Patients with hematologic malignancies showed a lower risk of ventilator associated pneumonia compared to other forms of immunosuppression 

An international, multicenter study published in Critical Care Medicine has brought new evidence on the relationship between different types of immunosuppression and the risk of respiratory infections in patients admitted to Intensive Care Units (ICUs). The research, which involved the participation of the D’Or Institute for Research and Education (IDOR), showed that people with hematologic cancers have a lower incidence of ventilator-associated bacterial lung infections than other immunosuppressed patients. 

Respiratory infections: a critical challenge in the ICU
Among patients who require mechanical ventilation, respiratory infections are among the most common and serious complications. They may present as pneumonia or tracheobronchitis, conditions that increase hospital stay, healthcare costs, and, in many cases, mortality. 

With advances in treatments for cancer and other diseases, the number of immunocompromised patients requiring intensive care continues to grow. However, until now, there were uncertainties regarding how different forms of immunosuppression affected the risk of developing these infections. 

The MIMOSA study
The study, named MIMOSA, gathered data from 118 ICUs in nine countries, analyzing 854 immunocompromised patients who required mechanical ventilation for more than 48 hours. Among them, nearly 20% had hematologic malignancies, while the others had different causes of immunosuppression, such as solid tumors, organ transplantation, use of immunosuppressive drugs, or HIV infection. 

The analysis revealed a surprising result: only 13.6% of patients with hematologic cancer developed ventilator-associated bacterial respiratory infection within 28 days of hospitalization. Among other immunosuppressed patients, the rate reached 20.1%. The difference was particularly significant in cases of pneumonia. 

Multidrug-resistant bacteria and clinical impact
The most common microorganisms found included Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus. The study also highlighted that the presence of multidrug-resistant bacteria was similar in both groups, exceeding 60% of cases. 

Although the risk of developing the infection varied, once pneumonia was established, the clinical impact was similar for all patients: increased risk of death and longer ICU stays. 

Implications for treatment
The researchers highlight that the results have important implications for clinical management. In patients with hematologic cancer, bacterial infections appear to be less frequent, but viral or fungal infections may pose an even greater threat. Therefore, more precise diagnostics and targeted prevention strategies for this group are increasingly necessary. 

The study is considered a milestone as the first large international investigation aimed at comparing how different types of immunosuppression influence the risk of respiratory infections in critically ill patients. The authors argue that future research should deepen the understanding of these mechanisms and support the development of more effective protocols to reduce complications in the ICU.