Microbiology
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Institution Affiliation
Date
Microbiology
Staphylococcus Aureus
Background
This is a common microbe on the human body. The bacteria is commonly found on the skin, the lower reproductive tract of women, and the upper respiratory tract. It’s a sphere-shaped (coccal) Gram-positive bacteria commonly associated with bone infections, heart valve infections, skin infections (like scalded skin syndrome, abscesses, carbuncles, folliculitis, cellulitis, impetigo, boils, and pimples), sepsis, meningitis, food poisoning, and pneumonia. About 20 t 30 percent of humans are long-term carriers of this bacteria (Bush, 2019). It’s one of the top five causes of nosocomial (hospital-acquired) illnesses.
Transmission Route
The bacterial gets transmitted to humans via contact with infected body fluids or blood, especially via contaminated hands. As the microbe is a normal flora on most people’s skin, one can develop an infection from the microbe when the structural integrity of the skin or mucosal surface is breached as a result of trauma (Bush, 2019). Once an infection occurs, the microbe grows rapidly, leading to colony production.
Host-Pathogen Relationship
The relationship between a bacterial such as staphylococcus aureus and the host is a dynamic one. This constant interaction contributes to one of the following phenomena: the resistance of the bacteria or tolerance within the host, which eventually results in the host quiescent habitation or the development of the disease characterized by replication of the pathogen or damage to the host. Thus, the disease’s development from staphylococcus aureus is heavily dependent on the balance between the pathogen virulent factors and the host cutaneous immune defenses (Drãgulescu, & Codita, 2015).
Virulent Factors and Pathogenicity
According to Oogai et al., 2011, the bacterial has several virulent factors that promote its infectivity. This includes the production of cell surface proteins, which allow it to bind firmly to the hosts. Besides hse, the bacteria produce exoenzyme, immune-modulatory factors, and toxins. This includes iron acquisition factors, proteases, enterotoxins, and hemolysins, which are tightly regulated during the pathogen’s growth. The toxins produced by this bacterial are generally categorized into 3 groups: exfoliative toxins, superantigens, and other toxins like delta toxin, beta toxin, and Alpha toxin. The exfoliative toxin allows the bacterial to peel off the skin, promoting its further transmission as in Staphylococcal scalded skin syndrome. On the other hand, the superantigens are responsible for most of the clinical manifestation of illnesses such as toxic shock syndrome. The enzyme produced by the microbe facilitate its spread. For instance, coagulase results in the clotting of blood around the microbe, thus preventing ist phagocytosis, and staphylokinase help in the dissolution of fibrin, thus allowing it to spread. This bacterial also produces the following substances that allow it to suppress the host’s immunity: Staphylococcal pigments and Protein A, thus propagating the disease process.
Treatment
Various antibiotics have been developed to help deal with Staphylococcus aureus infections. However, the pathogen has become resistant to traditional antimicrobials such as methicillin and penicillin, thus immensely increasing the cost of treatment. Thus many experts recommend combining medications such as cephalosporin, penicillinase–resistant penicillin, and a quinolone or clindamycin (Elizabeth, 2020). According to Tulane University (2016), Vanacomycicn is recommended for highly administered strains. It gives intravenously and acts inhibition of cell wall synthesis. It achieves this via inhibition of transpeptidase, thus preventing cross-linking and further elongation of the peptidoglycan matrix.
References
Bush, L. (2019). Staphylococcus aureus Infections – Infections. Retrieved November 07, 2020, from https://www.msdmanuals.com/home/infections/bacterial-infections-gram-positive-bacteria/staphylococcus-aureus-infections
Oogai, Y., Matsuo, M., Hashimoto, M., Kato, F., Sugai, M., & Komatsuzawa, H. (2011). Expression of virulence factors by Staphylococcus aureus grown in serum. Applied and environmental microbiology, 77(22), 8097-8105.
Drãgulescu, E. C., & Codita, I. (2015). Host-pathogen interaction in infections due to staphylococcus aureus. Staphylococcus aureus virulence factors. Roum. Arch. Microbiol Immunol, 74, 46-64.
Elizabeth P Baorto, M. (2020, May 03). Staphylococcus Aureus Infection Treatment & Management: Medical Care, Surgical Care, Prevention. Retrieved November 07, 2020, from https://emedicine.medscape.com/article/971358-treatment.
