Posts

child using inhaler

The search for new Cystic Fibrosis clinical biomarkers

child using inhaler

Physician-scientists from Children’s National Hospital are unlocking new insights into Cystic Fibrosis by studying the type and number of bacteria in the lungs.

Cystic Fibrosis (CF) is a genetic disorder that chiefly affects the lungs and results in the production of abnormally dehydrated, viscous mucus. The inability to adequately clear this mucus leads to bacterial retention and both intermittent and chronic lung infections which require antibiotic therapy to treat. Researchers have used 16S rDNA amplicon sequencing for years in the attempts to characterize the airway microbiomes of CF patients, and more recently have used shotgun whole genome sequencing (WGS) techniques to obtain further details regarding bacterial species and strains. Previous studies on the airway microbiomes of CF patients have revealed that inter-person variability is high and can sometimes exceed intra-person variability. This can preclude generalizations regarding the CF population as a whole, which includes more than 30,000 Americans.

A recently published case study examined a young child with advanced and severely aggressive CF over a 12-month period, during which five pulmonary exacerbations occurred. A total of 14 sputum samples were collected across three clinical periods- baseline, exacerbation, and treatment. Samples were subsequently genetically sequenced (via 16s rDNA sequencing and, in three instances, WGS) and volatile metabolites were analyzed. The researchers hypothesized that if signature microbiome and metabolome characteristics correlated with one other and could be identified for each disease state, this data could serve as conglomerate biomarkers for the continuum of CF clinical states within an individual. In turn, this could inform future study design in a larger cohort.

Across all sputum samples, 109 individual operational taxonomic units (OTUs) and 466 distinct volatile metabolites were identified. 16s rDNA sequencing and WGS revealed that Escherichia coli and Staphylococcus aureus were the predominant bacteria during most baseline and exacerbation samples, despite some significant fluctuations in relative abundances. After the patient’s fifth antibacterial course, however, Achromobacter xylosoxidans became the new dominant bacterium.

Analysis revealed that the phylum Bacteroidetes and the genus Stenotrophomonas were significantly more abundant in treatment periods compared to baseline and exacerbation periods. WGS revealed the presence of bacteriophages as well as antibiotic resistance genes (mostly due to multi-drug resistance mechanisms), which can have important clinical ramifications and adds some dimensionality to the genetic analysis.

Volatile metabolite analysis found that observable fluctuations in metabolome composition coincided with fluctuations in the sputum microbiome. In this case, the microbiome and volatile metabolites produced by these bacteria provided an accurate assessment of the child’s clinical state. More specifically, the authors saw a distinct shift in both the microbiome and volatile metabolites with antibiotic treatment across the five independent pulmonary exacerbations. These additional assessments of the bacteria within the CF airway could provide an additional technique beyond standard bacterial cultures to better understand how the patient is responding to antibiotic treatment. Future studies in a larger group of children with CF may provide further insights into bacteria and volatile metabolite combinations that predict pulmonary exacerbation.

The article, “Longitudinal Associations of the Cystic Fibrosis Airway Microbiome and Volatile Metabolites: A Case Study,” was published in Frontiers in Cellular and Infection Microbiology. The lead author is Andrea Hahn, M.D., M.S., an investigator at the Children’s National Research Institute. Notable authors include Iman Sami, M.D., pulmonologist at Children’s National; Anastassios C. Koumbourlis, M.D., M.P.H, director of the Cystic Fibrosis Center; and Robert J. Freishtat, M.D., M.P.H, senior investigator at the Center for Genetic Medicine Research.

coronavirus

Study finds children can become seriously ill with COVID-19

coronavirus

Despite early reports suggesting COVID-19 does not seriously impact children, a new study shows that children who contract COVID-19 can become very ill.

In contrast to the prevailing view that the novel coronavirus known as COVID-19 does not seriously impact children, a new study finds that children who contract the virus can become very ill—many of them critically so, according to physician researchers at Children’s National Hospital. Their results, published in the Journal of Pediatrics and among the first reports from a U.S. institution caring for children and young adults, shows differences in the characteristics of children who recovered at home, were hospitalized, or who required life support measures. These findings highlight the spectrum of illness in children, and could help doctors and parents better predict which pediatric patients are more likely to become severely ill as a consequence of the virus.

