Incidence and outcomes of bloodstream infections among hematopoietic cell transplant recipients from species commonly reported to be in over-the-counter probiotic formulations.

BACKGROUND: Probiotic supplementation has been promoted for numerous health conditions; however, safety in immunosuppressed patients is unknown. We evaluated bloodstream infections (BSIs) caused by common probiotic organisms in hematopoietic cell transplant recipients. METHODS: All blood culture (BC) results from a cohort of hematopoietic cell transplant recipients transplanted at Fred Hutchinson Cancer Research Center in Seattle, Washington, between 2002 and 2011 were reviewed. Patients with at least 1 positive BC for common probiotic organisms (Lactobacillus species, Bifidobacterium species, Streptococcus thermophilus, and Saccharomyces species) within 1 year post hematopoietic cell transplantation (HCT) were considered cases. Data were collected from center databases, which contain archived laboratory data, patient demographics, and clinical summaries. RESULTS: A total of 19/3796 (0.5%) patients developed a BSI from one of these organisms within 1 year post HCT; no Bifidobacterium species or S. thermophilus were identified. Cases had a median age of 49 years (interquartile range [IQR]: 39-53), and the majority were allogeneic hematopoietic cell transplant recipients (14/19, 74%). Most positive BCs were Lactobacillus species (18/19) and occurred at a median of 84 days (IQR: 34-127) post transplant. The incidence rate of Lactobacillus bacteremia was 1.62 cases per 100,000 patient-days; the highest rate occurred within 100 days post transplant (3.3 per 100,000 patient-days). Eight patients (44%) were diagnosed with acute graft-versus-host disease of the gut prior to the development of bacteremia. No mortality was attributable to any of these infections. CONCLUSION: Organisms frequently incorporated in available over-the-counter probiotics are infrequent causes of bacteremia after HCT. Studies evaluating the use of probiotics among high-risk patients are needed.

Bioactive exopolysaccharides from a S. thermophilus strain: Screening, purification and characterization.

A lactic acid bacteria strain AR333 with high-production of exopolysaccharides (EPS) was screened out from 350 bacteria strains isolated from naturally fermented dairy products. It was identified as Streptococcus thermophilus by morphological observation, physiological and biochemical characteristics, and 16S rDNA sequence determination. The EPS from AR333 were purified through DEAE-Sepharose Fast Flow and Sepharose CL-6B, and the purified fraction was designated as EPS333. In vitro test showed that EPS333 could stimulate macrophage RAW 264.7 to release NO significantly (p<0.05). The further work tried to elucidate the structural features of EPS333 via FT-IR spectrum, high-performance anion exchange chromatography (HPAEC) and high-performance size exclusion chromatography (HPSEC). The results showed that EPS333 was a pure neutral polysaccharide with monosaccharide composition of galactose and glucose in a molar ratio of 6:5. A certain amount of acetyl groups might exist in EPS333 according to the FT-IR spectrum. The molecular weight (Mw) was estimated to be 332 kDa. Current study suggested that the lactic bacteria strain AR333 could be a potential source of immunoregulatory polysaccharide.

Petit suisse from black soybean: bioactive compounds and antioxidant properties during development process.

This study aimed to evaluate the antioxidant properties, bioactive compounds and other physico-chemical parameters from black soybean and its derivatives over 30 days under refrigeration at 4 °C and develop a probiotic petit suisse produced from black soybean. The soymilk showed the highest levels of isoflavones (109 mg/100 g), total phenolics (600 mg/100 g) and total anthocyanins (388 mg/100 g) with the highest response in the tests with DPPH• and ABTS+• on a dry basis. There was a significant increase (p ≤ 0.05) in antioxidant activity during storage due to the hydrolysis of isoflavone glycosides to aglycones in soymilk sample, having a strong linear correlation between the concentration of isoflavone aglycones and the antioxidant activity for ABTS+• (R = 0.9437, 0.9624 and 0.9992) and DPPH• (R = 0.9865, 0.9978 and 0.9911), respectively, for soymilk, quark and petit suisse. The conversion of isoflavone was influenced directly by the characteristics of each sample, inhibiting or promoting the action of the enzyme. The petit suisse developed is an alternative for consumers, providing isoflavones and anthocyanins, possessing probiotic average counts (108 CFU g⁻¹) during storage.

Growth and exopolysaccharide production by Streptococcus thermophilus ST1 in skim milk

To analyze the exopolysaccharide (EPS) production by Streptococcus thermophilus ST1, cultures were cultivated in 10 percent (w/v) reconstituted skim milk under different growth conditions including various temperatures and pHs of growth medium, supplementation of the medium with various carbon sources (glucose, lactose, sucrose, galactose and fructose) and nitrogen source (whey protein concentrate, or WPC). The results showed that most EPS production by strain ST1 was obtained at a temperature (42°C) and pH (6.5) optimal for its growth. Supplementation of the skim milk medium with either carbohydrates or WPC increased both growth and polymer formation by different extents, with sucrose being most effective among the carbon sources tested. Under the optimal cultural conditions, i.e. pH 6.5, 42°C with 2 percent (w/v) sucrose and 0.5 percent (w/v) WPC, 135.80 mg l-1 of EPS was produced by strain ST1. The monosaccharide composition of the EPS was determined to be glucose and galactose (2:1), and the molecular mass of the EPS was 3.97 × 10(6) Da. The aqueous solution of the EPS at 1 percent (w/v) showed relatively high viscosity, indicating the potential of this EPS-producing S. thermophilus strain for applications in the improvement of physical properties of fermented milk products.

Effect of freeze drying process on some properties of Streptococcus thermophilus isolated from dairy products

The present investigation represents the effect of freeze drying on some properties as acid and bile tolerance of Streptococcus thermophilus MTCC 1938 culture isolated from dairy products. The cell paste obtained from milk based medium was freeze dried with a pressure of 50-100 mtorr for 24h at -40ºC. Acid and bile tolerance test exhibited 3.8-4.9 and 3.2-3.8 log counts reduction after freeze drying respectively.

FTIR-based polyphasic identification of lactic acid bacteria isolated from traditional Greek Graviera cheese.

This study used a combination of phenotypic, physical (Fourier Transformed Infra-Red [FTIR] spectroscopy) and molecular (RFLP and SSCP analysis of 16S rRNA genes) methods to identify the lactic acid bacteria (LAB) flora present in traditional Greek Graviera cheese after five weeks of ripening. A total of 300 isolates collected from high dilution plates of TSAYE (incubated at 30 °C), M-17 (22 °C) and M-17 (42 °C) agar media were clustered by FTIR and then representative strains of each cluster were cross-identified blindly by all methods. Based on their FTIR spectra, 282 isolates were LAB grouped in 28 clusters. The LAB species identified and their prevalence in the cheese samples were: Lactobacillus casei/paracasei (68.8%), Lactobacillus plantarum (19.5%), Streptococcus thermophilus (8.9%), Enterococcus faecium (2.1%), and Lactococcus lactis (0.7%). Also, Staphylococcus equorum (11 isolates), Corynebacterium sp. (5 isolates) and Brevibacterium sp. (1 isolate) were recovered from TSAYE. Comparative identification results showed that phenotypic and molecular methods were in mutual agreement as regards the LAB species identified. The present polyphasic identification approach based on rapid FTIR screening of 10-fold more isolates than a previous classical identification approach allowed or improved detection of few sub-dominant species; however the predominant LAB species in the cheese samples were the same with both approaches.