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Streptococcus pneumoniae: Bacteria and Pneumococcal Diseases

Linda Crampton is a writer and teacher with a first-class honors degree in biology. She often writes about the scientific basis of disease.

Streptococcus pneumoniae lives in our nasal cavity and nasopharynx.

Streptococcus pneumoniae lives in our nasal cavity and nasopharynx.

What Are Pneumococcal Diseases?

Streptococcus pneumoniae is a bacterium that lives in the human nose. It may sound like a dangerous creature because of its name. The bacterium can certainly cause some unpleasant and even life-threatening diseases, including pneumonia. It often lives harmlessly in and around the nose without producing any symptoms, however.

S. pneumoniae (as it's often called) is also known as a pneumococcus. A coccus is a bacterium with round cells. The plural form is cocci. Diseases caused by S. pneumoniae are known as pneumococcal diseases or infections. The prefix "pneumo" refers to the lungs. Unfortunately, the bacterium sometimes travels beyond the respiratory system and may cause problems in the heart, brain, or other parts of the body.

S. pneumoniae often exists as pairs of bacteria known as diplococci. The green coloration in this photo is artificial.

S. pneumoniae often exists as pairs of bacteria known as diplococci. The green coloration in this photo is artificial.

The scientific name of an organism consists of the genus and the species. One convention in science is that when a scientific name has been written once in an article, subsequent references to the organism may abbreviate the genus. I've followed this convention.

Streptococcus pneumoniae

Streptococcus is a genus of microscopic, single-celled bacteria. The individual cells often join to form pairs and are sometimes found in chains. Each cell is surrounded by a protective capsule. S. pneumoniae was discovered in 1881 by Louis Pasteur. Pasteur was a French microbiologist and chemist who is famous for his discoveries of methods to prevent disease. He invented the process of pasteurization, which is named in his honour.

As is the case for other bacteria, researchers are discovering that S. pneumoniae is far more complex than was originally realized. It produces a variety of chemicals to help it adhere to cells in different parts of our body and to penetrate them when it becomes invasive. It also forms biofilms, which are layers of bacteria attached to a surface and covered by a protective polysaccharide coating. Bacteria in biofilms send chemical messages to each other and coordinate their behaviour. Like some other bacteria that have been studied, pneumococcus cells sometimes exchange genes with their neighbours. This means that they can change their characteristics during their lifetime.

Pneumococci are common inhabitants of the respiratory tract and may be isolated from the nasopharynx of 5% to 90% of healthy persons. Rates of asymptomatic carriage vary with age, environment, and the presence of upper respiratory infections.

— CDC (Centers for Disease Control and Prevention)

Coughs and sneezes spread diseases. This photo of a baby who is about to sneeze was taken at just the right moment.

Coughs and sneezes spread diseases. This photo of a baby who is about to sneeze was taken at just the right moment.

Transmission of Streptococcus pneumoniae

S. pneumoniae is transmitted in microaerosol form. When we sneeze, cough, or even talk, we release tiny droplets of liquid from our nose and throat. These droplets contain bacteria and are inhaled by other people. Close contact increases the risk that bacteria will be inhaled in sufficient quantity to hurt people.

Touching objects recently contaminated by bacteria, including eating and drinking utensils, and then touching our nose or mouth can also transfer pneumococci into our body. Until recently, it was thought that the bacterium didn't live long outside the body and that cells dropped on surfaces would soon die. Recent research has called this assumption into doubt. Tests have shown that S. pneumoniae has a good ability to survive desiccation and remain infective.

A view of Streptococuus pneumoniae at higher magnification

A view of Streptococuus pneumoniae at higher magnification

Invasive Bacterial Infections

Our immune system can often destroy bacteria that enter our body or at least restrict their spread, but this isn't always the case. Bacteria sometimes move beyond their infection area.

S. pneumoniae may travel away from the nasopharynx through passageways and cause conditions such as pneumonia and otitis media. It may also travel beyond the respiratory system via the bloodstream. If bacteria in the blood aren't destroyed by the immune system, they are said to be invasive. Infections that may be caused by invasive pneumococci include meningitis and endocarditis. Bacteria in the bloodstream may trigger sepsis.

