Background: H. pylori resistance to more than one antibiotic is the main reason for failure in bacterial eradication in a considerable number of patients. Rifabutin (RFB) with a broad spectrum of antimicrobial therapy has been suggested for treatment of refractory multidrug resistant infections.

Methods: H. pylori isolates from 104 patients were examined for resistance to 5 currently used antibiotics and RFB, using agar dilution method. Two-fold serial dilutions of antibiotics were used and MICs (µg/ml) determined as metronidazole (MTZ 8), clarythromycin (CLR 2), amoxicillin (AMX 1), tetracycline (TET 0.5), furazolidone (FRZ 0.5) and RFB (0.06).

Results: Out of 104 H. pylori isolates, only 7 (6.7%) were sensitive to all the 6 antibiotics. However, 30 (28.8%) were resistant to one antibiotic, 28 (26.9%) to two, 19 (18.2%) to three, 14 (13.4%) to four and 6 (5.7%) to five currently used antibiotics. Overall, 67(64.4%) of isolates were resistant to 2-5 currently used antibiotics and considered as multidrug resistant (MDR), with 59 (88.1%) showing sensitivity to RFB and 8 (11.9%) resistance (p<0.05). Out of 33 isolates resistant to both MTZ and CLR, 25(75.7%) were sensitive to RFB and 8 (24.3%) resistant (p<0.05).

Discussion: in vitro antimicrobial effectiveness of RFB on MDR H. pylori including those with resistance to both MTZ and CLR, was demonstrated. However, RFB efficacy decreased as the number of antibiotics responsible for MDR increased. Considering that RFB inhibits both extra- and intra-cellular H. pylori, it can be suggested as an effective antibiotic against of MDR H. pylori.