What is pneumococcus or streptococcus pneumonie?
The Pneumococcus, or streptococcus pneumoniae, is a bacterium Gram positive, one of the most frequent pathogenic bacteria for humans, responsible for pneumonia and meningitis.
What does Gram-positive mean?
Human pathogenic bacteria are classified in many ways; one of these is the Gram stain: it is picked up by a particular cellular component of some bacteria, called peptidoglycan, which forms the cell wall. Gram positive bacteria therefore have a cell wall rich in peptidoglycan and, by capturing the dye, under the microscope they are colored blue-violet; this does not happen in Gram-negative, because they do not have a solid peptidoglycan layer.
Pneumococcus is one of the Gram positive bacteria like lo staph and is classified among streptococci: a class of bacteria with a typical rounded structure (cocci) which are arranged in chains (hence the prefix strepto-). Another example is it Group A beta hemolytic streptococcus which causes the scarlet fever.
There pathogenicity Pneumococcus is multifactorial; that is, it depends on several characteristics (some peculiar, others common to the class to which it belongs) that allow it to adhere to fabrics (such as mucosa of the respiratory tract), to invade them (ie overcome the anatomical obstacle constituted by the mucosa itself) e circular in blood evading the immune system and then finally taking root at a distance from the site of infection (as occurs in meningitis).
- Sialic acid capsule: it is an additional structural component, present in some strains, which envelops the bacterium and protects it from phagocytosis; that is, it prevents it from escaping the cells of the immune system which have the task of "digesting" it in order to eliminate it. The capsule allows Pneumococcus (but also other bacteria that possess it, such as Meningococcus) to overcome the barrier blood-brain and cause so meningitis.
There are more stumps capsulated of pneumococcus: there are 90 serotypes, but only 7 are particularly widespread. The most pathogenic is the subtype 3. A-capsulated (capsule-free) strains are not pathogenic to humans.
- L'theic acid is a structural element of the surface of the bacterium that allows theadhesion to fabrics; it also contributes to the release of Pneumolysin, an important protein for invasiveness. It counteracts the immune system by binding to some whey proteins (such as C reactive Protein).
- Active proteases: they are proteins that, following adhesion to the epiglottis or other areas of the respiratory mucosa, cause direct damage to these tissues, compromising their functionality.
- Pneumolysin: it is a protein that damages the mucous membrane of the respiratory tract, compromising ciliary function (the cilia, in fact, are an important defense against bacteria and foreign bodies) and makes the bacterium more invasive. The consequence is a lung infection.
Pneumococcal Infection Diseases and Symptoms
How is streptococcus pneumoniae transmitted?
It s. pneumoniae often colonizes so asymptomatic the high respiratory tract (acts as diner), therefore man can be a healthy carrier. Given the frequency with which it colonizes, the most frequent infections are endogenous: for a decline in the carrier's immune defenses (eg for a tumor, a transplant, an autoimmune or pneumological disease), the infection becomes symptomatic because the compromised immune system is unable to contain the pathogen.
Where is pneumococcus taken?
The infection occurs mainly in the community. Another frequently asked question is: how do you take it pneumococcus? The answer is for aerosol (i.e. with droplets of saliva, coughing, sneezing) and, in rare cases, by direct contact. Those at risk are children, the elderly and people with immune deficiencies, especially in winter, as predisposing factors such as colds and flu are needed. Streptococcal incubation can last a few days before the first symptoms appear.
What symptoms does pneumococcal infection cause?
Regardless of the disease caused by pneumococcus, common symptoms (since typical of infections) are temperature, asthenia and state of general malaise.
Others symptomsinstead, they are more specific as closely associated with the disease. Pneumococcal diseases are typically divided into invasive (particularly severe, as they attack a vital organ or the blood) and non-invasive (more easily resolved without serious aftermath).
Streptococcal sinusitis media: in this case the bacterium infects the mucous membranes of the paranasal sinuses, causing an inflammatory reaction. This results in an increase in the volume of the mucosa, which thus becomes edematous. Communication with the nasal cavities is hindered and a stagnation of mucus and, in this case, bacteria, which proliferate here, ensues. Typical symptoms I'm:
- Sense of pressure in the face;
- Runny nose (runny nose)
- Sometimes even toothache.
Sinusitis can give complications Which meningitis, brain abscesses is ostiomyelitis.
Acute purulent streptococcal otitis media: inflammation of the middle ear (mucosa and eardrum), usually a consequence of an upper tract infection. Typical symptoms are:
- Otodynia (ear pain);
- Sense of wadding;
- Hypoacusis (reduced hearing) and pus production.
Osteomyelitis: inflammation of the bone marrow caused, in this case, by a bacterial infection. It can be secondary to bacteremia (the bacterium, following infection in another outbreak, passes into the blood) or direct infection, such as in the case of bone fractures, trauma or the application of prostheses.
Streptococcal pneumoniae pneumonia: pneumococcal pneumonia is lobar, because it usually affects only one lung lobe. It is typical of the adult and is acquired in the community (other bacterial pneumonia, on the other hand, are typically hospital or associated with care practice). In this case the bacterium reaches the deep respiratory tract (terminal bronchioles and alveoli) causing a strong inflammatory response.
