The Detection of Viral Infection in Bronchoalveolar Lavage Samples Collected From Recipients of Allogeneic Haematological Stem Cell Transplantation with Pneumonia (A 3 Year Epidemiological Study 2008–2010)

Both radiological (chest X-rays and High Resolution Computed Tomography) and PCR methods are essential for viral pneumonia diagnostic procedures. Bronchoalveolar lavage (BAL) samples obtained from patients with signs of lower respiratory tract infection were tested and analysed for viral agents.

Forty seven BAL samples were obtained from 32 recipients (20 males and 12 females) of allogeneic haematological stem cell transplantation. Of those, 30 patients (93 %) were transplanted for haematological malignancy (52 % with acute myeloid leukemia, 12 % with chronic lymphatic leukemia) and 2 for aplastic anemia. BAL sampling was performed in locations of maximum signs of pathological process according to X-ray or HRCT. For testing, 4× 50 ml of F1/1 was installed in alveoli and 3^rd and 4^th portions were used. Viral infection diagnosis was based on real-time PCR detection of nucleic acid and/or immunochromatography detection of viral antigens.

The following examinations were commonly performed on BAL samples: microscopic and cytologic examination (including staining for Pneumocystis jiroveci and branched fungi), cultivation (bacteriological, mycological and mycobacterial), real-time PCR (adenovirus, cytomegalovirus (CMV), herpes simplex virus (HSV) type 1,2, influenza virus A/B/H1N1, parainfluenza virus 1,2,3, respiratory syncytial virus (RSV), varicella zoster virus, rhinovirus, Epstein Barr virus, human metapneumovirus, Mycobacterium sp. et TBC, Streptococcus pneumoniae, Listeria monocytogenes, Chlamydia pneumoniae, Legionella pneumophila, Aspergillus fumigatus, panfungal DNA, Pneumocystis jiroveci (PCP)) and immunochromatography/immunofluorescence detection of antigens (Adenovirus, influenza virus A/B, respiratory syncytial virus, Chlamydia pneumoniae) and Aspergillus galactomannan.

Viral agents were detected in 20 (out of 47) samples (in some of those, several tests yielded more than one positive or grey zone result). No viral infection was detected in 27 samples. Dual viral infection was diagnosed in 4 cases. Overall, 20 tests proved significant viral load (10⁴cp/ml) (see Tab. 1).

Tab. 1 Viruses examined and detected by PCR and immunochromatography (therapy: G – ganciclovir, F – foscarnet, A - aciclovir, T oseltamivir, R – ribavirin).

Note: Influenza is mostly detected from nasal swab – this type of sample was not included in our study.

The examination of BAL is very helpful for early diagnosis of viral pneumonia.

The analysis must be performed from the 3^rd and 4^th portion of lavage fluid that comes in close contact with the terminal part of lungs - alveoli. As we expected CMV, HSV and RSV were found to be the most frequent causes of viral pneumonia. PCP pneumonia was not detected because of the sulfamethoxazolum/trimethoprimum prophylaction. In case of low viral load all other clinical, radiological and other laboratory findings must be evaluated to confirm viral etiology. High viral load is always alarming and it is necessary to start administration of causative antiviral therapy as soon as possible if it is available.

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