Marian Freedman

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. 

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.

Articles

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.

Known HRV infection may not decrease risk of IBI

	Urinalysis is extremely sensitive and specific for screening for urinary tract infections (UTIs) in febrile infants aged 60 days and younger, especially when the UTI is associated with bacteremia, a recent study showed.

	Investigators evaluated the test characteristics of the urinalysis in aggregate and of 3 individual components-leukocyte esterase (LE), nitrites, and pyuria-for diagnosing UTIs with and without associated bacteremia. They used 2 definitions of UTI: growth of 50,000 or more or of equal to or greater than 10,000 colony-forming units (CFU) per mL of a pathogen.

	The study was in almost 4500 febrile infants aged 60 days or younger from whom blood cultures were obtained as part of an emergency department evaluation for bacterial infection; 289 (7%) had UTIs with equal to or greater than 50,000 CFU/mL, including 27 (9.3% of the 289) with bacteremia. A positive urinalysis showed perfect sensitivity when accompanied by bacteremia (100%) and an excellent 94% sensitivity without bacteremia. Specificity was 91%. For UTIs defined by colony counts equal to or greater than 10,000 CFU/mL, sensitivity of the urinalysis was 87% and specificity 91%.

Next: BRUE in infancy does not increase risk of death

Most infants with UTIs had urinalyses positive for LE or pyuria, although nitrites generally were absent irrespective of UTI status. All patients with UTIs with bacteremia had either moderate or large concentrations of LE. Infants without bacteremia whose urine colony counts were below 100,000 CFU/mL were less likely than infants with higher counts to have LE, nitrites, or pyuria (Tzimenatos L, et al. 

	My takeaway here is that the urinalysis is often predictive of a UTI, even in a very young child, but, as with any test, we need to leave room for some clinical judgment when deciding which febrile infants have a UTI. No test is perfect.

Urinalysis is extremely sensitive and specific for screening for urinary tract infections (UTIs) in febrile infants aged 60 days and younger, especially when the UTI is associated with bacteremia, a recent study showed.

Urinalysis identifies the youngest infants with UTIs

A meta-analysis of 12 studies of the risk of death after a brief resolved unexplained event (BRUE) found that such an event does not increase an infant’s risk of dying during his or her first year. The American Academy of Pediatrics (AAP) introduced BRUE, a sudden alteration in an infant’s breathing, color, tone, or responsiveness, as a replacement for “apparent life-threatening event” (ALTE) in a 2016 clinical practice guideline.

The 12 studies involved 3005 children whose parents sought emergency care for a BRUE (termed ALTE in the pre-2016 studies). Twelve babies died, several in the hospital, within a few days of the event, but most weeks, months, or years later. Specifically, 8 infants died within 3 months of the BRUE and the remaining 4 between 4 months and 5.5 years after the event. The mortality rate after a BRUE, therefore, was 3.1 postevent deaths per month per 10,000 events.

Further analysis, using a 4-month time horizon, determined that the upper bound of the probability of death after a BRUE is about 1 in 800. This compares with a baseline risk of death during a 4-month period in the first year of life of 1 in 1200 for all infants (after excluding neonatal deaths), according to US infant mortality statistics (Brand DA, et al. 

This analysis of existing studies is meant to allow physicians to offer reassurance with minimal evaluation to parents of infants with low-risk BRUEs as defined in the 2016 AAP guideline (

). Low-risk BRUE infants include those who were not premature, were aged 2 months or older at diagnosis, had a first-time BRUE that lasted less than 1 minute, and did not require cardiopulmonary resuscitation by a healthcare professional. This guideline is one to keep close at hand.