Typical symptoms of lung infection are:
- Cough with sputum;
- Chest pain;
- Sore throat;
- Pleurisy (inflammation of the pleurae, the sheets that line the lungs and chest wall);
Streptococcal pneumoniae meningitisThis is an inflammation of the meninges, the membranes that line the brain and spinal cord. It is a lethal consequence of the infection. It can also be meningococcal meningitis, E.Coli, H. Influenzae. Whether it is pneumococcal meningitis or meningococcal meningitis, the clinical presentation is: headache, nuchal stiffness is temperature. Other typical symptoms can be:
- Jet vomiting;
- Photophobia and phonophobia (intolerance to light and noise);
- Confusion, lethargy or other changes in the state of consciousness.
Streptococcal pneumoniae sepsis: systemic disease caused by the invasion of sterile parts of the body by the bacterium. Bacterial dissemination occurs when the pathogen, having invaded and passed the mucous membranes, spreads through blood (bacteremia) or lymph. It's about a complication of other pneumococcal-mediated infectious diseases and is a medical emergency that must be treated promptly, as it leads to shock and multi-organ failure (MOF). Typical manifestations are:
- Tachypnea (increased breathing rate);
- Edema (accumulation of fluid in body tissues);
- Tachycardia or, in some cases, bradycardia;
- Fever or hypothermia;
- Hypoglycemia (low blood glucose);
- Hypotension (low blood pressure);
- Altered mental state;
- Oliguria (reduced urine production);
- Other associated symptoms (eg changes in blood coagulation, DIC) are a consequence of the decay of the various organs.
Sreptococcal pneumoniae endocarditis: Inflammation of the endocardium, the tissue that lines the internal cavities of the heart and the heart valves. Bacteria take root easily on it, especially in heart patients, therefore more at risk; the most serious consequences are acute valvular insufficiency and detachment of thrombi, resulting in embolism. The main manifestations are:
- Profuse sweating;
- Arthralgia (joint pain);
- Splenomegaly (enlarged spleen)
Streptococcal septic arthritis: When the bacterium infects a joint, the consequence is arthritis. The joints most affected are those of the hip, knee or shoulder. Pneumococcal joint is usually monoarticular (that is, it rarely affects more than one joint). The patient with septic arthritis warns intense pain and loses control of the joint during movement. The affected joint is swollen. Arthritis affects more easily predisposed subjects (patients undergoing surgery, rheumatoid arthritis patients or immunosuppressed subjects). Adults are usually affected in the knee, children in the hip. It can cause sepsis.
Pneumococcal therapy is based on the use of antibiotics: the most used cure is amoxicillin associated withclavulanic acid (one of the trade names is Augmentin) and the cephalosporins third generation. Antibiotic therapy must be prescribed by the physician in a reasoned way, after the culture tests are positive for pneumococcus.
Pneumococcal prevention and vaccine
There prevention for streptococcus pneumonia is equally important and is based on pneumococcal vaccine. Today the 13-valent or pvc13 conjugate vaccine is available which replaces the previous heptavalent or pvc7 conjugate vaccine. The trade name is PREVENAR 13 (Conjugated Polysaccharide Vaccine). Another possibility is the ppsv23 or 23-valent polysaccharide vaccine. Vaccines protect against the more frequent serotypes of s pneumoniae.
It is also important to bear in mind the side effects of vaccination: adverse or unwanted reactions of the vaccine can be fever, allergy, skin rash and injuries at the injection site.
What is strep vaccination for pneumoniae used for?
The purpose of the vaccine for the pneumonia it is active immunization: the vaccinated subject develops an antibody response that he would not have without the vaccine, and would therefore be more vulnerable. With the vaccine, the host's immune system defeats the bacterium before it gives important clinical manifestations. The immune response is developed within the third week of the vaccine and lasts for a few years.
When to get the pneumococcal vaccine?
The vaccine is especially suitable for people whose immune systems are weakened or particularly vulnerable, due to physiological issues or underlying diseases.
- Cancer patients who have to undergo radio or chemotherapy: cancer therapy greatly weakens the patient's immune defenses. Vaccination is indicated at least 14 days before the start of treatment.
- Adults with chronic diseases;
- Children over 2 years of age with HIV infection or chronic or congenital diseases that predispose to pneumococcal infection, one example is sickle cell anemia.
- Senior citizens;
- Immunosuppressed (AIDS patients, transplant patients or Hodgkin's lymphoma patients);
- People without a spleen or splenectomised, as they lack an organ important for the immune response to the bacterium.
Is the vaccine mandatory for infants?
The vaccine is important for infants especially for the prevention of pneumococcal meningitis and meningococcal meningitis. In the first year of life, pneumococcal and meningococcal vaccine is recommended. For this pathology, the administration of hexavalent and pneumococcal vaccine in a single session is available.
Tags: Infectious diseases Laboratory medicine