Immunocompromised hosts

Tuberculosis can produce atypical signs and symptoms in infants, the elderly, and immunocompromised hosts, and it can progress rapidly in these patients. 

Caseating granulomas, regardless of location, can undergo liquefaction, spread tubercle bacilli and cause symptoms.2,6 Because of muted or altered symptoms, the diagnosis of TB is difficult and often delayed in immunocompromised hosts.2,3,6 HIV-infected patients may present with only extrapulmonary TB, which is very uncommon in HIV-negative persons. A widely disseminated form of the disease called miliary TB can occur, particularly in children and immunocompromised hosts, and it can be rapidly fatal.17 Immediate treatment is required. 

Patients with AIDS and other immunocompromised hosts may be managed with chemotherapeutic regimens similar to those used in immunocompetent individuals, although treatment is... 

Hydration and electrolyte balance, often with ORT, are the cornerstone of treatment. The specific circumstances that antibiotics should be considered include high fevers, bloody stools, symptoms longer than 1 week, pregnancy, infection with HIV, and other immunocompromised hosts. 

There is no antimicrobial available that is effective at consistently eradicating Cryptosporidium, particularly in immunocompromised hosts. In general, immunocompetent persons... 

Disseminated or CNS cryptococcosis requires a more aggressive treatment approach, particularly in the immunocompromised host. Pretreatment predictors of poor outcome with antifungal therapy include ... 

Live virus vaccines should not be given to an immunocompromised host. 

Live attenuated influenza LAIV 0.5 mL Intranasal Severe egg allergy Asthma Chronic health problems Immunocompromised host Pregnant women History of Guillain-Barre syndrome... 

Measles, mumps, rubella MMR 0.5 mL Subcutaneous Allergic reaction to gelatin or neomycin Pregnant women Immunocompromised host Recently received a blood transfusion Severe egg allergy... 

The number of immunocompromised persons is continually increasing as advances are made in medicine. The life expectancy for persons with cancer, HIV infection, and solid organ or bone marrow transplantation is increasing. Vaccination provides one tool to prevent infection in the immunocompromised host however, the individual s immuno-suppressed state will alter the response to vaccine. In general all vaccinations should be updated prior to the person becoming immunosuppressed, if possible. Once a person becomes significantly immunosuppressed, live virus vaccines should be avoided. 

Household contacts of immunocompromised persons should have all routine vaccines as scheduled, including yearly influenza vaccination. Children in the household may receive live virus vaccines without special precautions however, if a rash develops following varicella vaccination, contact should be avoided with the immunocompromised host until the rash resolves. 

Lactoferrin, a protein found in secondary granules of polymorphonuclear cells, was observed to be mildly to moderately elevated in the stools of children with endemic cryptosporidiosis [91] and healthy adult volunteers with experimental infection [92], Indeed, in another study of malnourished children in Haiti, cryptosporidiosis was noted to stimulate an inflammatory response, as evidenced by elevated IL-8, TNF-a, lactoferrin, IL-13 and IL-10 [93]. Further studies are needed to elucidate the role of inflammatory mediators in the development of prolonged diarrhea, malabsorption and malnutrition in immunocompromised hosts and children in endemic areas. 

Fantry L Gastrointestinal infections in the immunocompromised host. Curr Opin Gastroenterol 2001 17 40-45. 

In patients exposed to a large inoculum and in immunocompromised hosts, progressive illness, disseminated histoplasmosis, occurs. The clinical severity of the diverse forms of disseminated histoplasmosis (Table 38-1) generally parallels the degree of macrophage parasitization observed. 

Immunocompromised host (including patients with acquired immune deficiency syndrome, transplants, or receiving chronic glucocorticoid therapy)... 

In the immunocompromised host, aspergillosis is characterized by vascular invasion leading to thrombosis, infarction, and necrosis of tissue. 

Immunocompromised hosts should receive annual influenza vaccination with TIV but not LAIV. 

Risk factors in the host can give a clue for the causative pathogen e.g. Chronic Obstructive Lung Disease (COPD) - Haemophilus, alcoholism - Klebsiella, HIV - Pneumocystis. The immunocompromised host is also at increased risk for certain fungal (Aspergillus) and viral infections (cytomegalovirus or CMV). Pseudomonas aeruginosa is frequently involved in exacerbations of cystic tibrosis. 

The cancer patient and the HIV-positive patient are the two clinically important groups were the natural defence systems are disturbed either by the disease or by the treatment (chemotherapy, radiotherapy). Infections in the HIV-positive patient are discussed in Chapter 33B. Less prevalent immunocompromised hosts are patients with hypo- or agamma-globulinaemia or patients after splenectomy. These last patient groups with mainly humoral dysfunction generally suffer from infections by encapsulated bacteria S. pneumoniae, H. influenzae and N. meningitidis). In this section we will discuss patients with cellular immune dysfunction, mainly granulocytopenia. 

Important factors in the immunocompromised host predisposing to infection are granulocytopenia, T- or B-cell dysfunction, antibody deficiency. 

Ophtalmia neonatorum by N. gonorrhoeae and Chlamydia trachomatis is acquired during delivery. Contact lens wear predisposes to corneal infections, mostly by Pseudomonas sp. and the ameba Acan-thamoeba and Naegleria. Immunocompromised hosts are predisposed to severe retinitis by CMV and to other intra-ocular eye infections by opportunistic pathogens. 

Prophylaxis is defined as antibiotics used to prevent infection. The reasons to administer prophylaxis can be the same for surgical and non-surgical prophylaxis, and for immunocompetent or immunocompromised hosts alike. These reasons are ... 

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