Multidrug-Resistant Bacteria in a COVID-19 Hospital in Zagreb

Area of Science:

• Infectious Diseases
• Critical Care Medicine
• Microbiology

Background:

• The COVID-19 pandemic led to a surge in hospitalizations, particularly in intensive care units (ICUs).
• Bacterial superinfections are a known complication of severe viral pneumonia, increasing morbidity and mortality.
• Multidrug-resistant (MDR) and extensively drug-resistant (XDR) pathogens pose a significant threat in healthcare settings.

Purpose of the Study:

• To investigate the causative agents of bacterial superinfections in critically ill COVID-19 patients.
• To determine the prevalence and characteristics of multidrug-resistant (MDR) and extensively drug-resistant (XDR) pathogens causing superinfections.
• To analyze the impact of bacterial superinfections on mortality rates in a COVID-19 intensive care unit.

Main Methods:

• Retrospective analysis of 118 patients admitted to a COVID-19 ICU between November and December 2020.
• Identification and characterization of bacterial pathogens isolated from patients with severe bacterial infections (ventilator-associated pneumonia or bloodstream infections).
• Assessment of antimicrobial resistance patterns, including carbapenem resistance and the presence of specific resistance genes.

Main Results:

• 39% (46/118) of patients developed severe bacterial infections.
• The overall mortality rate was 70% (83/118).
• Mortality directly attributable to bacterial infection or ARDS with superinfection was 33% (40/118).
• Acinetobacter baumannii was the dominant species, with all 34 isolates being carbapenem-resistant (CRAB) and carbapenem-hydrolyzing oxacillinase (CHLO)-positive.
• Six patients had MDR organisms, and 34 had XDR organisms.

Conclusions:

• Bacterial superinfections, particularly those caused by XDR Acinetobacter baumannii, are a major contributor to mortality in critically ill COVID-19 patients.
• The high prevalence of CRAB highlights the challenge of treating bacterial infections in this setting.
• Local epidemiology and hospital overcrowding, especially in ICUs, may facilitate the spread of resistant pathogens.