Too few studies to steer test protocols for pediatrics

But guidelines from the American Academy of Pediatrics disagree, noting that if a patient’s UA is negative, the likelihood of an infection is slim. Indeed, a series of studies performed in the 1970s examined the long-term outcomes of healthy school-age girls with routine urine cultures that were positive and found no differences in bacterial recurrence, renal growth, reflux, or pyelonephritis in treated versus untreated girls.

“This suggests asymptomatic bacteriuria is something that happens in kids, and just like in adults, it’s not significant and does not need to be treated,” Dr. Humphries says.

Despite the availability of data to support UA as a preliminary step in pediatric patients, the practice has not been adopted widely in the clinical microbiology community. At UCLA, for example, physicians routinely place simultaneous orders for the UA and a urine culture.

“They’d just rather get both results at the same time,” says Dr. Humphries. “The unfortunate problem with that is even if the UA is negative but something grew on the culture, they kind of feel obliged to treat it.”

Instead of ordering both tests simultaneously, Dr. Humphries advocates an algorithmic approach in which the presence of pyuria is incorporated into an initial UA screen, followed later by a urine culture. The algorithm, she argues, could potentially save money and prevent over-reporting of catheter-associated urinary tract infection rates by screening out patients with negative UAs and asymptomatic bacteriuria.

But there is a flip side to every argument, and Dr. Dien Bard notes that a pediatric-adapted algorithm would not be appropriate for all young patients.

“I would argue that it’s appropriate to culture all urine specimens, regardless of the urinalysis result,” says Dr. Dien Bard, whose tertiary care hospital has a large population of oncology patients. “Immunocompromised patients, for example, are not eliciting a sufficient immune response to flag for criteria like white blood cells in the urine.”
Seemingly unremarkable urinalysis results in immunocompromised patients could potentially hide urinary tract infections and place patients at greater risk of serious complications like urosepsis or renal dysfunction, she argues. In such a situation, Dr. Dien Bard does not see a strong reason to stray from adult protocols.

“A pathogen is a pathogen, regardless of how old the patient is,” she says. “The quantity may change. A lower quantity of bacteria may be considered more important in a pediatric patient than it would in an adult patient. But there just aren’t a lot of studies out there right now to support a pediatric protocol.”

In particular, the debate might benefit from studies that examine UA with reflex to culture in hospitalized pediatric patients or studies that explore the parameters of a UA that best reflect a urinary tract infection.

In the past few years, a number of studies have suggested that multiplex respiratory viral panel testing can limit antibiotic use and reduce the duration of hospital stays. But access to viral multiplex panels remains a topic of debate.

“When we talk about algorithms as a means of restricting highly multiplexed respiratory virus testing, the first thing everybody will say is, ‘Oh, but except for pediatrics. You run everything for a peds patient,’” Dr. Humphries says. “There’s not very much literature out there to say one way or another if that’s true.”

Whether reflex testing is warranted in children remains unclear.

“I’d argue that we should allow multiplex testing for any patient—inpatient or outpatient, pediatric or nonpediatric—whenever a physician determines it’s appropriate to order the tests,” Dr. Dien Bard says.
She points to acute respiratory infection—more likely to be viral than bacterial in origin but tricky to evaluate on initial presentation.

“It’s all about limiting antibiotic use,” she says. “Why not give the primary care physician access to multiplex respiratory viral panel testing that can be done within an hour or two, so they can rule out a viral etiology and then possibly give an antimicrobial agent if required?”

Dr. Dien Bard recalls when a colleague’s daughter was diagnosed with respiratory syncytial virus in the primary care physician’s office using a multiplex molecular panel. The test took about an hour, and the young patient was sent home without a prescription for antibiotics. “That was actually quite amazing, as an alternative to sending the patient home with a script and then following up later to say the antibiotic could be discontinued,” she says.

While the benefits seem clear, the literature remains divided.

“A lot of people will say that you always want to do the full respiratory viral panel for kids, because they could have multiple infections,” Dr. Humphries says. “But there are probably an equal number of studies that say co-infections are associated with worse outcomes versus studies that say there’s no difference in outcomes. So the jury’s still out, if you look at it from an objective perspective.”

In particular, she notes, more data are needed to fully characterize the impacts of respiratory virus panels in outpatient and inpatient settings. “If you’re in the outpatient domain, would a full respiratory virus panel actually help prevent antimicrobial treatment or would it just reveal a better sense of what’s going on with the kid? Does it really make a difference, or should we focus instead on better education to prevent the treatment of viral respiratory infections with antimicrobials?” Dr. Humphries asks.

Data from the Centers for Disease Control and Prevention suggest that the use of antimicrobials in outpatients is significantly high, and Drs. Dien Bard and Humphries suspect that many of the drugs are used to treat pediatric patients who come in with the sniffles. “If we could give physicians a better answer to what’s causing the infection, that would be helpful. But multiplex tests would have to be much cheaper for us to use them in that way,” Dr. Humphries says.

They have a few ideas for further studies.

“Depending on your institution, if you’re not cohorting patients during respiratory virus season, you might be able to do some algorithm testing,” Dr. Humphries says. “You could do a flu A/B and RSV test first, and if that’s negative, move on to the respiratory virus panel.”

Of the three issues—blood cultures, urinalysis, and respiratory virus testing—the most controversial by far is the respiratory virus test, she says. “There’s definitely a camp that wonders why you would withhold information. Why wouldn’t you use that test routinely if it’s ordered, and not restrict it in some way for cost reasons?”

Until further research brings a better understanding of pediatric populations, professional opinions will remain just that.
Says Dr. Dien Bard: “I recommend that anyone in this position look for studies, textbooks, or other material to support what they think are the correct practices. And if the evidence doesn’t exist, that’s when we need to think about carrying out these studies ourselves.”
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Ann Griswold is a writer in San Francisco.