Evaluation of the campyslide agglutination test for confirmatory identification of selected Campylobacter species

Development of an indirect competitive ELISA for detection of Campylobacter jejuni subsp.jejuni O:23 in foods

An indirect enzyme immunoassay for rapid detection of Campylobacter jejuni subsp. jejuni 0:23 has been developed. Optimum concentrations of immobilized cells, polyclonal chicken IgY, and rabbit anti-IgY antibody-horseradish peroxidase conjugate were 3.1 CFU/nL, 10 microg/mL, and 8 microg/mL, respectively. Under such conditions, the detection limit reached 50 CFU/microL, limit of quantification being 480 CFU/microL. By testing 5 chromogens, viz. 1,2-benzenediamine, 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid), 3,3',5,5'-tetramethylbenzidine, bi(4,4'-anisidine) and 3-methyl-2-benzothiazolinone hydrazone, in horseradish peroxidase substrate, 1,2-benzenediamine or 3,3',5,5'-tetramethylbenzidine as H-donors in the enzyme substrate provided the highest ELISA sensitivity. The applied polyclonal antibody was specific for homogeneous antigen. The cross-reactions were observed only with one strain of C. sputorum subsp. sputorum (21.5 %) and with G+ bacterium Micrococcus luteus (6.1 %). Preliminary tests have been performed with a limited number of artificially contaminated food samples. No matrix effects on the ELISA sensitivity were observed. The results (by means of ELISA) were comparable with those given by both a standard cultivation method performed according to CSN ISO 10272 and commercially available Singlepath Campylobacter GLISA-Rapid Test.

Direct analysis and identification of Helicobacter and Campylobacter species by MALDI-TOF mass spectrometry

Campylobacter jejuni, Campylobacter fetus, and Campylobacter coli were compared with Helicobacter pylori and Helicobacter mustelae by direct analysis of individual cultured colonies in 50% methanol-water with a matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (MALDI-TOF MS). H. pylori and Campylobacter species from blood agar culture produced unique, complex spectra with over 25 different ions in mass/charge (m/z) range from 2,000 to 62,000. A biomarker for H. pylori was centered around m/z 58,268, and H. mustelae was distinguished from H. pylori by its ions at m/z 49,608 and 57,231. Campylobacters could be distinguished from Helicobacters by their lack of ions around m/z 58,000 and 61,000 as well as distinguishing biomarkers of lower m/z: 10,074 and 25,478 for C. coli; m/z 10,285 and 12,901 for C. jejuni; m/z 10,726 and 11,289 for C. fetus. MALDI-TOF MS is a rapid and direct method for detection of these potentially pathogenic bacteria from culture.

Identification methods for campylobacters, helicobacters, and related organisms

The organisms which are referred to as campylobacteria are associated with a diverse range of diseases and habitats and are important from both clinical and economic perspectives. Accurate identification of these organisms is desirable for deciding upon appropriate therapeutic measures, and also for furthering our understanding of their pathology and epidemiology. However, the identification process is made difficult because of the complex and rapidly evolving taxonomy, fastidious nature, and biochemical inertness of these bacteria. These problems have resulted in a proliferation of phenotypic and genotypic methods for identifying members of this group. The purpose of this review is to summarize the problems associated with identifying campylobacteria, critically appraise the methods that have been used for this purpose, and discuss prospects for improvements in this field.

Clostridium perfringens type A enterotoxin (CPE): more than just explosive diarrhea

