Biomaterial Database

Identification of foodborne pathogens by nucleic acid hybridization. 1991

W E Hill, and S P Keasler

Molecular Biology Branch, Food and Drug Administration, Washington, DC 20204.

Nucleic acid hybridization methods have been developed and used to identify microorganisms in foods. Tests performed on mixed cultures save the time required to establish pure cultures. Enterotoxigenic or invasive strains of foodborne bacterial pathogens are detected with probes that identify genes responsible for virulence. Hybridization tests signal the presence or absence of a particular strain or an entire genus and are especially well suited for screening foods for specific pathogens. With the colony hybridization assay format, foodborne bacteria harboring a specific gene can be enumerated. However, hybridization tests require the presence of 10(5) to 10(6) cells to yield a positive result, thereby limiting sensitivity and necessitating a time-consuming growth step. In vitro DNA amplification techniques increase the amount of DNA segments 10(5)-10(6)-fold in 2 to 3 h, thus enhancing test sensitivity.

UI	MeSH Term	Description	Entries
D009693	Nucleic Acid Hybridization	Widely used technique which exploits the ability of complementary sequences in single-stranded DNAs or RNAs to pair with each other to form a double helix. Hybridization can take place between two complimentary DNA sequences, between a single-stranded DNA and a complementary RNA, or between two RNA sequences. The technique is used to detect and isolate specific sequences, measure homology, or define other characteristics of one or both strands. (Kendrew, Encyclopedia of Molecular Biology, 1994, p503)	Genomic Hybridization,Acid Hybridization, Nucleic,Acid Hybridizations, Nucleic,Genomic Hybridizations,Hybridization, Genomic,Hybridization, Nucleic Acid,Hybridizations, Genomic,Hybridizations, Nucleic Acid,Nucleic Acid Hybridizations
D005516	Food Microbiology	The presence of bacteria, viruses, and fungi in food and food products. This term is not restricted to pathogenic organisms: the presence of various non-pathogenic bacteria and fungi in cheeses and wines, for example, is included in this concept.	Microbiology, Food
D001419	Bacteria	One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophy (via chemical reaction) or PHOTOTROPHY (via light reaction); for chemotrophs by their source of chemical energy: CHEMOLITHOTROPHY (from inorganic compounds) or chemoorganotrophy (from organic compounds); and by their source for CARBON; NITROGEN; etc.; HETEROTROPHY (from organic sources) or AUTOTROPHY (from CARBON DIOXIDE). They can also be classified by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive.	Eubacteria
D001424	Bacterial Infections	Infections by bacteria, general or unspecified.	Bacterial Disease,Bacterial Infection,Infection, Bacterial,Infections, Bacterial,Bacterial Diseases
D014774	Virulence	The degree of pathogenicity within a group or species of microorganisms or viruses as indicated by case fatality rates and/or the ability of the organism to invade the tissues of the host. The pathogenic capacity of an organism is determined by its VIRULENCE FACTORS.	Pathogenicity
D014780	Viruses	Minute infectious agents whose genomes are composed of DNA or RNA, but not both. They are characterized by a lack of independent metabolism and the inability to replicate outside living host cells.	Animal Viruses,Zoophaginae,Animal Virus,Virus,Virus, Animal,Viruses, Animal
D015342	DNA Probes	Species- or subspecies-specific DNA (including COMPLEMENTARY DNA; conserved genes, whole chromosomes, or whole genomes) used in hybridization studies in order to identify microorganisms, to measure DNA-DNA homologies, to group subspecies, etc. The DNA probe hybridizes with a specific mRNA, if present. Conventional techniques used for testing for the hybridization product include dot blot assays, Southern blot assays, and DNA:RNA hybrid-specific antibody tests. Conventional labels for the DNA probe include the radioisotope labels 32P and 125I and the chemical label biotin. The use of DNA probes provides a specific, sensitive, rapid, and inexpensive replacement for cell culture techniques for diagnosing infections.	Chromosomal Probes,DNA Hybridization Probe,DNA Probe,Gene Probes, DNA,Conserved Gene Probes,DNA Hybridization Probes,Whole Chromosomal Probes,Whole Genomic DNA Probes,Chromosomal Probes, Whole,DNA Gene Probes,Gene Probes, Conserved,Hybridization Probe, DNA,Hybridization Probes, DNA,Probe, DNA,Probe, DNA Hybridization,Probes, Chromosomal,Probes, Conserved Gene,Probes, DNA,Probes, DNA Gene,Probes, DNA Hybridization,Probes, Whole Chromosomal
D015347	RNA Probes	RNA, usually prepared by transcription from cloned DNA, which complements a specific mRNA or DNA and is generally used for studies of virus genes, distribution of specific RNA in tissues and cells, integration of viral DNA into genomes, transcription, etc. Whereas DNA PROBES are preferred for use at a more macroscopic level for detection of the presence of DNA/RNA from specific species or subspecies, RNA probes are preferred for genetic studies. Conventional labels for the RNA probe include radioisotope labels 32P and 125I and the chemical label biotin. RNA probes may be further divided by category into plus-sense RNA probes, minus-sense RNA probes, and antisense RNA probes.	Gene Probes, RNA,RNA Probe,Probe, RNA,Probes, RNA,Probes, RNA Gene,RNA Gene Probes
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