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.
Unit of Clinical Microbiology, Regional Reference Centre for Microbiological Emergencies, St. Orsola Malpighi University Hospital, Via Massarenti 9, 40138 Bologna, Italy. Electronic address: cate.vocale@gmail.com.
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C
Vocale
Laboratory of Clinical Microbiology, Virology and Bioemergency, "L. Sacco" University Hospital, Milan, Italy.
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SG
Rimoldi
Laboratory of Clinical Microbiology, Virology and Bioemergency, "L. Sacco" University Hospital, Milan, Italy.
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C
Pagani
Laboratory of Clinical Microbiology, Virology and Bioemergency, "L. Sacco" University Hospital, Milan, Italy.
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R
Grande
Unit of Clinical Microbiology, The Hub Laboratory of the Greater Romagna Area, Pievesestina, Cesena, Italy.
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Pedna
Department of Clinical Chemistry and Microbiology, Bacteriology and Virology Units, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy.
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Arghittu
Department of Clinical Chemistry and Microbiology, Bacteriology and Virology Units, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy.
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Lunghi
Department of Clinical Chemistry and Microbiology, Bacteriology and Virology Units, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy.
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A
Maraschini
Laboratory of Clinical Microbiology, Virology and Bioemergency, "L. Sacco" University Hospital, Milan, Italy.
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Gismondo
Unit of Clinical Microbiology, Regional Reference Centre for Microbiological Emergencies, St. Orsola Malpighi University Hospital, Via Massarenti 9, 40138 Bologna, Italy; DIMES, University of Bologna, Bologna, Italy.
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MP
Landini
Department of Clinical Chemistry and Microbiology, Bacteriology and Virology Units, Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Milan, Italy.
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Torresani
Luminex Corporation, Oosterhout NB, Netherlands.
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F
Topin
Unit of Clinical Microbiology, The Hub Laboratory of the Greater Romagna Area, Pievesestina, Cesena, Italy; DIMES, University of Bologna, Bologna, Italy.
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Sambri
D000328:Adult; D000818:Animals; D001419:Bacteria / Q000302:isolation & purification*; D003967:Diarrhea / Q000175:diagnosis* / Q000382:microbiology / Q000469:parasitology; D005243:Feces / Q000382:microbiology / Q000469:parasitology; D005260:Female; D005759:Gastroenteritis / Q000175:diagnosis* / Q000382:microbiology / Q000469:parasitology; D006801:Humans; D007124:Immunoenzyme Techniques; D007558:Italy; D008297:Male; D008875:Middle Aged; D025202:Molecular Diagnostic Techniques; D060885:Multiplex Polymerase Chain Reaction / Q000379:methods*; D010271:Parasites / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D014780:Viruses / Q000302:isolation & purification*
Acute diarrhoea; Gastrointestinal pathogens; Laboratory diagnosis; Molecular assay; Multiplex PCR