Comparative evaluation of the new xTAG GPP multiplex assay in the laboratory diagnosis of acute gastroenteritis. Clinical assessment and potential application from a multicentre Italian study

OBJECTIVE

Gastroenteritis caused by a single pathogen or multiple pathogens remains a major diagnostic challenge for the laboratory. The treatment of diarrhoea is based on microbiological results. Diagnosis is achieved using different laboratory techniques that have variable sensitivity and specificity. xTAG GPP is a new multiplex PCR assay that simultaneously detects 15 different pathogens responsible for diarrhoea. The results of the first multicentre study in Italy to evaluate the potential clinical application of the GPP assay in the laboratory diagnosis of diarrhoea are reported here.

METHODS

Faeces specimens (N=664) from hospitalized patients were tested with the GPP assay using a Luminex 200 instrument. All specimens were run using comparator methods following a routine algorithm: culture for bacteria, enzyme immunoassay and PCR for viruses, and microscopy for parasites.

RESULTS

Of the samples tested with the GPP, 53.61% (356/664) gave positive results, as compared to 45.33% by routine testing. Of the positive specimens, 34.55% showed the presence of genomic DNA from multiple pathogens. The Luminex method showed an increase in the percentage of positivity of 8.28%.

CONCLUSIONS

The GPP assay can be considered a helpful tool for the detection of gastrointestinal pathogens, with a hands-on time of 5h; it provides accurate data for the clinical management of hospitalized patients and for epidemiological surveillance.

Use of the concomitant serum dosage of CA 125, CA 19-9 and interleukin-6 to detect the presence of endometriosis. Results from a series of reproductive age women undergoing laparoscopic surgery for benign gynaecological conditions

BACKGROUND

Recent studies have proposed the measurement of CA 19-9 and IL-6 as an alternative to CA 125 as markers for endometriosis. This study was performed in order to verify the clinical value of serum CA 125, CA 19-9 and IL-6 levels, either by themselves or combined, in the detection of the disease.

METHODS

In a prospective cohort study, serum concentrations of CA 125, CA 19-9 and IL-6 were measured in a consecutive series of 80 women of reproductive age who underwent laparoscopy for benign gynaecological pathologies.

RESULTS

Endometriosis was documented in 45 women (stage I-II in 14 cases and stage III-IV in 31 cases). Patients with endometriosis had significantly higher levels of CA 125 than controls [23.4 IU/ml (13.3-37.6) versus 11.4 IU/ml (9.1-18.5), P < 0.001)]. Conversely, women with and without the disease were shown to have similar levels of both IL-6 pg/ml [0.6 (undetectable-1.4) versus 1.0 pg/ml (0.4-1.9), P = 0.09] and CA 19-9 [9.8 IU/ml (4.5-20.8) versus 7.4 IU/ml (2.8-11.5), P = 0.11]. The area under the receiver operating characteristics curve resulted in a statistically significant difference from the null hypothesis only for CA 125 (P < 0.001). Sensitivity and specificity of CA 125 were 27 and 97% respectively and were higher than those related to CA 19-9 and IL-6. Concomitant use of the three dosages led to a sensitivity and a specificity of 42 and 71% respectively.

CONCLUSIONS

The concomitant dosage of CA 125, CA 19-9 and IL-6 does not add significant information in respect to the CA 125 test alone in diagnosing either early or advanced stages of endometriosis.