Multiresistant Pseudomonal Respiratory Infection in Intensive Care Unit Patients

Abstract

In Brief The objective of this review is to describe intensive care unit (ICU)-acquired infections caused by multidrug-resistant Pseudomonas aeruginosa (MDRPA). P aeruginosa is a saprophytic microorganism characterized by its natural resistance to many β-lactam antibiotics. In addition, it readily acquires resistance to most or even all antipseudomonal agents, defining MDRPA strains. These strains are responsible for nosocomial outbreaks or sporadic, not epidemiologically linked cases. They are encountered worldwide but their proportions depend on the criteria defining them. According to US data, 16% of isolates are resistant to ≥3 of the core antipseudomonal antimicrobials. Ventilator-associated pneumonia is one of the main MDRPA infections in the ICU. Recent previous use of antibiotics with high antipseudomonal activity is a key factor for the emergence of MDRPA. MDRPA infections occur in critically ill patients with multiple comorbidities after long periods of hospitalization. When other severity factors are taken into account and when the initial treatment is appropriate, MDRPA strains are probably no more pathogenic than drug-susceptible strains, as suggested by equivalent mortality rates. The treatment of patients with MDRPA pulmonary infection is a difficult challenge, and some therapeutic modalities, such as aerosolized colistin, warrant evaluation. A strict antibiotic prescription policy and hygiene measures are the cornerstones of prevention. Multidrug-resistant Pseudomonas aeruginosa is one more warning sign of spreading antimicrobial resistance. These strains are responsible for nosocomial pneumonia in critically ill ICU patients. Among risk factors, previous use of broad-spectrum antibiotics appears to be a key factor. Therapeutic approaches and preventive measures are reviewed.