The Hidden Pathogen Of Late Onset Sepsis
If you work in the NICU then you have seen your fair share of septic workups for late onset sepsis. Sepsis is such a common diagnosis that if I had to guess I would say that at least 50% of all discharge summaries would include this in a list of final diagnoses for any VLBW infant. If you were to look through the chart though you would find that while workups are common, the recovery of a pathogenic bacterium is not as much. This is in part due to the low threshold that many people have for doing such workups. A little bit of temperature instability, a few more apneic events than normal or a rise in O2 requirements may all trigger such investigations. When they come back negative we all feel good that we looked but we also are then quick to blame the etiology on something else. Mild fluctuations in temperature are written off as overbundling, apnea due to outgrowth of caffeine and a rise in FiO2 to evolving CLD. Maybe though the explanation at least in some cases is that there was a pathogen but we didn’t test for it.
Viruses are everywhere
Tis the season so to speak so everyone is on high alert for viruses in our homes, schools, malls etc but many of us consider the NICU to be mostly free of such pathogens. The truth is we mostly are provided that we all wash our hands well, keep sick contacts from visiting and put on a mask when our coughing starts. Alas, if you have done a handwashing audit as we have you would know that when looking at technique and duration of handwashing, we don’t always hit 100%. These audits are for health care practitioners but I have often wondered what sort of results we would see were we to do the same for parents and visitors. When we know the viruses are out there such as during outbreaks of RSV and influenza we can’t help but send off our samples for respiratory viruses more frequently but what if we did this with intention for every late onset septic workup?
Lucky For Us Someone Did Just That!
Back in 2014 the following study was published. Viral respiratory tract infections in the neonatal intensive care unit: the VIRIoN-I study. This was a simple prospective and elegant study in which any infant in the NICU who had never been home and was greater than 72 hours had respiratory samples sent for viral panels within 72 hours of starting antibiotics for presumed late onset sepsis. The findings were certainly interesting in that 6% of 135 sepsis evaluations tested positive for a virus. In the analysis, the infants had the following characteristics:
- tended to be older (41 vs 11 days; P = .007)
- exposed to individuals with respiratory tract viral symptoms (37% vs 2%; P = .003)
- lower total neutrophil counts (P = .02)
- best predictor of viral infection was the caregivers’ clinical suspicion of viral infection (P = .006)
What interests me about these results are a couple things. The first is that as I was once told, the sensitivity of asking if someone has been around sick people is low during peaks in viral outbreaks as who hasn’t? Perhaps what this study tells us is that within the NICU environment we actually do a reasonable job of keeping such contacts away but when they slip through infections happen. The second point worth mentioning is that a low neutrophil count is associated which is interesting given how often neutropenia is pointed to as a reason to start antibiotics. These viruses are troublesome creatures indeed!
Further Evidence Arrives
At the end of last year a similar study was published by the same group Viral Respiratory Infections in Preterm Infants during and after Hospitalization. They took a different approach this time out and took nasopharyngeal samples from 189 infants in the NICU (96 term and 93 preterm) within 7 days of birth and then sent samples weekly while in hospital followed by monthly for four months after discharge. In this collection of infants a mere 4 patients tested positive in NICU and all of them under 28 weeks of age at birth! How do we account for the remarkable reduction in risk while in hospital? To answer that you can read through the NICU environment in the full article if you have access. In short, they had a very rigorous infection control set of precautions set up. Interestingly only one of the infections was with RSV and the unit did not provide prophylaxis for infants in hospital. Perhaps with precautions like theirs they felt it was unnecessary. Once discharged a little over a third of patients acquired a viral infection in the first four months at home. Given the potential risk for readmission and with that to a PICU this rate of viral infection is concerning.
Vision for the future!
Taken together we can state that viruses do make their way into the NICU but fortunately not as commonly as one might think. What the last study in particular does remind us though is that we need to ensure that as part of discharge teaching parents take home many of the practices that we have used in the hospital with respect to hand hygiene, limiting visitors and not being afraid to holster some hand sanitizer for those times when soap and water are not so easy to come by. To be sure viruses are out there but at least for the first few months after discharge for our most vulnerable babies a little paranoia about viruses could go a long way.