Tulane University (2016). Vancomycin. Retrieved November 07, 2020, from http://tmedweb.tulane.edu/pharmwiki/doku.php/vancomycin
SARS-CoV-2 (Virus for COVID 19)
Background
SARS-CoV-2 is a new virus that was initially discovered early this year in Wuhan, China. The virus has since spread to all parts of the globe, leading to the current pandemic that the world is still grappling to contain. It is closely related to MERS-Cov and SARS-CoV. They are single-stranded RNA viruses that can result in dyspnea and pneumonia. According to the World Health Organization. (2020) SARS-CoV-2 is thought to have originated from bats but jumped the species barrier after infecting an intermediate host. However, the intermediate hosts have not been identified yet but are thought to encompass a domesticated wild animal, a wild animal, or a domestic animal. Studies have demonstrated that the virus can survive on different surfaces for several days, depending on its light, humidity, and temperature.
Transmission Route
The virus is transmitted via separate modalities. This includes animal to human transmission, mother to child, bloodborne, fecal-oral, fomite, airborne, droplet, and contact. It has been demonstrated that the virus can spread via indirect, direct, or close contact by infected individuals via infected secretions like respiratory droplets or secretions and saliva expelled when infected individuals sing, talk, sneeze, or cough. Airborne transmission of the virus occurs during medical procedures that generate aerosols such as nebulization. Fomite transmission, on the other hand, occurs when droplets or secretions contaminate objects and surfaces (World Health Organization, 2020).
Host-Pathogen Relationship
Several forms of infection have been identified in coronavirus disease in 2019. This included a paucisymptomatic form, viral pneumonia that is associated with a severe form, and a moderately severe form. This difference in clinical manifestation has been linked to the variability in one’s immunological response, which in some cases rapidly progress between day 7 and day 10. This could be due to immunological dysregulation or type I interferon (IFN-I) response inhibition (Hospices Civils de Lyon, 2020).
Virulent Factors and Pathogenicity
COVID 19 has proven to be a lethal disease; already today, over 2 million people have lost their lives from the illness globally. According to Shah et al., 2020 SARS-CoV-2 is an RNA virus; these viruses can acquire genetic mutations that have to allow them to escape the immune system of humans. A minor mutation has been found in various patients, thus providing a partial explanation to its case fatality rate of 2-4 percent. Besides these, as an immense evasion mechanism, MERS-CoV and SARS-CoV-2, causes severe lymphopenia and leukopenia. Once this virus gains entry into cells, they interact with signaling molecules like the JAK-STAT and TLRs pathways, thus inhibiting IFN promoters’ production.
Treatment
Currently, there is no specific medicine or vaccine for covid 19. According to the Centers for Disease Control and Prevention (2020), The current treatment protocol emphasizes infection prevention measured and the use of mechanical, l ventilatory support and supplemental oxygen when it indicates. For patients with mild symptoms, self-isolation and home-based care are increasingly being advocated. FDA has approved remdesivir (Veklury) for the management of severe or emergency cases. It’s a five-day course of treatment. The drugs work by inhibiting the synthesis of RNA viral via their delaying their termination (Saha et al., 2020). This, in turn, immensely decreases their spread and propagation.
References
Centers for Disease Control and Prevention. (2020). Therapeutic Options for COVID-19 Patients. Retrieved November 07, 2020, from https://www.cdc.gov/coronavirus/2019-ncov/hcp/therapeutic-options.html
Hospices Civils de Lyon. (2020). Host-pathogen Interactions During SARS-CoV-2 Infection – Full Text View. Retrieved November 09, 2020, from https://clinicaltrials.gov/ct2/show/NCT04376476
https://www.frontiersin.org/articles/10.3389/fimmu.2020.01949/full
Saha, A., Sharma, A. R., Bhattacharya, M., Sharma, G., Lee, S. S., & Chakraborty, C. (2020). Probable Molecular Mechanism of Remdesivir for the Treatment of COVID-19: Need to Know More. Archives of Medical Research.
Shah, V., Firmal, P., Alam, A., Ganguly, D., & Chattopadhyay, S. (2020, July 20). Overview of Immune Response During SARS-CoV-2 Infection: Lessons From the Past. Retrieved November 07, 2020, from
World Health Organization. (2020). Coronavirus disease 2019 (COVID-19) Situation Report – 32. Retrieved 2020, from https://www.who.int/docs/default-source/coronaviruse/situation-reports/20200221-sitrep-32-covid-19.pdf?sfvrsn=4802d089_2#:~:text=The%20most%20likely%20ecological%20reservoirs,not%20yet%20been%20identified.
World Health Organization. (2020). Transmission of SARS-CoV-2: Implications for infection prevention precautions. Retrieved November 07, 2020, from https://www.who.int/news-room/commentaries/detail/transmission-of-sars-cov-2-implications-for-infection-prevention-precautions