Clostridioides difficile-associated diarrhea in surgical service patients in Mexico. / Diarrea asociada a Clostridioides difficile en pacientes de servicios quirúrgicos en México.

INTRODUCTION: Clostridioides difficile is the first cause of healthcare-associated diarrhea in developed countries. In recent years the incidence of C. difficile infection (CDI) has increased worldwide. There is not much information on the topic in Mexico, and little is known about the risk factors for the infection in patients that are hospitalized in surgical services. MATERIALS AND METHODS: A case-control study was conducted that compared the epidemiologic findings and risk factors between surgical patients with PCR-confirmed CDI, surgical patients with diarrhea and a negative PCR test, and surgical patients with no diarrhea. The statistical analysis was carried out using the SPSS version 22.0 program. RESULTS: The majority of the surgical patients with CDI belonged to the areas of neurosurgery, cardiac surgery, orthopedics, and general surgery. A total of 53% of the CDI cases were associated with the hypervirulent CD NAP1/027 strain. The presence of mucus in stools (OR: 1.5, P=.001), fever (OR: 1.4, P=.011), leukocytes in stools (OR: 3.2, P<.001), hospitalization within the past 12weeks (OR: 2.0, P<.001), antibiotic use (OR: 1.3, P=.023), and ceftriaxone use (OR: 1.4, P=.01) were independent risk factors for the development of CDI. CONCLUSIONS: C. difficile-induced diarrhea in the surgical services is frequent at the Hospital Civil de Guadalajara "Fray Antonio Alcalde".

Avalanches and Criticality in Driven Magnetic Skyrmions.

We show using numerical simulations that slowly driven Skyrmions interacting with random pinning move via correlated jumps or avalanches. The avalanches exhibit power-law distributions in their duration and size, and the average avalanche shape for different avalanche durations can be scaled to a universal function, in agreement with theoretical predictions for systems in a nonequilibrium critical state. A distinctive feature of Skyrmions is the influence of the nondissipative Magnus term. When we increase the ratio of the Magnus term to the damping term, a change in the universality class of the behavior occurs, the average avalanche shape becomes increasingly asymmetric, and individual avalanches exhibit motion in the direction perpendicular to their own density gradient.

Clinical and endoscopic features in patients with hospital-acquired diarrhea associated with Clostridium difficile infection. / Características clínicas y endoscópicas en diarrea hospitalaria asociada a infección por Clostridium difficile.

INTRODUCTION AND AIMS: Clostridium difficile infection is the main cause of hospital-acquired diarrhea, and the clinical and endoscopic findings in those patients have been studied very little in Mexico. The aim of the present study was to describe those findings. MATERIALS AND METHODS: A prospective cohort study was conducted that included patients with hospital-acquired diarrhea associated with Clostridium difficile diagnosed through polymerase chain reaction. The hypervirulent NAP027 strain was also determined. The clinical and endoscopic findings in the study patients, as well as the variables associated with severity, were analyzed. RESULTS: Of the 127 patients with hospital-acquired diarrhea, 97 were excluded from the study due to lack of colonoscopy. The remaining 39 study patients had a mean age of 48 years, and their most common signs/symptoms were abdominal pain (49%), mucus in stools (41%), and blood in stools (10%). The most common alterations in the laboratory results were leukocytosis in 49%, fecal leukocytes (61%), and hypoalbuminemia (67%). The main risk factor was antibiotic use in 62%, and ceftriaxone was the most widely used. The hypervirulent strain was present in 54% of the cases. Endoscopic abnormalities were found in 87% of the patients. Thirty-eight percent presented with pseudomembranous colitis, with lesions in the left colon in 53%, and in the right colon in 13%. No association was found between proton-pump inhibitor use and Clostridium difficile-associated diarrhea. There was a significant association between hypoalbuminemia (< 3.3g/dL) and a greater risk for severe colitis, with a RR of 8.2 (p=0.008). CONCLUSIONS: Pseudomembranous colitis lesions associated with the hypervirulent Clostridium difficile strain were predominant in the left colon. Hypoalbuminemia was a significant severity predictor.

Monitoring Enzymatic Proteolysis Using Either Enzyme- or Substrate-Bioconjugated Quantum Dots.

Rational design of enzyme-nanoparticle hybrids is still in its infancy and the design is often inspired by potential access to many beneficial sensing properties such as increased stability, sensitivity, and even enhanced enzyme activities in specific cases. Deriving quantitative kinetic data from these constructs is not trivial, however, since the intrinsic design gives rise to unique properties that can influence the enzymatic assays that are central to the application of the hybrids. Here, we present two distinct assay methodologies for following the kinetic activity of composite enzyme-nanoparticle constructs. We utilize luminescent semiconductor nanocrystals or quantum dots (QDs) as the prototypical nanoparticulate platform for these sensing formats and target proteolytic enzyme activity as the main assay. The first assay is analogous to most current enzymatic assays and is designed to compare QD-enzyme constructs; this format is based on utilizing a fixed concentration of enzyme displayed on the QD and excess substrate in the solution, and the analysis utilizes data from initial velocities. The second assay is designed to analyze kinetics using a QD-substrate construct, in which the enzyme and QD interactions are short lived. Here, the nanoparticle-substrate concentration is held constant and exposed to increasing concentrations of the enzyme in solution. This later methodology is based on a fluorescent ratiometric signal that follows the entire progress curve of the enzyme reaction. A comparison of these two different assays of the series of enzyme-nanoparticle and substrate-nanoparticle constructs provides deeper insight into the enzyme kinetics of these hybrids, while still testing of individual variables within a given format, to allow for further optimization within each set.