Wednesday, March 29, 2023

How Does Streptococcus Pneumoniae Cause Pneumonia

Medical History And Physical Exam

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Your doctor will ask about your signs and symptoms and when they began. Your doctor will also ask whether you have any risk factors for pneumonia. Your doctor also may ask about:

  • Exposure to sick people at home, school, or work or in a hospital
  • Flu or pneumonia vaccinations
  • Exposure to birds and other animals
  • Smoking

During your physical exam, your doctor will check your temperature and listen to your lungs with a stethoscope.

Accessing The Lower Respiratory Tract

Development of pneumonia is contingent on the ability of S. pneumoniae to establish a lower respiratory tract infection despite host defenses that either kill or clear the aspirated bacteria. The first barrier is the mucociliary escalator which mechanically works to keep aspirated particles and microorganisms out of the lungs. As is true for many respiratory viruses, neuraminidase plays an important role in initiating bacterial pneumonia. As indicated, neuraminidase deficient pneumococci do not cleave mucin efficiently and have a diminished capacity to adhere. Mutants deficient in nanA have a reduced capacity to bind to chinchilla tracheas ex vivo and are attenuated in their ability to cause a lower respiratory tract infection following intranasal challenge .

Pneumococcal Vaccine For Adults

Adults can have the pneumococcal vaccine or “pneumo jab” for free if they’re in a high-risk group for developing a pneumococcal infection.

If you think you could be eligible for the pneumococcal vaccine, speak to your GP or practice nurse to arrange an appointment.

Healthy adults usually only need one dose of the pneumo jab. However, if you’ve a weakened immune system or spleen disorder, you may need additional booster doses. Your GP can advise you about this.

After you’ve had the pneumo jab, you may experience some pain and inflammation at the site of the injection. This should last no longer than three days. Less commonly, some people report the symptoms of a mild fever. Again, this should pass quickly.

Read more about potential side effects of the pneumococcal vaccine.

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What Are The Causes Of Pneumonia

Pneumonia is commonly caused by an infection with a germ. The germ is usually a bacterium or a virus. There are three or four different bacteria that are the most common causes of pneumonia. There is also a well-known group of bacteria that causes pneumonia in about 3 out of 10 cases. They are called atypicals. Other germs such as fungi, yeasts, or protozoa can sometimes also cause pneumonia.

Rarely, non-infective pneumonia is caused by inhaling poisons or chemicals. Many different substances can cause this. They can be in the form of liquids, gases, small particles, dust or fumes.

You may breathe in some bacteria, viruses, or other germs. If you are normally healthy, a small number of germs usually doesnt matter. They will be trapped in your phlegm and killed by your immune system. Sometimes the germs multiply and cause lung infections. This is more likely to happen if you are already in poor health for example:

  • If you are frail or elderly.
  • If you have a chest disease.
  • If you have a low immunity to infection. Low immunity can be caused by such things as alcohol dependence, AIDS, or another serious illness.

However, even healthy people sometimes develop pneumonia.

Pneumonia can sometimes develop after an operation, particularly in the region of your head or neck. Having an anaesthetic can increase the risk.

Who Gets Pneumococcal Disease

Streptococcus Pneumoniae Photograph by Dennis Kunkel Microscopy/science ...

Although anyone can get pneumoccal disease, it most commonly occurs among young children, the elderly, or among people with serious underlying medical conditions, such as chronic lung, heart, or kidney disease. Others at risk include alcoholics, diabetics, and people with sickle cell anemia, or immunocompromising conditions such as HIV/AIDS, or those without a spleen .

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How Soon After Treatment For Pneumonia Will I Begin To Feel Better

How soon you will feel better depends on several factors, including:

  • Your age
  • The cause of your pneumonia
  • The severity of your pneumonia
  • If you have other at-risk conditions

If you are generally healthy, most symptoms of bacterial pneumonia usually begin to improve within 24 to 48 hours after starting treatment. Symptoms of viral pneumonia usually begin to improve within a few days after starting treatment. A cough can last for several weeks. Most people report being tired for about a month after contracting pneumonia.