People whose immune system isn't working at full effectiveness are most likely to experience an invasive infection. These people include children younger than 5, people aged 65 or older, people suffering from an HIV infection, cancer, or diabetes, and people receiving immunosuppressive drugs after an organ transplant. The people in these categories won't necessarily experience an invasive infection when S. pneumoniae is present, but the probability is increased.

Someone with pneumonia may not have all of the symptoms shown in the illustration above. "Pleuritic chest pain" refers to pain caused by inflammation of the membranes surrounding the lungs. "Hemoptysis" means coughing up blood.

Pneumonia

Pneumonia is a disease in which the air sacs in the lungs are inflamed. As a result of the inflammation, the sacs fill with fluid, which makes breathing difficult. The inflammation is caused by the presence of bacteria, viruses, fungi, or parasites. Pneumonia ranges from a mild to a very serious condition. S. pneumoniae is the most common cause of community-acquired pneumonia in North America and Europe.

People with certain pre-existing disorders are more susceptible to pneumonia than healthy people. The disorders include asthma, chronic bronchitis, and COPD (chronic obstructive pulmonary disease). People with these health problems may not be able to empty their lungs sufficiently during exhalation, which increases the risk of pneumonia.

The ear during a case of otitis media

The ear during a case of otitis media

Structure and Function of the Ear

S. pneumoniae sometimes contributes to an ear condition called otitis media. A disorder whose name ends in "itis" involves inflammation. In the case of otitis media, the middle ear is inflamed. The term "middle ear" has a specific meaning in human anatomy. Our ears consist of more than what is visible on the sides of our head.

  • The outer or external ear consists of the visible pinna and the ear canal inside the skull. Sound vibrations travel along the canal and hit the eardrum (or the tympanic membrane) at the end.
  • The middle ear is located behind the eardrum and is filled with air. It contains three tiny bones called ossicles that transmit sound vibrations.
  • The inner or internal ear contains the hearing organ or cochlea. It responds to sound vibrations by sending a signal along the auditory nerve to the brain. The inner ear also contains the semicircular canals, which are responsible for our sense of balance.

Acute Otitis Media or AOM

A channel called the Eustachian tube (or the auditory tube) connects the middle ear to the nasopharynx behind the nose. The main function of the tube is to equalize the air pressure in the middle ear and the atmosphere. It also allows for the drainage of secretions and debris that collect in the middle ear. The tube opens and closes as necessary.

Acute otitis media, or AOM, generally follows an upper respiratory tract infection. The development of AOM isn't fully understood. The middle ear and the Eustachian tube are lined with the same type of tissue that lines the nasal cavity and are thought to respond in the same way during an upper respiratory tract infection. Fluid is released from the inflamed and swollen lining of the middle ear. The Eustachian tube becomes blocked or narrowed when its lining becomes inflamed and swollen.

The narrowed Eustachian tube is unable to function properly. As a result, bacteria and viruses in the nasopharynx may travel through the Eustachian tube into the middle ear, resulting in a secondary infection and making conditions even worse. The bacteria are very often S. pneumoniae, although other bacteria may be present in addition to or instead of the pneumococcus.

The main symptom of AOM is often pain caused by the pressure of middle ear fluid on the eardrum. The patient may also experience partial hearing loss and a fever.

The meninges are three membranes that surround the brain and spinal cord. The outer membrane is known as the dura mater, the middle one is the arachnoid, and the inner one is the pia mater.

Meningitis

Meningitis is an inflammation of the membranes covering the brain or spinal cord. The membranes are collectively known as the meninges. Symptoms of meningitis may include a headache, a stiff neck, nausea, vomiting, and a fever. Meningitis can sometimes be dangerous because swelling of the meninges during inflammation can put pressure on the brain.

Meningitis is caused by both bacteria and viruses. Most cases are caused by viruses, but some result from a bacterial infection. Bacterial meningitis is more likely to be life-threatening and can be very serious. S. pneumoniae is the most common cause of bacterial meningitis.

