Immunomagnetic separation of Salmonella from foods and their detection using immunomagnetic particle (IMP)-ELISA.

An immunomagnetic particle based ELISA (IMP-ELISA) for the detection of Salmonella from foods has been developed using Dynabeads anti-Salmonella (Dynal, Oslo, Norway). Appropriate sample preparation protocols to allow rapid detection of Salmonella serovariants in processed (powdered egg products) and non-processed (raw chicken) samples have been established. Pre-enriched broths of heat processed samples likely to harbour only low levels of competitive enteric flora, were boiled and used directly for IMP-ELISA. For non-heat processed or raw samples likely to contain higher numbers of such competing organisms, live Salmonella cells were first isolated by immunomagnetic separation (IMS) from standard pre-enrichment broths, and then post-selectively enriched for a short time in M-broth followed by boiling before IMP-ELISA. The total assay time including sample preparation was under 26 h for both types of procedure, with a lower detection limit of 10(5) Salmonella cells/ml of sample. In an evaluation of naturally contaminated poultry samples, all 45 of 48 samples previously shown to contain salmonellae in a comparison of ISO, IMS-Plating, Salmonella-Tek ELISA (Organon Teknika, Inc. Durham, NC) and a modification of the latter based on IMS, were identified as positive. None of the other methods gave positives for all 45.

Addition of 2.5% lactate and 0.25% acetate controls growth of Listeria monocytogenes in vacuum-packed, sensory-acceptable servelat sausage and cooked ham stored at 4 degrees C.

A study of the inhibitory effects of propylparaben and of a combination of lactate and acetate against growth of Listeria monocytogenes in inoculated liquid medium, sliced servelat sausage and cooked ham, were performed using rifampicin resistant Listeria strains in inoculation experiments. A consumer acceptance test of products produced with and without the compounds was also performed. Propylparaben was found to be effective in a model liquid non-fat medium, but was without effect in the actual products. This illustrates the potential pitfalls in translating results from studies in liquid media to fat-containing food products. The combined inhibitory and sensory results showed that a mixture of 2.5% lactate and 0.25% acetate (w/w, calculated on the water phase), could be used to increase the margins of safety for sliced and spreadable vacuum-packed ready-to-eat cooked meat products stored for 4-6 weeks. In addition, strict control of temperature during production and storage is very important.

Computed tomography enhancement characteristics of lymphomatous lymph nodes of the neck.

OBJECTIVES: The objective of this study was to investigate prospectively CT contrast medium enhancement curves of lymphomatous lymph nodes of the neck. MATERIALS AND METHODS: Eleven patients with biopsy-proven lymphoma had their enlarged cervical lymph nodes examined with dynamic CT and compared with a control group. RESULTS: The mean contrast medium enhancement of the lymphomatous nodes was significantly lower than that of the control group in the time interval from 40 s to 180 s after injection. DISCUSSION: The enhancement pattern previously suggested from studies of retroperitoneal lymph nodes was confirmed in this prospective study of cervical nodes.

A new low-dose CT examination compared with standard-dose CT in the diagnosis of acute sinusitis.

A low-dose CT of the paranasal sinuses was designed with few, thin sections, non-uniform intersection gaps, low milliampere settings and avoidance of direct radiation to the eye lens. The low-dose CT was prospectively compared with standard-dose CT in patients with suspicion of acute sinusitis. Forty-seven patients were examined with low-dose CT immediately after standard-dose CT. The effective dose and the lens dose were calculated and compared. Using standard-dose CT as a gold standard the sensitivity and specificity of low-dose CT was calculated for each sinus group. The effective dose and the lens dose of the low-dose CT were reduced to, respectively, 3 and 2% of the standard-dose CT. The diagnostic yield of the low-dose CT with regard to acute sinusitis was good with a high specificity (> or =96%) for all sinus groups. The sensitivity was also high (> or =95%) except for the frontal sinus where the sensitivity was 83%. Low-dose CT offers considerable dose reduction and should be the standard for imaging patients with suspected acute inflammatory paranasal disease.

Conventional sinus radiography compared with CT in the diagnosis of acute sinusitis.

OBJECTIVES: To evaluate the value of plain film radiography in a prospective investigation of patients with clinical suspicion of acute sinusitis, using standard CT as a gold standard. METHODS: 47 consecutive patients were examined. Each patient underwent conventional X-ray and standard dose CT examinations on the same day. The sensitivity and specificity of the plain film examination were calculated. RESULTS: The specificity of the plain film examination was high, but the sensitivity was low except for the maxillary sinus (sensitivity 80%). Thus, for maxillary sinusitis, plain film examination was reasonably accurate. A negative finding in the other sinuses could not be relied upon. CONCLUSIONS: The sensitivity of plain film radiography for detecting sinus opacifications was unacceptably low for the ethmoid, frontal and sphenoid sinuses. The specificity was high.