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Streptococcus Pneumoniae Conjunctivitis Otitis Media Sinusitis Bronchitis And Tracheobronchitis

Most patients with conjunctivitis, otitis media, sinusitis, bronchitis, and tracheobronchitis due to Streptococcus pneumoniae infection can be treated on an outpatient basis with appropriate antibiotics. Compliance and follow-up should be ensured.

Infants and elderly patients, as well as those with immunodeficiencies, underlying disease, or signs of severe disease, should be treated more aggressively and hospitalized when indicated.

Otitis media

The guideline produced by the American Academies of Pediatrics and Family Practitioners for the treatment of pneumococcal otitis media recommends first-line treatment of most patients with amoxicillin 80-90 mg/kg/day or amoxicillin-clavulanate . Alternatives include cefdinir, cefuroxime, cefpodoxime, or ceftriaxone. These alternative antibiotics vary in their efficacy against the different pathogens known to cause otitis media. US data on in vitro susceptibility of Streptococcus pneumoniae to cefdinir and cefuroxime are 70% to 80%, respectively, compared with 84% to 92% to amoxicillin 123).

Patients who do not improve within 48-72 hours should be re-evaluated and their antibiotics switched to amoxicillin-clavulanate or a second- or third-generation oral cephalosporin, although highly resistant pneumococci may require treatment with parenteral ceftriaxone in order to achieve adequate serum levels of antibiotics.


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Viral Vs Bacterial Pneumonia Symptoms

Although viral and bacterial pneumonia symptoms can be very similar, there are some key differences between the two. The section below outlines some examples.

  • Lungs affected: Bacterial pneumonia tends to affect one particular part, or lobe, of a lung, whereas viral pneumonia typically affects both lungs.
  • Symptom onset: The symptoms of bacterial pneumonia can develop either suddenly or gradually, whereas symptoms of viral pneumonia typically develop over several days.
  • Symptoms: People with bacterial pneumonia usually experience a higher temperature and a wet cough, whereas people with viral pneumonia

Interaction With Haemophilus Influenzae

Streptococcus pneumoniae

Historically, Haemophilus influenzae has been a significant cause of infection, and both H. influenzae and S. pneumoniae can be found in the human upper respiratory system. A study of competition in vitro revealed S. pneumoniae overpowered H. influenzae by attacking it with hydrogen peroxide. However, in a study adding both bacteria to the nasal cavity of a mouse within two weeks, only H. influenzae survives further analysis showed that neutrophils exposed to dead H. influenzae were more aggressive in attacking S. pneumoniae.

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Interactions With Epithelial Cells Of The Nasopharynx

For over a century, S. pneumoniae has been categorized by serology with distinct serotypes identified on the basis of the greater than 90 immunologically and chemically distinct polysaccharide capsules that surround and protect the bacteria from phagocytosis .The capsular polysaccharide is also the basis of the current pneumococcal vaccines. Prior to the introduction of the 13-valent pneumococcal conjugate vaccine in 2010, studies found that only a small subset of the many capsular types was responsible for the majority of IPD isolates . The vast majority of pneumococci colonize the nasopharynx for up to 6 weeks and are then cleared with no systemic symptoms in the host . IPD is thought to occur most frequently early after the acquisition of a new capsular serotype as evidenced by shift in the strains most commonly isolated from IPD patients after vaccine introduction . Furthermore, attack rates are higher for serotypes that are carried for shorter periods of time versus those that colonize for extended periods .

Transmission Of S Pneumoniae

Until recently, all that was known about pneumococcal contagion was that spread requires close contact with a carrier and/or carriers , is more frequent during drier, colder months when airway secretions are more copious and is more likely to occur in conjunction with viral infections of the URT. This general ignorance about transmission was a consequence of a lack of tractable animal models and an inability to study human-to-human transmission in sufficient detail. In 2010, airborne transmission among closely housed ferrets co-infected with influenza A virus was described. Another group modelled murine transmission from index pups colonized at 4 days of age to littermate contact pups in the setting of IAV co-infection. Similar to human transmission, viral infection, close contact and younger age increased transmission. This infant mouse model has now enabled the study of the major steps during host-to-host spread, including exit from a colonized host , survival in the environment and acquisition by a new host.