Bacteria may reach the meninges after entering the bloodstream. They may sometimes reach the structures during another health problem, such as an ear infection or a fractured skull. Treatment often involves antibiotics to kill bacteria and corticosteroids to prevent swelling. Viral meningitis may require treatment, but according to the CDC (Centers for Disease Control and Prevention), it sometimes disappears on its own. It's always necessary to see a doctor about a possible case of meningitis, however.

The heart contains chambers that fill with blood. The wall of the heart is made of muscle, or myocardium, which contracts to push the blood to where it's needed. A double-walled membranous sac called the pericardium covers the outside of the heart muscle and a membrane known as the endocardium lines the inside.

Endocarditis

Endocarditis is inflammation of the endocardium. The inflammation is generally caused by a bacterial infection. The bacteria come from another part of the body, such as the mouth, and reach the heart via the bloodstream. S. pneumoniae is one cause of endocarditis, but some other bacteria also cause the disease.

Bacteria may enter a person's bloodstream as a result of the following processes.

  • Chewing food, brushing the teeth, and flossing when the gums are unhealthy
  • Undergoing dental surgery in which the gums are cut
  • Experiencing damage to the intestinal lining
  • Receiving a skin piercing with a needle
  • Experiencing an injury to the skin that leaves a sore

Even vigorously brushing the teeth when the gums are healthy may cause bacteria to enter the bloodstream. As long as the bacteria that enter the blood are present at a low concentration, the body should be able to get rid of them. A high concentration of bacteria in the blood may be dangerous, however.

Endocarditis is a potentially serious condition because it may damage the valves inside the heart. The valves prevent blood from flowing backwards as the heart beats. This is an essential process in order for blood to leave the heart. Valve damage is more likely if the valves have been weakened by another cause. Endocarditis is often treated with antibiotics and sometimes with surgery.

Bacteremia and Sepsis

Bacteremia

Bacteremia is a condition in which bacteria are present in the blood. Temporary bacteremia caused by activities such as brushing the teeth may not be a problem, but the disorder can be serious. Bacteria that stay in the blood can be transferred to different organs and tissues in the body and may trigger sepsis.

Sepsis

Sepsis arises due to an excessively strong reaction of the immune system to harmful items in the blood, such as bacterial cells or the toxins that they produce. The condition is sometimes referred to as blood poisoning by the general public. The blood is flooded by chemicals designed to fight the bacteria. These chemicals cause inflammation throughout the body and trigger reactions that damage multiple organs.

Septic Shock

Sepsis can lead to septic shock, a condition that involves dangerously low blood pressure. During inflammation, blood vessels dilate and fluid leaves them. In someone with mild inflammation in a limited area, the process can be useful because the fluid carries items that can deal with the problem that exists. In septic shock, so many blood vessels dilate and so much fluid leaves them that blood pressure decreases dramatically.

S. pneumoniae and Sepsis

In some situations, S. pneumoniae can cause sepsis. It's a very serious condition that is life threatening and requires a hospital visit. Antibiotics, intravenous fluids, and procedures to protect organs are generally part of the treatment. The sooner the treatment begins, the better.

The inflammatory response is a normal part of the immune system's activities as it fights invaders and damage. It's usually a temporary and helpful action that occurs in a limited area of the body. The excessive and widespread inflammation that occurs during sepsis is dangerous, however.

Preventing Pneumococcal Diseases

Antibiotics are generally the main treatment for pneumococcal infections. Additional treatments specific to the condition of the patient or the particular part of the body that is affected may also be used.

It's best to prevent pneumococcal diseases if we can. Since there is some uncertainty about the length of time that S. pneumoniae can survive outside the body, it's important to wash our hands frequently and to avoid touching our eyes, nose, and mouth as much as possible. These steps are helpful for avoiding any type of bacterial infection. Avoiding close contact with people who are sick would also be helpful, although it's not always possible to do this. Following a healthy diet and exercising regularly will help to keep our immune system working effectively.

A vaccine is available to prevent pneumococcal diseases. The bacterium exists in slightly different forms known as serotypes. A pneumococcal vaccine protects against the most common serotypes in an area, but it doesn't protect against all of them. Doctors often recommend that people with certain health problems or in certain life stages receive the vaccine, however. As more research is performed, we may have other ways to protect ourselves from the sometimes annoying and occasionally dangerous S. pneumoniae bacterium.

