SUMMARYBacteroides fragilis toxin (BFT) has been shown to be capable of inducing intestinal mucosal inflammation in animals. Such inflammation may be responsible for diarrhoea, which occurs in some, but not all human carriers of enterotoxigenic strains of B. fragilis (ETBF). We have studied responses to BFT by different human intestinal epithelial cell lines and subsequently investigated the expression of IL-8 and TGF-b by T84 cells. The latter were selected because their responses to BFT, characterized by morphological changes and cell death by apoptosis, were similar to those we have recently observed in primary human colonocytes. We show that BFT dose-dependently increased the expression of transcripts and protein of the polymorphonuclear cell chemoattractant IL-8. BFT also dose-dependently induced the release of TGF-b , which has been shown to enhance the repair of the injured intestinal epithelium. However, the secreted TGF-b was almost exclusively in the biologically inactive form, as determined by Mv1Lu bioassay. Our studies therefore suggest that exposure of colonic epithelial cells in vivo to high concentrations of BFT can initiate an inflammatory response via secreted IL-8. BFT-induced release of latent TGF-b may facilitate the subsequent repair of the injured epithelium, following its activation by proteases from neighbouring cells. Variation in cytokine responses by colonic epithelial cells in vivo could be an important determinant in the development of mucosal disease and symptoms in response to ETBF.

Stool samples from children and adults with and without diarrhea were examined for the presence of enterotoxigenic Bacteroides fragilis (ETBF) and its enterotoxin. A cytotoxic assay with HT-29 cells followed by neutralization with a hyperimmune antiserum were used to detect B. fragilis enterotoxin. ETBF isolates were recovered from 12% of healthy children and 17% of children with diarrhea (P = .42) and from 15% of healthy adults and 9.4% of adults with diarrhea (P = .31). Fecal B. fragilis enterotoxin was detected in four children (two with diarrhea and two without diarrhea) and in four adults with diarrhea. This study shows that in Italy, the rate of ETBF carriage is high, regardless if diarrhea is present. In some instances, the presence of ETBF is associated with detectable levels of fecal enterotoxin, but the significance of this finding deserves further evaluation.

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The performance of the BD Phoenix Automated Microbiology System (BD Diagnostic Systems, Sparks, Md.) was assessed for identification (ID) and antimicrobial susceptibility testing (AST) for the majority of clinically encountered bacterial isolates in a European collaborative two-center trial. A total of 469 bacterial isolates of the genera Staphylococcus (275 isolates), Enterococcus (179 isolates), and Streptococcus (15 isolates, for ID only) were investigated; of these, 367 were single patient isolates, and 102 were challenge strains tested at one center. Sixty-four antimicrobial drugs were tested, including the following drug classes: aminoglycosides, beta-lactam antibiotics, beta-lactam-beta-lactamase inhibitors, carbapenems, cephems, folate antagonists, quinolones, glycopeptides, macrolides-lincosamides-streptogramin B (MLS), and others. Phoenix ID results were compared to those of the laboratories' routine ID systems (API 32 Staph, API 32 Strep, and VITEK 2 [bioMérieux, Marcy l'Etoile, France]); Phoenix AST results were compared to those of frozen standard broth microdilution (SBM) panels according to NCCLS guidelines (NCCLS document M 100-S 9, approved standard M 7-A 4). Discrepant results were repeated in duplicate. Concordant IDs of 97.1, 98.9, and 100% were observed for staphylococci, enterococci, and streptococci, respectively. For AST results the overall essential agreement was 93.3%; the category agreement was 97.3%; and the very major error rate, major error rate, and minor error rate were 1.2, 1.9, and 1.3%, respectively. In conclusion, the Phoenix ID results showed high agreement with results of the systems to which they were being compared; the AST performance was highly equivalent to that of the SBM reference method.The clinical microbiology laboratory is confronted with an alarming increase of antimicrobial resistance on a global scale (7,8,9,13). Furthermore, the emergence of bacterial isolates with special resistance mechanisms such as oxacillin-resistant staphylococci or vancomycin-resistant enterococci constitutes a major problem, especially in intensive care units (1, 4). Both accurate and rapid diagnosis of oxacillin-resistant staphylococci and vancomycin-resistant enterococci has therefore become essential in the current health care environment.The BD Phoenix Automated Microbiology System (BD Diagnostic Systems, Sparks, Md.[BD]) is a newly developed instrument for the reliable and accurate identification and susceptibility testing for the majority of clinically encountered strains. The system is comprised of disposable panels, which combine both identification testing (ID) and antimicrobial susceptibility testing (AST), and an instrument which performs automatic reading at 20-min intervals during incubation. The system claims to provide accurate and rapid susceptibility results with easy workflow for the laboratory worker.We report on the ability of the Phoenix system to accurately perform ID and AST of clinical and challenge isolates in a large collaborative two-center trial involving th...

Strains of enterotoxigenic Bacteroides fragilis (ETBF) are associated with diarrhea in young farm animals and, at least in particular settings, in children. Enterotoxin production by ETBF is currently detected by a tissue culture assay with HT-29 cells. We have developed a PCR assay based on the detection of the enterotoxin gene to identify ETBF in culture and in stool samples. Overall, 113 bacterial strains were examined, including 3 B. fragilis reference strains, 75 B. fragilis isolates (comprising 40 ETBF isolates), 20 Bacteroides spp. other than B. fragilis, and 15 strains belonging to other genera. Complete agreement was found between the results of the tissue culture assay and those of the PCR for our strains. PCR was also used to detect ETBF directly in fecal samples. Stools from two healthy volunteers were spiked with known numbers of ETBF and were processed by three different methods. A culture method, which required inoculation of the stools on selective plates and the collection of the whole bacterial growth ("sweeps"), was found to be the most sensitive. PCR performed with the plate sweeps yielded amplification products with a detection limit of 10 5 to 10 4 CFU/g of feces. By this method 18 samples of diarrheic stools (10 positive and 8 negative for ETBF) were examined. The results of the PCR were in accordance with the culture results in all cases. The proposed PCR assay represents a diagnostic tool for the rapid identification of ETBF in culture as well as in fecal samples.