The relative efficacy of different strain combinations of lactic acid bacteria in the reduction of populations of Salmonella enterica Typhimurium in the livers and spleens of mice

Multispecies probiotics have been reported to be more effective than monostrain probiotics in health promoting for the host. In this study, 12 lactic acid bacteria (LAB) strains were selected based on the level of induction of tumor necrosis factor (TNF)-alpha in RAW 264.7 macrophage cells. Their adherence to Caco-2 cells and inhibitory effects on Salmonella invasion of Caco-2 cells were compared. Strains with different probiotic properties were then combined and BALB/c mice were fed with LAB strains for 63 days; then the mice were challenged with Salmonella on day 64. For Salmonella-unchallenged mice that received a multistrain combination of LAB strains that have greater TNF-alpha production in macrophages, greater adherence and inhibit Salmonella invasion of Caco-2 cells to a greater extent, their peritoneal macrophages had greater phagocytic activity. For Salmonella-challenged mice, a significant reduction of Salmonella cells in the livers and spleens of the mice was observed 8 days post challenge. The addition of 12% skim milk powder together with LAB strain combinations significantly enhanced the reduction of Salmonella cells in the mice livers and spleens. In conclusion, we have shown that LAB strain combinations with particular probiotic properties when fed to mice can inhibit Salmonella invasion of the liver and spleen

Antagonistic activity against Helicobacter pylori infection in vitro by a strain of Enterococcus faecium TM39

Lactic acid bacteria (LAB) strains from infant feces were screened for anti-Helicobacter pylori use. In the beginning, we selected the strains based on their capability to adhere to the human intestinal epithelial cell (Int-407), colonial enterocyte-like Caco-2 cell, human cervical epithelioid carcinoma cell (HeLa), and human gastric carcinoma cell (TSGH 9201). Then, acid and bile salt tolerance of these LAB strains was evaluated. In addition, the ability of these LAB strains to inhibit the growth of H. pylori and to expel H. pylori cells from TSGH 9201 were studied. The spent culture supernatant (SCS) of a selected strain TM39, i.e., TM39-SCS, significantly inhibited the viability of H. pylori in vitro. It also inhibited the urease activity of H. pylori in vitro. For these antagonistic effects, in addition to pH and lactic acid, some factors in TM39-SCS might play the major role. Treatment of H. pylori with the SCS or cells of strain TM39 significant reduced its binding to TSGH 9201 cells. Although strain TM39 is identified as Enterococcus faecium, it is not vancomycin resistant and is proved to be safe through the invasion study and a 28-day feeding study with Wistar rats. (C) 2004 Published by Elsevier B.V

Use of a multiplex PCR system for the simultaneous detection of heat labile toxin I and heat stable toxin II Escherichia coli cells in environmental waters near Taichung City

The enterotoxins produced by enterotoxigenic Escherichia coli (ETEC) cells include heat labile (LT) and heat stable toxins (ST), These toxins cause diarrheal in humans and domestic animals. In this study, we combined LT I and ST II gene specific PCR primers into a multiplex PCR system and used this system for the simultaneous detection of LT I and ST II ETEC cells in tap water and environmental waters. Using Chromocult coliform agar (CCA), we found that tap water and underground water were contaminated with 0-10(0) CFU / ml of E. coli and coliform cells while the waters from four rivers near Taichung City were contaminated with 10(2)-10(4) CFU / ml of E. coli and coliform cells. Furthermore, three of the four river waters were contaminated with LT I / ST II and ST II ETEC cells. The high levels of microfloral contamination in these river waters near an urban area should be attended to urgently

Screening the enteroaggregative Escherichia coli activity and detection of the aggA, aafA, and astA genes with novel PCR primers for the Escherichia coli isolates from diarrhea cases in Taiwan

Enteroaggregative Escherichia coli (EAggEC) are emerging enteropathogens associated with human diarrhea diseases and food poisoning cases. They show distinctive aggregative pattern of adherence to cultured human epithelial cells. However, EAggEC strains are diverse and not all of them have the aggregative adherence fimbria I (AAF/1), AAF/II and heat-stable enterotoxin 1 (EAST1) genes. We attemptd to determine the incidence of EAggEC in E. coli isolates from diarrhea patients in Taiwan and to characterize these EAggEC strains. We used three activity assays including HeLa, cell adhesion, human blood hemagglutination and bacterial clumping tests and polymerase chain reaction (PCR) primers designed from an aggregative adherence pattern associated plasmid (pCVD432) to screen the EAggEC strains in 403 E. coli isolates including 63 laboratory isolates and 340 clinical isolates obtained from diarrheal disease cases. All these 403 E. coli strains were also assayed with novel PCR primers designed from AAF/I (aggA), AAF/II (aafA) and EAST I (astA) genes. Results showed that except for the three EAggEC reference strains, only three clinical isolates were identified as EAggEC strains. Including the reference strains, all the E. coli strains with EAggEC activity generated positive PCR results to the aggA gene based primers, but not to the aafA and astA gene targeted primers. (C) 2003 Elsevier Inc. All rights reserved

Use of polymerase chain reaction, cell adhesion, hemagglutination and bacterial clump formation tests in detection of enteroaggregative Escherichia coli strains

Enteroaggregative Escherichia coli (EAggEC) is one of the pathogenic E. coli strains which may cause diarrhoea. In vitro studies have shown that EAggEC strains could establish a "stacked-brick" like adherence pattern on the surface of tissue culture cells and such a pattern is termed as aggregative adherence (AA). The purpose of this study is to compare the methods of polymerase chain reaction (PCR). HeLa cell adhesion. hemagglutination. and bacteria clumping tests for the specific detection of EAggEC suspected strains. This study isolated 340 E. coli strains from clinical samples of diarrhea cases which were firstly screened with the PCR method for the presence of suspected EaggEC strains. Strains of negative PCR results were also confirmed with HeLa cell adhesion and bacteria clumping tests for the EAggEC activity. Results showed that of these 340 clinical isolates, only three are EAggEC strains. Thus, EAggEC strains accounted for 0.88% in total strains. Also, for the above described methods, the in vitro HeLa cells adhesion test gave the dearest results followed by the bacteria clumping test. The hemagglutination tests might generate ambiguous results