Clostridium difficile pilot study: effects of probiotic supplementation on the incidence of C. difficile diarrhoea.

Colonic infection with Clostridium difficile, leading to pseudomembranous colitis, is a common complication of antibiotic therapy, especially in elderly patients. It has been suggested that non-pathogenic probiotic bacteria might prevent the development and recurrence of C. difficile infection. This double-blind, placebo-controlled study examines the role of probiotic administration in the prevention of C. difficile-associated diarrhoea (CDAD) in elderly patients receiving antibiotic therapy. Consecutive patients (150) receiving antibiotic therapy were randomised to receive either a probiotic containing both Lactobacillus and Bifidobacterium or placebo for 20 days. Upon admission to hospital, bowel habit was recorded and a faecal sample taken. Trial probiotic or placebo was taken within 72 h of prescription of antibiotics, and a second stool sample was taken in the event of development of diarrhoea during hospitalisation or after discharge. Of the randomised patients, 138 completed the study, 69 with probiotics in conjunction with antibiotics and 69 with antibiotics alone. On the basis of development of diarrhoea, the incidence of samples positive for C. difficile-associated toxins was 2.9% in the probiotic group compared with 7.25% in the placebo-control group. When samples from all patients were tested (rather than just those developing diarrhoea) 46% of probiotic patients were toxin-positive compared with 78% of the placebo group.

Clostridium difficile pilot study: effects of probiotic supplementation on the incidence of C. difficile diarrhoea / Estudio piloto de Clostridium difficile: efecto del aporte suplementario de probióticos sobre la incidencia de diarrea causada por C. difficile

Colonic infection with Clostridium difficile, leading to pseudomembranous colitis, is a common complication of antibiotic therapy, especially in elderly patients. It has been suggested that non-pathogenic probiotic bacteria might prevent the development and recurrence of C. difficile infection. This double-blind, placebo-controlled study examines the role of probiotic administration in the prevention of C. difficile-associated diarrhoea (CDAD) in elderly patients receiving antibiotic therapy. Consecutive patients (150) receiving antibiotic therapy were randomised to receive either a probiotic containing both Lactobacillus and Bifidobacterium or placebo for 20 days. Upon admission to hospital, bowel habit was recorded and a faecal sample taken. Trial probiotic or placebo was taken within 72 h of prescription of antibiotics, and a second stool sample was taken in the event of development of diarrhoea during hospitalisation or after discharge. Of the randomised patients, 138 completed the study, 69 with probiotics in conjunction with antibiotics and 69 with antibiotics alone. On the basis of development of diarrhoea, the incidence of samples positive for C. difficile-associated toxins was 2.9% in the probiotic group compared with 7.25% in the placebo-control group. When samples from all patients were tested (rather than just those developing diarrhoea) 46% of probiotic patients were toxin-positive compared with 78% of the placebo group (AU)

La infección de colon por Clostridium difficile, que produce colitis pseudomembranosa, es una complicación frecuente en las terapias con antibióticos, especialmente en pacientes de la tercera edad. Se ha sugerido que las bacterias probióticas no patógenas podrían prevenir el desarrollo de la infección por C. difficile. Este estudio de doble ciego con control mediante placebos examina la influencia de la administración de probióticos en la prevención de diarrea asociada a C. difficile (CDAD) en pacientes de la tercera edad sometidos a terapia con antibióticos. Se escogieron al azar 150 pacientes consecutivos sometidos a terapia con antibióticos y se les administró aleatoriamente durante 20 días un probiótico que contenía Lactobacillus y Bifidobacterium o un placebo. Tras su ingreso hospitalario, se anotó su régimen intestinal y se tomó una muestra fecal. El probiótico o el placebo se administró durante las 72 h primeras del tratamiento con antibióticos, y se tomó una segunda muestra de heces en el caso de aparecer diarrea durante la hospitalización o tras el alta médica. De los pacientes escogidos, 138 completaron el estudio, 69 tratados con antibióticos y probióticos y 69 solamente con antibióticos. Entre los pacientes que tuvieron diarrea, se encontró un 2,9 por ciento de muestras positivas para la toxina asociada a C. difficile en el grupo tratado con probióticos, en comparación con el 7,25 por ciento detectado en el grupo control tratado con placebo. Cuando se analizaron muestras de todos los pacientes (no solamente los que tuvieron diarrea), un 46 por ciento de los pacientes tratados con probióticos dieron positivo para la toxina, en comparación con el 78 por ciento del grupo tratado con placebo (AU)

The "primitive" microaerophile Giardia intestinalis (syn. lamblia, duodenalis) has specialized membranes with electron transport and membrane-potential-generating functions.

