Antibiotic-associated diarrhea: Clinical characteristics and the presence of Clostridium difficile. / Diarrea asociada a antibióticos: características clínicas y presencia de Clostridium difficile.

INTRODUCTION AND AIMS: Evidence in Colombia and Latin America has been insufficient for establishing the clinical characteristics of patients with antibiotic-associated diarrhea (AAD). The present study attempts to describe the clinical characteristics of patients with AAD and to determine the presence of Clostridium difficile, utilizing the polymerase chain reaction (PCR) technique. MATERIALS AND METHODS: Forty-three patients with AAD, managed at the Hospital Universitario San Ignacio in Bogotá, Colombia, were evaluated. Prospective patient information was collected, with respect to demographic characteristics, profile of the antibiotic management received, clinical manifestations, risk factors, and paraclinical reports. In addition, the real time PCR test for Clostridium difficile (Cepheid Xpert®, Sunnyvale, CA, United States) was performed. RESULTS: Patient mean age was 58 years (19.31 SD). The majority of the patients received 2 or more antibiotics (62.9%) and the beta-lactams were the most frequently used. Hospital stay ranged from 2 to 104 days with a median of 10 days. The most frequent clinical manifestations were abdominal pain and bloating, followed by fever and tachycardia. At the time of diagnosis, 23 patients had noninflammatory results in the stool sample analyses and 18 had kidney failure. The mean level of albumin was 2.4mg/dl (0.7 SD). The presence of Clostridium difficile was documented through PCR in 6 patients (13.95% of the cases). CONCLUSIONS: AAD patients were characterized by a high frequency of severe comorbidities and prolonged hospital stay. The presence of Clostridium difficile in only 13.9% of the cases suggests that other causes of diarrhea in the hospitalized patient should be considered.

Phosphorescent sensing of carbon dioxide based on secondary inner-filter quenching.

A study of different strategies to prepare phosphorescence-based sensors for gaseous CO(2) determination has been performed. It includes the characterization of different configurations tested, a discussion of the results obtained and possibilities for the future. The optical sensor for gaseous CO(2) is based on changes in the phosphorescence intensity of the platinum octaethylporphyrin (PtOEP) complex trapped both on oxygen-insensitive poly(vinylidene chloride-co-vinyl chloride) (PVCD) membranes and PVCD microparticles, due to the displacement of the alpha-naphtholphthalein acid-base equilibrium with CO(2) concentration. A secondary inner-filter mechanism was tested for the sensor and a full range linearized calibration was obtained by plotting (I(100)-I(0))/(I-I(0)) versus the inverse of the CO(2) concentration, where I(0) and I(100) are the detected luminescence intensities from a membrane exposed to 100% nitrogen and 100% CO(2), respectively, and I at a defined CO(2) concentration. The different configurations tested included the use of membranes containing luminophore and pH-sensitive dye placed on two opposite sides of a transparent support to prevent the observed degradation of the PtOEP complex in the presence of the tetraoctylammonium hydroxide (TOAOH) phase transfer agent, which produced better results regarding stability and sensitivity. The CO(2) gas sensor based on PtOEP homogeneous membranes presented better properties in terms of response time and sensitivity than that based on PtOEP microparticles. With a detection limit of 0.02%, the response time (10-90% maximum signal) is 9 s and the recovery time (90-10%) is 115 s. The lifetime of the membranes for CO(2) sensing preserved in a 94% RH atmosphere and dark conditions is longer than at least 4 months.

Chemosensitization of a multidrug-resistant Leishmania tropica line by new sesquiterpenes from Maytenus magellanica and Maytenus chubutensis.

Parasite resistance to drugs has emerged as a major problem in current medicine, and therefore, there is great clinical interest in developing compounds that overcome these resistances. In an intensive study of South American medicinal plants, herein we report the isolation, structure elucidation, and biological activity of dihydro-beta-agarofuran sesquiterpenes from the roots of Maytenus magellanica (1-14) and M. chubutensis (14-17). This type of natural products may be considered as privileged structures. The structures of 10 new compounds, 1, 3, 6-9, and12-15, were determined by means of (1)H and (13)C NMR spectroscopic studies, including homonuclear (COSY and ROESY) and heteronuclear correlation experiments (HMQC and HMBC). The absolute configurations of eight hetero- and homochromophoric compounds, 1, 3,6-9, 12, and 13, were determined by means of CD studies. Fourteen compounds, 1-3 and 6-16, have been tested on a multidrug-resistant Leishmania tropica line overexpressing a P-glycoprotein-like transporter to determine their ability to revert the resistance phenotype and to modulate intracellular drug accumulation. From this series, 1, 2, 3, 14, and 15 showed potent activity, 1 being the most active compound. The structure-activity relationships of the different compounds are discussed.

New sesquiterpenes fromMaytenus species (Celastraceae). Taxonomic and chemotaxonomic considerations concerning chileanMaytenus.

Three new dihydro-ß-agarofuran sesquiterpenes from two species ofMaytenus were isolated and their structures were elucidated by means of(1)H and(13)C NMR studies. The differences and similarities noted in the chemical content of the dihydro-ß-agarofuran sesquiterpenes from the fourMaytenus species from Chile are in line with the taxonomic characterization of these species; their geographical distribution is also given.

Minor sesquiterpenes from Maytenus chubutensis.

Four new minor dihydro-beta-agarofuran-skeleton sesquiterpenes, 9 beta-benzoyloxy-1 alpha,2 alpha,6 beta-triacetoxy-15-hydroxydihydro-beta- agarofuran [1], 9 beta-benzoyloxy-1 alpha,2 alpha,6 beta,15-tetracetoxydihydro-beta-agarofuran [6], 9 alpha-benzoyloxy-1 alpha,2 alpha,6 beta-triacetoxy- 8 alpha,15-dihydroxydihydro-beta-agarofuran [7], and 9 alpha-benzoyloxy-1 alpha,2 alpha,6 beta,8 alpha-tetracetoxy-15- hydroxydihydro-beta-agarofuran [8] were isolated from the aerial parts of Maytenus chubutensis and identified by spectroscopy and chemical reactions.