Mutant screens and transcriptome studies led us to consider whether the metabolism of glucose polymers, i.e., maltose, maltodextrin, and glycogen, is important for Escherichia coli colonization of the intestine. By using the streptomycin-treated mouse model, we found that catabolism of the disaccharide maltose provides a competitive advantage in vivo to pathogenic E. coli O157:H7 and commensal E. coli K-12, whereas degradation of exogenous forms of the more complex glucose polymer, maltodextrin, does not. The endogenous glucose polymer, glycogen, appears to play an important role in colonization, since mutants that are unable to synthesize or degrade glycogen have significant colonization defects. In support of the hypothesis that E. coli relies on internal carbon stores to maintain colonization during periods of famine, we found that by providing a constant supply of a readily metabolized sugar, i.e., gluconate, in the animal's drinking water, the competitive disadvantage of E. coli glycogen metabolism mutants is rescued. The results suggest that glycogen storage may be widespread in enteric bacteria because it is necessary for maintaining rapid growth in the intestine, where there is intense competition for resources and occasional famine. An important implication of this study is that the sugars used by E. coli are present in limited quantities in the intestine, making endogenous carbon stores valuable. Thus, there may be merit to combating enteric infections by using probiotics or prebiotics to manipulate the intestinal microbiota in such a way as to limit the availability of sugars preferred by E. coli O157:H7 and perhaps other pathogens.

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ABSTRACT Introduction Psychiatric complaints account for a sizable and increasing portion of emergency department (ED) visits. Compared with other medical patients, these patients often require substantial resources because of limited specialized resources and prolonged boarding times, which can be detrimental to the safety and satisfaction of other patients. This can prompt early and indiscriminate laboratory testing to expedite early requests for admission consideration. Numerous emergency medicine literature and clinical policies already recommend against indiscriminate screening labs for these patients, yet many psychiatric services require these tests. This study further evidences the limited clinical utility and high associated costs of mandatory protocol screening labs for psychiatric patients evaluated in military EDs. Materials and Methods A retrospective chart review of 441 active duty military patients and their families presenting to Madigan Army Medical Center’s ED who received psychiatric diagnoses underwent analysis. A 3-physician review panel evaluated each identified patient case to confirm eligibility and determine whether or not laboratory studies led to a change in patient disposition that was not identified by history, review of systems, physical exam, and known past medical history. The review was approved by the hospital’s institutional review board. Contemporary laboratory tests ordered in the evaluation of these patients included complete blood count with differential, complete metabolic panel, thyroid-stimulating hormone, serum ethanol, serum acetaminophen, serum salicylates, urine drug screening, urinalysis, urine human chorionic gonadotropin, and electrocardiograms. Results Broad screening labs may have altered dispositions for 0.9% ( 4) of patients. In total, 93% (202) of admitted patients were dispositioned to a psychiatric service. Of the 15 patients admitted to a medical service, 10 involved overdoses or intoxication. One patient had anemia in addition to opioid use disorder as diagnoses and was dispositioned to a medicine service. One pediatric patient was admitted for observation only. The remaining patients had diagnoses based on physical exam and history requiring medical service admission. In total, 7 patients had unknown dispositions, of which 4 carried solely psychiatric diagnoses. Conclusions The cumulative reimbursement costs of broad testing in the studied population were estimated at $36,325.17 and rarely altered patient disposition. Further testing does not increase the incidence of disposition altering diagnoses and is associated with increased costs. When individual state laws and the clinical assessment by the responsible emergency physician are considered, future standardized ED lab screening evaluations of psychiatric patients in military EDs may be concentrated to breathalyzer alcohol level, urine drug screen, serum salicylates, serum acetaminophen, and urine human chorionic gonadotropin.

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