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Enhancing Healthcare Team Outcomes

Streptococcal pneumonia is best managed with an interprofessional team that includes a pulmonologist, an infectious disease expert, an ICU nurse, a pharmacist, a respiratory therapist, and a dietitian. Patients need to be educated on the importance of vaccination and its benefits. In addition, patients should be advised to stop smoking and remain compliant with antibiotics. Since many patients with pneumonia are frail, a dietary consult should be sought to help improve the calorie intake. Others may need rehabilitation to restore muscle mass and increase exercise endurance.


The prognosis for patients with streptococcal pneumonia depends on the underlying risk factors, comorbidity, age, the extent of lung involvement, the need for mechanical ventilation and the type of antibiotic. Overall, the pneumonia is associated with high morbidity and mortality. Even those who survive tend to have residual deficits in lung mechanics and recovery is prolonged. Patients in the ICU tend to have the highest mortality approaching 3-20%.

Adults At Risk For Pneumococcal Disease

Streptococcus Pneumoniae Bacteria Photograph by Juergen Berger/science ...

Adults 65 years or older are at increased risk for pneumococcal disease.

Adults of all ages are also at increased risk for pneumococcal disease if they have:

  • Alcoholism
  • CSF leak
  • Diabetes
  • HIV infection, cancer, solid organ transplant, or another condition or taking medicine that weakens the immune system
  • Nephrotic syndrome
  • Sickle cell disease, a damaged spleen, or no spleen

Adults with certain medical conditions are at highest risk for invasive pneumococcal disease. Adults who smoke cigarettes are also at increased risk for pneumococcal disease.

For adults age 18 through 64 years with hematologic cancer, the rate of invasive pneumococcal disease in 20132014 was 129 per 100,000 population. Other conditions that place adults at highest risk for invasive pneumococcal disease include other immunosuppressive conditions from disease or drugs, functional or anatomic asplenia, and renal disease. Other conditions that increase the risk of invasive pneumococcal disease in adults include chronic heart disease, chronic lung diseases , liver disease, smoking cigarettes, alcoholism, CSF leak, and having a cochlear implant.

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Interactions At The Blood Brain Barrier

Pneumococcal invasion from blood into the CSF is thought to occur either in the choroid plexus or by crossing the blood brain barrier in the cerebral capillaries that traverse the subarachnoid space. The pneumococcus is thought to initially bind to the blood brain barrier endothelium through interactions of the NEEK motif of CbpA with the laminin receptor . Such binding to laminin receptor is a common strategy of meningeal pathogens, including H. influenzae, meningococcus, prions, and several viruses. Studies in mice have determined that once bound to the endothelium, actual translocation across the barrier is dependent on the interaction between ChoP and PAFr . PAFr knockout mice were resistant to development of meningitis . Likewise CbpA mutants were unable to cross the blood brain barrier despite bacterial titers in the blood of 108 CFU/ml . Thus, the two-step process of recognition of laminin receptor on the cerebrovascular endothelium by homologs of CbpA followed by translocation across the barrier using surface ChoP binding to PAFr is a conserved process of invasion of the central nervous system that is shared by the most successful meningeal pathogens.

Is Pneumonia Contagious

Certain types of pneumonia are contagious . Pneumonia caused by bacteria or viruses can be contagious when the disease-carrying organisms are breathed into your lungs. However, not everyone who is exposed to the germs that cause pneumonia will develop it.

Pneumonia caused by fungi are not contagious. The fungi are in soil, which becomes airborne and inhaled, but it is not spread from person to person.

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Going To The Hospital

If you have severe pneumonia, you may have to go to the hospital:

  • In most cases of pneumonia you get in your daily life, such as at school or work , it is not necessary to go to the hospital.footnote 2
  • About one-third of people with community-based pneumonia are age 65 or older.footnote 2 Older adults are treated in the hospital more often and stay longer for the condition than younger people.footnote 2 Pneumonia is more serious in this group, because they often have and may develop other medical problems.

