Procalcitonin as a Marker of Antibiotic Therapy in Patients With Lower Respiratory Tract Infections

An increasing amount of antibiotics are being consumed and along with the increased resistance they carry along, they pose an increasing problem for the health sector. A method to decrease the use of antibiotics is highly desirable and of great importance in order to halt the spread of multi-resistant bacteria that is becoming an increasing problem in Denmark. Lower respiratory tract infections such as pneumonia and acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are frequent reasons for patient contact in both the primary and secondary sectors. Identifying which patients that could benefit from treatment with antibiotics is a great challenge to the health sector. This is why patients often are treated with antibiotics if there is a mere suspicion of the above-mentioned disorders, even if they are not proved for certain. An increasing amount of data suggests that procalcitonin (PCT) could serve as a possible marker of respiratory tract infections caused by bacteria. Alongside the conventional clinical parameters, the level of PCT is regarded as a promising means to decide whether to treat with antibiotics and how long such a treatment should endure. When an infection is under control by the immune system of the individual or by treatment with antibiotics, the level of PCT will diminish by 50% on a daily basis. Accordingly, a decline in the PCT levels should indicate a favorable response to antibiotic treatment. Therefore there is a need to further investigate if the PCT levels can be used, in the everyday clinic, to diagnose patients with pneumonia or AECOPD caused by bacteria and if this could have an effect on the use of antibiotics, thus optimizing the treatment of the patients. The purpose of this research project is to compare the amount of antibiotics consumed using standard treatment and treatment based on the PCT levels of patients with lower respiratory tract infections, respectively. With the research at hand, a clarification of whether a measurement of PCT can serve as a diagnostic tool to distinguish between bacterial and non-bacterial infections in patients that are suspected of having pneumonia or AECOPD is desirable. In extension, this study wants to clarify if the PCT levels can indicate when a potential antibiotic treatment should be initiated and if the use of a PCT-based treatment in the daily clinical work could lower the consumption of antibiotics. The hypothesis is that PCT will be increased (≥0.25 µg/l and ≥0.10 µg/l for pneumonia and AECOPD respectively) in lower respiratory tract infections caused by bacteria, whereas PCT should only be slightly increased in non-bacterial lower respiratory tract infections if at all. It is expected that using a PCT-based treatment in lower respiratory tract infections could lower the consumption of antibiotics, while at the same time it should not prove a greater health risk to patients than by using a standard treatment.