The identification of pneumonia, whether community-, nosocomial-, or ventilator-acquired, is still a difficult problem. In the community setting, the presence of new chest infiltrates, fever, leukocytosis, and purulent secretions usually reflect the presence of an underlying pulmonary infection.<sup>8 Celis R., Torres A., Gatell J.M. , e al. Nosocomial pneumonia. A multivariate analysis of risk and prognosis Chest 1988 ;  93 : 318-324  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti, 15 Chevret S., Hemmer M., Carlet J. , e al. Incidence and risk factors of pneumonia acquired in intensive care units Intensive Care Med 1993 ;  19 : 256-264  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti, 17 Craven D.E., Dricks M.R. Nosocomial pneumonia in the intubated patient Semin Respir Infect 1987 ;  2 : 20-33

Cliccare qui per andare alla sezione Riferimenti</sup> However, in the hospital setting, this is not always true. Several conditions, particularly in mechanically ventilated patients, can cause chest infiltrates and fever and can mimic pneumonia. The identification of the cause of pulmonary infections is still more complex. Variations in the clinical presentation warrant bacteriologic confirmation to direct the initial antimicrobial therapy, particularly in the hospital setting or for immunocompromised hosts. It has been estimated that as many as 15% of all deaths occurring in hospitalized patients are directly related to pneumonia. Recently several studies have shown that one third of all deaths occurring in nosocomial pneumonia patients are directly attributable to pneumonia.<sup>24 Fagon J.Y., Chastre J., Hance A.J. , e al. Nosocomial pneumonia in ventilated patients: A cohort study evaluating attributable mortality and hospital stay Am J Med 1993 ;  94 : 281-288  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti, 25 Fagon J.Y., Chastre J., Vuagnat A. , e al. Nosocomial pneumonia and mortality among patients in intensive care units JAMA 1996 ;  20 : 866-869

Cliccare qui per andare alla sezione Riferimenti, 45 Leu H.S., Kaiser D.L., Mori M. , e al. Hospital acquired pneumonia. Attributable mortality and morbidity Am J Epidemiol 1989 ;  135 : 426-432

Cliccare qui per andare alla sezione Riferimenti</sup> Other studies have shown that inadequate initial antibiotic treatment is related to prognosis.<sup>8 Celis R., Torres A., Gatell J.M. , e al. Nosocomial pneumonia. A multivariate analysis of risk and prognosis Chest 1988 ;  93 : 318-324  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup> In addition, overtreatment with antibiotics may lead to infections with more virulent microorganisms such as Pseudomonas aeruginosa or Acinetobacter calcoaceticus.<sup>79 Rello J., Ausina V., Ricart M. , e al. Risk factors for infection by Pseudomonas aeruginosa in patients with ventilator-associated pneumonia Intensive Care Med 1994 ;  20 : 193-198  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup> It seems obvious that early detection of pneumonia and the obtaining of a microbiologic diagnosis are important goals when facing this frequent infection. Unfortunately, these goals are still difficult to achieve, since many patients have received prior antibiotics before sampling, and the inherent imperfections of sampling methods with regard to sensitivity and specificity make the identification of the causal microbial agents more difficult.<sup>57 Meduri G.U., Mauldin G.L., Wunderink R.G. , e al. Causes of fever and pulmonary densities in patients with clinical manifestations of ventilator-associated pneumonia Chest 1994 ;  106 : 221-235  [cross-ref]

Cliccare qui per andare alla sezione Riferimenti</sup> Microbiologic diagnosis of nosocomial pneumonia may also be a problem, since the oropharyngeal cavity of hospitalized patients is commonly colonized by potential pulmonary pathogens. This can lead to misinterpretation of respiratory samples that do not by-pass the oropharynx. During the last decade, several investigators have reported results about diagnosis of pneumonia using techniques that try to avoid oropharyngeal colonization. These techniques, also called invasive, have become very popular, especially in Europe, for diagnosing hospital-acquired pneumonia and particularly ventilator-associated pneumonia. More severely ill patients or patients not responding to initial empiric antibiotic regimens may potentially benefit from these techniques.

This article reviews various techniques (protected specimen brush (PSB), bronchoalveolar lavage (BAL), and lung biopsy) and their potential risks and benefits in the diagnosis of lower respiratory tract infection.