Biomaterial Database

Detection of heat injury in Listeria monocytogenes Scott A. 2001

J S Novak, and V K Juneja

US Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, Wyndmoor, Pennsylvania 19038, USA. jnovak@arserrc.gov

Methods of detecting live pathogens in foods that may be growth inhibited following heat treatment are essential to food safety. Among the techniques available, reverse transcription polymerase chain reaction (RT-PCR) amplification of messenger RNA from heat-injured Listeria monocytogenes Scott A is preferable to direct PCR in an attempt to avoid false positives from dead cells. The RT-PCR has a detection limit of 3 x 10(6) CFU/g, compared to 3 CFU/g for untreated controls, but may not be suitable for the identification of all viable cells. Physically apparent changes in cellular structures from heat injury in L. monocytogenes are expected to result. Ultrastructural analyses did depict notable heat damage as cytoplasmic clearing after 5 min at 60 degrees C. The heat-injured survivors can be readily distinguished from total viable cells using selective media. As a result, combinations of molecular and visual methods including selective media improve detectability of heat-injured, viable L. monocytogenes Scott A.

UI	MeSH Term	Description	Entries
D008089	Listeria monocytogenes	A species of gram-positive, rod-shaped bacteria widely distributed in nature. It has been isolated from sewage, soil, silage, and from feces of healthy animals and man. Infection with this bacterium leads to encephalitis, meningitis, endocarditis, and abortion.
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D003470	Culture Media	Any liquid or solid preparation made specifically for the growth, storage, or transport of microorganisms or other types of cells. The variety of media that exist allow for the culturing of specific microorganisms and cell types, such as differential media, selective media, test media, and defined media. Solid media consist of liquid media that have been solidified with an agent such as AGAR or GELATIN.	Media, Culture
D005189	False Positive Reactions	Positive test results in subjects who do not possess the attribute for which the test is conducted. The labeling of healthy persons as diseased when screening in the detection of disease. (Last, A Dictionary of Epidemiology, 2d ed)	False Positive Reaction,Positive Reaction, False,Positive Reactions, False,Reaction, False Positive,Reactions, False Positive
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
D006358	Hot Temperature	Presence of warmth or heat or a temperature notably higher than an accustomed norm.	Heat,Hot Temperatures,Temperature, Hot,Temperatures, Hot
D012333	RNA, Messenger	RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.	Messenger RNA,Messenger RNA, Polyadenylated,Poly(A) Tail,Poly(A)+ RNA,Poly(A)+ mRNA,RNA, Messenger, Polyadenylated,RNA, Polyadenylated,mRNA,mRNA, Non-Polyadenylated,mRNA, Polyadenylated,Non-Polyadenylated mRNA,Poly(A) RNA,Polyadenylated mRNA,Non Polyadenylated mRNA,Polyadenylated Messenger RNA,Polyadenylated RNA,RNA, Polyadenylated Messenger,mRNA, Non Polyadenylated
D012680	Sensitivity and Specificity	Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Specificity is the probability of correctly determining the absence of a condition. (From Last, Dictionary of Epidemiology, 2d ed)	Specificity,Sensitivity,Specificity and Sensitivity
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
D020133	Reverse Transcriptase Polymerase Chain Reaction	A variation of the PCR technique in which cDNA is made from RNA via reverse transcription. The resultant cDNA is then amplified using standard PCR protocols.	Polymerase Chain Reaction, Reverse Transcriptase,Reverse Transcriptase PCR,PCR, Reverse Transcriptase,Transcriptase PCR, Reverse