Streptococcus pneumoniae - Research Paper Example

? Streptococcus pneumoniae Streptococcus pneumoniae Streptococcus pneumoniae is among the group of pathogenic micro-organisms that cause life threatening diseases in human beings. The organism belongs to Kingdom of Bacteria (Procaryotae), phylum Firmicutes, and class bacilli. Streptococcus pneumoniae is classified under the Order of Lactobacillales, family Streptoccaceae and Genus Streptococcus. The species name is Streptococcus pneumoniae. Luis Paster discovered the organism in 1800’s. At that time he named it Micrococcus Pasteur. In 1886 and 1920, the name of the organism changed to Pseumococcus and Diplococcus pneumoniae respectively. Finally, in 1974 the micro-organism name became the Streptococcus pneumoniae (Toder, 2012). The micro-organism is Gram-positive, non-spore forming, non-motile and lancet-shaped. Predominantly, the micro-organisms occur in pairs. However, they can form short and straight chains. The micro-organism has a capsule that serves as a protective layer to antibiotics. In addition, the capsule stains positive during Gram staining process. The diameter of individual cells measures 0.5 and 1.25 micrometers. The cell wall of Streptococcus pneumoniae comprises of peptidoglycan and teichoic acid. The peptidoglycan component of the cell wall responds positively to Gram staining technique. This technique identifies and distinguishes different species in the genera streptococci. Steptococcus pneumoniae lacks the catalase activity. In addition, they are facultative anaerobes and metabolizes through lactic acid fermentation (Toder, 2012). There are more than 90 highly antigenic capsular serotypes differentiated in the types of presenting antigen in the capsule. Antibodies to specific types of serotypes are protective. The features responsible for pathogenic nature of organism are innumerable. These include presence of pro-inflammatory cell wall components (C-polysaccharides and F-antigen), IgA2 protease, pneumolysin, adhesins, and enzymes that damages tissue. Pneumolysin is a cytotoxin that stimulates immune response and adhesin bind to cell surface carbohydrates. Some of examples of adhesin include choline binding protein A, and the pneumococcal surface protein A [PspA]. The micro-organism incorporates the genetic material of other micro-organism through a process of transformation. The presence of F-antigen helps in acquiring of genetic material from different sources. Therefore, it means that the organism can change from one serotype to the other. This is quite significant to the development of resistance to antibiotics in the organism. It increases the virulence of the organism. The increasing severity of micro-organism is attributed to its ability to assume different shapes. When the organism acquires genetic material with genes of resistance to antibiotics, it replicates to resist the host defense mechanism. The virulence in these micro-organisms is associated with the capsular material. The capsule resists the hosts’ phagocytosis mechanism thereby surviving and multiplying in the host tissues. The virulence factors of the micro-organism include surface protein A. autolysin, and immunoglobulin A (Toder, 2012). Streptococci pneumoniae are found in the host’s upper airways, nose, or throat. They are part of normal flora in human beings. However, the organism becomes infectious depending on the immunity status of the host. In the immune comprised host, they cause some of the deadly diseases that include pneumonia, meningitis, sinusitis, acute otitis media, peritonitis, and bacteremia. These are diseases of upper and lower respiratory tract. When in the host tissues, pneumococcal undergoes genetic changes that convert the colonies from opaque to transparent ones. However, the rate is very low in number; it is 1 in 105 micro-organisms. The transparent colony is best adapted for proliferation in the nasopharynx. The opaque colonies thrive very well in the host’s blood. The opaque colonies increase their virulence during systemic infections. These differences in colony opacity match well with the virulence. The opaque variant has capsular polysaccharide in large amounts. The transparent phenotype of streptococcus pneumoniae is secrets large amounts of teichoic acid. The difference in virulence in the two variants is attributed to differential expression of surface protein components. The transparent variant possesses large amounts of surface protein. This explains why it flourishes in the nasopharynix. The protein confers adhesive properties that enable the transparent variant to colonize the nasopharynx well. Conversely, the small amount of surface proteins renders the opaque variant poorly adapted to colonize nasopharynix. That is the principal reason why it is found in blood. It does not require adhesions in the blood. When the streptococcus pneumoniae crosses the brain barrier, they cause meningitis. In the blood, the opaque variant of micro-organism is responsible for bacterema (Toder, 2012). The people with weak immunity are at highest risk of S. pneumoniae infection. The cause of weak immunity is either through compromise or through suppression. Defects