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Interactions With The Placenta And Fetus

Streptococcus pneumoniae and flu vaccines | Respiratory system diseases | NCLEX-RN | Khan Academy

PAFr is found on a number of tissues including the placenta during pregnancy. Infection and inflammation during pregnancy has been shown to lead to postnatal cognitive deficiencies in a number of different studies reviewed in Loughran et al 2016 . The pneumococcus itself does not cross the placenta to the fetus. However, fragments of cell wall released during antibiotic treatment cross the placenta in a PAFr dependent manner and accumulate in the developing fetal cortex in mice. Rather than neuronal death, as seen in postnatal meningitis in mice, the fetal brain responds with an increase in neuroproliferation . Neuroproliferation is increased by interfering with the levels of the cytostatic transcription factor FoxG1 as a result of cell wall interaction with TLR2. The abnormal brain architecture is associated with behavioral abnormalities in the postnatal period in mouse models. This leads to the possibility that bacterial products encountered during pregnancy may be associated with cognitive disorders in children.

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Risk Of Pneumococcal Disease

Certain groups are at increased risk of infection, including:

  • children aged under two years
  • children under five years with underlying medical conditions predisposing them to invasive pneumococcal disease
  • Aboriginal and Torres Strait Islander children, especially in central Australia
  • Aboriginal and Torres Strait Islander people
  • people aged 65 years and over
  • people with weakened immune systems
  • people with chronic diseases such as diabetes, lung disease, cancer or kidney disease
  • people who have impaired spleen function or have had their spleen removed
  • people who smoke tobacco.

Pneumococcal Disease Is Deadly

Pneumococcal disease is a leading cause of serious illness and death among Australian children under two years of age and persons over 85 years of age. The rates are highest among Aboriginal and Torres Strait Islander children, especially in central Australia. Pneumococcal disease is also an important cause of pneumonia in adults 65 years of age or over. Older people are especially at risk of death from this disease. It is estimated to kill around one million people worldwide every year. While pneumococcal disease can occur at any time, infections seem to be more common during winter and spring. Young children, older people and people with impaired immune systems are among the most susceptible.

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What Are The Complications Of Pneumonia

Most people with pneumonia respond well to treatment, but pneumonia can be very serious and even deadly.

You are more likely to have complications if you are an older adult, a very young child, have a weakened immune system, or have a serious medical problem like diabetes or cirrhosis. Complications may include:

  • Acute respiratory distress syndrome . This is a severe form of respiratory failure.

  • Lung abscesses. These are pockets of pus that form inside or around the lung. They may need to be drained with surgery

  • Respiratory failure. This requires the use of a breathing machine or ventilator.

  • This is when the infection gets into the blood. It may lead to organ failure.

How Is It Treated

Pneumonia found to harm DNA in lung cells

Penicillin is normally used to treat pneumococcal infections. In some cases the bacteria may have developed resistance to penicillin and another antibiotic will be used. It usually takes 24 – 48 hours for the treatment to work. People who have the bacteria in their nose and throat, but are not sick, should not be treated.

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Osteomyelitis And Septic Arthritis

Streptococcus pneumoniae infection is an uncommon cause of osteomyelitis and septic arthritis , causing approximately 4% and 20% of cases in children, respectively.

  • Pneumococcal septic arthritis usually manifests as painful, swollen, and hot joints. The ankles and knees are most commonly involved, and one or more joints may be affected. Blood or synovial cultures usually grow S pneumoniae. Up to half of patients with pneumococcal septic arthritis have concomitant osteomyelitis.
  • Osteomyelitis: The femur and humerus are most often involved in cases of pneumococcal osteomyelitis in children the vertebral bones are often involved in adult patients. Up to 20% of patients with pneumococcal osteomyelitis develop long-term sequelae, a figure similar to that of rates of osteomyelitis of other causes. One clinical study performed by the Pediatric Multicenter Pneumococcal Surveillance Study Group 63) showed that more than 40% of patients with joint and bone pneumococcal infections had associated bacteremia. Patients with joint prostheses or rheumatic fever are at increased risk for joint disease.

When Would I Need To Be Hospitalized For Pneumonia

If your case of pneumonia is more severe, you may need tostay in the hospital for treatment. Hospital treatments may include:

  • Oxygen
  • Fluids, antibiotics and other medicines given through an IV
  • Breathing treatments and exercises to help loosen mucus

People most likely to be hospitalized are those who are most frail and/or at increased risk, including:

  • Babies and young children
  • People with weakened immune systems
  • People with health conditions that affect the heart and lungs

It may take six to eight weeks to return to a normal level of functioning and well-being if youve been hospitalized with pneumonia.

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