Streptococcus Pneumoniae – How to Understand the Bacterial Strains

streptococcus pneumoniae

Out of the few bacterial strains that have created remarkable devastation in the history of mankind, the streptococcus pneumoniae holds an important position. In the year 1881, Louis Pasteur isolated a specific strain of bacteria.

Later on, specifically in the year 1886, the organism was spotted as the causative organism for the diseased condition – pneumonia. Hence, such a nomenclature. It holds a place of special interest in the field of research because the experiment that is the milestone in discovery of genetic material was carried out using this strain of bacteria.

Extent of action

Today, according to medical statistics it is the seventh leading devastating bacterial strains in the world. The majority of community acquired pneumonia commonly termed as CAP is due to streptococcus pneumoniae infection. A large number of hospitalizations occur each year due to the infection of this pathogen. It is also ranked as one of the leading common pathogens that causes hospitalizations even in the developed countries like the Unites States

General characteristics

It is a type of diplococcus. It is included in the streptococcus genus and is a gram-positive bacterium. Streptococcus pneumoniae is a facultative anaerobe. Hence it exhibits both characteristics of aerobic bacteria (alpha hemolytic) and anaerobic bacteria (beta hemolytic).

No spore formation phenomenon in the strain is known. They are essentially pathogenic. Still today, this particular bacterial strain forms an important tool in the field of immunologic study.

The bacterias are lancet in shape. The encapsulated bacterias are highly virulent. The polysaccharide coating of the lancet shaped bacteria is mainly responsible for the virulence of the bacteria. The bacterias reside normally in the bacterial flora population of the upper portion of human respiratory tract. The total number of scientifically isolated stereotypes of the bacteria is 92.

These bacteria are negative to catalase. Though they are facultative anaerobes, yet their growth is enhanced up to more than 5 percent in the presence of carbon dioxide or in anaerobic conditions.


It possesses a circular closed DNA. It possesses 1553 genes in its genome. 2 million base pairs are present in the genome, it might vary according to the strain.


If we talk about occurrence then it must be mentioned that there is no specific area where this bacterium is found. If we ask the answer where is the streptococcus pneumoniae found the answer would be ,the bacteria are found almost anywhere. Their potency remains at the peak during the spring months. The most vulnerable victims are kids below the age of 10 and adults above the age of 65.

Any normal human being can be a victim of the bacteria but a weakened immune system is the most overwhelming place for them. The rate of death due to streptococcus pneumoniae infection is exceedingly high and mostly observed in the age group of 60 years and above

Smokers, drinkers, HIV AIDS infected individuals are among the top rankers of victims. Asthma or Chronic Obstructive Pulmonary Disorder COPD patients are also vulnerable towards infection. Actually, the fact that the incidence of the disease is maximum in the extreme age groups, is due to their underdeveloped immunity system

Initially, the bacterium starts to spread in the form of a vicious colony especially in the upper respiratory tract. Later on, it spreads the infection to the lungs. The oropharynx and nasopharynx are the mostly infected areas.

Distinguishing tests

The distinguishing tests for the streptococcus pneumoniae bacteria are Optochin test and bile solubility test. This is due to the particular sensitivities of the bacteria towards bile and optochin. A culture from the suspected region is taken and diagnosed in the laboratory.

When allowed to grow on blood agar media culture, they exhibit themselves as alpha hemolytic. Thereafter these can be identified by the latex agglutination test. If they have to be further distinguished on the type of their polysaccharide wall composition which gives a fair idea about their virulence, then sera techniques can be used. In such cases complex molecular biology techniques can be employed. Polymerase chain reaction has literally opened new areas for the research on such bacterias.

Clinical Diagnosis

When you visit the doctor with the complaint of facing symptoms of pneumonia, the physician will perform a few routine tests that will expose the presence of pneumococcal infection in your body if it has taken place.

  1. Blood test – a routine blood test is enough to understand whether there is presence of streptococcus pneumonia infection in the blood stream or not
  2. Sputum test – the sputum being an important body fluid can also provide information about the occurrence of pneumococcal infection in the body.
  3. X ray of the chest – a proper chest Xray image will show if there is any inflammation in your chest, which is an important indication of pneumonia
  4. If the oxygen delivery in the body can be estimated then the doctor can get a fair idea about pneumonia. Due to the inflammation of lungs in pneumonia, they are unable to supply oxygen as per requirement. Pulse oximeter can unleash the information whether the lungs are in proper working condition or not

Activity of streptococcus pneumoniae

The humans are a carrier of the bacteria. They reside mostly in the respiratory tracts of humans and the nasal cavities. In the carrier’s body, they do not exhibit any kind of symptoms. When they are transmitted to a recipient who is an immunologically weaker person, it starts to show its effects.

Other than pneumonia, pneumococcus is also the causative agent of multiple other diseases like meningitis, acute otitis media, conjunctivitis, bronchitis, rhinitis and acute sinusitis. Pneumococcus spreads by person to person contact. The respiratory droplets are the major means of the spread of the disease. Nasal colonization is also the outcome of infection caused due to pneumonia.

