الفهرس 
Normal immune responseOnly 14 pages are availabe for public view
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Abstract
Immunocompromised patients have alterations in cellular , humoral immunity and phagocytosis that increase both the risk of infection and the ability to combat infection. Immunodeficiency may be congenital, acquired or induced by cytotoxic, immunosuppressive or radiation therapy (organ transplantation or malignant diseases).The cause and duration of immunodeficiency affects the degree of risk towards infection. The predominant pathogens in immunocompromised patients vary with the type of immunosuppression and by degree and duration of the immunodeficiency. A very wide range of organisms can cause infection in immunocompromised patients. Opportunistic pathogens must not be overlooked. A profoundly immunocompromised patient who has been immunosuppressed for a long time may be vulnerable to more than one infection and different organisms may emerge during a single febrile episode. Generally, the treatment should target the pathogens which are most likely to be involved, depending upon the host condition and duration of immunosuppression. Resistant or opportunistic organisms should always be considered. The core regimen should include: A combination of broad-spectrum antibiotics at high-doses to combat Gram-positive and Gram-negative aerobes, plus antifungal therapy which should be administered intravenously from the outset of treatment to prevent secondary fungal infection and administration. Once results of the culture and sensitivities are known, antibiotic treatment should be tailored accordingly.There is five different types of empiric antibiotic regimens: aminoglycoside plus antipseudomonal beta-lactam, beta-lactam monotherapy, empiric regimens containing vancomycin, double-beta lactam therapy, and fluoroquinolone plus aminoglycoside, beta-lactam, or vancomycin.In primary and secondary B-cell defects e.g. Common variable immunodeficiency, hypogammaglobulinaemia, X linked (Bruton’s agammoglobulinaemia), Selective IgA deficiency, splenectomy, hematopoietic cell transplantation, and malignancies, the most common bacteria which can cause severe and recurrent infections are Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitides. After obtaining appropriate cultures the antibiotics which target likely causes should include a combination of : penicillin plus Gentamicin or amikacin, or tobramycin or clarithromycin, for Streptococcus pneumoniae and other streptococci. Vancomycin plus Ampicillin or amoxicillin for Haemophilus influenzae and Vancomycin plusCeftriaxone or amoxicillin or Penicillin G for meningococcal meningitis which is the drug of choice. Alternative antibiotics with extended spectrum such as: cefotaxime or ceftriaxone, macrolides, and clindamycin can be used. In primary and secondary T-cell defects e.g., severe combined immunodeficiency (SCID), bare lymphocyte syndrome, CD3, CD4, and CD8 deficiency, natural killer cell deficiency, T-cell signaling deficiency, Wiskott-Aldrich syndrome, malignancies, immunosuppressive therapy chemotherapy, bone marrow transplantation, and malnutrition, the most common bacteria which can cause severe and recurrent infections are Mycobacterium tuberculosis, Atypical mycobacteria, Legionella spp, Listeria monocytogenes, Enterobacteriaeae, and Salmonella typhi. After obtaining appropriate cultures the antibiotics which target likely causes should include: Erythromycin, clarithromycin, azithromycin minocycline for Mycobacterium tuberculosis, Atypical mycobacteria. Rifampin, Erythromycin, clarithromycin, azithromycin for Legionella spp. Ampicillin, amoxicillin for Listeria monocytogenes. Ampicillin, amoxicillin for Enterococcus faecalis. Imipenem, meropenem for Enterobacteriaeae. Ampicillin, amoxicillin, Ceftriaxone for Salmonella typhi. In Phagocyte disorders e.g., Severe congenital neutropenia, , Leukocyte adhesion deficiency types 1, 2 and 3, Chronic granulomatous disease, Interferon γ receptor 1and 2 deficiency, and Chédiak-Higashi syndrome, the most common bacteria which can cause severe and recurrent infections are Staphylococcus spp., Klebsiella spp., Serratia spp., Steptococcus spp., Nocardia spp., Escherichia spp., Salmonella spp., mycobacterial infection, P. aeruginosa, and pneumococcal infections. After obtaining appropriate cultures the antibiotics which target likely causes should include: amikacin, cefoxitin, imipenem, and clarithromycin or only amikacin, imipenem, tobramycin, and clarithromycin fo M. abscessus and M. chelonae, Long-term suppressive therapy with a quinolone or trimethoprim-sulfamethoxazole, could be used for treating Salmonella, Rifabutin, clarithromycin, and azithromycin, either alone or in combination with rifabutin for M. avium, Nafcillin, oxacillin, Cefazolin, , Rifampin, Linezolid for Staphylococcus spp., Cefazolin for Escherichia spp., Piperacillin plus tazobactam, Polymyxin E (colistin) for P. aeruginosa.