[Bacterial bloodstream infections in critical patients]

Bloodstream infection, together with ventilator-associated pneumonia, is the most frequent nosocomial infection in critically ill patients; it is associated with significant morbidity and mortality. As bloodstream infections in critical patients are usually due to intravascular catheters, they can be caused by both gram-positive and gram-negative microorganisms. Furthermore, infection with multiresistant organisms is becoming more common, and this makes the choice of empirical antibiotic treatment more difficult. Patients with severe community-acquired infections account for a large percentage of patients who require admission to intensive care units for hemodynamic instability or organ dysfunction. Many of these also have bacterial bloodstream infections; about 30% of all bacterial bloodstream infections in critical patients occur in this group of patients. Among this group, 70% develop severe sepsis or septic shock, both of which have high mortality. Recently, another classification scheme included a distinct group comprising patients with community-acquired bloodstream infections after recent or intermittent contact with healthcare facilities. When choosing the empirical antibiotic treatment, it is important to bear in mind that this group has specific characteristics that are often comparable to nosocomial infections. We describe the characteristics, origins, causes, and most common complications of nosocomial, community-acquired, and healthcare-related bacterial bloodstream infections in critical patients to make it easier to recognize them early and initiate efficacious empirical antibiotic therapy and thus improve the prognosis of these patients.