In late 2019, researchers identified a new coronavirus, known as SARS-CoV-2, which causes COVID-19. As the disease spread around the world, the vast majority of reports suggested that elderly patients bear the vast majority of the disease burden and that children are at less risk for either infection or severe disease. However, study leader Roberta DeBiasi, M.D., M.S., chief of the Division of Infectious Diseases at Children’s National, states that she and her colleagues began noticing an influx of children coming to the hospital for evaluation of a range of symptoms starting in mid-March 2020, who were tested and determined to be infected with COVID-19. One quarter of these children required hospitalization or life support.

“It was very apparent to us within the first several weeks of the epidemic that this was a very different situation than our colleagues on the West Coast of the US had described as their experience just weeks before,” DeBiasi says. “Right away, we knew that it was important for us to not only care for these sick children, but to examine the factors causing severe disease, and warn others who provide medical care to children.”

To better understand this phenomenon, she and her colleagues examined the medical records of symptomatic children and young adults who sought treatment at Children’s National for COVID-19 between March 15 and April 30, 2020. Each of these 177 children tested positive using a rapid assay to detect SARS-CoV-2 performed at the hospital. The researchers gathered data on each patient, including demographic details such as age and sex; their symptoms; whether they had any underlying medical conditions; and whether these patients were non-hospitalized, hospitalized, or required critical care.

The results of their analysis show that there was about an even split of male and female patients who tested positive for COVID-19 at Children’s National during this time period. About 25% of these patients required hospitalization. Of those hospitalized, about 75% weren’t considered critically ill and about 25% required life support measures. These included supplemental oxygen delivered by intubation and mechanical ventilation, BiPAP, or high-flow nasal cannula – all treatments that support breathing – as well as other support measures such as dialysis, blood pressure support and medications to treat infection as well as inflammation.

Although patients who were hospitalized spanned the entire age range, more than half of them were either under a year old or more than 15 years old. The children and young adults over 15 years of age, Dr. DeBiasi explains, were more likely to require critical care.

About 39% of all COVID-19 patients had underlying medical conditions, including asthma, which has been highlighted as a risk factor for worse outcomes with this infection. However, DeBiasi says, although underlying conditions were more common as a whole in hospitalized patients – present in about two thirds of hospitalized and 80% of critically ill – asthma didn’t increase the risk of hospitalization or critical illness. On the other hand, children with underlying neurological conditions, such as cerebral palsy, microcephaly, or global developmental delay, as well as those with underlying cardiac, hematologic, or oncologic conditions were significantly more likely to require hospitalization.

In addition, although early reports of COVID-19 suggested that fever and respiratory symptoms are hallmarks of this infection, Dr. DeBiasi and her colleagues found that fewer than half of patients had both concurrently. Those with mild, upper respiratory symptoms, such as runny nose, congestion, and cough were less likely to end up hospitalized than those with more severe respiratory symptoms, such as shortness of breath. The frequency of other symptoms including diarrhea, chest pain and loss of sense of smell or taste was similar among hospitalized and non-hospitalized patients.

Dr. DeBiasi notes that although other East Coast hospitals are anecdotally reporting similar upticks in pediatric COVID-19 patients who become seriously ill, it’s currently unclear what factors might account for differences from the less frequent and milder pediatric illness on the West Coast. Some factors might include a higher East Coast population density, differences between the genetic, racial and ethnic makeup of the two populations, or differences between the viral strains circulating in both regions (an Asian strain on the West Coast, and a European strain on the East Coast).

Regardless, she says, the good news is that the more researchers learn about this viral illness, the better prepared parents, medical personnel and hospitals will be to deal with this ongoing threat.

Other researchers from Children’s National who participated in this study include Xiaoyan Song, Ph.D., M.Sc.Meghan Delaney, D.O., M.P.H.Michael Bell, M.D. Karen Smith, M.D.Jay Pershad, M.D., Emily Ansusinha, Andrea Hahn, M.D., M.S., Rana Hamdy, M.D., M.P.H., MSCE, Nada Harik, M.D.Benjamin Hanisch, M.D.Barbara Jantausch, M.D.Adeline Koay, MBBS, MS.c., Robin Steinhorn, Kurt Newman, M.D. and David Wessel, M.D.