Safety evaluation of Lactobacillus pentosus strain b240

Lactobacillus pentosus has a long history of use in cooked and uncooked fermented foods. Viable and heat-killed nonviable preparations of L. pentosus strain b240 were evaluated for short term and subchronic toxicity and genotoxic potential. Dose levels were determined through acute oral toxicity tests with viable (LD₅₀ > 2500 mg/kg) and nonviable (LD₅₀ > 2000 mg/kg) b240. In the short term study, rats received 2500 mg/kg/day (∼1.7 × 10¹¹ cfu/kg/day) viable b240 for 28 days. In the subchronic study, rats received 500, 1000 or 2000 mg/kg/day (up to ∼3.0 × 10¹² cfu equivalents/kg/day) nonviable b240 for 91 days followed by a 28-day recovery. No mortalities occurred. No treatment-related effects were identified for general condition, body weight, food-water consumption, ophthalmology, urinalysis, hematology, blood chemistry, organ weights, histopathology and gross pathology. Although statistically significant effects were noted for several endpoints in the short term and subchronic studies, none were related to the test materials. The NOAEL for nonviable b240 was 2000 mg/kg/day, the highest dose tested. Additionally, nonviable b240 (?5000 μg/plate) was not mutagenic in Salmonella typhimurium or Escherichia coli tester strains nor did nonviable b240 orally administered to rats at levels ? 2000 mg/kg/day for two days, induce a clastogenic response.     

Sterile cerebrospinal fluid pleocytosis in young infants with urinary tract infections

In a multicenter prospective study, 91 of 1025 febrile infants 相似文献   

Relationships between dietary behaviours,oral hygiene and mutans streptococci in dental plaque of a group of infants in southern England

This report is part of a prospective study on dietary behaviours, feeding practices, oral hygiene and dental health during the first 18 months of life in a cohort of infants living in southern England. In this part of the study the prevalence of mutans streptococci in the plaque of 1-year-old children and its correlation with sociodemographic status, dietary behaviour and oral hygiene practices over the first 12 months of life were studied. Dietary habits, oral hygiene and dental health at 18 months were also studied. The study group comprised 163 infants. At 12 months of age all children had a dental examination and a plaque sample was removed from the labial surfaces of upper incisors for microbiological examination. A further dental examination took place at 18 months of age; no plaque was sampled. Longitudinal dietary information was obtained with a 3-day food diary at 6, 12 and 18 months of age. Parents/carers completed two structured questionnaires on sociodemographic factors, oral hygiene and feeding behaviour over the first 18 months of life when their children were 12- and 18-month-old. No child exhibited dental caries at 12 and 18 months of age; 18 and 25% had visible dental plaque at 12 and 18 months, respectively. Seven children (4%) had detectable mutans streptococci in their plaque at 12 months of age. Children who had started brushing their teeth or who had had their teeth brushed by 12 months of age were less likely to have detectable mutans streptococci in their plaque than those who had not (P=0.02). The amount of mutans streptococci was significantly correlated with the total number of eating/drinking events per day (P<0.001) and bordered on significant correlation with the mean daily frequency of consumption of foods and drinks containing non-milk extrinsic sugars (P=0.05). None of the sociodemographic variables-sex, social class, mother's level of education-were associated with the detection of mutans streptococci in this group of infants. Multiple logistic regression analysis revealed that two variables were independently and positively correlated with the presence of mutans streptococci in the plaque; these were age when tooth brushing started and total eating and drinking events per day.     

High-molecular-weight polyethylene glycol prevents lethal sepsis due to intestinal Pseudomonas aeruginosa