such as congenital agammaglobulinemia and lymphomas affect antibody formation. This leaves the host less immunologically protected and hence exposed to S. pneumoniae attack. The children under the age of one year and the adults over the age of 65 years are vulnerable to suffer from acute pneumonia. Other factors that expose one to S. pneumoniae infection include smoking, alcoholism, splenectomy, HIV infection, and complement deficiency. This makes the bacteria to adhere to pneumocytes and invade blood stream. This happens through hijacking the platelet-aggregating factor receptor pathway. They produce complement-mediated damage to the alveolus of lungs. Pneumolysin plays a significant role in pneumonia infection (Department of Health Services, 2011). The bacterium is transmitted from person to person through direct oral contact, spread of droplets or contact of articles with fresh respiratory secretions. S. pneumoniae spreads quickly when the colonized or infected persons live in closed and crowded environments. The unvaccinated people are highly susceptible to the bacterial attack. When infected person inhales, the bacteria pass from that individual to the immediate persons. The ideal conditions of breeding of Streptococcus pnuemoniae include moist, warm, and optimum temperatures of 37 degrees Celsius. The human lungs have these conditions and therefore they support the growth and multiplication of bacteria. Streptococcus pneumoniae causes a host of diseases apart from pneumonia. These illnesses include sinusitis, otitis media, meningitis, endocarditis, and brain abscess among others. The bacteria lead in the main cause of meningitis in adults. The Center for Disease Control (CDC) reveals that S. pneumoniae infections amounted to 100,000-135,000 pneumonia hospitalization cases. Otitis media, invasive diseases, and meningitis recorded 6 million, 60,000, and 3300 cases respectively. This was a data taken in United States in the year 2000 (CDC, 2008). Further, the report shows that the disease incidences varied from region to region. Streptococcus pneumoniae causes the swelling of lungs tissues. This leads to accumulation of fluids in the alveoli thereby inhibiting the process of gaseous exchange. The signs and symptoms include, cough, production of sputum from lungs, fever, and chest wall pain that worsen through coughing. Other signs comprise of fast heartbeat, nausea, and vomiting. All these signs affect respiratory system of the affected person. This particular individual has trouble in breathing. The symptoms and signs are severe in young children and adults above the age of 65 years. Development of new and effective vaccines is underway to manage the Streptococcal diseases. In United States, administration of the vaccines happens at the start of each flu season. This is usually during the winter season. The logic behind this intervention is that people are together, mostly indoors, during the winter period. The CDC report of 2002 revealed that vaccination decreased the rate of invasive infections from 20-33 per 100,000 to 13 per 100,000 people in United States (CDC, 2008). Other interventions mechanisms include observation of personal hygiene. Strict adherence to cleanliness curbs the spread of the bacteria. This leaves the bacteria with unsuitable conditions to support their growth. In addition, hygiene prevents transmission through physical contacts. These intervention mechanisms are responsible for diminishing incidents of streptococcal diseases. Streptococcus pneumoniae presents a challenge to most antibiotics that are used to manage it. The bacteria changes constantly. It has ability to alter its penicillin-binding proteins and therefore demonstrates low affinity for bete lactam antibiotics. Medical Practitioners keep informing on the importance of completing treatment once people contract Streptococcal diseases. However, it their ignorance to complete the antibiotic dose enables the bacteria to thrive in hosts’ bodies. These bacteria replicate and become more virulent with new antibiotic resistant mechanisms. The Center for Disease Control (CDC) recommends since campaigns for reliable use of antibiotics. The use of new vaccines promises to slow down or reverse the drug resistance in the pathogens. This will reduce the incidences of S. pneumoniae infections in the United States. It is prudent enough to take precaution measures to prevent the spread of the streptococcal diseases. The best approach to ensure that there is no transmission of the bacteria is to maintain high hygienic conditions. This is achieved through covering one’s mouth and nose when coughing or sneezing (Department of Health Services, 2011). In addition, washing of hands frequently will minimize Streptoccocci pneumoniae transmission. References Center for Disease Control and Prevention. (2008). Streptococcus pneumoniae Disease. Accessed on 7 Apr 2012, from http://www.cdc.gov/ncidod/dbmd/diseaseinfo/streppneum_t.htm Department of Health Services. (2011). Accessed on 7 Apr 2012, from http://www.dhs.wisconsin.gov Toder, K. (2012). Online Textbook of Bacteriology. Accessed on 7 Apr 2012, from http://textbookofbacteriology.net/S.pneumoniae.html Read More