Forty-four NPWs collected between December, 2004, and July, 2005, were analyzed independently by MassTag-PCR at CU and by RT-PCR at CU and UCDSOM. MassTag-PCR identified at least one respiratory pathogen in 27 (61%) of the 44 specimens that had previously tested negative by culture and DFA (). Co-infections were found in 6 (14%) specimens. MassTag-PCR detected FLUBV in 1, HPIV-2 in 1, and HPIV-3 in 5 patients, suggesting a greater sensitivity than the DFA and culture assays.
Table 1 Candidate pathogens found by MassTag-PCR and singleplex PCR in nasopharyngeal washes from pediatric patients with previously undiagnosed respiratory illnesses. HRV – human rhinovirus, HRV-CO – human rhinovirus Colorado, HEV – human (more ...)
Conventional RT-PCR detected HBoV in 3 (7%) of 44 specimens. Two of these were co-infected with either HMPV or HPIV-3 (). The patient co-infected with HMPV was a 16-month old girl with hypoxia and bronchiolitis hospitalized for one day. The patient co-infected with HPIV-3 was a 12 month old boy seen in the emergency department on two occasions with fever but no other symptoms. HBoV was the sole identified agent in a 17-month old boy admitted to the intensive care unit with respiratory failure.
HMPV was found in 7 (16%) specimens ( and ) from patients with a median age of 37 months who were all admitted during a six-week period from February 14 through March 30, 2005 with fever, cough, and hypoxia. Five (71%) had radiographic evidence of pneumonia.
Clinical summaries of pediatric patients with respiratory disease in whom human metapneumovirus (HMPV), human rhinovirus A (HRV-A), and a recently discovered rhinovirus clade (HRV-CO) were detected by MassTag-PCR.
Sixteen (36%) specimens were positive for picornaviruses, of which 14 were rhinoviruses. Sequencing of a 500 nucleotide region in their VP4/2 coding regions showed further that 5 of the 14 (36%) rhinovirus specimens contained HRV-A, while 9 (64%) of the sequences, HRV-Colorado (HRV-CO), matched with a recently described rhinovirus clade divergent from established HRV-A and –B (7
). The demographic and clinical features of these patients are summarized in ; amplified VP4/2 sequences are accessible under GenBank Acc. No. EU743920 – EU743927. Four (44%) of the HRV-CO positive patients were under two years of age; and all but one patient (89%) were under five years of age. The positive specimens did not cluster in time: specimens were positive in the months of December, January, March, May, June and July, indicating prolonged circulation of these viruses in the community. Six (67%) of the 9 HRV-CO patients were hospitalized, and two required admission to the intensive care unit. One of these patients was a 3-year old girl admitted for a severe asthma exacerbation and hypotension. The other patient was admitted for an accidental inhalation injury and subsequently developed fever, copious secretions, and respiratory distress necessitating ventilatory support. A chest X-ray taken at that time was consistent with pneumonia. The NPW obtained on hospital day 6 was positive for HRV-CO, suggesting a recently acquired, possibly nosocomial infection.
Although 7 (78%) of the 9 patients with HRV-CO had typical upper respiratory tract infection symptoms including rhinorrhea, cough, and congestion, 5 (56%) also had respiratory distress (retractions), 3 (33%) were hypoxic, and 4 (44%) were wheezing. One patient undergoing chemotherapy for anaplastic lymphoma was admitted with a diagnosis of fever and neutropenia. Another patient with severe cerebral palsy, was admitted with clinical signs of respiratory distress and hypoxia.