Identification Of Bacteria: Streptococcus Pneumoniae

Name
Institutional Affiliation
Course Title/Module
Instructor’s Name
Date
Identification of Bacteria
Sample A: Streptococcus pneumoniae
Staphylococcus pneumoniae, also known as pneumococcus colonizes the nasopharynx of humans and produces a number of virulence factors such as surface proteins and enzymes, polysaccharide capsule and the toxin pneumolysin (PLY). According to Blumental et al (2015, p.2), polysaccharide capsule is the main determinant of virulence in S. pneumoniae, which plays a role in the promotion of adhesion of the microbe to epithelial surfaces and in the escape from the host immune system through both complement-dependent and complement-independent phagocytosis. The bacteria cause a range of diseases, including pneumonia, otitis media, meningitis and bacteremia (A. Mitchell & T. Mitchell, 2010, p.411). the role played by these factors has been established in part, although studies from whole genome sequences indicate that different pneumococci strains present varied ways of producing virulence factors. It is important to understand the role played by such factors in appreciating pathogenesis of infections and identifying potential points of intervention for disease prevention and treatment.
Treatment for infections due to S. pneumoniae is only attained following prompt and appropriate antibiotic administration, with the route of administration and treatment duration varying depending on age, disease severity, clinical syndrome and local patterns of resistance to antimicrobial agents (Johns Hopkins University, 2010). Since it is not always that people exposed to individuals with pneumococcal infection to develop the disease, the Centers for Disease Control and Prevention (CDC) does not advise on the use of preventive or prophylactic antibiotics for contacts of individuals with the infections (CDC, 2017). Preventive measures involve the use of vaccines to protect healthy individuals against more than 90 pneumococcal bacteria strains. For instance, the pneumococcal conjugate vaccine, also known as PCV13 or Prevnar 13® protects healthy individuals against 13 strains of the bacteria, which are responsible for most forms of severe illnesses among adults and children (CDC, 2017).
Sample B: Staphylococcus aureus
Staphylococcus aureus is one of the leading causes of nosocomial infections globally, particularly methicillin-resistant S. aureus. (Harris, Foster & Richards, 2002, p.39). The pathogen is the leading cause of infective endocarditis, bacteremia, pleuropulmonary, skin and soft tissue, osteoarticular, and infections. A number of virulence factors are secreted by the microbe, including several membrane-damaging toxins that are responsible for forming pores in the host cells’ cytoplasmic membrane thus resulting in cell lysis (Tong et al., 2015, p.603). Examples of membrane-damaging factors include phenol-soluble Modulins (PSMs), which are often small, helical and amphipathic peptides (Lacey, Geoghegan, & McLoughlin, 2016, p.2). S. aureus also expresses up to 25 different cell wall-anchored (CWA) proteins that are bound to the cell wall peptidoglycan, with a majority of these proteins carrying out multiple functions while having functional redundancy at the same time. another virulent factor in S aureus is clumping factor A (ClfA), which is a major fibrinogen binding protein that the bacteria express. This factor results in the clumping or aggregation of platelets or bacteria in plasma. Other factors common in S. aureus are clumping factor B (ClfB), fibrinonectin-binding protein, SasX, Protein A, and iron regulated surface proteins (Lacey, Geoghegan, & McLoughlin, 2016, p.5-10).
Most S. aureus strains are known to be resistant to penicillin, which is a common antibiotic used in the management of bacterial diseases. For instance, methicillin-resistant strains of S. aureus (MRSA) have become common in hospital settings and in the community. In this case, penicillinase-resistant penicillin such as dicloxacillin and flucloxacillin have become the antibiotic of choice in the management of serious MRSA infections, although first generation cephalosporins such as cephalothin, cefazolin and cephalexin and other lines of antibiotics, including lincomycin, clindamycin and erythromycin have shown to be potent in treating less serious MRSA cases (Rayner & Munckhof, 2005, p.3). Serious MRSA infections should be managed using parenteral vancomycin or teicoplanin, in case the patients show allergic reactions towards vancomycin. Daptomycin is increasingly being used today in place of vancomycin, in case patients fail to respond to treatment (Bhattacharya, Wozniak, Stoodley & Hall-Stoodley, 2015, p. 1508). In case of nocosomial MRSA strains, multi-resistance is common in the development of multi-resistant MRSA (MrMRSA) MrMRSA is treated using a combination of two antimicrobials such as fusidic acid and rifampicin since resistance often develops when used as a single agent.
There are two approaches used in preventin...