What is Streptococcus pneumoniae?
Community-acquired pneumonia, which is pneumonia contracted outside a medical or healthcare setting, is the seventh leading cause of death in the United States. It also costs up to $9 billion each year due to hospital stays. Sadly, up to 22% of people who are hospitalized for this type of pneumonia die within a month, making it the most deadly of all infectious diseases.
A type of bacteria called Streptococcus pneumoniae has historically been the leading culprit in causing this pneumonia worldwide. Before the use of antibiotics, it was believed to be the cause of 95% of all pneumonia cases. Today, this bacterium is responsible for about 15% of pneumonia cases in the United States and 27% of cases globally. However, only about 20% to 25% of pneumonia cases caused by S. pneumoniae can be confirmed by blood tests, making it difficult for doctors to diagnose.
What Causes Streptococcus pneumoniae?
: S. pneumonia, a type of bacteria, was first found by Louis Pasteur in 1881 in the saliva of a patient suffering from rabies. In 1883, experts reported the bacteria’s connection to a type of pneumonia. Even though there were attempts to create a vaccine starting from 1911, it wasn’t until 1977 when the first vaccine for this type of bacteria was produced in the United States. After that, the first conjugate vaccine – which is a type of vaccine that creates a stronger immune response – was launched in 2000.
S. pneumonia is a specific shape (lancet-shaped) and typically found in pairs or short chains. It’s a “gram-positive, facultative anaerobic organism,” which is just a way of categorizing bacteria based on how they react to a certain stain test and whether they need oxygen to survive. They can cause illness in humans, mainly when they’re encapsulated, or covered with a protective layer. This layer also helps to classify the bacteria into different types. By 2011, 92 distinct serotype – or variations – of this bacteria have been discovered.
Risk Factors and Frequency for Streptococcus pneumoniae
Pneumococcal infections are found all over the world, and they are most likely to appear in the winter and early spring. A bacteria known as IS. pneumoniae is widespread because it can thrive in the nasopharynx – the area behind your nose. Almost half of all healthy kids and up to 30% of healthy adults carry this bacteria. But, thanks to a vaccine for Streptococcus pneumoniae, fewer children now carry it.
Pneumonia caused by S. pneumoniae can happen to anyone but it is seen more often in people over 65, kids under 2, smokers, alcohol misusers, people with asthma or COPD (a lung condition), and people without a spleen. In the United States, around 5 to 6 in every 100,000 adults are diagnosed with a confirmed S. pneumoniae infection. The rates go up for those over 65 (36.4 in 100,000) and babies under 1 (34.2 in 100,000). The World Health Organization has reported that in 2005, 1.6 million people, including 1 million children under 5, died because of streptococcus pneumoniae. It’s also a common extra infection in people who already have the flu, which can increase illness and death rates.
- Pneumococcal infections happen globally, and are most frequent in winter and early spring.
- Half of healthy children and 30% of healthy adults can carry the bacteria that causes it.
- With vaccination, fewer children carry the bacteria.
- People over 65, under 2, smokers, alcohol misusers, people with asthma or COPD, or people without a spleen are more at risk.
- In the United States, 5 to 6 adults in every 100,000 are diagnosed with a confirmed infection.
- The rate is higher in those over 65 and babies under 1.
- In 2005, around 1.6 million people died from streptococcus pneumoniae globally.
- It’s also a common additional infection in flu patients, increasing disease and death rates.
Signs and Symptoms of Streptococcus pneumoniae
Pneumonia is an illness that can show up with a variety of symptoms, but the most common ones include shortness of breath, coughing, chest pain, mucus production, and fever. However, these symptoms don’t always definitely indicate pneumonia. Particularly in older adults, the symptoms might be different, such as general weakness, changes in mental state, or fatigue. These less typical symptoms can sometimes lead to delays in diagnosing the condition, which can be serious because pneumonia can be particularly dangerous for older people.
When a doctor is checking someone for pneumonia, their vital signs can be very helpful. If the patient has a higher than normal heart rate (tachypnea), lack of oxygen (hypoxia), or fever (hyperthermia), the doctor will likely want to do further tests. They might also listen for certain sounds in the lungs that would suggest pneumonia, though these signs aren’t always reliable.
- Shortness of breath
- Coughing
- Chest pain
- Mucus production
- Fever
- In older adults, symptoms can also include general weakness, changes in mental state, or fatigue
Testing for Streptococcus pneumoniae
Regular lab tests might not help in identifying the specific germ causing pneumonia, but they can assist in determining how serious the condition might be for the patient.
A chest x-ray is a commonly used technique to diagnose pneumonia. Traditionally, it was believed that a specific type of pneumonia was caused by a particular organism called S. pneumonia. However, recent studies have shown that an x-ray may not reliably determine the exact organism causing pneumonia in patients. It’s also important to note that x-rays do not always detect pneumonia.
CT scans have proven to offer better accuracy and reliability in diagnosing this kind of pneumonia than a regular chest x-ray. However, they are not always the go-to option because they can be expensive and they expose the patient to a relatively high amount of radiation.
