Seminars in respiratory infections
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Semin Respir Infect · Dec 1993
ReviewSelective decontamination of the digestive tract: risks outweigh benefits for intensive care unit patients.
Selective decontamination of the digestive tract (SDD) involves the administration of non-absorbable antibiotics (+/- a systemic antibiotic) to prevent colonization and infection in intensive care unit patients. The regimen is targeted at nosocomial gram-negative bacilli, some gram-positive bacteria and yeast. ⋯ To date, there is conflicting evidence that SDD significantly reduces length of stay, mortality, or hospital costs. Currently, there are concerns that SDD may result in increased colonization and infection with gram-positive organisms and multi-drug resistant pathogens, particularly in medical ICU patients or when used for extended periods of time.
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Semin Respir Infect · Dec 1993
ReviewIndications for selective decontamination of the digestive tract.
Controversy exists as to the utility of selective decontamination of the digestive tract (SDD) as a method of infection prevention in critically ill patients. A number of prospective randomly controlled studies and 2 meta-analyses have shown a statistically significant protective effective of SDD against nosocomial infection. Most other SDD trials have shown reductions in nosocomial infections, but these reductions have not been statistically significant. ⋯ SDD may be an effective infection prevention method in intensive care units in which there is a high rate of nosocomial pneumonia and/or other infections and in the postoperative period of orthotopic liver transplantation. SDD may also be useful to eliminate resistant gram-negative bacilli colonizing patients who are at high risk for infection sequelae. When SDD is used, periodic surveillance for the emergence of resistant microorganisms is imperative.
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Infection with the human immunodeficiency virus (HIV) produces profound alterations in host defense mechanisms throughout the respiratory tract. The extent of alteration of specific defenses varies with the stage or duration of HIV infection in the host. In the upper respiratory tract, HIV-infected individuals have decreased concentrations of salivary immunoglobulin A, which may predispose to colonization of the oropharynx with pathogenic microorganisms. ⋯ B lymphocytes from HIV-infected persons show deficient production of opsonizing antibodies, which may predispose to bacterial pneumonias. Defective responses of polymorphonuclear leukocytes in the lung are also likely to contribute to impaired host responses. Collectively, these multiple defects in the defense mechanisms of the respiratory tract explain the unique susceptibility of the HIV-infected host for opportunistic pulmonary infections.
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Resolution of pneumonia has to be considered as two different phases: resolution of the acute illness and resolution of radiographic opacities. Age, comorbidities, immunosuppression, and etiological agent(s) are all important in determining whether the acute illness resolves; there is a considerable mortality rate from pneumonia requiring hospitalization. ⋯ In 96% of patients whose pneumonia has not resolved in 30 days, an underlying disease is found; emphysema, chronic bronchitis, or bronchogenic carcinoma are the most common. Normal resolution of community-acquired pneumonia has to be defined in terms of the severity of the illness, comorbidity (ies), and infecting pathogen(s).
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Radiographic imaging modalities that have been applied to the staging and prognostication of the lung lesion in cystic fibrosis (CF) include conventional chest radiographs, computed tomography (CT), and magnetic resonance imaging (MRI). Conventional chest radiographs are usually adequate to detect the salient radiographic features of CF and provide objective parameters for longitudinal disease progression. Although the lung manifestations of CF can be highly variable most patients with CF demonstrate some of the classic chest radiographic findings that reflect chronic bronchiectasis: hyperinflation, bronchial thickening and dilatation, peribronchial cuffing, mucoid impaction, cystic radiolucencies, an increase in interstitial markings, and scattered nodular densities. ⋯ The use of MRI in the clinical management of CF has been limited. MRI may be helpful in determining the cause of linear lung markings, differentiating mucous plugging, and peribronchial thickening from normal pulmonary blood vessels. MRI is an excellent imaging modality to differentiate hilar or mediastinal adenopathy from blood vessels or mediastinal fat.