Comparison of conventional and molecular detection of respiratory viruses in hematopoietic cell transplant recipients

Abstract

Background: Sensitive detection of respiratory viruses is important for early diagnosis of infection in patients following hematopoietic cell transplantation (HCT). To evaluate the relative sensitivity of respiratory virus detection in specimens from HCT recipients, we compared the results of conventional and quantitative molecular methods.

Methods: We tested 688 nasal wash samples collected prospectively from 131 patients during the first 100 days after HCT by viral culture, fluorescent antibody staining (FA), and real-time quantitative reverse transcription-polymerase chain reaction (PCR) assay for detection of respiratory syncytial virus (RSV), influenza virus types A (FluA) and B (FluB), and parainfluenza virus types 1 (PIV1) and 3 (PIV3). Testing for human metapneumovirus (MPV) was performed only by PCR. Data regarding 10 respiratory symptoms were collected with each sample.

Results: By any method 37 specimens were positive for a respiratory virus; 34 were positive by PCR, 15 by culture, and 6 by FA. Four specimens were positive by all 3 methods (3 RSV, 1 FluA). One specimen was positive for PIV1, and 2 were positive for rhinovirus by culture alone. Specimens positive by PCR alone included 2 RSV, 2 PIV1, 8 PIV3, and 8 MPV. In 10 specimens positive for RSV, PIV, or influenza virus collected from patients reporting no respiratory symptoms, 9, 4, and 1 specimen were positive by PCR, culture, and FA, respectively. Overall, specimens positive only by PCR had significantly fewer viral copies/mL (mean log(10)=4.32) than specimens positive by both PCR and culture (mean log(10)=5.75; P=0.002) or PCR and FA (mean log(10)=6.83; P<0.001).

Conclusions: FA testing alone did not detect a significant proportion of respiratory virus-positive samples in HCT recipients, especially in patients with no respiratory symptoms and patients with PIV detection. PCR increased the yield of positive specimens 2 times relative to culture and more than 4 times relative to FA. Detection of respiratory viruses by PCR alone was associated with lower virus quantities and with fewer reported respiratory symptoms compared with concomitant detection by both PCR and conventional methods, indicating that PCR may be important to detect asymptomatic or mildly symptomatic stages of respiratory viral infections.

Fig. 1

A. Quantity of virus (log10 copies/mL) in 26 real-time polymerase chain reaction (RT-PCR)- positive specimens according to result of conventional detection method and respiratory virus type: respiratory syncytial virus (RSV) (), parainfluena virus (PIV) (), influenza virus type A (FluA) (), influenza virus type B (FluB) (). B. Mean quantity of virus (log10 copies/mL) quantified by RT-PCR in 12 specimens positive for any respiratory virus by RT-PCR alone, 12 positive by both RT-PCR and culture, and 6 positive by both RT-PCR and fluorescent antibody staining. C. Mean quantity of virus (log10 copies/mL) quantified by RT-PCR in 6 specimens positive for RSV (open bars) and 15 specimens positive for PIV type 3 (solid bars) by method of detection.

Fig. 1

A. Quantity of virus (log10 copies/mL) in 26 real-time polymerase chain reaction (RT-PCR)- positive specimens according to result of conventional detection method and respiratory virus type: respiratory syncytial virus (RSV) (), parainfluena virus (PIV) (), influenza virus type A (FluA) (), influenza virus type B (FluB) (). B. Mean quantity of virus (log10 copies/mL) quantified by RT-PCR in 12 specimens positive for any respiratory virus by RT-PCR alone, 12 positive by both RT-PCR and culture, and 6 positive by both RT-PCR and fluorescent antibody staining. C. Mean quantity of virus (log10 copies/mL) quantified by RT-PCR in 6 specimens positive for RSV (open bars) and 15 specimens positive for PIV type 3 (solid bars) by method of detection.