DNA typing for Helicobacter pylori isolates from eradication-failed patients: comparison of the isolates before and after therapy.
BACKGROUND
Failure of Helicobacter pylori eradication occurs frequently despite use of multiple microbial agents.


OBJECTIVE
We aimed to study differences between H. pylori strains isolated before and after eradication failure.


METHODS
We treated 87 patients with peptic ulcer using triple therapy consisting of omeprazole plus combinations of clarithromycin, amoxicillin, or metronidazole. We studied the status of cagA, vacA, and iceA by PCR, and examined the differences in H. pylori isolates by pulsed-field gel electrophoresis and arbitrary primer polymerase chain reaction. The minimum inhibitory concentration of clarithromycin, amoxicillin, or metronidazole was determined by an agar dilution method.


RESULTS
Eradication therapy failed in 12 patients (14%); H. pylori isolates were obtained from all of these both before and after therapy. After eradication therapy, 10 patients were colonized with the same strain as before therapy, while the other two patients were colonized with different strains from those before therapy. In the former group, one isolate changed from metronidazole-sensitive to -resistant, one changed from clarithromycin- and metronidazole-sensitive to -resistant, and four were resistant to clarithromycin or metronidazole both before and after therapy. The other four isolates remained sensitive to clarithromycin and metronidazole after therapy. In the two patients who yielded apparently different isolates after therapy, they changed from clarithromycin- and metronidazole-sensitive to -resistant.


CONCLUSIONS
Eradication of H. pylori by first-line therapy is an important goal in the treatment of H. pylori-positive peptic ulcer, and that appropriate antimicrobial sensitivity testing should be conducted in patients with eradication failure.
Department of Clinical Laboratory, Nagoya University Hospital, Nagoya, Japan.
T
T
Nada
T
T
Ando
K
K
Nobata
T
T
Tsuzuki
M
M
Minami
K
K
Ina
Y
Y
Iinuma
S
S
Ichiyama
M
M
Ohta
E
E
El-Omar
K
K
Kusugami
H
H
Goto
D000328:Adult; D000658:Amoxicillin / Q000627:therapeutic use; D000897:Anti-Ulcer Agents / Q000627:therapeutic use; D000942:Antigens, Bacterial / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D017291:Clarithromycin / Q000627:therapeutic use; D016172:DNA Fingerprinting / Q000379:methods; D004269:DNA, Bacterial / Q000032:analysis; D004359:Drug Therapy, Combination / Q000627:therapeutic use; D016521:Electrophoresis, Gel, Pulsed-Field / Q000379:methods; D005260:Female; D016481:Helicobacter Infections / Q000188:drug therapy / Q000235:genetics*; D016480:Helicobacter pylori / Q000235:genetics*; D006801:Humans; D008297:Male; D008795:Metronidazole / Q000627:therapeutic use; D008875:Middle Aged; D009853:Omeprazole / Q000627:therapeutic use; D016133:Polymerase Chain Reaction / Q000379:methods; D016896:Treatment Outcome
D000897:Anti-Ulcer Agents; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D004269:DNA, Bacterial; C074689:VacA protein, Helicobacter pylori; C080866:cagA protein, Helicobacter pylori; D008795:Metronidazole; D000658:Amoxicillin; D017291:Clarithromycin; D009853:Omeprazole