Presence of human metapneumovirus in bronchoalveolar lavage fluid samples detected by means of real-time polymerase chain reaction

Introduction

Human metapneumovirus (hMPV) is a paramyxovirus causing symptoms of the respiratory tract infection comparable with those of respiratory syncytial virus. The virus can play a causative role in respiratory tract infection in infants, the elderly and immunocompromised patients. Analysis of bronchoalveolar lavage fluid (BALF) samples obtained from patients with hematological malignancies suspected of pneumonia often do not result in the identification of a causative infectious organism. To investigate the potential role of hMPV, we analysed BALF samples of these patients for the presence of hMPV by means of real-time PCR.

Methods

The study was conducted in the ICU and the hematology ward of the University Hospital Maastricht. All consecutive BALF samples obtained in the period April 1999–June 2006 from patients with a hematological malignancy suspected of pulmonary infection were eligible for inclusion. Data on the BALF total cell count, differential cell count, quantitative bacterial culture and detection of viruses, mycobacteria and fungi were noted. All samples were analyzed by real-time RT-PCR targeting the nucleoprotein gene of hMPV.

Results

A total of 117 BALF samples from 95 patients (82 patients from the hematology ward, 15 ICU patients) were included. RNA of hMPV was detected in seven out of 117 (6%) BALF samples from five patients (three patients from the hematology ward, two ICU patients). In two out of five hMPV-positive patients, the underlying disease was non-Hodgkin lymphoma; the other three patients suffered from multiple myeloma, myelodys-plastic syndrome and mantle cell lymphoma. In one patient, four BALF samples were retrieved within 1 month. The first three BALF samples were hMPV PCR-positive, the fourth (collected 1 month after the first) was PCR-negative. No other infectious agents were detected in the hMPV-positive BALF samples. Neither the total cell count nor the differential cell count was significantly differenced between the hMPV-positive and hMPV-negative groups.

Conclusion

In 6% of BALF samples collected from adult patients with a hematological malignancy suspected of a pulmonary infection, hMPV RNA was detected whereas no other infectious agents were found. hMPV may thus be considered the causative agent of pulmonary infection in patients with a hematological malignancy when analysis for other infectious agents is negative.