Circulating cytokines as markers of systemic inflammatory response in severe community-acquired pneumonia
Introduction
According to the results of meta-analyses, the average mortality rate for community-acquired pneumonia (CAP) ranges from 1% in hospitalized and ambulatory patients to 36.5% in patients who need to be admitted to an intensive care unit [1], [2]. Diverse molecular mechanisms of inflammation and cellular damage have been implicated in the pathogenesis of severe pneumonia, including those related to overt generation of cytokines. Several studies demonstrated that serum TNFα, IL-6 and IL-8 are involved in the pathogenesis of organ injury and death from severe infection [3], [4], [5]. Marchant et al. [6] reported that plasma IL-10 was increased in patients with circulatory shock of septic and nonseptic origin. The role of TNFα gene polymorphism was shown in a study with CAP patients where septic shock and respiratory failure were strongly associated with a specific haplotype of the studied gene. The inflammatory response to local infection such as pneumonia has been shown to be largely compartmentalized [7]. However, significantly elevated systemic concentrations of TNFα and IL-6 have been reported in patients with severe pneumonia [8], [9]. An enhanced anti-inflammatory response was also found in severe CAP [10]. The relationship between the degree of illness severity assessed by clinical features and the profile of the cytokines response in patients with CAP has not been clearly established.
In this study, we have investigated the influence of empirical antibacterial therapy on the illness severity as assessed by the British Thoracic Society (BTS) score and on the degree of systemic inflammatory reaction in patients with CAP meeting SIRS criteria.
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Materials and methods
The presence of clinical symptoms on admission, such as pyrexia, productive or dry cough, dyspnea, pleuritic pain and auscultatory findings (altered breath sounds, crepitations and/or localised rales) corresponding to an acute infiltrate on a chest radiograph were considered as indicators of pneumonia. CAP patients met two or more of the ACCP/SCCM criteria (1992) for SIRS: (temperature > 38 °C or < 36 °C, heart rate > 90/min, respiratory rate > 20/min, PaCO2 < 32 Torr [<4.27 kPa], leukocytosis
Results
There were 30 patients with CAP meeting SIRS criteria included in the study (Table 1). Fifteen patients were classified as having severe CAP on admission (group I), while the remaining 15 patients (group II) had non-severe CAP. Eight patients from group I and 3 patients from group II had received antibiotics before admission. Antibacterial treatment as monotherapy was initiated in 67% (10/15) of non-severe patients and in 13% (2/15) of patients from group I. According to clinical data, 10
Discussion
In the present study, we found that stratification of CAP patients according to BTS could help to identify those individuals with a severe state due to systemic inflammatory response. These patients possibly require additional care, as for patients with confirmed diagnosis of severe sepsis. The data obtained by serial measurements confirmed that patients with severe CAP meeting SIRS criteria had significantly increased levels of the circulating cytokines IL-6, IL-8, IL-10 as well as CRP in
Acknowledgements
We gratefully acknowledge the skillful technical assistance of Christa Scholz.
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