SUMMARY The ancient UbiB protein kinase-like family is involved in isoprenoid lipid biosynthesis and is implicated in human diseases, but demonstration of UbiB kinase activity has remained elusive for unknown reasons. Here, we quantitatively define UbiB-specific sequence motifs and reveal their positions within the crystal structure of a UbiB protein, ADCK3. We find that multiple UbiB-specific features are poised to inhibit protein kinase activity, including an N-terminal domain that occupies the typical substrate binding pocket and a unique A-rich loop that limits ATP binding by establishing an unusual selectivity for ADP. A single alanine-to-glycine mutation of this loop flips this coenzyme selectivity and enables autophosphorylation, but inhibits coenzyme Q biosynthesis in vivo, demonstrating functional relevance for this unique feature. Our work provides mechanistic insight into UbiB enzyme activity and establishes a molecular foundation for further investigation of how UbiB family proteins affect diseases and diverse biological pathways.

Background One-fifth of patients with Crohn’s Disease (CD) are primary non-responders (PNR) to anti-tumor necrosis factor (anti-TNF) therapy, and an estimated 10–15% will fail therapy annually. Little is known about the genetics of response to anti-TNF therapy. The aim of our study was to identify genetic factors associated with PNR and loss of response to anti-TNFs in CD. Methods From a prospective registry, we characterized the response of 427 CD patients to their first anti-TNF therapy. Patients were designated as achieving primary response, durable response, and non-durable response based on clinical, endoscopic, and radiologic criteria. Genotyping was performed on the Illumina Immunochip. Separate genetic scores based on presence of predictive genetic alleles were calculated for PNR and durable response and performance of clinical and genetics models were compared. Results From 359 patients, 36 were adjudged to have PNR (10%), 200 had durable response, and 74 had non-durable response. Primary non-responders had longer disease duration and were more likely to be smokers. Fifteen risk alleles were associated with PNR. Patients with PNR had a significantly higher genetic risk score (p=8 × 10−12). A combined clinical-genetic model more accurately predicted PNR when compared to a clinical only model (0.93 vs. 0.70, p < 0.001). Sixteen distinct SNPs predicted durable response with a higher genetic risk score (p=7 × 10−13). The genetic risk scores for PNR and durable response were not mutually correlated suggesting distinct mechanisms. Conclusion Genetic risk alleles can predict primary non-response and durable response to anti-TNF therapy in Crohn’s disease.

BACKGROUND Clostridium difficile infection (CDI) is the most common healthcare-associated infection and is associated with considerable morbidity. Recurrent CDI is a key contributing factor to this morbidity. Despite an estimated 83,000 recurrences annually in the United States, there are few accurate estimates of costs associated with recurrent CDI. OBJECTIVE We performed this study (1) to identify the health consequences of recurrent CDI including need for repeat hospitalization, intensive care unit (ICU) stay, and surgery; (2) to determine costs associated with recurrent CDI and identify determinants of such costs; and (3) to compare the outcomes and costs of recurrent CDI to those who develop reinfection. METHODS We identified all patients with confirmed recurrent CDI between January to December 2013 at a single referral center. Healthcare burden associated with recurrence including diagnostic testing, pharmacologic treatment, and inpatient and outpatient healthcare visits were identified in the 12 months following the first recurrence. Total healthcare costs were calculated, and the predictors of high healthcare utilization were identified. RESULTS Our study population included 98 patients with recurrent CDI. The median interval between the initial infection and recurrence was 37 days. The mean age of the cohort was 67 years, two-thirds were women (62%), and the mean Charlson index was 8.6. During the year following the first recurrence of CDI, each patient underwent a mean of 4.4 stool C. difficile toxin tests and received a mean of 2.5 prescriptions for oral vancomycin (range, 0-6). Most patients (84%) with recurrence had a CDI-related hospitalization, and 6% underwent colectomy. The mean total CDI-associated cost was $34,104 per patient, with hospitalization costs accounting for 68%, surgery 20%, and drug treatment 8% of this cost, respectively. Extrapolating to the United States overall, we estimate an annual cost of $2.8 billion related to recurrent CDI. CONCLUSION Recurrent CDI is associated with considerable morbidity and cost. Infect Control Hosp Epidemiol 2017;38:196-202.

The incidence of intestinal infections among hospitalized IBD patients has increased over the past 15 years, primarily driven by C. difficile infections. Intestinal infections are associated with length of stay, hospital charges, and all-cause mortality. More aggressive measures for prevention of C. difficile infections are needed. 10.1093/ibd/izy086_video1izy086.video15779257979001.