Rhinovirus in febrile infants and risk of bacterial infection

BACKGROUND: Febrile infants with viral respiratory infections have a reduced risk of bacterial infection compared with virus-negative infants. The risk of concomitant bacterial infection in febrile infants positive for human rhinovirus (HRV) by polymerase chain reaction (PCR) is unknown. METHODS: Infants 1-90 days old managed using the care process model for well-appearing febrile infants and with respiratory viral testing by PCR (RVPCR) in the emergency department or inpatient setting of 22 hospitals in the Intermountain Healthcare system from 2007-2016 were identified. Relative risk (RR) of bacterial infection was calculated for infants with HRV, non-HRV viruses, or no virus detected. RESULTS: Of 10 964 febrile infants identified, 4037 (37%) had RVPCR. Of these, 2212 (55%) were positive for a respiratory virus; 1392 (35%) for HRV alone. Bacterial infection was identified in 9.5%. Febrile infants with HRV detected were more likely to have bacterial infection than those with non-HRV viruses (7.8% vs 3.7%; P < .001; RR 2.12 [95% CI 1.43-3.15]). Risk of urinary tract infection was not significantly different for HRV-positive infants at any age, nor was risk of invasive bacterial infection (IBI; bacteremia and/or meningitis) meaningfully different for infants 1-28 day olds. Infants 29-90 days old with HRV had a decreased likelihood of IBI (RR 0.52 [95% CI 0.34-0.80]). CONCLUSIONS: HRV is common in febrile infants. Detection did not alter risk of concomitant urinary tract infection at any age or risk of IBI in infants 1-28 days old. HRV detection may be relevant in considering risk of IBI for infants 29-90 days of age.