Characterization of clarithromycin resistance in Malaysian isolates of Helicobacter pylori.
OBJECTIVE
To characterize the types of mutations present in the 23S rRNA genes of Malaysian isolates of clarithromycin-resistant Helicobacter pylori (H pylori).


METHODS
Clarithromycin susceptibility of H pylori isolates was determined by E test. Analyses for point mutations in the domain V of 23S rRNA genes in clarithromycin-resistant and -sensitive strains were performed by sequence analysis of amplified polymerase chain reaction products. Restriction fragment length polymorphism was performed using BsaI and MboII enzymes to detect restriction sites that correspond to the mutations in the clarithromycin-resistant strains.


RESULTS
Of 187 isolates from 120 patients, four were resistant to clarithromycin, while 183 were sensitive. The MIC of the resistant strains ranged from 1.5 to 24 microg/mL. Two isolates had an A2142G mutation and another two had A2143G mutations. A T2182C mutation was detected in two out of four clarithromycin-resistant isolates and in 13 of 14 clarithromycin-sensitive isolates. Restriction enzyme analyses with BsaI and MboII were able to detect the mutations.


CONCLUSIONS
Clarithromycin resistance is an uncommon occurrence among Malaysian isolates of H pylori strains and the mutations A2142G and A2143G detected were associated with low-level resistance.
Ahmad
Norazah
N
Bacteriology Unit, Institute for Medical Research, Jalan Pahang, Kuala Lumpur, Malaysia. norazah@imr.gov.my
Zakaria
Wan-Rasinah
WR
Abdullah
Sheikh-Anwar
SA
Mohamed
Ramelah
R
D001483:Base Sequence; D001706:Biopsy; D017291:Clarithromycin / Q000494:pharmacology / Q000627:therapeutic use; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D016481:Helicobacter Infections / Q000188:drug therapy*; D016480:Helicobacter pylori / Q000187:drug effects / Q000235:genetics; D006801:Humans; D008296:Malaysia; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009154:Mutation; D012150:Polymorphism, Restriction Fragment Length; D012338:RNA, Ribosomal, 23S / Q000235:genetics*; D017422:Sequence Analysis, DNA
D012338:RNA, Ribosomal, 23S; D017291:Clarithromycin