathogens that lead to pneumonia in different groups of people.
The most common bacterial causative agents of pneumonia include:
Streptococcus pneumoniae - typical pneumonia
Haemophilus influenzae - typical pneumonia
Staphylococcus aureus - typical pneumonia
Mycoplasma - atypical pneumonia
Chlamydia pneumoniae - atypical pneumonia
Rarer causes of pneumonia include:
Klebsiella - especially in people who have problems with alcohol abuse
Pseudomonas aeruginosa - especially in people with frequent hospitalization
Burkholderia cepacia - especially in people with cystic fibrosis
Listeria monocytogenes - especially in very young babies (neonates).
Bacterial pneumonia treatment
How do we treat bacterial pneumonia? The answer is with antibiotics. But which antibiotics? That depends on the organism that is causing pneumonia.
Some bacterial pneumonia is treated empirically, with some well-known drugs like penicillin or lesser-known drugs like cephalosporins and vancomycin.
Empiric treatment means it occurs based on a doctor's best guess or educated guess.
Sometimes, if a person is too ill and cannot wait for extensive blood work, cultures, and lab tests, they must be treated immediately. A doctor will assess the patient's symptoms and history and give them an antibiotic treatment that they believe will work best for them, at least for the time being.
Usually, while empiric treatment is being given, lab tests are run and the exact bacteria that the patient is infected with becomes known. Then, the doctor can tailor, fine-tune or change if necessary, the antibiotic that the patient is being given. The benefit of empiric treatment is that it can be lifesaving for patients, giving doctors and laboratories time to get blood work done.
Oftentimes, features that are pathognomonic to certain bacteria help doctors to determine which bacteria a patient is infected with and give them an antibiotic that is active against that kind of bacteria.
Due to too much unnecessary antibiotic treatment in the past, many bacteria are now resistant to many antibiotics. This can be a downside of empiric treatment that doctors must weigh when treating patients. Doctors need to give patients medicines that the bacteria they are infected with are still susceptible to.
Recovery time for bacterial pneumonia
Recovery time for bacterial pneumonia can vary depending on a number of factors, including the overall health of the individual, the severity of the infection, and the type of bacteria that caused the pneumonia.
For healthy individuals with mild to moderate cases of bacterial pneumonia, recovery time can take anywhere from one to three weeks. However, more severe cases or those in people with chronic health conditions can take longer, up to six weeks or more.
If a person is hospitalized, recovery time may depend on the treatment given such as antibiotics and oxygen therapy. They may need to stay in the hospital for several days to a week to get the proper treatment.
It is important to note that even after completing treatment, some people may continue to experience fatigue, weakness and shortness of breath for several weeks or even months.
It's also crucial to follow the healthcare provider's instructions and finish the full course of antibiotics and avoid activities that can stress the body, such as sports and heavy lifting.
Difference between viral and bacterial pneumonia
In this lesson, we discussed only bacterial pneumonia. However, there are fungal, protist, and, most importantly, viral agents of pneumonia as well.
There are some typical differences between viral pneumonia and bacterial pneumonia.
- Treatment:
- One of the biggest and most clinically relevant differences is that bacterial pneumonia can be treated with antibiotics, while viral cannot. If you treat viral pneumonia with antibiotics, you will probably just cause increased bacterial resistance to antibiotics in the population.
- X-ray:
- Viral pneumonia always presents with diffuse interstitial infiltrates, while only atypical pneumonia presents this way in bacterial pneumonia. Typical bacterial pneumonia presents with lobar consolidations.
- Fever:
- For the first few days of viral pneumonia, there often isn't any fever. If there is a fever, it's very mild. For the first few days of typical bacterial pneumonia, the fever will be high and severe.
- Vaccination:
- You can vaccinate against many bacterial causes of pneumonia, especially the number one culprit: Strep. pneumoniae. Most viral pneumonia agents are not vaccinated against.
Bacterial Pneumonia - Key takeaways
- Bacteria can cause pneumonia, so can viruses and fungi
- Bacterial pneumonia can be either atypical or typical
- Atypical pneumonia is usually milder in symptoms
- Typical pneumonia usually has more severe symptoms
References
- Figure 1: Auscultation (https://commons.wikimedia.org/wiki/File:Auscultation_of_a_women.jpg) by Wesley Carter, U.S. Air Force. Public Domain.
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