Known HRV infection may not decrease risk of IBI

Michael G Burke, MD

Infection with human rhinovirus (HRV) confirmed by polymerase chain reaction (PCR) does not decrease the likelihood of concurrent urinary tract infection (UTI) in infants aged from 1 to 90 days old, according to a study in well-appearing febrile infants in this age group. Nor does HRV positivity affect the risk of invasive bacterial infection (IBI) in the youngest infants, those aged from 1 to 28 days. In infants aged 29 to 90 days, however, the presence of HRV decreases the likelihood of IBI (bloodstream infection or meningitis).

These were the findings of a study in about 4000 well-appearing febrile infants who underwent respiratory viral testing by PCR in 1 of 22 hospitals in Utah. Investigators calculated and compared the relative risk of bacterial infection for infants who were positive for HRV or another virus or in whom no virus was detected.

Overall, 55% of the infants were positive for 1 or more respiratory viruses, although those aged 29 to 90 days had a significantly higher rate of respiratory infection than did younger infants (61% vs 39%, respectively). The most common virus was HRV, which was detected by itself in 35% of infants (more than all other respiratory viruses combined) and was more common among infants aged 29 to 90 days than in those who were younger. About 20% of participants had a non-HRV virus, such as adenovirus, respiratory syncytial virus (RSV), or influenza.

The presence of respiratory viruses other than HRV was associated with an almost fourfold reduction in frequency of bacterial infection compared with no virus being detected. However, in infants in whom HRV was detected this risk reduction was smaller-a 7.8% decrease in those with non-HRV respiratory viruses vs 3.7% for those with HRV. Two-thirds of bacterial infections were UTIs (Blaschke AJ, et al. Pediatrics. 2018;141[2]:e20172384 ).

Thoughts from Dr. Burke

Previous studies have shown that febrile infants with a known influenza or RSV infection are less likely than those without viral disease to have an invasive bacterial infection. The viral infections explain some of the fevers. This study shows that this is not the case for human rhinovirus, at least in the first 28 days of life. And for the first 90 days of life, UTIs are not less likely in children with HRV. So, if you are working in a setting where rapid viral PCR panels are available and you are looking for a viral source to spare a child a septic workup, forget it if you are dealing with HRV: Presence of this virus doesn’t mean absence of a bacterial source.