Here it is shown that the flagellated protozoon Giardia intestinalis, commonly regarded as an early branching eukaryote because of its lack of mitochondria, has membraneous structures that partition the cationic, membrane-potential-sensitive fluorophore rhodamine 123. This organism also reduces a tetrazolium fluorogen at discrete plasma-membrane-associated sites. That these functions occur in distinctive specialized membrane systems supports the growing evidence that G. intestinalis may not be primitive, but is derived from an aerobic, mitochondria-containing flagellate.

Giardia intestinalis, a eukaryote without hydrogenosomes, produces hydrogen.

The microaerophilic flagellated protist Giardia intestinalis, the commonest protozoal agent of intestinal infections worldwide, is of uncertain phylogeny, but is usually regarded as the earliest branching of the eukaryotic clades. Under strictly anaerobic conditions, a mass spectrometric investigation of gas production indicated a low level of generation of dihydrogen (2 nmol x min(-1) per 10(7) organisms), about 10-fold lower than that in Trichomonas vaginalis under similar conditions. Hydrogen evolution was O2 sensitive, and inhibited by 100 microM metronidazole. Fluorescent labelling of G. intestinalis cells using monoclonal antibodies to typical hydrogenosomal enzymes from T. vaginalis (malate enzyme, and succinyl-CoA synthetase alpha and beta subunits), and to the large-granule fraction (hydrogenosome-enriched, also from T. vaginalis) gave no discrete localization of epitopes. Cell-free extracts prepared under anaerobic conditions showed the presence of a CO-sensitive hydrogenase activity. This first report of hydrogen production in a eukaryote with no recognizable hydrogenosomes raises further questions about the early branching status of G. intestinalis; the physiological characterization of its hydrogenase, and its recently elucidated gene sequence, will aid further phylogenetic investigations.

Giardia: highly evolved parasite or early branching eukaryote?

The phylogeny of the commonest protozoal agent of intestinal disease, Giardia, is unclear. Although recent intensive research suggests this important human parasite is an early branching eukaryote that evolved before the endosymbiotic origin of mitochondria, there is also evidence to suggest that, as a highly evolved parasite, it has lost many of its ancestral characteristics. In this case, these organisms might have arisen much more recently from aerobic free-living flagellates.

The microaerophilic flagellate Giardia intestinalis: oxygen and its reaction products collapse membrane potential and cause cytotoxicity.

Trophozoites of the microaerophilic flagellate parasitic protozoon Giardia intestinalis have only a limited capacity to detoxify O(2). Thus, when exposed to controlled concentrations of dissolved O(2) >8 microM, they gradually lose their ability to scavenge O(2). In a washed cell suspension stirred under 10% air in N(2) (equivalent to 25 microM O(2)), inactivation of the O(2)-consuming system was complete after 3.5 h; during this period accumulation of H(2)O(2) (3 micromol per 10(6) organisms) and oxidation of cellular thiols to 16% of their initial level occurred. Under 20% air (50 microM O(2)), respiratory inactivation was complete after 1.5 h, and under air (258 microM O(2)), after 50 min. Loss of O(2)-consuming capacity was accompanied by loss of motility. Use of the fluorogen 2, 7-dichlorodihydrofluorescein acetate indicated that intracellular H(2)O(2) is produced at extranuclear sites. Flow cytometric estimation of the plasma membrane electrochemical potentials using bis(1,3-dibutylbarbituric acid) trimethine oxonol, DiBAC(4)(3), showed that values declined from -134 mV to -20 mV after 4.5 h aeration. Incubation of organisms with 60 microM H(2)O(2) for 10 min gave partial collapse of plasma membrane potential and complete loss of O(2) uptake capacity; motility and viability as assessed by DiBAC(4)(3) exclusion were completely lost after 1 h. Inactivation of the O(2)-consuming system and loss of viability were also observed on exposure to singlet oxygen photochemically generated from rose bengal or toluidine blue.

The microaerophilic flagellate Giardia intestinalis: Allium sativum (garlic) is an effective antigiardial.

Whole garlic (Allium sativum L.) extract and some of its components were assayed for antigiardial activity. Whole garlic extract gave an IC(50) at 24 h of 0.3 mg ml(-1). Most of the components assayed were inhibitory to the organism, especially allyl alcohol and allyl mercaptan, with IC(50) values of 7 microg ml(-1) and 37 microg ml(-1) respectively. Studies with calcofluor white indicated that whole garlic and allyl alcohol collapse the transmembrane electrochemical membrane potential (Deltapsi) of the organism, as indicated by uptake of the fluorochrome. Electron microscopy allowed the morphological changes that occur with garlic inhibition to be recorded. Both the surface topography and internal architecture of the organism changed during incubation with the biocides. Both whole garlic and allyl alcohol resulted in fragmentation of the disc and an overexpression of disc microribbons, internalization of flagella, vacuole formation and an increase in distended vesicles. Allyl mercaptan, however, only gave an increase in distended vesicles, suggesting that this biocide has a different mode of action.