Primary and secondary resistance of Helicobacter pylori to metronidazole and azithromycin in the northern part of Croatia
Abstract number: 1733_427
Maru[scaron]ic Z., Plecko V., Katicic M., [Zcaron]ele-Starcevic L., Budimir A., Bedenic B., Presecki Stanko A., Bo[scaron]njak Z., Kalenic S.
Objectives: The aim of this study was to assess primary and secondary antibiotic resistance rates in Helicobacter pylori isolates over a period of three and a half years (20032005 and the first 6 months of 2006).
Methods: A total of 378 H. pylori from 347 patients were isolated from 1211 gastric biopsies taken from patients visiting CHC Zagreb and CHC Merkur in Zagreb, Croatia. Isolates from January 1st 2003 to July 1st 2006 were included in the study. From each patient 4 gastric biopsies were taken for histology and 2 were sent to the Department for Clinical and Molecular Microbiology CHC Zagreb for culture and determination of antibiotic activity against H. pylori by means of agar dilution. Susceptibility to clarithromycin, azithromycin, metronidazole, tetracycline and amoxicillin was determined. Primary resistance was assessed in H. pylori strains isolated before the first eradication therapy. Secondary resistance was assessed in H. pylori strains repeatedly isolated after treatment failure.
Results: Resistance of H. pylori to amoxicillin and tetracycline was not detected. Clarithromycin and azithromycin showed a common resistance pattern in all tested isolates. Among the 342 pre-therapy isolates, 124 (36.25%) were susceptible to all antibiotics tested. Primary resistance to macrolids was detected in 167 (48.83%) strains and 192 (56.14%) strains were resistant to metronidazole. The mean dual resistance rate (resistance to both macrolids and metronidazole) was 37.72% (129/342). Among the 36 isolates cultured after unsuccessful therapy, only 1 was susceptible to all antibiotics tested (2.78%), 2 (5.56%) were resistant only to macrolids and 5 (13.89%) were resistant only to metronidazole. The dual resistance rate was 77.78% (28/36). Among the macrolid resistant strains, therapy-induced resistance was determined in 30.0% (9/30), while the rest (21/30) was attributed to primary resistance. Therapy-induced resistance was determined in 21% (7/33) of the metronidazole resistant strains.
Conclusions: The resistance rates to metronidazole and macrolids and dual resistance rates are high among H. pylori in northern Croatia. There are increased rates of resistance to macrolids and metronidazole among post-therapy isolates which can mainly be attributed to pre-existing primary resistance and in part to therapy-induced resistance.
|Session name:||European Society of Clinical Microbiology and Infectious Diseases|
|Location:||ICC, Munich, Germany|
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