Seminars in respiratory infections
-
Patients with multiple trauma and head injuries are high-risk populations for developing nosocomial infections, which are the first cause of death after 3 weeks of admission. Pneumonia caused by methicillin-sensitive Staphylococcus aureus is the most frequent infection in patients with a decreased level of consciousness. ⋯ The diagnosis of meningitis is difficult because CSF biochemical data are not specific. Patients with spinal cord injuries are at greater risk for developing infections caused by multiresistant microorganisms because of their prolonged hospital stay.
-
The second most common nosocomial infection in the United States is pneumonia, with the highest rates seen in patients requiring mechanical ventilation. Nosocomial pneumonia is a serious disease associated with significant morbidity and mortality; crude mortality rates have been estimated at 20% to 50%. The rapid institution of appropriate antimicrobial therapy has been shown to improve mortality in patients with ventilator associated nosocomial pneumonia. ⋯ There are, however, many challenges which confront the laboratory including: the ability to identify organisms from an extensive microbiologic spectrum; distinguishing colonization from infection of predominately gram-negative oropharyngeal flora; and providing timely results. This article reviews the various diagnostic tests available for nosocomial lung infections, and in particular, ventilator associated pneumonia including: blood cultures; pleural fluid; expectorated sputum; endotracheal aspirates; and respiratory specimens obtained by more invasive techniques using bronchoscopy and transthoracic needle aspiration. Emphasis is placed on optimal specimen collection, the processing of samples in the laboratory, and on the evaluation of potential risks and benefits associated with the varying techniques.
-
Semin Respir Infect · Jun 2000
ReviewPneumonia in the immunocompromised host: the role of bronchoscopy and newer diagnostic techniques.
The microbiology laboratory plays an essential role in the laboratory diagnosis of pneumonia in the immunocompromised host. Both the diversity of underlying or predisposing host conditions that increase risk for pneumonia and the variety of microbial agents that may be etiologically responsible make the laboratory's role in the diagnostic process a challenging one. ⋯ Respiratory specimens available for testing are also diverse and are often obtained by the use of fiberoptic bronchoscopy, but may be complemented by use of blood samples when dissemination is likely or more recently by urinary antigen testing in select cases. Given the large number of variables in the design of a diagnostic approach to pneumonia in the immunocompromised host, it is critical that laboratorians and clinicians cooperate in the development of protocols that are cost effective and appropriate to their specific clinical settings.
-
Although pulmonary diseases are important causes of illness and death in patients with human immunodeficiency virus (HIV) infection, advances in treatment and the demographics of HIV-infected populations are changing their incidence and manifestations. The rates of acquires immune deficiency syndrome (AIDS)- related mortality and opportunistic infections have fallen drastically since the introduction of highly active antiretroviral therapy (HAART) in 1996. ⋯ Bronchitis and sinusitis occur commonly in the general population, but more frequently in HIV-infected persons. With progressive immunocompromise, the risk of developing bacterial pneumonia, Pneumocystis carinii pneumonia, and tuberculosis increases.
-
Respiratory failure is one of the most important causes of death in patients with acute pneumococcal pneumonia. There are two forms that may or may not coexist: ventilatory failure and hypoxemic respiratory failure. Ventilatory failure is principally caused by mechanical changes in the lungs resulting from pneumonia. ⋯ Factors that tend to increase flow to consolidated lung and worsen shunt include endogenous vasodilator mediators, exogenous systemically administered vasodilator drugs, positioning the patient with the affected lung dependent, and increasing positive airway pressure. Factors that tend to reduce shunt include effective HPV, inhaled locally acting vasodilators that act primarily on ventilated lung, and positioning the patient with the affected lung up. Although thoughtful application of what is known about the pathophysiology of the lung in pneumococcal pneumonia can help the clinician deploy most effectively the available technologies of respiratory support in these patients, even the best intensive supportive measures are frequently inadequate, and mortality rates for patients requiring such support remain unacceptably high.