Clostridioides difficile infection (CDI) imposes a substantial burden on the health care system in the United States. Understanding the biological basis for the spectrum of C. difficile-related disease manifestations is imperative to improving treatment and prevention of CDI. Here, we investigate the correlates of asymptomatic C. difficile colonization using a multi-omics approach. We compared the fecal microbiome and metabolome profiles of patients with CDI versus asymptomatically colonized patients, integrating clinical and pathogen factors into our analysis. We found that CDI patients were more likely to be colonized by strains with the binary toxin (CDT) locus or strains of ribotype 027, which are often hypervirulent. We find that microbiomes of asymptomatically colonized patients are significantly enriched for species in the class Clostridia relative to those of symptomatic patients. Relative to CDI microbiomes, asymptomatically colonized patient microbiomes were enriched with sucrose degradation pathways encoded by commensal Clostridia, in addition to glycoside hydrolases putatively involved in starch and sucrose degradation. Fecal metabolomics corroborates the carbohydrate degradation signature: we identify carbohydrate compounds enriched in asymptomatically colonized patients relative to CDI patients. Further, we reveal that across C. difficile isolates, the carbohydrates sucrose, rhamnose, and lactulose do not serve as robust growth substrates in vitro, consistent with their enriched detection in our metagenomic and metabolite profiling of asymptomatically colonized individuals. We conclude that pathogen genetic variation may be strongly related to disease outcome. More interestingly, we hypothesize that in asymptomatically colonized individuals, carbohydrate metabolism by other commensal Clostridia may prevent CDI by inhibiting C. difficile proliferation. These insights into C. difficile colonization and putative commensal competition suggest novel avenues to develop probiotic or prebiotic therapeutics against CDI.

Background Healthcare-associated infections due to antibiotic-resistant organisms pose an acute and rising threat to critically ill and immunocompromised patients. To evaluate reservoirs of antibiotic-resistant organisms as a source of transmission to patients, we interrogated isolates from environmental surfaces, patient feces, and patient blood infections from an established and a newly built intensive care unit. Methods We used selective culture to recover 829 antibiotic-resistant organisms from 1594 environmental and 72 patient fecal samples, in addition to 81 isolates from blood cultures. We conducted antibiotic susceptibility testing and short- and long-read whole genome sequencing on recovered isolates. Results Antibiotic-resistant organism burden is highest in sink drains compared to other surfaces. Pseudomonas aeruginosa is the most frequently cultured organism from surfaces in both intensive care units. From whole genome sequencing, different lineages of P. aeruginosa dominate in each unit; one P. aeruginosa lineage of ST1894 is found in multiple sink drains in the new intensive care unit and 3.7% of blood isolates analyzed, suggesting movement of this clone between the environment and patients. Conclusions These results highlight antibiotic-resistant organism reservoirs in hospital built environments as an important target for infection prevention in hospitalized patients.

Objectives: To investigate the laser safety of photoacoustic imaging. In photoacoustic imaging, a pulsed laser of several nanoseconds is used to illuminate biological tissue, and photoacoustic waves generated by optical absorption are used to form images of the tissue. Photoacoustic imaging is emerging in clinical applications; however, its potential use in reproductive medicine has yet to be reported. Design: Assessment of photoacoustic laser safety before its adoption by clinical reproductive medicine. Setting: Academic medical center. Animals: Blastocyst-stage mouse embryos. Interventions: Potential DNA damage of photoacoustic laser exposure on preimplantation mouse blastocyst stage embryos was examined. Different embryos groups were exposed to either 5-or 10-minute 15-Hz laser doses (typical clinical doses) and 1-minute 1-kHz laser dose (significantly higher dose), respectively. Main Outcome Measures: A terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was used to identify the rate of DNA damage in the laser-exposed blastocysts. Results: The negative control blastocyst group (no laser exposure) had a mean of 10.7 TUNEL-positive nuclei. The 5-and 10-minute 15-Hz laserÀexposed groups had a mean of 11.25 and 12.89 TUNEL-positive nuclei, respectively. The embryos exposed to the 1-kHz laser for 1 minute had an average mean of 12.0 TUNEL-positive nuclei. Conclusion:We demonstrated that typical lasers and exposure times used for photoacoustic imaging do not induce increased cell death in mouse blastocysts.

Clostridioides difficile infection (CDI) imposes a substantial burden on the health care system in the United States. Understanding the biological basis for the spectrum of C. difficile-related disease manifestations is imperative to improving treatment and prevention of CDI. Here, we investigate the correlates of asymptomatic C. difficile colonization using a multi-omics approach, comparing the fecal microbiome and metabolome profiles of patients with CDI versus asymptomatically-colonized patients. We find that microbiomes of asymptomatic patients are significantly enriched for species in the class Clostridia relative to those of symptomatic patients. Asymptomatic patient microbiomes were enriched with fucose, rhamnose, and sucrose degradation pathways relative to CDI patient microbiomes. Fecal metabolomics corroborates this result: we identify carbohydrate compounds enriched in asymptomatic patients relative to CDI patients, and correlated with a number of commensal Clostridia. Further, we reveal that across C. difficile isolates, the carbohydrates rhamnose and lactulose do not serve as robust growth substrates in vitro, corroborating their enriched detection in our metagenomic and metabolite profiling of asymptomatic individuals. We conclude that in asymptomatically-colonized individuals, carbohydrate metabolism by other commensal Clostridia may prevent CDI by inhibiting C. difficile proliferation. These insights into C. difficile colonization and putative commensal competition suggest novel avenues to develop probiotic or prebiotic therapeutics against CDI.

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