Critically ill patients are physiologically unstable and recent studies indicate that the intestinal microbiota could be involved in the health decline of such patients during ICU stays. This study aims to assess the intestinal microbiota in critically ill patients with and without sepsis and to determine its impact on outcome variables, such as medical complications, ICU stay time, and mortality. A multi-center study was conducted with a total of 250 peri-rectal swabs obtained from 155 patients upon admission and during ICU stays. Intestinal microbiota was assessed by sequencing the V3-V4 hypervariable regions of the 16S rRNA gene. Linear mixed models were used to integrate microbiota data with more than 40 clinical and demographic variables to detect covariates and minimize the effect of confounding factors. We found that the microbiota of ICU patients with sepsis has an increased abundance of microbes tightly associated with inflammation, such as Parabacteroides, Fusobacterium and Bilophila species. Female sex and aging would represent an increased risk for sepsis possibly because of some of their microbiota features. We also evidenced a remarkable loss of microbial diversity, during the ICU stay. Concomitantly, we detected that the abundance of pathogenic species, such as Enterococcus spp., was differentially increased in sepsis patients who died, indicating these species as potential biomarkers for monitoring during ICU stay. We concluded that particular intestinal microbiota signatures could predict sepsis development in ICU patients. We propose potential biomarkers for evaluation in the clinical management of ICU patients.

Objective: To determine the concentration of stool short-chain fatty acids (SCFAs) in critically ill patients with sepsis and to compare the results between the critically ill patient and the control group. Methods: This descriptive, multicenter, observational study was conducted in five health institutions. Over a 6-month study period, critically ill patients with sepsis who were admitted to the intensive care unit (ICU) and met the inclusion criteria were enrolled, and a control, paired by age and sex, was recruited for each patient. A spontaneous stool sample was collected from each participant and a gas chromatograph coupled to a mass spectrometer (Agilent 7890/MSD 5975 C) was used to measure the concentrations SCFAs. Results: The final sample included 44 patients and 45 controls. There were no differences in the age and sex distributions between the groups (p > 0.05). According to body mass index (BMI), undernutrition was more prevalent among critically ill patients, and BMI in control subjects was most frequently classified as overweight (p ¼ 0.024). Propionic acid, acetic acid, butyric acid, and isobutyric acid concentrations were significantly lower in the critically ill patient group than in the control group (p ¼ 0.000). No association with outcome variables (complications, ICU stay, and discharge condition) was found in the patients, and patients diagnosed with infection on ICU admission showed significant decreases in butyric and isobutyric acid concentrations with respect to other diagnostic criteria (p < 0.05). Conclusions:The results confirm significantly lower concentrations of stool SCFAs in critically ill patients with sepsis than in control subjects. Due to its role in intestinal integrity, barrier function, and anti-inflammatory effect, maintaining the concentration of SCFAs may be important in the ICU care protocols of the critical patient.

Los ácidos biliares, cuyo precursor es el colesterol de la dieta, tienen una importancia fundamental en el metabolismo de los lípidos ingeridos, siendo tal vez su función más divulgada. Sin embargo, estos interactúan de manera recíproca con el metabolismo bacteriano intestinal, mediante las señales moleculares, que permiten una modificación tanto en la abundancia como en la diversidad de la microbiota intestinal. Esta última se ha considerado como el nuevo órgano, y ha tenido un estudio a profundidad en los últimos años gracias a los avances y la optimización en los métodos diagnósticos, lo que permite determinar su implicación en enfermedades no solo del tracto gastrointestinal, sino a nivel sistémico. El objetivo de la presente revisión es identificar las diferentes alteraciones en la transformación de los ácidos biliares primarios a secundarios, y cómo estos cambios generan una modificación en la composición de la microbiota intestinal, lo que genera procesos de inflamación crónica, mediado por diferentes vías de señalización, siendo factores etiológicos para un sin número de patologías que comprometen los colangiocitos. Palabras clave: microbiota, ácidos biliares, colangiopatías.

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