Urgent need for a rapid microbiological diagnosis in critically ill pneumonia

ABSTRACT

Severe lower respiratory tract infection is a common issue in Intensive Care Units that causes significant morbidityand mortality. The traditional diagnostic-therapeutic approachhas been grounded on taking respiratory samples and/or bloodcultures as soon as possible and starting empirical antibiotictherapy addressed to cover most likely pathogens based onthe presence of the patient’s risk factors for certain microorganisms, while waiting for the culture results in the following 48-72 hours to adequate the antibiotic treatment to thesensitivity profile of the isolated pathogen. Unfortunately, thisstrategy leads to use broad-spectrum antibiotics more timesthan necessary and does not prevent possible therapeuticfailures. The recent development of rapid molecular diagnostic techniques, based on real time polymerase chain reaction(RT-PCR), makes it possible to determine the causative agentand its main resistance pattern between 1 and 5 hours aftersampling (depending on each technique), with high precision,some of them reaching a negative predictive value greaterthan 98%, facilitating the very early withdrawal of unnecessary broad-spectrum antibiotics. Its high sensitivity can alsodetect unsuspected pathogens based on risk factors, allowingadequate treatment in the first hours of stay. This short review discusses the potential usefulness of these techniques incritically ill patients with lower respiratory tract infection andadvocates their immediate implementation in clinical practice. (AU)