In Microbiology Issues - Case Study Example

In this case scenario, all the elements of this case will be analysed to find out the cause of this specific patient’s history. Once the diagnosis is established, the answers to the questions as to why treatment in such cases often breaks down and what the underlying factors of such phenomena will be found out and discussed.

Scenario: This is a 26-year-old male whose presentation has been fever, productive cough, diarrhoea, headache, dizziness, anorexia, and nausea. He has never felt well in the last 10 years and had noted a marked loss of weight for the last 2 months. The diarrhoea has been distressing for him, and chest examination was consistent with interstitial pneumonia leading to a compromise in oxygen saturation to a critical level. Bronchoscopy with BAL has revealed organisms that are consistent with Pneumocystis carinii (Kovacs et al., 2001, 2450-2460).

Analysis: His long-drawn disease is consistent with HIV infection that has turned into AIDS over the last 2 months leading to most probably an opportunistic infection of the gastrointestinal tract leading to disturbing diarrhoea associated with nausea and vomiting. His decreased leukocyte count and pulmonary infection with Pneumocystis carinii indicate an opportunistic pulmonary infection that is very characteristic of immunodeficiency associated with AIDS and consequently diminished CD4 count (Newton et al., 2003, 185-186).

Thus the original disease that the patient is suffering from is AIDS, the hallmark of which is an immune deficiency. The treatment with antibacterial agents thus has a chance to break down. This has been ascribed to the profound deficiency in immune function that eventually develops in an infected individual. The virus, HIV suppresses immune function since this has a predilection to infect the immune system, and as a result of continued infection, these cells are eventually destroyed (Adler, 2001, 12-17).

The most significant targets of this virus are a subset of thymus-derived lymphocytes that carry surface molecule CD4. CD4 has been demonstrated to bind to the envelop glycoprotein of HIV. Many other cells and tissues, such as monocytes and macrophages also bear CD4 receptors. Coupled with G-protein coupled receptor family co-receptors, the processing of chemokines in these cells is affected, leading to defective migration, differentiation, and function of leukocytes during the immune response to any infective process in the body. Two specific receptors, CCR5 and CXCR4 are important particularly. CCR5 is expressed widely in cells of the immune system that fight disease, such as lymphocytes, macrophages, and dendritic cells. When the virus strains infect the primary macrophages through these co-receptors, the macrophages which are prime immune cells themselves are rendered defunct (Adler, 2001, 12-17).

From that point of view, the CD4 lymphocytes or T helper cells have known significant and central roles in immune functions, and as a result of HIV infection, these cells are destroyed. In consequence, the body's immune response of affected, and this in part explain the immunosuppressive effects of the virus. These cells are normally stimulated by antigen contact, and normally they respond through enhanced cell division and synthesis and release of lymphokines, namely, interferons, tumour necrosis factors, interleukins, and other chemotactic factors that are involved in the recruitment of more immune cells. The whole cascade of these phenomena are affected, and as a result, the functions of the lymphokines to act as promoters of cytotoxic or suppressor CD8 cells and their maturation and behaviour are all affected, culminating in the suppressed synthesis of antibody from the B lymphocytes. Other cells participating in the process of this innate immunity against diseases functionally contribute to the process. These are monocytes, tissue macrophages, and dendritic cells, and hence with infection with HIV, the total immune system is compromised. Macrophages and particularly dendritic cells are important antigen-presenting cells that primarily initiate the immune responses of the lymphocytes. This conglomeration of events would lead to the failure of conventional treatments to eradicate these infections (Adler, 2001, 12-17).