Investigation of Various Tissue Culture Monolayers Sensitivity in Detection of Clostridium difficile Toxin

Backround: clostridium difficile is the most common cause of nosocomial diarrhea. it is usually a consequence of antibiotictreatment, but sporadic cases can occur. the purpose of this study was to investigate five tissue culture monolayers sensitivityin detection of c. difficile-toxin.methods: a total of 402 stool samples from patients with nosocomial diarrhea hospitalized in three hospitals of tehranuniversity of medical sciences (tums) were collected. the samples were cultured on a selective cycloserine cefoxitinfructose agar (ccfa) and incubated in anaerobic conditions, at 37 degreec for 4 days. isolates were characterized to species levelby conventional biochemical tests. bacterial cytotoxicity was assayed on five tissue culture monolayers.results: our findings show that of the total patients, 24 toxigenic c. difficile (6%) were isolated. all 24 c. difficile toxinsshowed cytotoxic effect at >/= 1:10 dilution on hela, hep2, vero, mccoy and mdck cells after 16, 20, 24, 24 and 30 hours,respectively. c. difficile toxin showed cytotoxic effect at >/= 1:100 dilutions only on hela cell monolayer after 48 hours.conclusion: hela cell monolayer may be a satisfactory substitute for the detection of c. difficile toxin in clinical specimens.