Impact of multidrug-resistant bacteria on outcome in patients with prolonged weaning

Pneumonia and septic pneumonic shock are the most common indications for long-term mechanical ventilation and prolonged weaning, independent of any comorbidities. Multidrug resistant (MDR) bacteria are emerging as a cause of pneumonia or occur as a consequence of antimicrobial therapy. The influence of MDR bacteria on outcomes in patients with prolonged weaning is unknown.

Patients treated in a specialized weaning unit of a university hospital between April 2013 and April 2016 were analyzed. Demographic data, clinical characteristics, length of stay (LOS) in the intensive care unit (ICU) and weaning unit, ventilator-free days and mortality rates were determined in prolonged weaning patients with versus without MDR bacteria (methicillin-resistant Staphylococcus aureus bacteria, [MRSA]; extended spectrum beta lactamase [ESBL]- and Gyrase-producing gram negative bacteria resistant to three of four antibiotic groups [3 MRGN]; panresistant Pseudomonas aeruginosa and other carbapenemase-producing gram-negative bacteria resistant to all four antibiotic groups [4 MRGN]). Weaning failure was defined as death or discharge with invasive ventilation.

Of 666 patients treated in the weaning unit, 430 fulfilled the inclusion criteria and were included in the analysis. A total of 107 patients had isolates of MDR bacteria suspected as causative pathogens identified during the treatment process. Patients with MDR bacteria had higher SAPS II values at ICU admission and a significantly longer ICU LOS. Four MRGN P. aeruginosa and Acinetobacter baumanii were the most common MDR bacteria identified. Patients with versus without MDR bacteria had significantly higher arterial carbon dioxide levels at the time of weaning admission and a significantly lower rate of successful weaning (23% vs 31%, p < 0.05). Mortality rate on the weaning unit was 12.4% with no difference between the two patient groups. There were no significant differences between patient groups in secondary infections and ventilator-free days.

In patients with pneumonia or septic pneumonic shock undergoing prolonged weaning, infection with MDR bacteria may influence the weaning success rate but does not appear to impact on patient survival.