# Bloodstream Infection in the Intensive Care Unit: Evolving Epidemiology and Microbiology

## TL;DR

Bloodstream infections in ICU patients are a growing global problem, with varying causes and increasing antibiotic resistance, especially in patients with COVID-19.

## Contribution

This paper provides a narrative review of the evolving epidemiology and microbiology of ICU bloodstream infections, highlighting regional differences and pandemic impacts.

## Key findings

- Gram-positive bacteria dominate in the U.S., while Gram-negative bacteria are more common in Europe, Asia, and Latin America.
- ICU bloodstream infections in patients with SARS-CoV-2 are associated with higher mortality rates.
- Antimicrobial resistance is rising, particularly in MRSA, CRE, and Acinetobacter baumannii.

## Abstract

Bloodstream infections (BSIs) arising in the intensive care unit (ICUs) present a significant challenge and we completed a narrative review of the emerging literature on this issue. Multiple reports document that these infections are associated with substantial morbidity and mortality. Also, they can be caused by a variety of pathogens. Generally classified as either community or hospital in onset, or as either primary or secondary in origin, the microbiology of ICU BSIs varies across the globe. Gram-positive pathogens predominate in certain regions such as the United States while Gram-negative organisms occur more frequently in Europe, Asia, and Latin America. The incidence of ICU BSIs climbed during the recent pandemic. BSIs complicating the care of persons suffering from Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) infection significantly heighten the risk for death compared to patients who develop ICU BSIs but who are not infected with SARS-CoV-2. Furthermore, rates of antimicrobial resistance are generally increasing in ICU BSIs. This fact complicates attempts to ensure that the patient receives initially appropriate antimicrobial therapy and is of particular concern in Methicillin-resistant Staphylococcus aureus, Carbapenem-resistant Enterobacterales, and Acinetobacter baumannii. Fortunately, with respect to clinical application, preventive measures exist, and recent analyses suggest that increased collaboration between infectious disease specialists and intensivists can improve patient outcomes.