3 results
34 - Aspiration pneumonia
- from Part V - Clinical syndromes: respiratory tract
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- By Suttirak Chaiwongkarjohn, VA Greater Los Angeles Health Care System, Arash Heidari, Kern Medical Center, Christopher J. Graber, David Geffen School of Medicine at UCLA, Matthew Bidwell Goetz, David Geffen School of Medicine at UCLA
- Edited by David Schlossberg, Temple University, Philadelphia
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- Book:
- Clinical Infectious Disease
- Published online:
- 05 April 2015
- Print publication:
- 23 April 2015, pp 226-232
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Summary
Introduction
Aspiration is the introduction of oropharyngeal or gastric contents into the respiratory tract. Three major syndromes may develop as a consequence of aspiration: chemical pneumonitis, bronchial obstruction secondary to aspiration of particulate matter, and bacterial aspiration pneumonia. Less commonly, interstitial lung disease occurs in persons with chronic aspiration. Which of these consequences emerges is determined by the amount and nature of the aspirated material as well as by the integrity of host defense mechanisms.
The term aspiration pneumonia refers to the infectious consequences of introduction of relatively large volumes of oral material into the lower airways (macroaspiration). Although healthy persons frequently aspirate small volumes of pharyngeal secretions during sleep, the development of pneumonia after such microaspiration is normally prevented by mechanical (e.g., cough and mucociliary transport) and immunologic responses. Pneumonia arises when these host defenses are not able to limit bacterial proliferation either because of microaspiration of highly virulent pathogens to which the host lacks specific immunity (e.g., Streptococcus pneumoniae or enteric gram-negative bacteria) or because of macroaspiration of large quantities of organisms that may not necessarily be highly virulent.
Aspiration may be clinically obvious, as when acute pulmonary complications follow inhalation of vomited gastric contents. Such acute chemical pneumonitis, representing damage to lung parenchyma by highly acidic gastric contents, is often referred to as Mendelson’s syndrome. On the other extreme, so-called silent aspiration, as occurs in persons with neurologic impairment who lack cough responses, is often followed by the indolent onset of infectious pneumonia consequent to contamination of the lower airways by low virulence mixtures of aerobic and anaerobic microorganisms from the oropharynx.
160 - Yersinia
- from Part XVIII - Specific organisms: bacteria
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- By Royce H. Johnson, David Geffen School of Medicine, Arash Heidari, David Geffen School of Medicine
- Edited by David Schlossberg, Temple University, Philadelphia
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- Book:
- Clinical Infectious Disease
- Published online:
- 05 April 2015
- Print publication:
- 23 April 2015, pp 1034-1036
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Summary
Introduction
The genus Yersinia consists of 17 species. Only three species are consistently pathogenic for humans. These are Yersinia pestis, the agent of plague, Yersinia enterocolitica, and Yersinia pseudotuberculosis, which are usually, but not entirely, gastrointestinal pathogens.
Yersinia pestis
An ongoing result of the unfortunate events of September 11, 2001 has been an increase in research on Yersinia, particularly, Y. pestis. This is an ancient organism and since its divergence from Y. pseudotuberculosis 1500 to 20 000 years ago has largely existed as a rodent pathogen with only occasional human transmission. Three well-described pandemics of plague have occurred. The last of these began in the nineteenth century. Alexandre Yersin first isolated Y. pestis in 1894. The twentieth century saw major outbreaks in Vietnam and India. The majority of cases currently are seen in sub-Saharan Africa, particularly Madagascar.
The majority of cases seen in the United States are from the southwestern states of New Mexico, Arizona, Colorado, Texas, and California. Climate change may well affect the bacteria, the vector, and the hosts, resulting in potential worldwide changes in the frequency and distribution of disease. In 2010 two human cases were reported in Oregon
There has been remarkable progress in the understanding of the pathogenesis of Yersinia infections, particularly those caused by Y. pestis. A partial list of these advances include the effects of Y. pestis on flea behavior, and its avoidance of both innate and adaptive (both humeral and cellular) immune response.
33 - Aspiration Pneumonia
- from Part V - Clinical Syndromes – Respiratory Tract
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- By Arash Heidari, University of California, Matthew Bidwell Goetz, University of California
- Edited by David Schlossberg
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- Book:
- Clinical Infectious Disease
- Published online:
- 05 March 2013
- Print publication:
- 12 May 2008, pp 233-240
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- Chapter
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Summary
INTRODUCTION
Aspiration is the introduction of oropharyngeal or gastric contents into the respiratory tract. Three major syndromes may develop as a consequence of aspiration: chemical pneumonitis, bronchial obstruction secondary to aspiration of particulate matter, and bacterial aspiration pneumonia. Less commonly, interstitial lung disease occurs in persons with chronic aspiration. Which of these consequences emerges is determined by the amount and nature of the aspirated material as well as by the integrity of host defense mechanisms. Aspiration is the main means of bacterial contamination of the lower airways.
The term aspiration pneumonia is used to refer to the infectious consequences of introduction of relatively large volumes of material (macroaspiration). Although healthy persons frequently aspirate small volumes of pharyngeal secretions during sleep, the development of pneumonia after such microaspiration is normally prevented by mechanical (eg, cough and mucociliary transport) and immunological responses. Pneumonia arises when these host defenses are not able to limit bacterial proliferation either because of microaspiration of highly virulent pathogens to which the host lacks specific immunity (eg, Streptococcus pneumoniae or enteric gram-negative bacteria) or because of macroaspiration of lower or higher virulence organisms.
Aspiration may be clinically obvious, as when acute pulmonary complications follow inhalation of vomited gastric contents. Such acute chemical pneumonitis is often referred to as Mendelson syndrome. On the other extreme, so-called silent aspiration, as occurs in persons with neurological impairment who lack cough responses, is often followed by the indolent onset of infectious pneumonia consequent to the inhalation of the low virulence mixtures of aerobic and anaerobic microorganisms normally resident in the oropharynx.