References

This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.

Questions & Answers

Question: How long is recovery?

Answer: The recovery time varies considerably. It depends on many factors, such as the age and overall health of the patient, the type of treatment being received, and the time when the treatment began. A patient may start to feel better a few days after treatment begins, but complete recovery may take considerably longer. A doctor will be able to give you a better idea of recovery time, especially if they are familiar with a patient's case.

© 2016 Linda Crampton

Comments

Linda Crampton (author) from British Columbia, Canada on September 08, 2019:

Thank you, Cynthia. I appreciate your kind comment.

Cynthia Zirkwitz from Vancouver Island, Canada on September 08, 2019:

Hi Linda

This is a very comprehensive article about streptococcus. I think you answered any questions I might have had in the past and this article will make a great future reference. I have had something called "walking pneumonia" and hope not to have it again any time soon. What you write about "inflammation" fits into what I am learning about the reasons for disease in our bodies. I appreciate your ability to take a science subject and make it interesting and accessible to those of us who are not very scientifically-knowledgeable.

Linda Crampton (author) from British Columbia, Canada on May 11, 2019:

Thank you very much, Suzette. I appreciate your comment. I'm sorry that you were sick during the winter.

suzettenaples on May 11, 2019:

Linda; fascinating article. I had streptococcus pneumonia this winter and it was not fun. This article explained very well what was going on in my body. Thumbs up!

Linda Crampton (author) from British Columbia, Canada on June 09, 2018:

Thanks for the comment, Peg. I'm very sorry that your auntie experienced such bad symptoms.

Peg Cole from Northeast of Dallas, Texas on June 09, 2018:

Your explanation of this disease was understandable and fascinating. I understood a lot more about the diagnosis my 97 year old auntie received at the very end. She had a case of severe sepsis that shut her organs down. I had noticed toward the end of her time that her normally hearty appetite was diminished and her energy had dropped and her level of pain had increased. I appreciate reading your detailed article that clarified much for me.

Linda Crampton (author) from British Columbia, Canada on December 13, 2017:

Thank you very much, Glenn. I appreciate your visit and comment.

Glenn Stok from Long Island, NY on December 13, 2017:

I learned a lot more from you article Linda. You included important detail and gave clear explanations that made it easy to follow.

I recently read a book written by a brain surgeon who was in a coma with bacterial meningitis. His recovery caught my attention and I became interested in studying S. Pneumoniae. Your article was very worthwhile reading.

Linda Crampton (author) from British Columbia, Canada on November 05, 2017:

You need to ask your doctor this question, Paige.

Paige on November 05, 2017:

Is it necessary to get a pneumonia shot?

Linda Crampton (author) from British Columbia, Canada on November 06, 2016:

Congratulations on your good health, ValKaras! Whatever you're doing seems to be working very well. I hope you continue to stay healthy. I appreciate your comment.

ValKaras on November 06, 2016:

Hi, Linda,

What a great and informative hub! It actually makes me feel good to see how well my immune system is working at this age of 72, as I haven't seen a doctor for more than 8 years, and haven't been taking any medications whatsoever.

Since immune and nervous systems work so closely, I am not surprised as I am quite a happy camper, also staying away from sugar and wheat, and not using any chemicals, including coffee.

It's good to know of all these diseases that I don't get, LOL.

Linda Crampton (author) from British Columbia, Canada on November 06, 2016:

Thank you very much for the comment and for sharing the interesting information, Martie. What a shame that Louis Washkansky was unable to live for longer with his new heart.

Martie Coetser from South Africa on November 06, 2016:

The first patient in the world who have had a heart transplant - performed on December 3, 1967 by Dr Chris Barnard from South Africa - died due to a streptococcus pneumoniae, which was detected in his nose before the operation. Because the body's immune system was suppressed after the operation in order to prevent rejection of the new heart, the single streptococcus pneumoniae in the nose multiplied within days, killing Louis Washkansky.

Very interesting, usable and well -presented article! Thank you, Alicia.

Linda Crampton (author) from British Columbia, Canada on October 25, 2016:

Thank you very much, Devika. I appreciate your visit and comment.

