ALGORITHM FOR LABORATORY DIAGNOSTICS OF CLOSTRIDIUM DIFFICILE ASSOCIATED DIARRHEA

Aim. To develop an optimal algorithm for laboratory diagnosis of C. difficile associated diarrhea in context of obtaining the most reliable analysis results. Materials and methods. 211 patients with clinically significant C. difficile associated diarrhea participated in the study. Luminal faeces were analysed by immunological (immune chromatographic assay, ICA; ELISA) bacteriological and molecular (GENEexpert rtPCR system, Cepheid, USA) methods. Results. We isolated 126 C. difficile strains from 211 samples of luminal faeces. We identified glutamate dehydrogenase (GDH) in 54% of cases (n=68) by means of immune ICA, and in 11.1% of cases (n=14) by means of ELISA. The increase of bacterial concentration is associated with the growth of sensitivity of GDH detection by immunological tests (p<0.05). We defined a dramatic increase of GDH detection sensitivity starting from 10⁷ CFU/g concentration. Toxins A and B evaluation by immunological tests only leads to false-negative results in 19,8% (ICA) and 55,6% (ELISA) of toxin A positive cases and in 35,7% (ICA) и 44,4% (ELISA) of toxin B positive cases. Conclusion. Three-step diagnostic algorithm for antibiotic-associated diarrhea is characterized by high replicability, sensitivity and specificity. It is based on step-by-step performance of the tests for detection of toxinproducing C. difficile. Application of such approach ensures timely diagnosis, local microbiological monitoring and epidemiological control of C. difficile associated infection.

C. difficile-ассоциированная инфекция, C. difficile associated infection, glutamatedehydrogenase, toxin A, toxin B, binary toxin, antibiotic-associated diarrhea, sensitivity, specificity