Strategies and options for minimizing resistance emergence in pulmonary infections

Triggering receptors expressed on myeloid cells in pulmonary aspiration syndromes

OBJECTIVE

To investigate the potential role of serum and alveolar soluble triggering receptor expressed on myeloid cells (sTREM-1) as a biological marker of pulmonary aspiration syndromes.

DESIGN

Prospective cohort study.

SETTING

University-affiliated intensive care unit.

PATIENTS

Seventy-five patients with pulmonary aspiration and 13 controls receiving mechanical ventilation.

INTERVENTIONS

Blood and bronchoalveolar lavage (BAL) fluid samples were collected on enrollment. Soluble TREM-1 levels were measured by an enzyme-linked immunosorbent assay.

MEASUREMENTS AND RESULTS

Thirty-eight of 75 participants had documented BAL culture-positive pulmonary aspiration. While circulating levels of sTREM-1 were comparable between those with aspiration syndromes (19.81 +/- 12.09 pg/ml) and controls (15.96 +/- 11.16 pg/ml) (p=0.27), the alveolar levels of sTREM-1 were higher in patients with culture-positive pulmonary aspiration (344.41 +/- 152.82 pg/ml) compared with those culture-negative pulmonary aspiration (142.76 +/- 89.88 pg/ml; p < 0.001). A cut-off value of 250 pg/ml for alveolar sTREM-1 achieved a sensitivity of 65.8% (95% CI 48.6-80.4) and a specificity of 91.9% (95% CI 78.1-98.2) with an area under the curve of 0.87 (95% CI 0.78-0.94).

CONCLUSIONS

Alveolar sTREM-1 levels can be a potential biomarker for distinguishing BAL culture-positive from BAL culture-negative pulmonary aspiration.

Soluble form of the triggering receptor expressed on myeloid cells-1 as a marker of microbial infection

Sepsis is a common cause of morbidity and mortality in intensive care units. Unfortunately, there is no gold standard for diagnosing sepsis as clinical and laboratory signs are neither sensitive enough nor specific enough, and microbiological studies often remain negative. Thus, there is a need for clinical or laboratory tools to distinguish between sepsis and non-infectious inflammatory disorders. Among the potentially useful markers of sepsis, procalcitonin has been suggested to be the most promising, although results are variable depending on the severity of illness and degree of infection in the patient population studied. The triggering receptor expressed on myeloid cells-1 (TREM-1) is a member of the immunoglobulin superfamily, of which expression is upregulated on phagocytic cells in the presence of bacteria or fungi. Here we report on the potential usefulness of assessing the soluble form of TREM-1 (sTREM-1) in biological fluids for the diagnosis of microbial infection.

Soluble triggering receptor expressed on myeloid cells and the diagnosis of pneumonia

BACKGROUND

The diagnosis and treatment of bacterial pneumonia in patients who are receiving mechanical ventilation remain a difficult challenge. The triggering receptor expressed on myeloid cells (TREM-1) is a member of the immunoglobulin superfamily, and its expression on phagocytes is specifically up-regulated by microbial products. The presence of soluble TREM-1 (sTREM-1) in bronchoalveolar-lavage fluid from patients receiving mechanical ventilation may be an indicator of pneumonia.

METHODS

We conducted a prospective study of 148 patients receiving mechanical ventilation in whom infectious pneumonia was suspected. A rapid immunoblot technique was used to measure sTREM-1 in bronchoalveolar-lavage fluid. Two independent intensivists who were unaware of the results of the sTREM-1 assay determined whether community-acquired pneumonia and ventilator-associated pneumonia were present or absent.

RESULTS

The final diagnosis was community-acquired pneumonia in 38 patients, ventilator-associated pneumonia in 46 patients, and no pneumonia in 64 patients. The presence of sTREM-1 by itself was more accurate than any clinical findings or laboratory values in identifying the presence of bacterial or fungal pneumonia (likelihood ratio, 10.38; sensitivity, 98 percent; specificity, 90 percent). In multiple logistic-regression analysis, the presence of sTREM-1 was the strongest independent predictor of pneumonia (odds ratio, 41.5).

CONCLUSIONS

In patients receiving mechanical ventilation, rapid detection of sTREM-1 in bronchoalveolar-lavage fluid may be useful in establishing or excluding the diagnosis of bacterial or fungal pneumonia.