Detection of enterotoxigenic Bacteroides fragilis by PCR. 1997

A Pantosti, and M Malpeli, and M Wilks, and M G Menozzi, and F D'Ambrosio
Laboratory of Bacteriology and Medical Mycology, Istituto Superiore di Sanità, Rome, Italy. pantosti@net.iss.it

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.

UI MeSH Term Description Entries
D003967 Diarrhea An increased liquidity or decreased consistency of FECES, such as running stool. Fecal consistency is related to the ratio of water-holding capacity of insoluble solids to total water, rather than the amount of water present. Diarrhea is not hyperdefecation or increased fecal weight. Diarrheas
D004768 Enterotoxins Substances that are toxic to the intestinal tract causing vomiting, diarrhea, etc.; most common enterotoxins are produced by bacteria. Staphylococcal Enterotoxin,Enterotoxin,Staphylococcal Enterotoxins,Enterotoxin, Staphylococcal,Enterotoxins, Staphylococcal
D005243 Feces Excrement from the INTESTINES, containing unabsorbed solids, waste products, secretions, and BACTERIA of the DIGESTIVE SYSTEM.
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D001427 Bacterial Toxins Toxic substances formed in or elaborated by bacteria; they are usually proteins with high molecular weight and antigenicity; some are used as antibiotics and some to skin test for the presence of or susceptibility to certain diseases. Bacterial Toxin,Toxins, Bacterial,Toxin, Bacterial
D001441 Bacteroides fragilis Gram-negative bacteria occurring in the lower intestinal tracts of man and other animals. It is the most common species of anaerobic bacteria isolated from human soft tissue infections.
D001442 Bacteroides Infections Infections with bacteria of the genus BACTEROIDES. Infections, Bacteroides,Bacteroides Infection,Infection, Bacteroides
D015169 Colony Count, Microbial Enumeration by direct count of viable, isolated bacterial, archaeal, or fungal CELLS or SPORES capable of growth on solid CULTURE MEDIA. The method is used routinely by environmental microbiologists for quantifying organisms in AIR; FOOD; and WATER; by clinicians for measuring patients' microbial load; and in antimicrobial drug testing. Agar Dilution Count,Colony-Forming Units Assay, Microbial,Fungal Count,Pour Plate Count,Spore Count,Spread Plate Count,Streak Plate Count,Colony Forming Units Assay, Microbial,Colony Forming Units Assays, Microbial,Agar Dilution Counts,Colony Counts, Microbial,Count, Agar Dilution,Count, Fungal,Count, Microbial Colony,Count, Pour Plate,Count, Spore,Count, Spread Plate,Count, Streak Plate,Counts, Agar Dilution,Counts, Fungal,Counts, Microbial Colony,Counts, Pour Plate,Counts, Spore,Counts, Spread Plate,Counts, Streak Plate,Dilution Count, Agar,Dilution Counts, Agar,Fungal Counts,Microbial Colony Count,Microbial Colony Counts,Pour Plate Counts,Spore Counts,Spread Plate Counts,Streak Plate Counts
D015373 Bacterial Typing Techniques Procedures for identifying types and strains of bacteria. The most frequently employed typing systems are BACTERIOPHAGE TYPING and SEROTYPING as well as bacteriocin typing and biotyping. Bacteriocin Typing,Biotyping, Bacterial,Typing, Bacterial,Bacterial Biotyping,Bacterial Typing,Bacterial Typing Technic,Bacterial Typing Technics,Bacterial Typing Technique,Technic, Bacterial Typing,Technics, Bacterial Typing,Technique, Bacterial Typing,Techniques, Bacterial Typing,Typing Technic, Bacterial,Typing Technics, Bacterial,Typing Technique, Bacterial,Typing Techniques, Bacterial,Typing, Bacteriocin
D016133 Polymerase Chain Reaction In vitro method for producing large amounts of specific DNA or RNA fragments of defined length and sequence from small amounts of short oligonucleotide flanking sequences (primers). The essential steps include thermal denaturation of the double-stranded target molecules, annealing of the primers to their complementary sequences, and extension of the annealed primers by enzymatic synthesis with DNA polymerase. The reaction is efficient, specific, and extremely sensitive. Uses for the reaction include disease diagnosis, detection of difficult-to-isolate pathogens, mutation analysis, genetic testing, DNA sequencing, and analyzing evolutionary relationships. Anchored PCR,Inverse PCR,Nested PCR,PCR,Anchored Polymerase Chain Reaction,Inverse Polymerase Chain Reaction,Nested Polymerase Chain Reaction,PCR, Anchored,PCR, Inverse,PCR, Nested,Polymerase Chain Reactions,Reaction, Polymerase Chain,Reactions, Polymerase Chain

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