Presence of human metapneumovirus in bronchoalveolar lavage fluid of critically ill patients

Introduction

Human metapneumovirus (hMPV) is a paramyxovirus that has been shown to cause respiratory infections in children, the elderly and immunocompromised patients. In this study we retrospectively evaluated the presence of hMPV in bronchoalveolar lavage fluid (BALF) of critically ill patients.

Methods

Between January 2005 and December 2007 all consecutive BALF samples from critically ill patients in the ICU of the Maastricht University Medical Center clinically suspected of hospital-acquired pneumonia were included. BALF work-up included: differential cell count, quantitative bacterial culture, PCR for relevant respiratory pathogens and additional stains and cultures guided by clinical suspicion. All samples were analysed retrospectively by quantitative real-time PCR targeting the nucleoprotein gene of hMPV.

Results

A total of 144 BALF samples were included from 121 patients in the ICU (75 men and 46 women). RNA of hMPV was detected in two out of 144 BALF samples (1.4%) of two patients. The first hMPV-positive patient had an underlying hematological malignancy (multiple myeloma). Already being treated with broad-spectrum antibiotics, the patient developed signs of respiratory distress. Five days after hospital admission, the patient was admitted to the ICU because of respiratory insufficiency. A BAL performed the same day yielded no causative microorganism at that time. The second hMPV-positive patient had been admitted to the hospital with a community-acquired pneumonia for which no causative organism was identified. Five days after hospital admission, progressive respiratory insufficiency necessitated ICU admission. Twelve days after ICU admittance a bronchoalveolar lavage was performed, which yielded Candida albicans in 10² colony-forming units/ml. In both patients no causative micro-organism for pneumonia could be identified during hospitalisation, and therefore we speculate that hMPV may at least have contributed to or perhaps even caused the respiratory deterioration under antibiotic therapy.

Conclusion

In critically ill patients 1.4% of collected BALF samples revealed the presence of hMPV RNA. Therefore, hMPV may play a part in respiratory complications in ICU patients. An additional study is necessary to investigate the extent to which hMPV contributes to respiratory failure in patients admitted to the ICU.