H pylori selective supplement dent

Gradient diffusion test (E‐test) (AB Biodisk, Solna, Sweden) was used to assess clarithromycin susceptibility in isolated H. pylori strains. The bacterial inoculum was prepared in Brucella Broth (BBL) from subcultures grown on Columbia Blood Agar (Oxoid) containing 7% (vol/vol) defibrinated horse blood (Oxoid) and H. pylori selective supplement (DENT) (Oxoid). The Mueller‐Hinton agar (Oxoid) supplemented with 5% (vol/vol) defibrinated sheep blood (Oxoid) was used to inoculate 100 µl of H.pylori culture suspension of a McFarland standard 3 (∼10⁹ CFU/ml) turbidity in Brucella broth (BBL). Plates with clarithromycin E‐test strips were incubated at 37 °C in a jar including the GasPak Campy Container System (BD) under microaerophilic conditions for 72 h. The minimum inhibitory concentration (MIC) was considered the lowest concentration of the drug that inhibited visible growth of H. pylori. Isolates were defined as clarithromycin resistant when the MIC was ≥1 µg/ml, susceptible when MIC was <0.5 µg/ml, and intermediate when MIC was 0.5–1 µg/ml according to Clinical Laboratory Standard Institutes (CLSI) recommendation 42. However, these breakpoints were defined only for the agar dilution method and they have not yet been established for the E‐test. A plate without antibiotic strip was used to confirm the purity of the culture and the lack of contamination.