There are other ways to figure out what organism is causing pneumonia. These can include blood tests, analyzing mucus coughed up from the lungs (sputum analysis), and testing urine for antigens (substances that trigger an immune response). However, routinely collecting blood samples to culture has been a point of debate among medical professionals. Some major health organizations like the Centers for Medicaid and Medicare Services, as well as the Joint Commission on Accreditation of Healthcare Organizations, have said that routinely collecting blood cultures is not a main practice that they track. The American College of Emergency Physicians also doesn’t usually recommend routine blood cultures for patients admitted with community-acquired pneumonia (CAP).
Blood cultures should be considered in severe cases or patients with certain conditions like low white blood cell count (leukopenia), cavity-like lesions in the lung, severe liver disease, alcohol abuse, lack of a spleen (asplenia), or fluid buildup around the lungs (pleural effusions). Even when these blood cultures are positive, they usually show S. pneumonia but seldom alter the treatment plan.
Sputum cultures are typically not very reliable in identifying the organism causing pneumonia. However, sputum cultures should be obtained for patients suspected to have a drug-resistant organism.
A urinary antigen test can help doctors diagnose cases of S. pneumonia – it is sensitive 80% of the time and specific 97% of the time. However, its relevance in children is questionable as many children naturally carry traces of S. pneumonia.
Treatment Options for Streptococcus pneumoniae
The main treatment for patients with S. pneumonia, a kind of bacteria that can cause diseases such as pneumonia and meningitis, involves antibiotics and supportive care. Supportive care might require mechanical ventilation, which is a machine that helps you breathe if it’s difficult to do so on your own. Though the exact method for treating pneumonia can depend on where you live and the severity of your condition, some general trends can be observed.
Generally speaking, patients with a lower-risk case of community-acquired pneumonia (CAP) — that is, pneumonia that was contracted outside of a hospital or healthcare facility — are usually treated outside the hospital using a specific class of antibiotics called macrolides.
For higher-risk patients treated outside hospital, a type of antibiotics called respiratory fluoroquinolones is usually used. If they’re admitted to the hospital but aren’t severe enough to require intensive care unit (ICU) admission, they’re typically treated with two types of antibiotics usually a beta-lactam, another class of antibiotics, combined with either a macrolide or a respiratory fluoroquinolone.
For patients admitted to the ICU, the recommendation is a combination of a beta-lactam with either a macrolide or a respiratory fluoroquinolone. Note that a recent review found no antibiotic regimen to be superior to others in the outpatient setting, which means the choice of antibiotic can vary.
When diagnosed, patients should begin taking antibiotics as soon as possible. However, there isn’t strong enough evidence to suggest that beginning antibiotics within a specific timeframe, such as less than 4, 6, or 8 hours from diagnosis, leads to better patient outcomes.
If the pneumonia is complicated and involves what is known as a parapneumonic effusion — a buildup of fluid between the lung and the chest wall — a tube may need to be inserted to drain the fluid. If this condition advances to an abscess (called an empyema) which can’t be effectively drained with a tube, then a procedure called video-assisted thoracoscopic surgery (VATS) might be performed. VATS uses a small camera and surgical tools to examine and potentially treat problems inside your chest.
What else can Streptococcus pneumoniae be?
While pneumococcal pneumonia doesn’t present with specific signs and symptoms, when the diagnosis is considered, it’s important to also think about the following potential conditions:
- Viral pneumonia
- PCP (Pneumocystis pneumonia)
- Influenza
- Klebsiella pneumonia (another type of bacterial pneumonia)
- Legionella pneumonia
- Pleural effusion (fluid accumulation around the lungs)
- Upper respiratory tract infection
Possible Complications When Diagnosed with Streptococcus pneumoniae
If pneumococcal pneumonia isn’t treated with the right antibiotics at the right time, or if it’s caused by particularly harmful or resistant strains of bacteria, it can lead to several complications.
Here are some common complications:
- Necrotizing pneumonia: a severe form of pneumonia that causes tissue death in the lungs
- Lung abscess: a condition where a pus-filled cavity forms in the lung
- Parapneumonic effusion: fluid building between the lung and chest cavity
- Empyema: infection in the space between the lungs and the chest wall
- Septicemia and septic shock: serious infections that spread throughout the body
Preventing Streptococcus pneumoniae
All children should receive a shot known as a “conjugate pneumococcal vaccine”. This vaccine helps protect against certain types of infections caused by pneumococcal bacteria. These bacteria can cause illnesses like pneumonia and meningitis. People who are more likely to get these infections should also be vaccinated. These include people over 65 years old, those with lung diseases, people who drink alcohol heavily, those with ongoing liver or kidney diseases, and people who have had certain surgical procedures like the removal of the spleen.
Smoking cigarettes can make a person more likely to get a pneumococcal infection, even if they’re otherwise healthy. So, it’s a good idea for people to quit smoking to reduce this risk. Eating a balanced diet, living in healthy surroundings, and avoiding places with many children (like daycare centers) can also help lower the chances of getting this infection.
