Rapid detection of Giardia intestinalis and Cryptosporidium spp. in stool samples using an antigen- based detection approach : evaluation of a new commercial immunochromatographic strip test Introduction & purpose Materials & methods Results Acknowledgements We are grateful to CORIS BioConcept for providing the reagents used in this study. Microscopy is the gold standard for routine laboratory diagnosis in faecal parasitology but there is a growing interest for alternative methods to overcome the limitations of microscopic examination, which is time-consuming and dependent on the operator’s skills and expertise [1,2]. In this context, antigen-based detection using rapid detection tests (RDTs) could represent attractive alternatives. Purpose To evaluate a new immunochromatographic strip test (Crypto-Giardia K-SeT ® , Coris BioConcept, Belgium) for the simultaneous detection of both Giardia intestinalis and Cryptosporidium spp. antigens from stool specimens. Evaluation performed using a reference panel of 184 cryopreserved human stool samples [2]: q 134 positive samples (Table 1) q 50 negative samples q Each sample previously determined by a standardized protocol (microscopy+/-PCR) [2] Each sample was tested blindly to the results of microscopy Visual reading performed after 15 min (Figure 1). Discrepancies with microscopy were investigated by specific PCR assays Determination of sensitivity and specificity Correct agreement with microscopy (Table 2). Four false-negative samples. One false-positive (PCR/microscopy negative). This RDT facilitates the detection of G. intestinalis and Cryptosporidium spp. from stool samples, being easy to use and time-saving compared to microscopy (45 min for processing 15 samples). A prospective evaluation of its performances in routine diagnosis is currently undergoing. Table 1: Diversity of the gastrointestinal parasites included in the reference panel (n= 134) Genus/Species N= Giardia intestinalis 37 Cryptosporidium spp. 30 C. parvum/C. hominis 28 C. felis 1 C. meleagridis 1 Other gastrointestinal parasites Entamoeba coli 35 Endolimax nana 20 E. histolytica/E. dispar 16 Entamoeba hartmanni 4 Blastocystis sp. 15 Schistosoma mansoni 4 Iodamoeba bütschlii 3 Cystoisospora belli 2 Hookworms 2 Hymenolepis nana 1 Trichuris trichiura 1 Taenia sp. 1 Dientamoeba fragilis 1 Sarcocystis hominis 1 Chilomastix mesnili 1 Pentatrichomonas intestinalis 1 Enterocytozoon bieneusi 1 Table 2: Antigen detection findings for Giardia intestinalis Conclusions Gardia intestinalis Cryptosporidium spp. Microscopy + - Crypto-Giardia K-SeT® + 33 1 - 4 146 Se= 89.2%, Sp= 99.3% Microscopy + - Crypto-Giardia K-SeT® + 26 0 - 4 154 Se = 86.7%, Sp = 100% Correct agreement with microscopy (Table 3). Four false-negative samples. Both C. meleagridis and C. felis detected (n=2). Each sample was tested blindly. This test appeared time-saving due to a reduced turnaround time. No cross-reactivity with other gastro- intestinal parasites included in the reference panel was observed. Individual results for G. intestinalis and Cryptosporidium spp. are presented below. Table 3: Antigen detection findings for Cryptosporidium spp. Figure 1: The Crypto-Giardia K-SeT diagnostic test (here positive for G. intestinalis) C: Control-band, Cr: Crypto-specific band; Gi: Giardia-specific band 1 Laboratoire de Parasitologie-Mycologie, CHU de Nantes ; 2 Laboratoire de Parasitologie-Mycologie, CHU de Dijon ; 3 Service de Parasitologie-Mycologie-Médecine Tropicale, CHU de Tours; 4 Laboratoire de Parasitologie-Mycologie, AP-HP, Hôpital Bichat, Paris ; 5 Laboratoire de Parasitologie-Mycologie, CHU de Clermont-Ferrand ; 6 Laboratoire de Parasitologie-Mycologie, CHU de Nice ; 7 Laboratoire de Parasitologie-Mycologie, CHU de Nancy ; 8 Laboratoire de Parasitologie-Mycologie, CHU d’Angers ; 9 Laboratoire de Parasitologie-Mycologie, AP-HP Hôpital Henri Mondor, Créteil ; 10 Laboratoire de Parasitologie-Mycologie, CHU de Montpellier ; 11 Laboratoire de Parasitologie-Mycologie, CHU de Poitiers ; 12 Laboratoire de Microbiologie, CH de la Roche-sur-Yon. For more information, please contact: [email protected] GOUDAL A. 1 , LAUDE A., VALOT S. 2 , DESOUBEAUX G. 3 , ARGY N. 4 , NOURRISSON C. 5 , POMARES C. 6 , MACHOUART M. 7 , LE GOVIC Y. 8 , DALLE F. 2 , BOTTEREL F. 9 , BOURGEOIS N. 10 , CATEAU E. 11 , LETERRIER M. 12 , LAVERGNE RA. 1 , LE PAPE P. 1 , MORIO F 1 . References: [1] Becker et al., Clin Microbiol Infect. 2015 Jun;21(6):591.e1-10. [2] Laude et al., Clin Microbiol Infect. 2016 Feb;22(2):190.e1-8.