The bacterial pathogen Clostridium perfringens is the most prolific toxin-producing species within the clostridial group. The toxins are responsible for a wide variety of human and veterinary diseases, many of which are lethal. C. perfringens type A strains are also associated with one of the most common forms of food-borne illness (FBI). The toxicosis results from the production and gastrointestinal absorption of a protein-enterotoxin known as CPE. The regulation, expression, and mechanism of action of CPE has been of considerable interest as the protein is unique. CPE expression is sporulation associated, although the mechanism of cpe-gene regulation is not fully elucidated. Cloning studies suggest the involvement of global regulators, but these have not been identified. Although very few type A strains are naturally enterotoxigenic, the cpe gene appears highly conserved. In FBI strains, cpe is chromosomally encoded; whereas in veterinary strains, cpe may be plasmid-encoded. Variation in cpe location suggests the involvement of transposable genetic element(s). CPE-like proteins are produced by some C. perfringens types C and D; and silent remnants of the cpe gene can be found in C. perfringens type E strains associated with the iota toxin gene. CPE has received attention for its biomedical importance. The toxin has been implicated in sudden infant death syndrome (SIDS) because of its superantigenic nature. CPE can destroy a wide variety of cell types both in vitro and in vivo, suggesting that it could have potential in the construction of immunotoxins to neoplastic cells. It is obvious that CPE is an interesting protein that deserves continued attention.

Differentiation between thermophilic Campylobacter species by species-specific antibodies

The four species of thermophilic campylobacters, Campylobacter jejuni, C. coli, C. upsaliensis and C. lari, are difficult to distinguish from each other because of their lack of reactivity in many conventional biochemical and physiological tests. Those tests which do discriminate sometimes give discordant results. Species-specific antibody preparations (APs), capable of discriminating between the thermophilic campylobacter species by dot-ELISA, were raised by inoculation of mice with partially purified membrane protein. The APs produced were absorbed with cells of cross-reactive species and tested by dot-ELISA against reference and natural strains, the identities of which were confirmed by DNA/DNA hybridization. The results showed that such APs could be useful as an alternative to DNA/DNA hybridization for rapid species identification, for example in epidemiological surveys. Western blotting experiments with the APs showed that the specificity of the antibodies was not due to a single antigen.

DNA probe culture confirmation assay for identification of thermophilic Campylobacter species

We studied the ability of a new DNA probe-based assay system to correctly identify isolates of the thermophilic campylobacters Campylobacter jejuni, C. coli, and C. laridis grown in vitro. We examined 424 organisms, including 214 Campylobacter isolates and 210 other aerobic and anaerobic isolates. The probe assay, which uses a new homogeneous system in which all reactions take place within a single tube, demonstrated 100% accuracy, producing neither false-positive nor false-negative results. The assay does not, however, distinguish among C. jejuni, C. coli, and C. laridis.

Culture confirmation of Campylobacter spp. by latex agglutination

A commercial latex agglutination test [Meritec-Campy (jcl), Meridian Diagnostics, Cincinnati, Ohio] was evaluated for identification of Campylobacter jejuni, C. coli, C. laridis, and other Campylobacter isolates. The test had 100% sensitivity in detecting C. jejuni and C. coli but low sensitivity with C. laridis isolates. C. upsaliensis strains reacted with the test. The test had 100% specificity for 101 non-Campylobacter organisms.

Enzymatically labelled nucleic acid (NA) probe assays for detection of Campylobacter spp. in human faecal specimens and in culture

Seventy-two stock clinical isolates of C. jejuni were tested with the SNAP Culture Identification Test Kit (Molecular Biosystems, Inc., San Diego, CA), an enzyme labelled nucleic acid probe colony blot assay, and with the Campyslide (BBL Microbiology Systems, Cockeysville, MD), a latex agglutination test. The sensitivity and overall agreement of both the SNAP and Campyslide tests were 100% in comparison with standard culture and identification tests. In addition, 14 C. jejuni, two C. laridis, and one 'C. upsaliensis', and one C. hyointestinalis, all fresh isolates from acutely ill patients, were detected with both tests. Ninety-eight faecal specimens from acutely ill patients were tested within 48 h using the probe based SNAP Diagnostic Test Kit (Molecular Biosystems, Inc.). Results were compared with standard culture. The probe test detected 4/6 specimens positive by culture; sensitivity was 66%. However, the two culture positive specimens, undetected by the probe test, had pathogens present at levels well below the probe test sensitivity (10(5) CFU g-1 stool). Specificity of the probe test was 98% (90/92 negative specimens) compared to culture. The results of this study demonstrate the accuracy of enzyme labelled oligonucleotide probes in the identification of C. jejuni isolated on culture and suggest a potential role for such probes in the direct detection of campylobacter in clinical faecal specimens.