DDE on October 25, 2016:

Informative and needs more comments. An important hub to learn from as most people don't know about it.

Linda Crampton (author) from British Columbia, Canada on October 03, 2016:

Hi, Faith. Thanks for the visit. Unfortunately, there are some nasty bacteria that infect humans. It's good to try to protect ourselves from them when we can. I think they're fascinating creatures, though!

Faith Reaper on October 03, 2016:

Nasty diseases here! Since my children are grown and on there own now, I haven't been as devoted to Chloroxing my house or lysoling it, like I had when they were growing up, except before the grandchildren come up. This is a good reminder that these nasty diseases are still here. May have to think about getting that shot now too.

Thank you for the important hub here.

Linda Crampton (author) from British Columbia, Canada on October 03, 2016:

Thank you very much for the comment, Dianna. As you say, it is important to detect the source of a disease as soon as possible.

Dianna Mendez on October 03, 2016:

It is always good to know the background on these diseases. The earlier one can detect the source the better. As always, you present a great post and well written.

Linda Crampton (author) from British Columbia, Canada on September 28, 2016:

Thanks, Vellur. I appreciate your comment a great deal.

Nithya Venkat from Dubai on September 28, 2016:

Informative and an easy to understand article about Streptococcus Pneumoniae Bacteria and Pneumococcal Diseases. Love the way that you have explained in short about the part that is being affected before delving into the disease. Great hub.

Linda Crampton (author) from British Columbia, Canada on September 28, 2016:

Thank you very much, Manatita. Bacteria are interesting and sometimes useful creatures, but they can worry us at times!

manatita44 from london on September 28, 2016:

A very detailed and well-presented Hub. Trouble is that I'm worried now. (smile) I really love your attention to detail as usual, Alicia C.

Linda Crampton (author) from British Columbia, Canada on September 27, 2016:

Thanks for the comment and for telling your daughter about the hub, Penny. I think that microbiology is a very interesting topic.

Penny Leigh Sebring from Fort Collins on September 27, 2016:

Well written. I passed this hub on to my teenager. She wants to be a microbiologist so this is of particular interest to her!

Linda Crampton (author) from British Columbia, Canada on September 27, 2016:

Thank you very much, Bill. Infections can certainly be scary. It's impressive that microscopic, single-called creatures can cause so many problems, though!

Bill De Giulio from Massachusetts on September 27, 2016:

Hi Linda. What an education, thank you. We've had our share of scary infections over the years and this is serious stuff. Great job of explaining this in terms that we can all understand.

Linda Crampton (author) from British Columbia, Canada on September 27, 2016:

Thanks for the comment, Larry. It's sad that fighting disease seems to be a constant battle for humanity.

Larry Rankin from Oklahoma on September 27, 2016:

Oh great, more scary diseases;-)

Always fun and enlightening, Alicia.

Linda Crampton (author) from British Columbia, Canada on September 27, 2016:

Hi, Mel. I'm glad your son recovered. As you say, the bacterium is responsible for some common health problems that many of us have encountered. It can definitely be a nuisance! I've had pneumonia twice, though without tests I don't what organism caused it. Thanks for the visit.

Mel Carriere from San Diego California on September 27, 2016:

My son once had miocarditis, which is an inflammation of the lining around the heart. He was hospitalized for several days. I wonder if this condition is related to this bacterium, as well.

I think all of us have had, or know someone who has suffered from these elements. Very interesting review.

Linda Crampton (author) from British Columbia, Canada on September 27, 2016:

Thanks for the visit and comment, Bill. Bev's illness must have been very scary for both her and you. I hope she stays healthy and that your good health continues.

Linda Crampton (author) from British Columbia, Canada on September 27, 2016:

Hi, Flourish. Thank you for the comment. Bacteria are interesting creatures. Some are very useful and some are very scary!

Bill Holland from Olympia, WA on September 27, 2016:

This article brought back vivid memories of Bev in the hospital for ten days.....scary stuff, my friend. I thank the gods each day for my good health...crossing my fingers.

Thanks, again, for some great information.

FlourishAnyway from USA on September 27, 2016:

This is an important hub and made me want to get a pneumonia vaccine and Chlorox everything. Very well researched and written.