Synthetic cystic fibrosis sputum medium diminishes Burkholderia cenocepacia antifungal activity against Aspergillus fumigatus independently of phenylacetic acid production.

Phenylacetic acid (PAA), an intermediate of phenylalanine degradation, is emerging as a signal molecule in microbial interactions with the host. In this work, we explore the presence of phenylalanine and PAA catabolism in 3 microbial pathogens of the cystic fibrosis (CF) lung microbiome: Pseudomonas aeruginosa, Burkholderia cenocepacia, and Aspergillus fumigatus. While in silico analysis of B. cenocepacia J2315 and A. fumigatus Af293 genome sequences showed complete pathways from phenylalanine to PAA, the P. aeruginosa PAO1 genome lacked several coding genes for phenylalanine and PAA catabolic enzymes. High-performance liquid chromatography analysis of supernatants from B. cenocepacia K56-2 detected PAA when grown in Luria-Bertani medium but not in synthetic cystic fibrosis sputum medium (SCFM). However, we were unable to identify PAA production by A. fumigatus or P. aeruginosa in any of the conditions tested. The inhibitory effect of B. cenocepacia on A. fumigatus growth was evaluated using agar plate interaction assays. Inhibition of fungal growth by B. cenocepacia was lessened in SCFM but this effect was not dependent on bacterial production of PAA. In summary, while we demonstrated PAA production by B. cenocepacia, we were not able to link this metabolite with the B. cenocepacia - A. fumigatus microbial interaction in CF nutritional conditions.

Prevalence of Physician-Reported Food Allergy in Canadian Children.

BACKGROUND: Food allergy prevalence data have largely been derived from self-report, and estimates vary. OBJECTIVE: Determine the prevalence of physician-reported food allergy in children using electronic medical record data from the Canadian Primary Care Sentinel Surveillance Network (CPSSN). METHODS: This was a retrospective cohort study using the CPCSSN repository, Canada's only primary care practice-based surveillance system. Machine learning algorithms were applied to assess for food allergy documentation. Demographic information, chronic diseases of interest, prescribed medications, and health behaviors from the CPCSSN repository were identified. RESULTS: The prevalence of physician-reported food allergy in Canadian children was 2.53% (95% CI, 2.48%-2.59%). The most common food allergies documented were peanut (0.8% of children), tree nut (0.6%), cow's milk (0.4%), egg (0.3%), fruit (0.2%), finned fish (0.2%), and shellfish (0.2%). Among children with food allergy, only 33.7% had an epinephrine autoinjector prescription. In logistic regression analysis, children with food allergy were more likely to have an atopic comorbidity (odds ratio [OR], 2.20; 95% CI, 2.06-2.35) and less likely to be obese than children without food allergies (OR, 0.84; 95% CI, 0.78-0.90). In the age- and sex-adjusted models, patients with food allergy were significantly more likely to have a psychiatric morbidity, specifically: attention deficit/hyperactivity disorder (OR, 1.81; 95% CI, 1.66-1.96), autism (OR, 1.89; 95% CI, 1.63-2.19), and depression (OR, 1.17; 95% CI, 1.02-1.35). CONCLUSIONS: Our study is the first to estimate national physician-reported prevalence of food allergy, and demonstrates a lower rate than that based on self-report. Further studies into the association of food allergy and psychiatric comorbidities (attention deficit/hyperactivity disorder, autism, depression) and the association of food allergy and obesity are needed.