Proliferation of the bacteria

Initially streptococcus pneumoniae initially proliferates in the air sacs of the lungs and colonizes in the area. To this condition, the body produces an inflammatory response by stimulating the protective elements of the body. These includes white blood cells, macrophages. They aggregate at the site of infection. The concurrent inflammation due to the accumulation of the cells, leads to a full-fledged infection termed as pneumoniae.

They get into various foci of the bloodstream of the infected person. Conditions may worsen with poor humoral immunity of the individual. Asymptomatic colonization makes the biggest problem in case of their infection. It leaves absolutely no trail to identify the carrier. The infection symptoms also appear after considerable colonization and proliferation has already taken place.

Symptoms of pneumonia

Symptoms of pneumonia includes fever chills, cough and cold, excess mucous secretion and a few others. It might also cause other problems such as shortness of breath, dizziness and mental confusion. Loss of appetite and feeling of a low energy state are also important symptoms of pneumonia. The cough might be bloody or greenish to yellow in color tinge

If meningitis is caused then, photophobia, stiff neck and fever, headache and confusion. Otitis media in children will cause extreme pain in the ears along with all these symptoms. It is literally very difficult to differentiate between the symptoms of influenza and pneumonia. So, it is always better to seek timely medical help.

Preventing streptococcus infection

The only way of preventing a probable streptococcus pneumoniae is getting vaccinated against it: –

There are two most common vaccines for prevention of streptococcus pneumoniae infection and disease. They are: –

  1. PCV13 vaccine, which should be administered to children between 6 and 18 years. This vaccine is actually included in the normal vaccination schedule of all new born kids. It consists of four doses. The injections are equally spaced. Getting vaccinated with PCV13 actually ensures the primary protection of the individuals against streptococcus infection.
  2. PPSV23 is actually a sort of booster dose of the streptococcus pneumoniae vaccine. Adults who are in the age group of 65 years or older must receive this vaccine. Though the young children are extremely susceptible to pneumococcus infection, adults are also not spared. Hence, it is equally important for adults to receive this vaccine.
  3. Adults who are affected by any associated medical issues that could even include respiratory disorders in smokers are entitled to this PPSV23 vaccine.

Precautions to prevent the onset of pneumococcus infection

There are a few essential and precautionary measures that every individual must take, which ensures their safety against pneumococcal infection.

  1. The streptococcus pneumoniae resides in the upper respiratory tract of the infected person. It gets transmitted mostly through the body fluids. Therefore, avoiding close physical contact with the infected person is the best way to keep safe from infections. Hugging, kissing or such intimate physical contact is better to avoid
  2. Stop sharing daily use items like handkerchief, utensils or tea cups with the infected person. These are potential ways in which the infection can spread within your body.
  3. Streptococcus pneumoniae spreads very rapidly in public places. Public transport, schools, offices, restaurants are the most viable places where the chances of catching an infection is maximum. A simple sneeze by your infected co passenger in the bus will put you into trouble. So, when you are in any area that is crowded, try to cover your mouth and nose. Keep in mind, the most vulnerable part of your body that can catch a pneumococcus infection is the respiratory tract
  4. Washing hands often is also a good way to get rid of the germs. Make a habit to wash your hands often. Specially when you touch doorknobs or taps, that are common objects of use in public places, you must wash your hands.
  5. Always carry a clean tissue with yourself for self-protection. Abstain from touching your nose or eyes with dirty hands. Always carry a mini sanitizer with yourself to keep your hands clean even in absence of water.
  6. Last but not the least, always consult the doctor in case of any instances of long-term fever or respiratory tract infection. Delaying the medical consultancy will only worsen the problem and make treatment all the more difficult.

Microbiological aspect

It is mostly identified as a major respiratory pathogen. The body mainly responds to the pneumococcal infection by producing antibodies. The pathogen is killed mainly by two ways. First is the phagocytosis by neutrophils and macrophages. Secondly, by the complement lysis system. The substance which damages the endo and epithelial cells too exhibit greater infectious stages and damage is pneumolysin. It also becomes an obstacle in the way of complement killing system.

Medical remedies

If at all the infection has already occurred then there is no other way than effective  streptococcus pneumoniae treatment  with medications. Vaccines can be used as a preventive measure but once the infection has already set in, there is no use of vaccinating at that instance.

  1. The most effective medication in case of a typical pneumococcal invasion is Beta Lactam antibiotic. In this case, penicillin cannot be used as an antibiotic. This is because, the penicillin binding proteins are modified in pneumococcus. So penicillin cannot bind to appropriate receptors and hence, does not produce any desirable effect.
  2. Vancomycin and quinolines can be administered in combination with beta lactam. This shall increase the activity of the antibiotic. It will also speed up the reaction
  3. If the oral medication takes too long to work, then intravenous administration of cefotaxime and ceftriaxone can help out.