Cpe And Gi Disease Disease Summary

CPE-positive strains cause C. perfringens type A food poisoning, which currently ranks as the third most common cause of food poisoning in the United States.[12] In addition, enterotoxin-producing C. perfringens is an important etiological agent of non-food-borne human GI illnesses such as antibiotic-associated diarrhea (AAD) and sporadic diarrhea (SD).[13] The symptoms of CPE-related illnesses range from acute diarrhea and abdominal

Fig. 2 Duplex PCR genotyping assay for distinguishing between C. perfringens type A isolates carrying a plasmid-borne cpe gene vs. a chromosomal cpe gene. This assay exploits organizational differences between different cpe loci to amplify either a PCR product of ~ 3.3 kb (dcm-cpe) from plasmid cpe type A isolates (A), or an ~ 2.1-kb PCR product (cpe-IS1470) from chromosomal cpe type A isolates (B). (C) Representative duplex PCR results obtained using purified genomic DNA as template from five chromosomal and five plasmid type A cpe isolates. Primers and PCR conditions were from Ref. [15]. Arrows to the right of gel depict the expected ~3.3- and ~ 2.1-kb products from plasmid and chromosomal cpe type A isolates, respectively. (From Ref. [15].)

Fig. 2 Duplex PCR genotyping assay for distinguishing between C. perfringens type A isolates carrying a plasmid-borne cpe gene vs. a chromosomal cpe gene. This assay exploits organizational differences between different cpe loci to amplify either a PCR product of ~ 3.3 kb (dcm-cpe) from plasmid cpe type A isolates (A), or an ~ 2.1-kb PCR product (cpe-IS1470) from chromosomal cpe type A isolates (B). (C) Representative duplex PCR results obtained using purified genomic DNA as template from five chromosomal and five plasmid type A cpe isolates. Primers and PCR conditions were from Ref. [15]. Arrows to the right of gel depict the expected ~3.3- and ~ 2.1-kb products from plasmid and chromosomal cpe type A isolates, respectively. (From Ref. [15].)

cramping (C. perfringens type A food poisoning) to more severe and chronic diarrhea (AAD and SD).

Diagnosis

CPE-associated (GI) disease is now typically diagnosed by identifying the enterotoxin directly in fecal samples. CPE enzyme-linked immunosorbent assay (ELISA) and reverse passive latex agglutination (RPLA) tests are available commercially for detecting CPE present in feces, although the RPLA test has a significant false positive rate and the CPE ELISA is not yet licensed for diagnostic use in the United States.

Genetic characterization of C. perfringens food-borne and non-food-borne illness isolates has been performed by several groups (e.g., Ref. [14]) using genomic techniques such as ribotyping, restriction fragment length polymorphism (RFLP), and pulsed-field gel electrophoresis

(PFGE). These techniques are useful in assessing the clonality of various outbreak and disease isolates. However, because C. perfringens is also present in the normal intestinal flora, detection of the cpe gene in disease isolates is crucial for identifying C. perfringens as the etiological source of GI disease. Multiplex PCR typing of C. perfringens[11] can be performed to confirm the presence of cpe in disease isolates (Fig. 1, lanes A and A/cpe).

As mentioned, the cpe gene can be located on either the chromosome or a large plasmid. CPE-positive C. perfringens isolates from cases of C. perfringens type A food poisoning typically carry their cpe gene on the chromosome, whereas cpe is usually plasmid-borne in AAD/SD C. perfringens isolates.[7] These correlations are useful for molecular diagnostic and epidemiological studies of CPE-based disease (e.g., if a CPE-positive C. perfringens disease isolate is shown to carry a chromosomal cpe gene, that finding supports identification of a food poisoning case). Alternatively, identifying a plasmid enterotoxin gene in a disease isolate would usually support a diagnosis of AAD/SD.

A recent study by Miyamoto et al.[9] compared the genetic loci of chromosomal vs. plasmid cpe-containing type A isolates. This study identified distinct differences in the sequences flanking the cpe gene between the two cpe genotypes (Fig. 2A and B). An assay recently put forth by Wen et al. exploits these sequence differences by amplifying different size products from each cpe genotype (Fig. 2). This genotyping assay can be performed with either isolated DNA or colony lysates as template DNA,[15] with the use of the latter template eliminating at least 2 days from the preparation and isolation of DNA.

This duplex PCR reaction is an ideal presumptive assay for helping to distinguish between food-borne and nonfood-borne cases of CPE-associated GI illness. Because the assay provides results within 6 hr of isolating C. perfringens colonies from contaminated food or feces, the speed and high-throughput nature of the technique provide a distinct advantage over the classical and more cumbersome techniques of RFLP and PFGE. Limitations of the PCR method include a requirement for a special poly-merase (Advantage2® Polymerase Mix; BD Biosciences Clontech, Palo Alta, CA), which is expensive and displays some lot-to-lot efficiency variation (unpublished results). Despite these shortcomings, the cpe duplex PCR assay is an extremely useful and time-saving assay for determining the etiological genotype of CPE-positive C. perfringens GI disease isolates and should prove useful for clinical laboratories investigating CPE-associated disease.

Management

C. perfringens type A food poisoning is typically self-limiting (the diarrhea removes the enterotoxin from the GI tract), so only the replenishment of fluids and electrolytes is required for treatment. Patients suffering from AAD or

SD are also given symptomatic treatment to restore their fluid/electrolyte balance, but antibiotics such as metroni-dazole can be prescribed for serious cases.

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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