Role of procalcitonin in assessment of bacterial infection and antibiotic guidance in patients with acute exacerbations of chronic obstructive pulmonary disease on mechanical ventilation

ABSTRACT

This study was designed to investigate the diagnostic and prognostic values of serum procalcitonin concentrations "PCT' in comparison with other bacterial infection markers e.g. C-reactive protein concentrations "CRP" and microbiological cultures of protected specimen brush "psb" in patients with respiratory failure due to acute exacerbations of chronic obstructive pulmonary disease "COPD". We deemed that PCT concentrations could be used as a guide to reduce antibiotic overuse in these patients. Fifty-nine patients with acute respiratory failure due to exacerbations of COPD on mechanical ventilation were divided into two groups. PCT group "30 patients" were given antibiotic only if PCT concentrations were above 0.5ug/L and standard group "29 patients" were given antibiotic according to the physician opinion regardless of PCT concentrations levels. PCT guided antibiotic use resulted in reduction of antibiotic use by 46% without worsening the outcome in comparison with the standard group. Also, PCT was a good tool in diagnosis of bacterial infection as reflected by a higher PCT concentrations in patients with positive bacterial cultures of psb of the lower respiratory tract. 29 of 59 patients [49%] had positive bacterial growth, of them 28 patients were had high PCT concentrations "more than 0.5 ug/L" and only one patient had PCT concentration less than 0.5 ug/L. Patients with high PCT concentrations were also had significant leucocytosis in comparison with patients with low PCT concentrations "white blood cell count [13.2 +/- 9.4 vs 8.2 +/- 6.71 x 109/L respectively". CRP was also higher in patients with high PCT concentrations in comparison with patients who had low PCT concentrations [99.4 +/- 96.5 vs 94.7 +/- 103.2mg/L respectively], but the difference was not statistically significant. Also, PCT concentrations declined earlier than CRP after proper treatment of bacterial infection. PCT levels reached physiological concentrations within 10 -15 days while CRP was still above normal range, which means that PCT was of better diagnostic and prognostic values in patients with acute exacerbations of COPD on mechanical ventilation