BACKGROUND & AIMS: During stress, erosion of protective intestinal mucus occurs in association with adherence to and disruption of the intestinal epithelial barrier by invading opportunistic microbial pathogens. The aims of this study were to test the ability of a high-molecular-weight polyethylene glycol compound, polyethylene glycol 15-20, to protect the intestinal epithelium against microbial invasion during stress. METHODS: The ability of polyethylene glycol 15-20 to protect the intestinal epithelium against the opportunistic pathogen Pseudomonas aeruginosa was tested in cultured Caco-2 cells. Bacterial virulence gene expression, bacterial adherence, and transepithelial electrical resistance were examined in response to apical inoculation of P. aeruginosa onto Caco-2 cells. Complementary in vivo studies were performed in a murine model of lethal sepsis due to intestinal P. aeruginosa in which surgical stress (30% hepatectomy) was combined with direct inoculation of P. aeruginosa into the cecum. RESULTS: High-molecular-weight polyethylene glycol (polyethylene glycol 15-20) conferred complete protection against the barrier-dysregulating effects of P. aeruginosa in Caco-2 cells. Intestinal application of polyethylene glycol 15-20 in stressed mice protected against the lethal effects of intestinal P. aeruginosa. Mechanisms of this effect seem to involve the ability of polyethylene glycol 15-20 to distance P. aeruginosa from the intestinal epithelium and render it completely insensate to key environmental stimuli that activate its virulence. CONCLUSIONS: High-molecular-weight polyethylene glycol has the potential to function as a surrogate mucin within the intestinal tract of a stressed host by inhibiting key interactive events between colonizing microbes and their epithelial cell targets.     

Thermal treatment of the bacteriophage lysate of Klebsiella pneumoniae B5055 as a step for the purification of capsular depolymerase enzyme

The lytic bacteriophage which produces the hydrolase enzyme capable of depolymerizing exopolysaccharide of Klebsiella pneumoniae and of other bacteria was isolated earlier. In this study, a simple method of depolymerase purification from the phage lysate by dissociating the enzyme from the phage particle was developed. The bacteriophage showed a relatively smaller plaque size surrounded by a wide halo indicating a depolymerase action on the capsular polysaccharide of K. pneumoniae B5055. The depolymerase activity was associated predominantly with the phage particles. Different methods have been used by various researchers to dissociate the enzyme associated with phage particles either by exposure to chemicals or by altering the environmental conditions. In this study, the potential application of thermal treatment of the bacteriophage lysate was evaluated as a step for the purification of depolymerase in comparison to the mild acid treatment method of Rieger et al. (1975). The results showed that the relative thermal stability of phage depolymerase at 60 °C for 30 min was the basis for harvesting the enzyme leading to disintegration of all phage particles in the lysate. Both thermal and mild acid treatment resulted in comparable enzyme levels, however; mild acid treatment appeared to be cumbersome and cause chemical contamination.     

Bioscreening of Australian olive mill waste extracts: biophenol content, antioxidant, antimicrobial and molluscicidal activities.

The biophenolic fraction was characterized in olive mill waste (OMW) obtained as a by-product from processing of Mission and Frantoio olive fruit. OMW produced from the Mission fruit contained higher total phenol content. Individual biophenols with the exception of verbascoside and a hydroxytyrosol-secoiridoid were also present at higher concentrations in the OMW produced from Mission cultivar. Antioxidant activities were measured in aqueous (DPPH) and emulsion (BCBT) systems. The Frantoio extract was more active than the Mission extract in the DPPH assay - EC(50) values were 28.3+/-1.7 ppm and 34.7+/-1.7 ppm, respectively. Activities were reversed in the BCBT, with the Mission extract (EC(50) 60.6+/-2.3 ppm) more potent than the Frantoio extract (EC(50) 79.9+/-2.0 ppm), and this may be related to the more lipophilic nature of the Mission extract. Both extracts showed broad spectrum antibacterial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa; whereas individual biophenols (hydroxytyrosol, luteolin, oleuropein) showed more limited activity. Molluscicidal activity was measured against Isidorella newcombi and LD(50) values were 424 ppm and 541 ppm for Mission and Frantoio extracts, respectively. The results suggest that OMW may be utilised as a source of bioactive compounds.     

Teratogenicity and maternal effects of Lactobacillus brevis KB290 in rats and rabbits

Lactobacillus brevis KB290 (KB290), a plant-derived probiotic lactic acid bacterium, improves gut health and stimulates immune function. Here we extensively investigated the teratogenicity of KB290 in rats and rabbits. We observed no adverse maternal or fetal effects and concluded that the no observable adverse effect level for maternal general toxicity, maintenance of pregnancy, and teratogenicity should be ?10¹⁰ cfu/kg/day. Our results suggest that KB290 would be safe for pregnant females and their offspring.